AAIB investigation to Boeing A75N1(PT17) Stearman, N707TJ
Loss of power during flying display and ditching off Sandbanks, Poole, Dorset, 4 September 2021.
Summary:
While performing an aerobatic wing walking display over the sea at Bournemouth Air Festival, the aircraft experienced a reduction in engine power. The pilot stopped the display routine and flew the aircraft west, along the coast, with the intention of returning to Bournemouth Airport. The wing walker returned to her seat in the front cockpit. Although the aircraft was initially able to maintain height, the engine subsequently experienced a complete loss of power and the pilot ditched in the entrance to Poole Harbour. The aircraft flipped over on contact with the water, but both occupants were able to exit the aircraft unaided.
The investigation determined that during the display the engine suffered a loss of engine power due to failure of the oil inlet pipe, most likely due to fatigue, which prevented oil being supplied to the engine. This was precipitated by a fatigue failure of the metal strap which supported the weight of the oil inlet pipe. The fatigue failure initiated at an area of mechanical damage on the surface of the support strap, which had been caused by overtightening of the retaining nut.
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