Tail rotor malfunction involving a Robinson R22, registration VH-HPH

times more than permitted) allowed binding to occur, with resultant fatigue failure to the pitch link. › 3 ‹ ATSB – AO-2014-181 Pilot operating handbook Robinson Model R22 Pilot’s Handbook, Section 4 Normal Procedures Daily or Prefight checks, dated 20 April 2007 page 4-3, included an item to check the tail rotor pitch links for “No looseness”. Robinson maintenance manual The Robinson Maintenance Manual Model R22 contains inspection requirements to be conducted at the 100-hour or annual inspection. Section 2.410 Inspection procedures and checklist item 12. Rotor Hub Hinge Bolts, dated October 2014, required the condition of the pitch links and rod ends to be inspected. This inspection was to be in accordance with section 2.120 Push-Pull Tubes, Rod Ends, and Spherical Bearings (dated October 2014), with reference to Figure 2-1 (reproduced below in Figure 3). The inspection needed to meet the following conditions: • the maximum allowed axial play of 0.020 inch (0.508 mm). The axial play of HPH’s failed pitch link was about 0.108 inch (2.743 mm) and the intact pitch link was about 0.041 inch (1.041 mm) • the maximum radial play of 0.010 inch (0.254 mm) for the rod end spherical bearings • with no looseness between the bearing outer race and the rod end housing. The maintenance manual also contained a caution that the Teflon-lined bearings must not be lubricated or cleaned with solvent. Figure 3: Robinson maintenance manual spherical bearing limits Source: Robinson › 4 ‹ ATSB – AO-2014-181 ATSB comment CASA SDR database search The operator reported to the ATSB that the R22 helicopter tail rotor pitch links had been failing regularly in mustering operations. CASA provided information from their Service Difficulty Report (SDR) database from 1983 to 2014. The database showed three previously reported defects with the same part number tail rotor pitch link as HPH where the pitch link had failed (Table 1). Two of the failures had occurred in flight. Table 1: CASA SDR database - Tail rotor pitch link failures month/year of SDR Failure Time since new (hours) Part number pitch link Operation 09/2009 Tail rotor pitch link failed in flight. 434 B345-3 Mustering 11/2009 Tail rotor pitch link failed in flight. Spherical bearing attached to the tail rotor blade was found worn to limits. 562 B345-3 Mustering 04/2014 During the scheduled 100 hourly inspection the tail rotor pitch link fractured near the spherical bearing attached to the tail rotor blade. 289 B345-3 Unknown CASA reported two important points in relation to the CASA SDR system: in the case of the Robinson R22, there is no legislation requiring the manufacturer to be notified of the tail rotor pitch link failures in Australia that have been reported to CASA. While there is no requirement to provide this information, CASA usually provides data dumps of defect reports on an annual basis to North American NAAs [National Airworthiness Authorities including the US Federal Aviation Administration and Transport Canada]. CASA encourages the industry to pass the defect information to the approval holder [manufacturer] and, as part of any follow up action CASA is likely to send the information to the approval holder [manufacturer], foreign or domestic. Safety message Continuing airworthiness relies on inspections identifying damage so that parts can be repaired or replaced prior to failure. Therefore, scheduled maintenance inspections and the pilot’s daily inspection are a central element of the continuing airworthiness of the aircraft. Regulators and aircraft manufacturers depend on accurate data to ensure the ongoing continued airworthiness of the aircraft. It is important that defects are reported to CASA through the Service Difficulty Reports (SDR) system, and to the manufacturer, so issues can be identified and rectified. › 5 ‹ ATSB – AO-2014-181 General details Occurrence details Date and time: 18 November 2014 – 1730 CST Occurrence category: Accident Primary occurrence type: Technical – rotor malfunction Location: La Belle Downs Station, Northern Territory Latitude: 13° 06.78' S Longitude: 130° 29.93' E Helicopter details Manufacturer and model: Robinson Helicopter Co R22 Registration: VH-HPH Serial number: 3988 Type of operation: Private Persons on board: Crew – 1 Passengers – 1 Injuries: Crew – Nil Passengers – Nil 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 fare-paying passenger operations. 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 order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. › 6 ‹ ATSB – AO-2014-181