Propeller Loss Involving Jabiru J430, VH-TJP North of French Island, Victoria, 8 March 2013
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InsertPropeller document loss involving title Jabiru J430, VH-TJP LocationNorth of French| Date Island, Victoria | 8 March 2013 ATSB Transport Safety Report Investigation [InsertAviation Mode] Occurrence Occurrence Investigation Investigation XX-YYYY-####AO-2013-046 Final – 19 August 2014 Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Publishing information Published by: Australian Transport Safety Bureau Postal address: PO Box 967, Civic Square ACT 2608 Office: 62 Northbourne Avenue Canberra, Australian Capital Territory 2601 Telephone: 1800 020 616, from overseas +61 2 6257 4150 (24 hours) Accident and incident notification: 1800 011 034 (24 hours) Facsimile: 02 6247 3117, from overseas +61 2 6247 3117 Email: [email protected] Internet: www.atsb.gov.au © Commonwealth of Australia 2014 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this publication is owned by the Commonwealth of Australia. 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Addendum Page Change Date Safety summary What happened VH-TJP in flight On 8 March 2013, during climb after departure from Tyabb aerodrome, Victoria, the pilot and sole occupant of a Jabiru J430 aircraft, registered VH-TJP, reported the onset of vibration through the airframe. As a precaution, the pilot began to turn the aircraft back towards Tyabb. During the turn, the propeller separated from the aircraft, necessitating a forced landing upon tidal flats at the western edge of Source: VH-TJP Pilot Westernport Bay. The pilot was not injured and was able to disembark the aircraft safely. What the ATSB found The ATSB investigation found that most of the cap screws connecting the propeller mounting flange to the engine crankshaft had failed by bending fatigue fracture – principally due to repeated relative movement between the mounted components. This movement was traced to a combination of an ineffective, multi-step torqueing method and the relaxation of tension within the crank–flange joint due to the compression of multiple layers of paint within the joint. It was also found that there were some anomalies within the maintenance documentation that related to these areas. After attempting to analyse the origin of the worsening vibration in the aircraft, the pilot correctly followed emergency procedures both before and after the propeller loss. The over-water return decision limited the risks associated with the forced landing, and the pilot effectively maintained control of the aircraft throughout the descent and landing. What's been done as a result In July 2011, the manufacturer had improved the strength and reliability of the crank–flange joint by adding positive-location dowels in all new-production engines. However, that modification was not extended to earlier design assemblies, which included VH-TJP. The current (revised) issue of the Engine Overhaul Manual has an added, strong recommendation for inclusion of these dowels at the next full overhaul or at bulk strip of engines manufactured prior to July 2011. Furthermore, in addition to the earlier requirement for no paint on mating faces or where screw heads bear, a broad requirement was introduced to ensure that no paint, thread-locking compound or contaminants remain in the propeller flange joint. The fastener torqueing method has been amended to a single-step process in which the required torque is to be obtained dynamically while the fastener is being turned. Finally, the manufacturer’s Propeller Flange Attachment Service Bulletin now refers maintainers directly to the engine overhaul manual for installation procedures – removing the variability that previously existed between documents. Safety message A potentially serious accident was avoided by the pilot’s adherence to emergency procedures and maintaining control of the aircraft after a significant mechanical failure. Regarding the mechanical assembly, the ATSB encourages manufacturers and maintainers to consider older and legacy operating assemblies when designs are optimised or improved to enhance safety and reliability. Contents The occurrence ........................................................................................................................1 Context ......................................................................................................................................2 Safety analysis .........................................................................................................................8 Occurrence flight 8 Screw failures 8 Insufficient joint clamping 8 Document anomalies 9 Findings ................................................................................................................................. 10 Contributing factors 10 Other findings 10 Safety issues and actions ................................................................................................... 11 Engines with undoweled crankshaft–propeller flange joints 11 Safety issue description: 11 Current status of the safety issue: 11 Insufficient joint clamping 11 Safety issue description: 11 Current status of the safety issue: 12 Document anomalies 12 Safety issue description: 12 Current status of the safety issue: 12 General details ...................................................................................................................... 13 Occurrence details 13 Aircraft details 13 Sources and submissions .................................................................................................. 14 Sources of information 14 References 14 Submissions 14 Appendix A ............................................................................................................................ 15 Australian Transport Safety Bureau .................................................................................. 17 Purpose of safety investigations 17 Developing safety action 17 ATSB – AO-2013-046 The occurrence On 8 March 2013, the pilot and sole occupant of a Jabiru J430 aircraft, registered VH-TJP (TJP), refuelled at Tyabb, Victoria and took off from runway 17, making a left turn towards French Island in Westernport Bay. During the subsequent climb to 2,000 ft, the pilot began to feel vibrations through the aircraft that progressively became more severe. The pilot unsuccessfully tried to identify their source by adjusting the engine controls. Approximately 18 km from the aerodrome, while heading in a south-easterly direction, the pilot elected to return to Tyabb. During the turn, the propeller separated from the aircraft and, relieved of its load, the engine speed surged before the pilot brought it under control. Exposed tidal flats at the western edge of the bay were identified as suitable for a forced landing, which was successfully carried out. The pilot was uninjured and after disembarking, he took photographs of the now-exposed end of the crankshaft, minus the propeller flange and propeller (Figure 1). The incoming tide later submersed and substantially damaged the aircraft. The intact wooden propeller/spinner assembly was found the following day by the Victorian Water Police, floating north-west of French Island about 5 km from the western shore of the bay. Figure 1: Forward end of TJP’s crankshaft showing five broken screws Source: VH-TJP Pilot Aircraft information TJP was an amateur-built Jabiru J430 kit aircraft, serial number 567, with a six-cylinder, 3300 cm3, Jabiru engine (serial number 33A1693) fitted. The aircraft was constructed and assembled in 2007 by its owners (with factory assistance) and was first registered on 13 November 2007. In October 2012, the aircraft underwent periodic inspection and maintenance; in addition, the propeller and mounting flange were removed because of rust. After derusting, cleaning, priming and painting, the components were re-installed in accordance with revisions of the relevant Service Bulletins1 current at the time, using new cap screws and bolts. At the time of that maintenance, the aircraft’s total time in service (TTIS) was 297.5 hours. The propeller separation occurred 3.7 flying hours later. 1 JSB 009-1 Alternate (sic) Propeller Mount System and JSB 022-1 Propeller Flange Attachment. › 1 ‹ ATSB – AO-2013-046 Context Propeller assembly description The as-recovered propeller–spinner–prop flange assembly is shown in Figure 2 with the propeller- mounting flange uppermost in the figure and highlighted in the drawing cross-section below (Figure 3). The laminated wooden propeller (Item 5) fastens to this flange via six bolts (Item 6). Figure 2: Recovered propeller/spinner assembly Source: Victorian Water Police Figure 3: Drawing cross-section of the spinner/prop/flange assembly Source:-Jabiru