Collision with water involving Robinson R44, VH-SCM

input is the main control for vertical velocity. › 3 ‹ ATSB – AO-2017-047 The maximum manifold pressure (or engine power) available for the flight based on the conditions was 25.9 inches. The pilot reported setting about 23 to 24 inches. Helicopter maintenance The Civil Aviation Safety Authority reviewed the helicopter log books and did not identify any anomalies. The helicopter engine had five cylinders removed, repaired or replaced in the preceding 50.8 hours due to low compression and high oil consumption. The engine had a total time of 1,778.2 hours since new, with a time between overhaul of 2,000 hours for that model engine. Safety analysis The helicopter was below the published maximum take-off weight and within the published weight limits for hovering in and out of ground effect. In addition, the speed at which minimum power is required is about 55 kt for the R44 II, therefore the power required at the accident speed was less than the power required to hover. In the reported calm conditions, the helicopter should have had sufficient power available to maintain rotor RPM. The ATSB was unable to determine the cause of the RPM decay. The take-off profile recommended by the manufacturer was for the helicopter to achieve a height of 25 ft at an airspeed of 50 kt. However, the helicopter was still at 5–10 ft at 50–60 kt, which provided the pilot with very little reaction time to the low rotor RPM warning. The pilot reported that there was no outstanding maintenance on the maintenance release (which was not retrieved from the helicopter) and that the helicopter had been running normally on the previous flight only minutes before the accident flight. As the helicopter had not been recovered from the water at the time of the ATSB investigation, no inspection of the engine had occurred. The helicopter had recently undergone significant engine maintenance, mostly working on the cylinders, and was using more oil than normal, but not an abnormal amount for a running-in period. The pilot had topped up the oil prior to the first flight of the day. The pilot did not observe any warnings after the low rotor RPM horn sounded, but there was very little time before the helicopter collided with the water. The pilot commented that even a small drop in engine performance, such as from a magneto failure, would have been difficult to recover from at 5–10 ft above the water. The pilot commented that as there was no wind, the water surface was glassy and they may not have been able to assess the height of the helicopter above the surface accurately. Operating at an estimated 5 ft above the water did not allow time to react in case of an engine failure or temporary reduction in performance. Findings These findings should not be read as apportioning blame or liability to any particular organisation or individual. • The rotor RPM decayed below 97 per cent at 5–10 ft above the water and the pilot was unable to recover control of the helicopter, resulting in a collision with the water. • The helicopter was below maximum take-off weight and had sufficient power to hover in and out of ground effect with the engine operating normally. Safety message According to the FAA rotorcraft handbook, pilots should avoid the low altitude, high airspeed portion of the height-velocity diagram, because their ‘recognition of an engine failure will most likely coincide with, or shortly occur after, ground contact. Even if you detect an engine failure, there may not be sufficient time to rotate the helicopter from a nose low, high airspeed attitude to one suitable for slowing, then landing.’ › 4 ‹ ATSB – AO-2017-047 Robinson Helicopter Company Safety Notice SN-19, Flying low over water is very hazardous, stated that ‘Many pilots do not realize their loss of depth perception when flying over water.’ General details Occurrence details Date and time: 23 April 2017 – 0940 WST Occurrence category: Accident Primary occurrence type: Collision with terrain Location: Talbot Bay, Western Australia Latitude: 16° 21.00' S Longitude: 123° 55.00' E Helicopter details Manufacturer and model: Robinson Helicopter Company R44 II Registration: VH-SCM Serial number: 11157 Type of operation: Charter – passenger Persons on board: Crew – 1 Passengers – 2 Injuries: Crew – 1 Minor Passengers – 2 Minor Aircraft damage: Substantial About the ATSB The Australian Transport Safety Bureau (ATSB) is an independent Commonwealth Government statutory agency. The ATSB is governed by a Commission and is entirely separate from transport regulators, policy makers and service providers. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport through excellence in: independent investigation of transport accidents and other safety occurrences; safety data recording, analysis and research; and fostering safety awareness, knowledge and action. The ATSB is responsible for investigating accidents and other transport safety matters involving civil aviation, marine and rail operations in Australia that fall within Commonwealth jurisdiction, as well as participating in overseas investigations involving Australian registered aircraft and ships. A primary concern is the safety of commercial transport, with particular regard to operations involving the travelling public. The ATSB performs its functions in accordance with the provisions of the Transport Safety Investigation Act 2003 and Regulations and, where applicable, relevant international agreements. The object of a safety investigation is to identify and reduce safety-related risk. ATSB investigations determine and communicate the safety factors related to the transport safety matter being investigated. It is not a function of the ATSB to apportion blame or determine liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in › 5 ‹ ATSB – AO-2017-047 order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.