ATSB Transport Safety Report: Aviation Occurrence Investigation (Systemic) AO-2022-009

conducting the operation with a piston helicopter increased the overall risk of the activity compared with use of a turbine helicopter, previous accident data showed fuel exhaustion was as likely to occur in a piston as it was in a turbine engine helicopter. Although not likely to result in sudden power loss, engine defects present at the time of the accident likely affected the engine’s maximum power output and fuel consumption. Additionally, Helibrook had likely overrun the helicopter's maintenance, inspection and overhaul periods, which increased the likelihood of the helicopter experiencing a technical failure or malfunction. The ATSB also found that the pilot’s exposure to cocaine within the previous few days increased the likelihood of fatigue, depression and inattention, however there was insufficient evidence to determine whether these effects occurred. Finally, the ATSB found that the helicopter's emergency locator transmitter had been removed from its mount prior to the accident. Therefore, it could not activate automatically, which likely delayed the emergency response. What has been done as a result CASA implemented significant changes to its internal processes to ensure that the assessment and management of safety risks of new aviation activities (and associated approvals) were standardised in accordance with the CASA Risk Management Manual and that decision-making was appropriately documented. Additionally, CASA developed an ‘exemption protocol suite’ of documents, which detailed the principles, protocols and work instructions for CASA’s regulatory exemption process. CASA also completed and provided exemplar bowtie and aviation safety risk assessments using the structured process. Following this accident, Helibrook advised that it had ceased operation and the helicopter fleet was being sold. In addition, the chief executive officer/chief pilot was no longer involved with the operation. CASA confirmed that as Helibrook no longer had the required key personnel, it was considered to be suspended from operation. Under those circumstances, the operator’s safety management system was no longer in use. Safety message The contributing factors to this fatal accident highlight the significant influence that the actions and decisions of pilots, operators and the regulator can all have on aviation safety. Fundamentally, this occurrence illustrates the importance of effective fuel management. It is vital to use all available means, including accurate fuel records and quantity cross-checks, to ensure that pilots accurately know their aircraft’s fuel state. This is especially critical when operating a helicopter where a fuel-related power loss offers few safe options, such as inside the height- velocity avoid area with a vulnerable human external load. Pilots also should understand the functionality and limitations of any installed low fuel warning systems. At the operator and regulatory level, effective safety management processes that identify and safely manage hazards are vital to preventing future accidents. › v ‹ Contents Executive summary................................................................................................................iii The occurrence ........................................................................................................................9 Context ................................................................................................................................... 13 Personnel information 13 Pilot information 13 Egg collector information 15 Wild Harvest Northern Territory annual requirements 15 Aircraft information 15 General history 15 Maintenance release 16 Recent maintenance 17 Recorded hours and other observations 17 Fuel capacity, calibration and indications 18 Manifold pressure limits 20 Hydraulic flight control assistance 20 Inadvertent engine stoppage 21 Skids 21 Emergency locator transmitter 21 Pannier 21 Dual hook system 21 Meteorological information 22 Recorded data 23 Mobile devices 23 In-flight photo 23 Crocodile nest data 24 OzRunways data 26 Communications 27 Accident site assessment 27 Helicopter examination 31 Hook system 31 Drivetrain 31 Main rotor 31 Control continuity 32 Engine RPM governor 32 Hydraulics 33 Emergency locator transmitter 33 Warning and caution lights 33 Electrical system 33 Hour meter 33 Indications of engine rotation at impact 33 Powerplant 34 Fuel system examination 37 Fuel considerations 43 Fuel uplift 43 Fuel testing and analysis 46 Fuel jerry cans 47 Fuel flow 47 Operational information 48 Loading and performance 48 Autorotation 49 Height-velocity diagram 50 Rotorcraft flight manual supplement 51 › vi ‹ Comparison emergency procedures 53 Operator information 54 Helibrook 54 Head of aircraft airworthiness and maintenance control 54 Chief pilot 55 Safety manager 56 Safety management system 56 Helibrook operations manual 60 Emergency procedures for crocodile egg harvesting 61 R44 human external cargo operations 63 Requirements for human external cargo operations 63 CASA authorisation 63 Key safety considerations 63 Certification of dual hooks for HEC 64 Instrument conditions 66 Delegate guidance material 69 Safety assessment 70 Human external cargo rotorcraft load combination decision 70 Risk management plan 71 Intent to amend approval conditions from 2014 73 Response to the proposed changes 73 Proposal to discontinue CAO amendments 74 Transitional regulations 74 Briefing note July 2021 75 Helibrook’s 2021 instrument 75 Engine failure probability analysis 77 US data 77 Australian data 77 At risk time 77 Exceeded maintenance intervals 78 Previous occurrences 78 HEC accident 78 Fuel exhaustion occurrences 78 Survivability 80 Post-mortem report 80 Height of fall 80 Freefall orientation 80 Injury assessment 81 Egg collector helmet 81 Pilot restraint and helmet 81 Pilot seat 81 Cocaine metabolites 81 Safety analysis ...................................................................................................................... 83 Introduction 83 Fuel uplift 83 Detection of low fuel state 85 In-flight event assessment 86 Reason for engine stoppage 87 Pilot action 87 Aircraft, engine and fuel system examinations 87 Fuel exhaustion 88 Release of sling person and helicopter terrain impact 88 Helibrook safety management 89 The Civil Aviation Safety Authority’s approval process 90 Approval process 90 Influence on human external cargo risks 91 › vii ‹ Continued unmitigated operational risk 91 Engine defects 92 Helicopter hours overrun 92 Cocaine metabolites 93 Emergency locator transmitter 93 Findings ................................................................................................................................. 94 Contributing factors 94 Other factors that increased risk 94 Safety issues and actions ................................................................................................... 96 General details ...................................................................................................................... 98 Glossary ................................................................................................................................. 99 Sources and submissions ................................................................................................ 101 Appendices ..............................................................................................................................1 Appendix A – Fuel analysis 1 Appendix B – CASA operational group risk matrix (2013) 1 Appendix C – HEC height, speed and distance/time conditions 2010–2021 1 Appendix D – Instrument conditions 1 Australian Transport Safety Bureau .....................................................................................4 ATSB – AO-2022-009 › 8 ‹ The ATSB referred matters concerning possible offences under the Transport Safety Investigation Act 2003 relating to the status of evidence available to the ATSB for the purposes of its 'no-blame' safety investigation to the Australian Federal Police for investigation. The referral did not concern the circumstances of the accident itself. The Australian Federal Police referred the matters to the Northern Territory Police as part of its broader investigations. ATSB – AO-2022-009 › 9 ‹ The occurrence On 28 February 2022, the crews of 3 Robinson R44 helicopters were preparing to conduct crocodile egg collection in Arnhem Land, Northern Territory. Each helicopter was operated by a different aircraft operator, contracted to Wild Harvest Northern Territory, and crewed by a pilot and an egg collector. One of the helicopters was an R44 Raven II, registered VH-IDW, operated by Helibrook. The method of egg collection included slinging the collector underneath the helicopter, in a harness attached to a 100 ft ‘long line’ (see the section titled R44 human external cargo operations).1 The pilot of VH-IDW reported that they arrived at Helibrook’s hangar at Noonamah, on the outskirts of Darwin, Northern Territory at about 0530 local time, conducted the daily inspection of the helicopter and found no defects. The other 2 R44 helicopters involved in the egg collection on the accident day arrived at Noonamah at about 0645. Their crews reported briefing together with the VH-IDW crew. The briefing involved discussing the day’s plan, including who was collecting from which nests, and where they would meet to refuel. The plan was to refuel at Mount Borradaile en route to King River, then collect eggs from about 15 nests located between King River and Maningrida, which was 90 km beyond King River (Figure 1). The crews then planned to refuel at Maningrida, before continuing south-east to collect additional eggs. At about 0703, the 3 helicopters departed Noonamah for Mount Borradaile, 205 km east-north- east, where fuel drums had been pre-positioned. At 0743, having travelled 111 km from Noonamah, a photo was taken in the cockpit of VH-IDW. The image showed the accident pilot as the passenger, seated in the left front seat, and the egg collector piloting the helicopter from the right seat. Based on the time taken to reach that point, the helicopter probably arrived at Mount Borradaile at about 0816. Figure 1: Map showing key locations and times Source: Google Earth with OzRunways data, annotated by the ATSB 1 Long lines are lightweight, high-strength, low-stretch ropes used for carrying loads underneath a helicopter. ATSB – AO-2022-009 › 10 ‹ The 3 R44 helicopters landed at Mount Borradaile for the planned refuelling, where the crews intended to ‘hot refuel’2 each helicopter from fuel drums. A witness reported that the 3 R44 helicopters departed Mount Borradaile at about 0830 to track towards King River. One helicopter continued past King River to the north-east and commenced collecting eggs. OzRunways3 data for the other 2 helicopters, including VH-IDW, recorded their arrival near King River at 0850. At a clearing near King River, 60 km beyond Mount Borradaile, the second helicopter’s crew retrieved a harness from VH-IDW. Two witnesses reported that the accident pilot was in the left passenger seat and the egg collector was in the pilot seat and flew VH-IDW to King River, where the dual controls were removed. However, the accident pilot and one other egg collector reported that the dual controls had been removed at Mount Borradaile and the pilot had swapped to the pilot seat and flown VH-IDW from Mount Borradaile to King River. While VH-IDW was still on the ground, the second helicopter departed to commence collecting eggs about 12 km to the north- east. Data recorded from an egg collection application showed that the crew of the 2 helicopters, other than VH-IDW, conducted operations from 9 nests (Figure 2) between 0911 and 1014. Figure 2: Accident area including King River, accident site and nests Source: Google earth overlaid with nest collection data, annotated by the ATSB At 1024, the pilot of one of those helicopters became concerned that they had not heard any radio communications from the crew of VH-IDW since they commenced egg collection operations and were unable to contact them. As a result, the pilot elected to return to the area where they expected VH-IDW to be operating. The pilot travelled in the reverse direction past the 3 planned nests assigned to the crew of VH-IDW (Figure 12). At 1036, they located the accident site closest to the first planned nest and landed nearby. They found the sling person (egg collector) fatally injured. VH-IDW was located 44 m beyond the sling person, substantially damaged having collided with trees and terrain (Figure 3). The accident pilot had sustained serious injuries and was found lying beside the helicopter. After providing reassurance to the pilot of VH-IDW, the other pilot returned to their helicopter and briefly became 2 Refuelling conducted while the engine(s) are operating and the rotors are turning. 3 OzRunways is an electronic flight bag application that provides navigation, weather, area briefings and other flight information. It provides the option for live flight tracking by transmitting the device’s position and altitude. ATSB – AO-2022-009 › 11 ‹ airborne to get mobile reception and call for assistance. The first call to emergency services was received at 1046. Figure 3: VH-IDW accident site Source: CareFlight The second helicopter and remaining crew arrived at the site about 1 hour later. They found spare egg collection equipment from VH-IDW in the clearing where VH-IDW was last seen before the accident. The accident site was between the clearing and the closest of 3 nests that were to be collected by VH-IDW’s crew. No eggs had been collected. Based on photos and reports from those who attended the site on the accident day, the egg collector’s bucket and pole were the first items in the accident trail (Figure 4). The pole was vertical with one end embedded in the ground. About 4 m beyond the pole, the long line attachment rings were found, also embedded in wet ground, with the long line loosely coiled over about 8 m. The egg collector was found wearing a harness, which was intact, firmly secured and attached to the long line, and their helmet was on the ground nearby. The long line was not connected to the helicopter. ATSB – AO-2022-009 › 12 ‹ Figure 4: Accident trail Source: Apple Maps annotated by the ATSB Following notification of the accident, a CareFlight rescue helicopter departed Darwin at 1122, arrived at the accident site at 1232, and departed with the injured pilot at 1310. As they departed the site, another Helibrook R44 helicopter arrived with Helibrook’s chief pilot, a Wild Harvest Northern Territory representative and an off-duty Northern Territory Police Force officer. A CareFlight nurse remained at the site until the rescue helicopter returned at 1532 to retrieve the deceased egg collector, departing about 20 minutes later. The crews of the other 3 helicopters reported departing about 20 minutes after the rescue helicopter. ATSB – AO-2022-009 › 13 ‹ Context Personnel information Pilot information Qualifications and experience The pilot held a commercial pilot licence (helicopter) with low-level and sling ratings. At the time of the accident, the pilot had recorded about 2,500 hours total aeronautical experience. The pilot’s most recent flight review was on 21 May 2021. The pilot had recorded 340.1 hours of sling experience, the most recent of which was gained in May 2021. The pilot had been contracting to Helibrook for 8–9 years, including for crocodile egg collection. In addition, the pilot operated their own R44 helicopters and contracted to other operators. According to the pilot’s logbook, they had first conducted slinging of human external cargo (HEC) for crocodile egg collection on 13 December 2017. Their last recorded HEC sling time was in March 2020, but the pilot reported having also conducted human slinging for egg collection in the wet season from December to May of 2020–2021 and 2021–2022. Documents provided by the operator indicated that the pilot had completed a proficiency check flight with the Helibrook chief pilot on 3 August 2021 in the pilot’s R44 II helicopter, which was not fitted with dual hooks. The pilot had recorded a flight time of 0.8 hours in their logbook with no reference to conducting sling operations, whereas the Helibrook Rotary Pilot Competency Check form stated the flight time as 1.1 hours. According to the form, the pilot had demonstrated competency in pre-flight tasks, normal and emergency procedures and the following specialised tasks: • search and rescue • charter • sling operations • croc egg harvesting • aerial advertising – banner towing • supply dropping • surveillance • hover exit entry. The pilot was also a licenced aircraft maintenance engineer and the head of aircraft airworthiness and maintenance control (HAAMC) for Helibrook. Medical and toxicology The pilot held a class 1 aviation medical certificate with no restrictions, valid to 27 May 2022. A blood sample was taken from the pilot at 1638 on the accident day, 11 minutes after the pilot’s arrival at Royal Darwin Hospital. Toxicology results from the sample identified several substances administered by CareFlight and Royal Darwin Hospital medical staff. Additionally, the results detected 2 metabolites of cocaine – ecgonine methyl ester and benzoylecgonine – at low levels (less than 0.01 mg/L). These results were identified using mass spectrometry and considered to be reliable indications of previous cocaine exposure. These metabolites can be detected in the blood up to 3–4 days after exposure (see the section titled Cocaine metabolites). Cocaine itself is generally detectable in blood tests for up to 1–2 days after exposure and was not detected in the pilot’s blood. ATSB – AO-2022-009 › 14 ‹ The pilot had no reported medical conditions and in the self-disclosure section of their aviation medical application, they had advised not using any drugs or recreational substances within the last 5 years. The pilot also advised the ATSB that they did not use cocaine. Anticonvulsant medication levetiracetam was also identified in the pilot’s toxicology results. There was no evidence of this having been administered by CareFlight or Royal Darwin Hospital medical personnel, although it was consistent with emergency treatment for the pilot's injuries. There was also no evidence obtained to indicate that the pilot had recently visited a doctor, had a condition requiring the medication, or obtained a prescription for it. A pharmacological expert advised the ATSB that even if it had been present before the accident, it was one of the least likely anticonvulsant drugs to interfere with cognitive process as there was evidence of its widespread positive effects on cognition. It was also less likely to produce ataxia4 and dizziness than other antiepileptic drugs. Recent history The pilot reported having limited recollection of events leading up to, and including, the accident sequence. Despite that, the ATSB was able to identify the following activity in the days leading up to the accident. On 24 February 2022, the pilot was operating a Robinson R22 helicopter (not associated with Helibrook) to locate crocodile nests, when an engine valve failed, requiring the pilot to conduct a forced landing. The pilot reported feeling ‘pretty rattled’ by it. The next day, after repairs were conducted on the R22, its engine again lost power during take- off. Additionally, the day’s egg collection activities were suspended due to rain and the pilot’s partner reported that they spent a quiet evening at home together. On 26 February, the pilot was involved in crocodile egg collection activities, which were again suspended due to rain. The pilot consumed alcohol that evening and reportedly attended a party, returning home between 0100 and 0200 the following morning. The pilot left again before their partner awoke between 1000 and 1100 on 27 February. Rideshare records from the pilot’s phone indicated that a car was used between 0243 and 0306, and again at 1040, with no end time recorded. Information obtained from the pilot’s phone showed that later that day, the pilot started operating VH-IDW at 1545 and conducted crocodile egg collection about 60 km south-west of Darwin, until 1810. This was consistent with information subsequently provided by the helicopter operator. The pilot’s partner reported that the pilot went to bed at about 2130 that evening and left for work at about 0445 on the accident morning. The ATSB considered whether the pilot’s activity in the preceding days may have led to them being fatigued at the time of the accident. Specific factors that potentially increased fatigue risk included: • the pilot likely experienced a high level of stress following 2 engine power losses, leading to an unscheduled overnight stay at accommodation away from the pilot’s home • the pilot’s usual sleep pattern was significantly disrupted on one night, getting to sleep around 6 hours after the usual reported sleep time • over the previous 4 nights, the pilot slept in 3 different locations, which had the potential to affect sleep quality 4 Loss of coordination of the muscles, especially of the extremities (Macquarie Dictionary). ATSB – AO-2022-009 › 15 ‹ • the pilot only had 6–7 hours sleep opportunity on each of the 2 nights before the accident, meaning that the pilot was probably carrying some level of sleep debt at the time of the accident • on the day of the accident the pilot awoke during the window of circadian low, which also has the potential to affect the pilot’s sleep debt • consumption of alcohol or exposure to recreational drugs is known to reduce sleep quality • hot, humid weather conditions, such as those in the Northern Territory in February, are associated with reduced sleep quality and quantity. While a number of these factors could combine to increase likelihood, there was insufficient evidence to establish if the pilot was likely experiencing a level of fatigue known to affect performance at the time of the accident. In a statement provided to the ATSB in response to the draft report, the pilot reported that they were not tired or affected by alcohol or drugs on commencing the operation of the helicopter. Egg collector information At the time of the accident, the egg collector had passed their private pilot licence (helicopter) flight test but not yet been issued that licence. Wild Harvest Northern Territory annual requirements Wild Harvest Northern Territory (WHNT) held a suite of documents for crocodile egg collection, which included safe work method statements5 and procedures. WHNT engaged multiple helicopter operators each season to undertake crocodile egg collection. At the start of each egg collection season, those intending to conduct egg collection, including pilots and collectors, attended a WHNT ground-based training and administration day. Both the accident pilot and the egg collector attended this training on 1 December 2021, and had signed safe work method statement sign-on sheets for: • ground operations for croc egg collecting, including: equipment checks personal protective equipment safety around helicopters firearm safety selecting and collecting nests • human sling operations (see the section titled Operator risk assessment) • safe handling of fuel. Aircraft information General history VH-IDW was a 4-seat Robinson Helicopter Company (Robinson) R44 Raven II (R44 II) helicopter, certified in accordance with United States (US) Federal Aviation Regulations (FAR) Part 27 and manufactured in the US in 2008. The helicopter was first registered in Australia in July 2008 and had a standard certificate of airworthiness and was to be operated in the normal category.6 The helicopter was powered by a 6-cylinder Textron Lycoming IO-540-AE1A5 engine derated to 205 brake horsepower (BHP) with a maximum 5-minute take-off power of 245 BHP. 5 Safe work method statement (SWMS): a document that sets out high risk activities, the hazards associated with the activities and measures required to be in place to control the risks to an acceptable level. 6 Normal category rotorcraft have a maximum take-off weight (MTOW) up to 3,175 kg and up to 9 passenger seats. ATSB – AO-2022-009 › 16 ‹ In December 2009, at 62.2 total hours in service, the helicopter was involved in a dynamic rollover that resulted in sudden stoppage/damage to the main/tail rotor and the engine. The aircraft was returned to Robinson for overhaul, including the engine. The hour meter was reset to zero, and the helicopter was returned to service in May 2012. Helibrook commenced operating VH-IDW on 15 October 2020 and, as the registered operator, was responsible for the continuing airworthiness of the helicopter. VH-IDW was to be maintained in accordance with the airframe and engine manufacturers’ maintenance schedule, which required a periodic inspection every 100 hours or 12 months, whichever occurred sooner. The engine and airframe were subject to overhaul at 2,200 hours or 12 years, whichever occurred first. Additionally, any instructions for continued airworthiness on approved modifications, such as cargo hooks, were to be complied with. The helicopter was fitted with an hour meter activated by a combination of oil pressure and an electrical switch on the collective.7 The hour meter was an acceptable means of recording time in service, however it could be disconnected, which would prevent flight hours being recorded. On 22 October 2020, shortly after the helicopter was purchased by Helibrook, a 100-hourly inspection was carried out on VH-IDW, at which time the helicopter’s total time in service, recorded in the maintenance records was 1,577.9 hours and the hour meter read 1515.75. The maintainer reported that in November 2021, the hour meter was rolled forward 62.2 hours to match the helicopter’s total time in service for ease of record-keeping. At the accident site, the helicopter hour meter read 2,070.05 hours, which equated to 2,007.85 hours since overhaul. Maintenance release A maintenance release is required to be carried on an aircraft as an ongoing record of the aircraft’s time-in-service and airworthiness status. Subject to conditions, a maintenance release is valid for a set period, nominally 100 hours in service or 12 months from issue. A daily inspection was required to be carried out and the maintenance release signed to show the inspection had been completed, prior to the first flight of the day. The inspection and certification could be made by any pilot licenced to fly the aircraft, or an appropriately licenced aircraft maintenance engineer. After the last flight of the day and before the aircraft was next flown, the total daily flight time was required to be entered and the progressive total time in service recorded. VH-IDW’s maintenance release, current at the time of the accident, was provided to the ATSB on 3 March 2022. It had been issued on 7 February 2022, with 2,036.3 hours total time in service recorded. The accident pilot’s signature was on the maintenance release for 8, 9 and 10 February, with 7.6, 4.3 and 1.5 hours recorded respectively. The accident pilot’s signature was on the maintenance release for the accident day. The pilot initially reported having conducted the daily inspection of VH-IDW on the morning of the accident, found no defects and signed the maintenance release. However, the pilot subsequently reported being unsure when they had signed the maintenance release for the accident day’s flight. No defects had been recorded on part 2 of the maintenance release. Additionally, there were no entries on part 2 of the maintenance releases from when the fuel calibration was certified on 1 May 2020 to the accident day to indicate any issue with the fuel calibration, calibration card or fuel quantity indication. 7 Collective: a primary helicopter flight control that simultaneously affects the pitch of all blades of a lifting rotor. Collective input is the main control for vertical velocity. ATSB – AO-2022-009 › 17 ‹ Recent maintenance On 15 January 2022, due to a pilot reporting that the engine was ‘low on power’, the maintainer adjusted the magneto engine timing and renewed the spark plugs. On 7 February 2022, the maintenance organisation completed a periodic inspection of VH-IDW. During that inspection, the No. 6 cylinder was replaced due to failed compression, however, there was no documentation supporting that a post-replacement compression check had been conducted. Other maintenance items completed at that time included replacement of the engine- driven fuel pump and the tail rotor assembly. On 11 February 2022, with 2,050.09 hours recorded in the engine logbook, a Helibrook pilot had reported an ‘intermittent miss in flight’ to the maintainer. The maintainer identified that the left magneto had a failed drive bearing and replaced it with an overhauled magneto. The right magneto timing was also adjusted. The worksheet stated ‘compression test ok’ but no figures were recorded. The maintainer reported checking compression during troubleshooting for the intermittent miss but did not record the figures as they were satisfactory. The maintainer then recorded conducting a post-maintenance flight of 0.8 hours with no issues identified. Recorded hours and other observations The pilot’s logbook did not contain any entries relating to the operation of VH-IDW, and the pilot’s last logbook entry was in their own helicopter on 12 February 2022. Additionally, and despite the pilot reporting conducting egg collecting using VH-IDW in previous seasons, the earlier VH-IDW maintenance releases covering the previous egg collection season did not contain any entries by the accident pilot. However, this did not preclude the pilot having flown VH-IDW after another person conducted the daily inspection and signed the maintenance release. The pilot reported that VH-IDW had flown significantly more hours than were recorded and that the hour meter was never operating when they flew it, although they could not recall whether the hour meter was operating on the accident morning. The pilot estimated that they had flown VH-IDW for about 70 hours in the 2021–22 crocodile egg collection season and had also flown it during 2020–21. The ATSB obtained invoices that indicated the pilot had conducted over 36 full days of egg collection in 2020–21 and 2021–22 seasons, all of which were reported to have been in VH-IDW. Due to the apparent discrepancy in operating hours, the ATSB compared the hours recorded on VH-IDW’s maintenance releases from November 2020 to the accident day with: • the pilot’s time (in units of days/half days) invoiced for crocodile egg collection • spreadsheets recording hours for helicopters (by operator and helicopter type) and day/half-day rates for personnel involved in crocodile egg collection • the pilot’s phone records of start and stop times for VH-IDW • recorded egg collection data (see the section titled Crocodile nest data) • fuel uplift records • evidence of VH-IDW being operated for a purpose other than egg collecting. There were 21 days identified when VH-IDW was operating and there was no entry on the maintenance release, some of which were recorded as 10 to 11 hours of helicopter operation. For all other entries for crocodile egg collection, only a portion of the spreadsheet time was recorded – including as little as 10% of the hours recorded on the spreadsheet on single days. On those days, collected nests were recorded on the crocodile egg collection application and for many of them, the pilot had retained a record of VH-IDW start and stop times consistent with the spreadsheet’s recorded hours. The review of the spreadsheets and comparison with VH-IDW’s maintenance release hours included consideration of whether multiple Helibrook R44s were operating on a given day. ATSB – AO-2022-009 › 18 ‹ The accident pilot reported that the helicopter had not ‘missed a beat this season’, then subsequently described VH-IDW’s performance as good and that it flew well, but that it was nearing the end of its overhaul life and had problems in the weeks prior to the accident. These included a damaged inlet valve, a loose induction tube and fuel injector. The latter 2 items were recorded as rectified on the maintenance release on 14 December 2021. There was no documented recent inlet valve replacement identified but the No. 2 cylinder exhaust valve was replaced on 22 April 2021. When questioned whether there was any indication that the helicopter was overrunning the 100-hour inspection intervals, the maintainer reported that it was difficult to determine whether a helicopter had done 100 or more hours when it arrived for maintenance. A maintainer who previously maintained Helibrook helicopters from June 2016 to January 2020, reported that they had previously found a Helibrook R44’s hour meter disconnected. In addition, the operator had leased a helicopter from the maintainer and a comparison of recorded GPS flight data with documented flight times showed that the hour meter had been disconnected and about 4 hours of the 14 hours flown during the cross-hire period were not recorded on the maintenance release. A Civil Aviation Safety Authority (CASA) airworthiness inspector produced a report as part of CASA’s review of this accident. The report identified that VH-IDW’s engine-driven fuel pump had been replaced at reducing hours since new: 733.4 in 2017, 651.9 in January 2020, then, after purchase by Helibrook, at 387.8 hours in April 2021 and 263.2 hours in February 2022. The report stated this was indicative of flight hours not being accurately recorded. Fuel capacity, calibration and indications The R44 II POH stated that for tanks fitted with bladders (including VH-IDW), the main fuel tank capacity was 115 L, of which 112 L was usable, and the auxiliary tank capacity was 65 L, of which 64 L was usable. Of the combined 180 L capacity, the total usable fuel was 176 L. The POH defined usable fuel as the fuel available for flight planning. Unusable fuel is the amount of fuel in the tank/s below which continued running of the engine while performing the most adverse manoeuvre cannot be assured. Below this level, there is the potential to un-port8 the fuel tank outlet due to fuel movement. In straight and level flight, some of the unusable fuel is likely to reach the engine. In the R44 II, the main tank to engine fuel union is located on the inboard side of the tank, forward and near its base. Calibration of the main and auxiliary tank fuel gauges was required every 48 months. The last calibration was conducted by a CASA-authorised maintainer in May 2020. The calibration is shown in Figure 5. The associated placards for the main and auxiliary tank gauge calibration were affixed in the cockpit, but the auxiliary tank placard was damaged and illegible (Figure 6). Figure 5: Fuel tank gauge calibration as recorded in May 2020 Main tank Auxiliary tank Source: Supplied 8 Manoeuvring with low fuel levels can result in fuel flowing away from the fuel tank outlet, or port, to the engine. This disrupts the engine fuel supply, resulting in power fluctuations and/or engine stoppage. ATSB – AO-2022-009 › 19 ‹ Figure 6: VH-IDW cockpit photo showing fuel gauges and placards Source: ATSB The main tank placard stated that the low fuel warning light would illuminate when 20 L total fuel (usable and unusable) remained (Figure 6). According to the maintenance manual, the low fuel warning switch was not subject to calibration. The organisation that conducted the fuel calibration reported that, to establish the 20 L figure, they drained the tank, checked the low fuel light was illuminated, then added fuel until the low fuel light went out. The pilot reported that the light would illuminate with 18 L total fuel remaining. Both those figures differed from the POH, which stated that the low fuel warning light would illuminate with approximately 3 US gallons (11 L) of usable fuel remaining (14 L total fuel in the main tank) (Figure 7). Figure 7: Low fuel warning Source: Robinson R44 II Pilot’s Operating Handbook The Robinson R44 II POH included Safety Notice SN-15 – Fuel exhaustion can be fatal, which advised pilots never to rely solely on the fuel gauge or low fuel warning light but to always record the hour meter reading each time the fuel tanks were filled. This enabled pilots to monitor fuel consumption and endurance. In addition, the POH required the pilot to visually check fuel quantity at each tank during the pre-flight. VH-IDW was also fitted with a fuel flow transducer and an associated Fuel Scan (totaliser) instrument in the cockpit. The instrument could display fuel flow and other parameters including fuel used and fuel or time remaining. However, the display of accurate fuel quantity relied on the correct amount of fuel to be entered following engine start and the in-flight photograph taken en route from Noonamah for Mount Borradaile identified that the Fuel Scan instrument display was not visible. ATSB – AO-2022-009 › 20 ‹ Manifold pressure limits Maximum continuous power manifold pressure limits were prescribed in the POH (Figure 8). Figure 8: R44 II Maximum continuous power, manifold pressure limits The red square depicts the limit for the conditions at the time the in-flight photo was taken. Source: Robinson Helicopter Company, annotated by the ATSB Flying with a higher manifold pressure than the prescribed limit may exceed the approved torque for the rotor drive system. Robinson advised that if excessive power was held continuously, the helicopter would exceed the normal flight envelope, likely causing stress to drive system components that were not designed for such loads. Robinson safety notice SN-37 – Exceeding approved limitations can be fatal, stated: Every second the limitations are exceeded, more stress cycles occur and additional fatigue damage can accumulate within the metal. Eventually, a fatigue crack will begin and grow until a sudden failure occurs…Do not operate the engine above its placarded manifold pressure limits… Robinson also advised that higher-than-normal manifold pressure for a given airspeed could also indicate an engine issue. If one or more cylinders were not operating correctly, higher manifold pressure would be required to produce the same power. In this case, the higher manifold pressure may not exceed the approved torque for the rotor drive system. Hydraulic flight control assistance The main rotor flight controls are hydraulically boosted to eliminate cyclic9 and collective feedback forces. The hydraulic system operates at a pressure between 450–500 psi and consists of a pump, 3 servos, a reservoir, and interconnecting lines. The pump is mounted on, and driven by, the main rotor gearbox. A servo is connected to each of the 3 push-pull tubes that activate the main rotor swashplate. The reservoir is mounted on the steel tube frame behind the main rotor gearbox and includes a filter, pressure relief valve, and pilot-controlled pump bypass valve. A sight gauge for pre-flight fluid level checks is incorporated in the reservoir, which has a vented filler cap. The pump bypass valve is solenoid-actuated and controlled by the hydraulic switch on the cyclic. When selected to HYD (on), the solenoid is deactivated. This fail-safe ensures hydraulic assist is retained in the event of a loss of electric system power. The switch should be on from start-up to shutdown, except during the hydraulic system check or simulated hydraulic failure training. When selected to off, power is applied to the solenoid and high-pressure hydraulic fluid is returned to the reservoir, removing hydraulic assist from the controls. Robinson reported being unaware of any instances of the solenoid actuating in flight and causing a loss of hydraulic assist in the controls. The ATSB occurrence database contained 3 hydraulic 9 Cyclic: a primary helicopter flight control that is similar to an aircraft control column. Cyclic input tilts the main rotor disc, varying the attitude of the helicopter and hence the lateral direction. ATSB – AO-2022-009 › 21 ‹ related occurrences in R44 helicopters since 1997, none of which resulted in a loss of control or an accident. The first was the result of the pilot inadvertently switching off the hydraulic master switch in flight, the second was a failure of the hydraulic pump, and the third was a hydraulic leak. Inadvertent engine stoppage Robinson advised that there had been several accidents in which a pilot had inadvertently induced an engine stoppage by rolling off the throttle too fast. This had occurred in flight training when simulating an engine failure and in response to abnormal situations such as rapid engine RPM changes or discrepancy between engine and rotor RPM. Skids The helicopter had previously been fitted with floats, which had been removed, but the skid extenders necessary for float fitment remained fitted to the helicopter. Emergency locator transmitter The helicopter had a factory mount for an emergency locator transmitter (ELT) and associated wiring in the main rotor gearbox bay however no ELT was fitted to VH-IDW, nor was one required to be. When fitted, the ELT is connected to an external antenna. The ELT had an arm/on/off switch, and a remote switch was located next to the cyclic, with a default position of ‘armed’. Pannier A pannier for the carriage of egg collection equipment was fitted on the left side of VH-IDW. This had been approved by a CASA-authorised aeronautical engineer under an engineering order, although the associated rotorcraft flight manual supplement (RFMS) was not inserted in the POH. Dual hook system VH-IDW was originally fitted with dual hooks for HEC under an engineering order. The engineering order required that the hook system be maintained in accordance with the instructions for continued airworthiness and operated in accordance with the associated flight manual supplement. The engineering order was replaced by a CASA-approved supplemental type certificate (STC)10 in 2021. The system and hook part numbers and the maintenance requirements were unchanged, and the only change was a reduction in the maximum allowable hook weight from 150 to 129 kg (and the associated placard). This was to provide a greater safety margin for HEC operations for the same hook and its strength rating. The STC approved nominated R44 and R44 II helicopters to be: • modified with a dual Onboard Systems International cargo hook kit for HEC operations in accordance with Master Document List R5106-07-R5 (28 July 2021) • maintained in accordance with Instructions for Continued Airworthiness (ICA) R5106-09-R11 (21 July 2021) • operated in accordance with RFMS R5106-25-R13 (11 June 2021), which was required to be inserted in the POH. The associated RFMS was not contained within VH-IDW’s POH. The dual hooks could attach to rings on a 100 ft long line, enabling the carriage of a person below the helicopter. The 2 hooks could be released by the pilot by pressing 2 independent buttons of the primary quick release system (PQRS) or pulling 2 manual handles of the back-up quick release system (BQRS). In addition to 2 independent actions, the PQRS buttons were recessed 10 A supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received regulatory approval to modify an aeronautical product from its original design. The STC, which incorporates by reference the related TC, approves not only the modification but also how that modification affects the original design. ATSB – AO-2022-009 › 22 ‹ into a housing to further reduce the likelihood of inadvertent pilot activation. The dual hook and release systems were designed to provide redundancy in case of failure. Following electrical or manual activation, the hook arm would remain open, until it was manually relatched by pushing the hook up by hand to the closed/locked position (Figure 9). (Note: the red component in Figure 9 is the manual release lever). Figure 9: Onboard Systems hook open and closed/locked (same part number as those installed on VH-IDW) Source: Onboard Systems Serviceability The Onboard Systems HEC dual hook system was installed on VH-IDW on 23 October 2020. The ICA required the external load operation hours to be recorded when the primary hook, or both hooks, were used for external load operations in flight.11 There was no evidence that external load operation hours were recorded on either hook. There was also no record in the aircraft maintenance documentation of the required 100-hourly/annual checks having been conducted. Finally, one of the hooks had been removed from another helicopter prior to being installed on VH-IDW and had exceeded its 3 years in-service limit. The RFMS included the requirement for the pilot to conduct a functional check of the quick release systems prior to commencing the day’s HEC operations. The pilot reported that their normal procedure was to test that the primary and back-up quick releases were functional before the sling person hooked up but could not recall whether they had done so on the accident day. Meteorological information The helicopter departed Noonamah on the accident morning at about 0703. The weather conditions at the time included a light northerly wind and scattered low cloud. At 0743, the helicopter was en route, 60 NM beyond Noonamah and 50 NM from Mount Borradaile. The 11 The primary hook could be used for non-human cargo lifting operations and, as such, could accrue more operational hours than the secondary hook (required for HEC operations). ATSB – AO-2022-009 › 23 ‹ nearest Bureau of Meteorology weather station was at Point Stuart (Figure 1), where, at 0800, the wind was a north-north-westerly at 10–14 kt, the temperature was 27.5 °C and the QNH12 1008 hPa. The Bureau of Meteorology weather station nearest the accident site was South Goulburn Island Airport (Warruwi), 29 km north-north-west. At 0930, the recorded meteorological conditions were westerly wind at 6 kt, temperature 29 ⁰C, dewpoint 24 ⁰C, QNH 1010 hPa and no cloud. Similar conditions were recorded at Oenpelli, 63 km south-west, and Maningrida, 90 km east-south-east of the accident site. Recognising that the winds at these recording stations were light and the actual accident time unknown, the accident trail was consistent with it being approximately into wind. At the sea level elevation of the accident site, with QNH 1010 hPa and temperature 29 ⁰C, the calculated pressure altitude was 90 ft and density altitude13 was 1,770 ft. Recorded data Mobile devices There was a mobile telephone and an iPad on board the helicopter at the time of the accident with the potential to contain data relevant to the accident sequence. The ATSB was able to recover information from the pilot’s phone pertaining to their activities in the days prior to the accident, records of hours the pilot operated VH-IDW and previous maintenance release practices. However, no data directly relevant to the accident flight was able to be recovered. The egg collector’s phone had been operating in the vicinity of the accident site, but was missing and could not be obtained by the ATSB for analysis and the iPad was severely damaged in the accident impact, rendering any stored data unrecoverable. Phone records show the last mobile data session before the accident, commenced on the pilot’s phone at 0847:37 and the egg collector’s phone at 0858:16. The egg collector was sent a text message at 0923:44 but the message was not received. This indicated that the phone was either out of mobile range, which occurred below about 300 ft in the vicinity of the accident site, or was off/not powered. In-flight photo A georeferenced in-flight photo was taken at 0743 on the accident morning, 111 km beyond Noonamah and 94 km prior to the Mount Borradaile refuelling stop, on a direct track between the 2 locations (Figure 10). The photo showed: • the fuel gauges reading just below three quarters full • the Fuel Scan instrument was not operating • the manifold pressure about 24 inches of mercury (inHg) • an indicated airspeed 90 kt • the engine and rotor RPM about 103% • a chronometer indicating 00:45. The photo also showed the accident pilot seated in the left seat as a passenger and the egg collector piloting the helicopter from the right seat. 12 QNH: the altimeter barometric pressure subscale setting used to indicate the height above mean sea level. 13 The altitude in the International Standard Atmosphere at which a given air density is found. ATSB – AO-2022-009 › 24 ‹ Figure 10: Cut-out of in-flight photo taken at 0743 showing cockpit indications Source: Northern Territory Police, annotated by the ATSB As detailed in VH-IDW’s POH, for the pressure altitude at sea level and temperature 30 °C, the maximum continuous power was 23.1 inHg manifold pressure (red box in Figure 8). Based on the aircraft’s height, temperature and QNH at Point Stuart and interpolating the POH table, the maximum continuous power was about 23 inHg. Robinson advised that exceeding the manifold pressure limits with an engine functioning normally would be expected to result in a higher airspeed or rate of climb than depicted in the photo. Assuming VH-IDW departed Noonamah at 0703, which was the time one of the other R44s departed, it averaged 90 kt ground speed to the in-flight photo location. Crocodile nest data A custom-built iPad application named ‘Crocpad’ was used to record the collection of eggs and nest locations. In the week prior to the accident, pilots (including the accident pilot) had conducted flights to locate the nests and entered each nest’s location into Crocpad. The Crocpad data included fields for the device name, status, created date and modified date. The device name was that used by the person who located the nest (for example, ‘my iPad’). The created date contained the date and time the nest was located, at which time the nest’s status was set to LOCATED. When a nest was subsequently either COLLECTED or DELETED, the modified date was amended with the date and time this occurred. This did not need to be the same person or Crocpad that located the nest. The device name was not updated when a nest was collected or deleted, and remained as the device name that had been used to locate the nest. The Crocpad data would update to the server when in mobile range, which the accident site was not. The iPad that was running Crocpad in VH-IDW had not updated the server with any information before it was severely damaged in the accident impact. The 9 nests amended on 28 February are shown in Table 1 and Figure 11. ATSB – AO-2022-009 › 25 ‹ Table 1: Crocpad data for 28 February 2022 Figure 11: Crocpad data showing nests recorded as collected or deleted on 28 February 2022 Source: Crocpad data overlaid on Google Earth, annotated by ATSB On the accident morning, after departing the King River set-down area, the pilots and egg collectors of the 2 helicopters other than VH-IDW, reported meeting at a patch of 3 nests (No.1 to No. 3), then one helicopter went to a single nest (No. 4), before re-joining the crew of the other helicopter at another patch of nests (No. 5 to No. 9). The accident pilot reported that one of the nests in the vicinity of the accident site could be collected on foot (without slinging). It was not known whether the crew of VH-IDW visited that nest before slinging towards the target nest where the accident occurred. However, the first person to attend the accident site reported no eggs had been collected and there was no indication any of the nests in the area had been visited. Nest number Local time Status 1 0911 COLLECTED 2 0912 DELETED 3 0915 COLLECTED 4 0935 COLLECTED 5 0955 COLLECTED 6 0955 COLLECTED 7 1009 COLLECTED 8 1011 COLLECTED 9 1014 COLLECTED ATSB – AO-2022-009 › 26 ‹ Figure 12: Inset from Figure 11 showing nests in the vicinity of the accident site with the status of ‘located’ on the Crocpad data Source: Crocpad data overlaid on Google Earth, annotated by ATSB OzRunways data OzRunways flight path data was obtained for 2 of the R44 helicopters, including VH-IDW. The data contained tracks commencing about halfway between Mount Borradaile and the King River, and ceasing near the clearing where VH-IDW and its crew were last seen prior to the accident (Figure 13). The data for VH-IDW was recorded on the egg collector’s iPhone from 0841:28 to 0850:13 local time and uploaded to the OzRunways server. The data covered about 15 NM, equating to a ground speed of about 100 kt. The other track was from 0840:22 to 0850:15, indicating the 2 helicopters were operating in company. Figure 13: Recorded OzRunways tracks of VH-IDW and another R44 helicopter Source: OzRunways data overlaid on Google Earth, annotated by ATSB ATSB – AO-2022-009 › 27 ‹ No OzRunways data was retrieved from the accident pilot’s phone and no data had uploaded to the server from the pilot’s phone or iPad. The pilot reported that they generally used landmarks to navigate for the ferry flight, and would only use OzRunways, in combination with Crocpad, for the egg collection. Communications The egg collector carried a UHF radio to enable communication with the pilot. It was reported that as the egg collector usually held a bucket in one hand and a pole in the other, it was difficult for them to press the transmit button to talk to the pilot, so they would usually use hand signals to communicate. The accident pilot subsequently reported that egg collectors could easily hold the crate and pole in one hand, making the radio accessible. Additionally, the accident pilot reported that as the helicopter radio was selected to VHF at the time of the accident, they could not have quickly communicated with the egg collector as it would have required switching the radio selector to UHF. The pilot who was first on the accident site estimated that the accident occurred at about 0922 while they were on the ground and out of radio range. This estimation was based on the pilot not hearing an unintelligible radio transmission, later attributed to IDW, that was reported to have been heard by the crew of the other R44 which was airborne at the time. Accident site assessment The ATSB attended the accident site on 2 March 2022. The site was in a paperbark swamp approximately 440 m east of the clearing where spare equipment was found and where VH-IDW was last seen. From the egg collector to the helicopter, the accident trail lay in an approximately north-westerly direction towards, and about 150 m before, a nest that was assigned to the crew of VH-IDW. Assuming a direct transit from the clearing towards the first nest, the trees between where the helicopter probably took off, and where the egg collector was released, were 12–15 m tall. The trees in the vicinity of the target crocodile nest were at least 18 m tall. The bucket and pole were reported to have been found on the ground between trees about 4 m prior to the long line attachment rings. The egg collector was located about 8 m beyond the attachment rings and between 2 trees (Figure 14). On the first tree in the direction of flight, a section of bark had peeled away, about 4–5 m above the ground. While this may have been evidence of possible recent impact, no associated bark was found on the equipment or egg collector. ATSB – AO-2022-009 › 28 ‹ Figure 14: Accident trail Source: Northern Territory Police annotated by ATSB The helicopter impacted the ground upright 44 m beyond the sling person, with the fuselage oriented on a heading of about 060° (Figure 15). The main rotor blades had struck one tall slender tree 3 times, indicating a vertical descent through the tree. The tree was about 9 m tall, with 2 distinctive upper branches that forked from the main trunk about 5 m above the ground. One rotor blade severed one upper branch 8 m above the ground, where the branch diameter was 35–40 mm). A blade then severed the trunk at the fork, 5 m above the ground, where the branch diameter was 50–55 mm. The final cut of the main trunk occurred 1.1 m above the ground, which was below the normal main rotor blade height above the ground in a level attitude. ATSB – AO-2022-009 › 29 ‹ The severed main tree stump (diameter 150 mm) was 2.4 m in front of the helicopter’s nose, leaning about 55° in the direction of main rotor rotation. The helicopter was facing over 90° right of the apparent direction of travel, consistent with rotation of the fuselage due to the main rotor blade’s impact with the tree trunk or pilot pedal input. During the accident sequence, one main rotor blade fractured about 1 m inboard from the blade tip, with the fragment located 45–50 m north-west of the wreckage. It was noted that the main rotor pitch control link associated with this blade had fractured in overstress, with no damage to the other pitch link. Figure 15: Site overview, with the orange arrow showing approximate direction of the accident trail Source: Northern Territory Police, annotated by the ATSB In addition to multiple rotor strikes to a single tree, indications of a mostly vertical descent, slightly right and nose-down attitude and a heavy impact included: • the landing gear had splayed almost to horizontal, and fractured • the forward cross tube was pushed up into the cabin, significantly reducing the available space in the rear cabin, resulting in empty egg crates in the middle of the back seats being distorted and wedged up against the internal cabin roof • both skids had fractured forward of the front struts • deformation to the nose was more pronounced to the right of the landing lights • the pilot’s seat was collapsed towards the front right corner. The base of the pilot’s seat had crushed, as designed, to absorb impact forces. The pilot’s restraint had reportedly been cut by those first on site and used in providing first aid to stabilise their injuries. All the helicopter components were located in the vicinity of the accident site, indicating that there was no in-flight breakup. The forward doors were not installed, and the rear doors had been ejected on impact but were reportedly moved and placed under the pilot for support. ATSB – AO-2022-009 › 30 ‹ The helicopter was in a black dirt swamp and surrounded by water, up to about 0.5 m deep. The swamp had a gentle flow away from the helicopter, in a northerly direction, toward a nearby creek that was part of the King River system. When the ATSB attended the site 2 days after the accident, both fuel tank caps were correctly fitted, there was no fuel smell, no fuel in the auxiliary tank and a very small quantity of fuel at the bottom of the main tank. The impact forced the right side of the transmission deck up to contact the underside of the auxiliary tank, such that the fuel drain could not be accessed. There was no evidence of fuel leaks on the transmission deck, from either tank or associated fuel lines. The right-side low orientation of the helicopter would have directed any fuel in the main tank to the engine fuel hose union near the base of the inboard side of the tank. Any fluid that leaked from the helicopter would have flowed downstream and away from the site. The first person to arrive at the site could not recall checking the fuel tanks, but 2 others who arrived in the second Helibrook helicopter reported having observed the first person to arrive look in one tank and advise that there was fuel visible. In addition, the Helibrook chief pilot who was on board the second Helibrook helicopter reported looking in one tank and seeing a shimmer of fluid however, they did not dip the tanks to check the quantity. The first person to arrive at the accident site reported that there had been a fuel smell, but subsequently reported that the fuel smell may have been from a damaged jerry can that had been behind the pilot’s seat at the time of the accident. A CareFlight first responder who arrived at 1232 reported that there was no smell or indication of fuel, only hydraulic fluid, which created a sheen on the water. A photo taken at 1555 on the accident day showed a slick on the water near the accident site. It was unknown whether that was from hydraulic fluid, fuel or another source. The ATSB obtained images of the site taken in June 2022, 4 months after the accident, in which there was no evidence of vegetation dieback that can indicate fuel contamination. However, 206.2 mm of rainfall had been recorded at the nearest Bureau of Meteorology weather station (Warruwi Airport) since the accident, reducing the likelihood that vegetation dieback would be evident. The first person to arrive at the accident site also reported that there was no power to the aircraft when they arrived, but they switched off the electrical system master and alternator switches as a precaution, and rotated the main rotor blades to provide shade for the pilot. They further reported the fuel mixture control was in the full rich position and the magnetos were selected to ‘Both’, consistent with positions identified by the ATSB on site. The engine RPM governor switch, located at the forward end of the collective, was found in the OFF position. The hour meter read 2070.05. The stowage space under both forward seats was inspected, with nothing being located under the left seat and several small items, including a damaged headset, under the pilot’s seat. The POH and maintenance release were not in the helicopter. No oil was found in the hydraulic system, however, hydraulic fluid was observed on the main transmission deck. The hydraulic switch was selected ON at the cyclic. Flight control continuity from the tail rotor to the main rotor head, above the transmission deck, was established. The fuses for the belt tensioning actuator, in-use and spare, were noted to be the correct amperage and undamaged. All 4 drive belts were present. The distorted pannier prevented easy access to the left side of the engine and the underside of the helicopter was not accessible due to the collapsed landing gear and distortion to the engine cowls. On-site images indicated that the engine was probably above the water level, however, water may have entered the cowls on impact. The tail cone remained connected to the fuselage. There was no damage to the upper vertical fin and horizontal stabiliser. The tail cone and the lower vertical fin displayed compression damage consistent with terrain impact. The tail rotor assembly was secure and rotated freely. Oil was evident in the tail rotor gearbox sight glass and the chip detector was clear of metal contamination. The tail rotor blades were in ATSB – AO-2022-009 › 31 ‹ new condition and undamaged, with some light wood debris at the tip on the leading edge of one tail rotor blade. There was some corresponding minor scuffing to a partially submerged, sodden tree branch immediately under the tail rotor, consistent with contact following a vertical descent. The ELT’s mount was located in the main rotor gearbox bay however, the ELT was not installed. The ELT harness, which included a quick disconnect socket, and antenna cable, were secured with cable-ties. The ELT end of the antenna cable was secured to the helicopter frame with tape. The remote switch, located next to the cyclic, was in the default ‘armed’ position. Following on-site examination, VH-IDW was slung from the site by another helicopter. People on the ground when VH-IDW was lifted from the accident site did not report observing any fuel leaking from the helicopter. During the retrieval, VH-IDW was lifted multiple times, and also put down heavily en route to Jabiru, Northern Territory due to a technical issue with the slinging helicopter. At Jabiru, VH-IDW was loaded upright onto a truck and transported 252 km by road to a secure facility in Darwin for detailed examination. The switch positions identified on site were not altered during the retrieval and arrived in the same positions. Helicopter examination Hook system The hook electric and manual release systems could not be functionally tested due to impact damage. However, both manual release T handles were found in the down position (not activated) and visual inspection did not identify any faults with the dual hook system. The hooks were found in the ‘up and locked’ position when the wreckage was lifted during retrieval from the accident site. Following activation, the hook arm would normally remain open, until manually relatched by pushing the hook up to the closed/locked position. In this instance, having had to open to release the egg collector, they were likely closed by the subsequent helicopter ground impact. Drivetrain Continuity of the drivetrain was established from the main rotor gearbox to the tail rotor gearbox, including all flex couplings. There was some distortion to the main rotor gearbox input driveshaft yoke and flex coupling, along with minor scraping on the transmission deck under the intermediate flex plate which was consistent with an unpowered rotor system (see the section titled Autorotation) during a heavy impact. The main rotor gearbox could be rotated without restriction and the oil level was in the middle of the sight glass. Several main rotor gearbox mounts were fractured and the chip detector was damaged from perforating the transmission deck but was clear of debris. There was no indication of overheating of the main gearbox or clutch assemblies. The clutch assembly was disassembled with no obvious damage to the sprags or race surface, consistent with the helicopter being in autorotation during multiple tree strikes before impacting the ground. The belt tensioning actuator assembly had fractured in overstress at the connection to the upper bearing assembly and at the actuating rod. The actuator rod extension was consistent with properly engaged belts, which included assessment of expected stretch typical of their time in service. The drive belts were intact and appeared in reasonable condition although they were displaced from their respective sheave grooves, which was typical of heavy impact and actuating rod failure. Main rotor The main rotor head droop stops were undamaged with no evidence of excessive teeter or mast bumping. Both blades exhibited rearward distortion about mid-span, with some mild upward ATSB – AO-2022-009 › 32 ‹ coning, indicative of low energy during the descent and tree strikes (Figure 16). The fractured pitch link failed in overstress at the upper rod end thread. The corresponding rod end was secured to the pitch horn, with a slight inboard deflection consistent with the rotor strike and blade fracture. The associated fractured blade had more pronounced coning near the hub, and impact marks and deformation on the lower surface, consistent with the blade being able to rotate about the pitch axis (up) following the pitch link failure. The blade tip was likely liberated at the stump strike. Figure 16: VH-IDW’s main rotor blades showing rearward bending and fracture Both main rotor blades were cut at the accident site to facilitate transport to Darwin Source: ATSB Control continuity Flight control continuity was established throughout. Many control tubes had fractured due to overstress associated with impact, but the corresponding rod ends were secured to bell cranks. The left seat quick-disconnect (dual) controls were not installed and the cyclic boot was in place. The collective friction device had fractured due to impact forces. There was some movement in the collective, but it was restricted due to damaged control tubes. The overtravel spring was bent in a manner consistent with impact damage. Engine RPM governor A power source was applied to the governor motor. The motor operated in both directions with no evidence of interference. The governor wiring loom connector was secure and there was no evidence of loose or deformed pins. The governor switch was functional, with the governor itself ATSB – AO-2022-009 › 33 ‹ sent to Robinson for testing under supervision of the US National Transportation Safety Board and found serviceable. Hydraulics The aft servo return line tee union was found to have fractured in overstress. The filter was clear with no sediment and the pump was secure. The solenoid that actuated the pressure shut-off valve was also tested and found functional. Emergency locator transmitter As detailed above, on-site examination identified that no ELT was fitted to the helicopter. The ATSB was subsequently provided with an ELT by the helicopter operator, who reported that they had removed it from the site after the accident. They advised that it was typically carried under one of the seats, otherwise it would get wet and erroneously activate. The produced ELT was registered to a former Helibrook chief pilot and not associated with any aircraft registration. It appeared intact, in reasonable condition, was switched off and its battery was due to expire in August 2022. The Australian Maritime Safety Authority confirmed that previous unintended ELT activations had occurred due to water ingress and identified one record of activation of the ELT associated with VH-IDW, which occurred on 28 December 2021. A company representative for VH-IDW had advised the authority that the ELT had self-activated, likely due to water making contact with the ELT while collecting crocodile eggs. That ELT was not the one provided to the ATSB. Warning and caution lights All warning and caution lights were inspected, and electrical continuity confirmed. The filaments of the low rotor, low fuel, alternator and governor warning lamps were subsequently inspected under a microscope with none found stretched or broken as sometimes occurs if illuminated at impact. However, due to variables that affect the rate of acceleration applied to the filament, the absence of filament stretch does not enable a conclusion regarding whether or not the light was illuminated. Electrical system The helicopter battery was found out of the battery box but still connected to the helicopter by the battery leads. The alternator control unit was secure and connected. Hour meter One of the 2 electrical connections at the back of the hour (Hobbs) meter was found finger tight. Despite that, the connector would not move freely and had a lock washer under the nut to prevent it from coming loose during operation. However, only a small amount of hand pressure was needed to move the connection, consistent with it having been tightened by hand rather than with a spanner or socket. Indications of engine rotation at impact There were no indications of engine rotation at impact, evidenced by: • no rotational damage to the engine cooling fan or housing • no slippage to the cooling fan retention nut alignment mark • no evidence of rotational scoring to the alternator housing or cooling fan and backing plate. Significantly, impact damage and bending to the upper sheave forward end, lower surface was consistent with impact with the starter ring gear, and showed defined teeth impact marks, with no smearing (Figure 17). This strongly supported the ring gear being stationary (engine stopped) when the helicopter collided with terrain. ATSB – AO-2022-009 › 34 ‹ Figure 17: Upper sheave damage from impact with non-rotating starter ring gear Source: ATSB Powerplant External engine examination External examination found no evidence of a catastrophic engine failure. The throttle butterfly was fully open at the fuel control unit, however as the impact forces would have tended to pull it open, the throttle position prior to impact could not be determined. Oil The engine oil cap and dipstick were secure, and the sump plug was relatively clean. The ATSB drained 8.6 L of oil from the engine with no significant debris found in the oil. The recommended maximum engine oil quantity was 9 quarts (8.5 L). Although the oil level slightly exceeded the maximum recommended capacity, it would not have affected the engine’s performance. The oil filter was opened and inspected with nil contamination identified on the filter element. Air Induction air enters through an opening on the right side of the fuselage and passes through the air filter within the air box. Air then passes along a flexible sceet duct, through the fuel control unit and into the engine. The air intake was damaged consistent with accident impact, but there was no evidence of blockage or ingestion of foreign material. The air box casing was distorted, also consistent with accident damage, though the filter was clean and there was no sign of blockage. The induction sceet hose had been crushed consistent with impact forces. The induction hose was also checked for delamination, due to a previously-identified issue with some induction hoses, and none was evident. ATSB – AO-2022-009 › 35 ‹ Engine examination The engine was shipped to a CASA-authorised maintenance facility for examination under ATSB’s supervision. Differential compression checks were carried out on the assembled engine. Cylinders No. 3 and No. 6 were below the limit of 60/80, which the engine manufacturer advised was the point that removal and overhaul should be considered (Table 2). However, cylinder compression is normally checked on a warm engine, as a cold engine may not provide reliable results. Table 2: Compression checks of assembled engine – red denotes below limit The cylinders were then removed from the engine and subjected to a second, differential compression check on a test bench. During testing, the valves were tapped to ensure any debris was not preventing a good seal. All cylinders then reached or exceeded 70/80 except cylinder No. 6, which only attained 5/80. The leak from cylinder No. 6 was visually identified as coming from both valve seats. The valves from cylinder No. 6 were removed and the seating surface contact was examined. The seating faces were uneven (nonconcentric), particularly on the intake, and the exhaust seat had a low spot consistent with the valve not sealing properly (Figure 18). The poorly seated valves would have accounted for the low compression although the valves appeared in good condition with no evidence of carbon build-up. The No. 6 cylinder had been overhauled in 2016 and a vacuum pressure test was reportedly conducted at the time to check for leaking, however the results weren’t recorded. After overhaul, the cylinder was stored until installation in VH-IDW in 2022. Cylinder No.: 1 2 3 4 5 6 Compression 78/80 70/80 45/80 60/80 78/80 0/80 ATSB – AO-2022-009 › 36 ‹ Figure 18: No. 6 cylinder intake and exhaust seats showing nonconcentric valve seating and low spot Source: ATSB The engine examination also found corrosion in all intake tubes, consistent with post-accident moisture from the impact in the swamp. Prior to removing the cylinders, the valve trains were removed, and the hydraulic plungers were returned to a dry/deflated condition. After reassembly, the rocker arm to valve clearances were checked and only 5 of the 12 clearances were found to be within the engine manufacturer’s service limits. Table 3 shows the resulting clearances, with those out of service limits highlighted in red. Valve clearances were set on installation of the cylinder and can vary with wear. Insufficient clearance may prevent the valve from closing properly and excessive clearance can reduce valve lift and duration. Table 3: Rocker arm to valve clearance – red denotes outside limits (0.28–0.80”) Cylinder No. Intake valve Exhaust valve 1 0.110 0.047 2 0.022 0.024 3 0.032 0.036 4 0.016 0.095 5 0.000 0.052 ATSB – AO-2022-009 › 37 ‹ The low compression in cylinder No. 6 would reduce the maximum power output and at any achievable power output, the fuel consumption would be higher than an engine with compressions within service limits. No defects were identified that should have resulted in sudden power loss or engine stoppage. The ATSB also obtained an expert opinion from the engine manufacturer, regarding the engine and specifically the low compression result. They advised that low compression in the cold test scenario was not necessarily representative of results obtained from a warm engine. They also stated that the low compression would not result in a significant power reduction or sudden engine stoppage. Loose B nut At the engine examination, it was identified that the ‘B’ nut14 on the fuel control unit (FCU) was loose – about 1.5 turns from tight. This was not indicative of its security at the time of the accident as it was loosened by an ATSB investigator during engine removal prior to shipping for examination. Ignition system The engine data plate recorded the engine-to-magneto timing as 20° before top dead centre. The left magneto15 timing to the engine was found at about 35° and the right magneto timing at 23°. The incorrect timing of the left magneto was assessed as having resulted from impact forces, which resulted in mount fracture and anticlockwise rotation of the magneto that advanced the timing. The external oil filter impacted the right magneto. Testing of spark plugs and visual inspection of the ignition leads found no defects of the ignition system. The magnetos were functionally tested and internally inspected at a CASA-authorised electrical and instrument maintenance facility, under the supervision of the ATSB. The magnetos were run on a test bench and both functioned throughout the normal operating range, with nil faults. The magnetos were then partially disassembled for internal examination and testing including points gap and continuity, internal timing, coil and capacitor serviceability. Both magnetos were found to be in normal operating condition. Fuel system examination Fuel tanks The fuel system includes one main and one auxiliary tank, a gascolator, and a shut-off valve, with the associated pilot control knob located between the front seats. The fuel shut-off selector knob was found separated from the control tube and free to rotate however, the valve position was consistent with the fuel selected to the on position. The auxiliary tank was correctly interconnected with the main tank and, due to it being mounted higher than the main tank, would empty first while fuel remained in the main tank. The inter-tank flexible hose assembly was found clear of obstructions. The fuel tank bladders remained intact despite splitting along riveted joins and punctures to the outer aluminium tanks. The aluminium tanks showed impact damage and subtle deformation 14 B nut - threaded sleeve nut that provides clamping force to ensure an effective/good seal to fuel, air and oil lines. 15 Due to engine installation orientation, the engine right magneto is located on the left side of the helicopter. Further, the engine right magneto contains a second set of points that provided a signal to the governor and engine tachometer. Cylinder No. Intake valve Exhaust valve 6 0.000 0.047 ATSB – AO-2022-009 › 38 ‹ (Figure 19 and Figure 20). Robinson assessed that the deformation of the fuel tanks was consistent with ‘lower fuel quantity’ but could not determine whether the deformation was due to impact damage, bulging of internal contents, or a combination of both. Robinson provided an image of an auxiliary tank that was known to have been nearly full at impact for comparison, which presented severe bulging over the entire tank (Figure 20). When compared with the exemplar image, the damage to VH-IDW’s fuel tanks was assessed as representative of the high vertical impact resulting in severe distortion to the airframe around the tanks, with little or no fuel within. This was also consistent with an ATSB investigation into a previous Robinson R22 accident, in which the tank was half-full on impact and displayed distinctive bulging from the internal contents that was not evident in the deformation of VH-IDW’s tanks. Figure 19: VH-IDW’s auxiliary and main tanks showing subtle deformation and compression damage Source: ATSB Figure 20: An exemplar auxiliary tank known to be nearly full at impact and VH-IDW’s Source: RHC, annotated by the ATSB All remnant fuel was drained from the main tank on arrival at Darwin. It comprised about 250 ml of blue fuel (Figure 25), contained minimal debris/sediment and was tested clear of water. No fuel ATSB – AO-2022-009 › 39 ‹ was found in the auxiliary tank. Noting as detailed previously (see the section titled Fuel capacity, calibration and indications) that the helicopter’s fuel system had 4 L of unusable fuel, the relatively small recovered quantity indicated that fuel had either been removed from the tanks after the accident or, considered more likely, had leaked out following the accident and/or during the transport from the accident site to Darwin. Pressurised fuel system The pressurised fuel system includes an engine-driven fuel pump, an electric (auxiliary) fuel pump and a fuel return line, which allows pump supply in excess of engine demand to return to the fuel tanks. If pressure from the electric pump is low in flight, a pressure switch illuminates the auxiliary fuel pump caution light. Return fuel passed through the fuel pressure relief valve (FPRV) and then flowed to a tee junction connected to the auxiliary tank. The return fuel jet and tee assembly were found to be installed correctly. The FPRV was tested on a rig, to simulate both fuel return and static leak from the tank back into the engine fuel system. The FPRV fully opened at about the expected parameter however, a small bypass at lower pressures was noted. Robinson reported that the flow curve was similar to other FPRVs they have seen with significant time in service, and advised that: We have done extensive testing, with [US Federal Aviation Administration] FAA involvement, on valves with variations in their flow curves, and found that they have very little to no effect on engine operation, both with and without the electric (auxiliary) pump operating and not operating. We found that the only FPRV valve condition that had any effect on the engine operation was a valve that was simulated as being stuck in an excessively open position, and in that case the stuck valve resulted in illumination of the auxiliary fuel pump caution light in idle and run-up (as well as at flight power levels). The electric fuel pump was connected to a power source and operated. The pump was then disassembled, and the pump vane could be rotated manually. The electric motor was worn, with brushes almost down to the leads and the commutator grooved (Figure 21). Figure 21: Electric fuel pump showing worn brush and commutator Source: ATSB ATSB – AO-2022-009 › 40 ‹ There was no sign of particulate contamination or water in the fuel system. The mechanical (engine-driven) fuel pump serial number matched that recorded as being installed on 7 February 2022. The pump was not blocked, and no defects were found. In addition, function of the driving plunger was observed with engine rotation. Fuel control unit examination The FCU was examined by a specialist at a CASA-authorised maintenance facility, overseen by the ATSB. There was no fuel found in the FCU, and the finger filter was clear. The throttle arm was distorted and there was damage to the FCU body, near the mixture control lever, consistent with impact forces. The nozzles were all visually clear and were bench tested. The fuel flow was within the service limits for overhauled nozzles (31.4–32.6 lb/h) except No. 6, which was slightly low (31.0 lb/h). The fuel system specialist advised the slightly reduced flow would not stop the engine from operating. On the test bench, the FCU tested slightly high (running slightly rich) at the lower power setting, and within limits at all other settings including maximum power. The specialist advised that it was not uncommon for the low-test point to become overly rich. During the testing, flushed fuel was passed through a filter membrane with no contaminants collected. The FCU diaphragm was in good condition and there was no evidence of water contamination in the FCU. Throughout the examination and disassembly no seals or O-rings were found to be failed or damaged. The throttle mechanism was functional. Fuel system disruption The fuel lines, flow divider and gascolator were all clean, and empty of fuel. The gascolator drain valve was found depressed against the firewall when examined at the Darwin hangar but reset when manipulated. Upward forces during impact distorted the aircraft structure around the drain assembly resulting in the drain extender tube, used to compress the drain valve, bending and splitting (Figure 22). Following removal from the accident site, yellow sand was observed in the end of the tube, which was consistent with the site where the helicopter was set down during the wreckage retrieval. The sand likely entered the tube as the skids were removed prior to extrication of the wreckage from the swamp, leaving the tube as the lowest point below the fuselage. The gascolator bowl was dry and the filter screen was clear. Examination of the cowls did not identify any discolouration or staining that would be associated with leaking fuel, either prior to, or after the accident. ATSB – AO-2022-009 › 41 ‹ Figure 22: Gascolator, drain valve and tube, and R44 II Illustrated Parts Catalog extract Source: Robinson Helicopter Company and ATSB The fuel flow transducer, positioned between the fuel control unit and flow divider, had a fractured outlet fitting. The fracture surface was consistent with impact damage, with no evidence of pre-existing fatigue. On behalf of the ATSB, Robinson conducted a test by removing the fuel line (and transducer) from the FCU outlet with the fuel valve open, mixture full rich and throttle full open. Robinson found that due to gravity, the fuel flowed out at a significant rate and would eventually empty the tanks. Loose black organic soil consistent with the accident site filled the transducer end of the fractured fitting (Figure 23), which likely would have been dislodged at the fuel flow rate demonstrated by Robinson. The flow divider was opened and noted to be dry and clean, and there were no contaminants or restrictions that would have prevented fuel flowing through each of the nozzles and into the cylinders. ATSB – AO-2022-009 › 42 ‹ Figure 23: Fractured fitting between transducer and flow divider Source: ATSB Fuel system indications The fuel gauges and low fuel switch were independent systems, in that the low fuel switch would illuminate the low fuel warning lamp, independently of the fuel sender position. The float-operated low fuel switch assembly, located in the main tank, was electrically tested, while manipulating the float up and down, and found to be functional. Additionally, the low fuel switch and lamp were signed off as having been tested by the maintainer on 7 February 2022, as part of the periodic inspection. The ATSB removed the fuel quantity senders from both tanks and tested the sender calibration in Darwin in June 2022. Further testing of the main tank senders and gauge was conducted by Northern Territory Police on behalf of ATSB in August 2023. ATSB – AO-2022-009 › 43 ‹ Both senders moved smoothly throughout the operating range. The R44 Maintenance Manual fuel quantity sender check specified positioning the float arm at 4 noted heights and measuring the resistance at each point to verify it was within the specified tolerance. The main tank sender could not be positioned to the up stop height and at the down stop was slightly below the down stop height for the testing, and measured slightly above the resistance range at the intermediate heights. When the fuel gauge was connected to the sender and a power source, the fuel quantity indicator needle moved smoothly from empty to full. The 4 sender test heights corresponded to the gauge indications at Empty, 1/4,1/2 and Full. As a result of the sender float arm position, the gauge very slightly overread (within a needle-width) at the lower 3 indications. The results were sent to Robinson for expert assessment. Robinson advised that the testing indicated the main tank gauge would have been reading slightly higher than what was actually in the main tank, but ‘nowhere near’ the calibration sticker figures, which indicated the main tank gauge was underreading. Examination of the auxiliary tank sender base plate identified a slight bend to the sender pole and that the strainer and siphon assemblies were distorted. It could not be determined if the distortion was associated with the fuselage impact forces, or pre-existing. Regardless, the strainer distortion would not have affected fuel flow to the tank interconnect hose. In addition, the siphon, part of the fuel tank drain system would have no effect on fuel supply to the engine. The ATSB determined that the auxiliary tank sender was within the required resistance range at the up and down stops. Partial power loss Robinson advised that main rotor blade strike, or strikes, to a tree could stall an engine at low power or idle, prior to impact with the terrain. The ATSB assessed all available evidence against the engine manufacturer’s troubleshooting tables for Low power and uneven running and Failure of engine to develop full power. In addition, the 29 items on Robinson’s troubleshooting checklist for low power were reviewed. All applicable items were tested where possible, within the constraints of damage. Nothing was identified that would likely result in a sudden onset of low power. Fuel considerations Fuel uplift Procedure for filling tanks The placard adjacent to the auxiliary fuel tank stated that the procedure to fill the tanks to full fuel entailed filling the main tank, then the auxiliary tank, then topping up the main tank. This procedure was required due to the self-levelling of the interconnected tanks. The Helibrook operations manual included a procedure for hot refuelling (with the engine running). The manual stated that Robinson helicopters were not to be refuelled with the engine running, unless a person remained at the controls and an authorised person who has undertaken training recorded on the Aircraft Refuelling Training Record Form 16 is available to carry out the refuel. The Helibrook safety manager advised that they did not have a completed form for the pilot or the egg collector of VH-IDW, and there was no other evidence to indicate whether they had undertaken the training. The egg collector in the second helicopter to land at Mount Borradaile previously flew and collected eggs for Helibrook and was the only person present who had completed the required training to hot refuel a Helibrook R44 helicopter. Noonamah Based on interviews with the helicopter operator, pilot and fuel supplier, and the 2 most recently delivered fuel batch receipts, the Noonamah fuel storage tank contained blue 100 low lead (LL) ATSB – AO-2022-009 › 44 ‹ Avgas. A total fuel quantity of 440 L was recorded as being taken from the Noonamah tank on 28 February, but there were no records of the quantity uplifted to individual helicopters. As well as VH-IDW, at least one of the other 2 R44 helicopters was reportedly refuelled when they arrived at Noonamah at about 0645 and several jerry cans were also filled from the Noonamah storage tank. The Helibrook R44 helicopter that flew to the site after the accident may also have used fuel included in that total. The quantity and source of fuel remaining in VH-IDW prior to refuelling on the accident morning could not be determined. The accident pilot reported that they would have filled the helicopter to full at Noonamah, in accordance with normal procedures. They also stated that their usual practice was to set the chronometer to zero after fuelling the helicopter. Other pilots reported that normal practice was to ensure sufficient fuel to get to Mount Borradaile, but not necessarily to fill both tanks. In a submission provided to the ATSB following review of the draft report, one of the egg collectors operating on the accident day reported that VH-IDW was filled with 100 LL fuel at a Helibrook base near Sweets Lagoon, 33 NM from Noonamah at the end of the previous day’s activities. They further reported that they were present at the hangar on the accident morning and had not observed VH-IDW being fuelled. Based on that account, if the helicopter was not refuelled at the hangar on the accident morning it would have departed Noonamah with 23-25 L less than the full fuel tank capacity. Mount Borradaile As detailed previously, based on the georeferenced in-flight photograph, VH-IDW probably arrived at Mount Borradaile at about 0816. This time was consistent with the departure and arrival time recorded on a GPS device on the third R44 helicopter to arrive at Mount Borradaile that morning. There were no records of the fuel uplifted at Mo