- An S-2R aerial application aircraft experienced a ground loop after part of its left shock assembly suffered an overstress failure;
- The ATSB determined it was highly likely the component was not replaced or modified to comply with a service bulletin issued by the manufacturer in 1994;
- The ATSB strongly encourages compliance with service bulletins related to aircraft safety.
A ground strike accident involving an Ayres S2R aerial application aircraft at Trangie, NSW, on 31 August 2022 highlights the importance of aircraft operators ensuring all relevant service bulletins have been addressed.
The aircraft was about 100 m into its take-off roll, when its left main landing gear shock assembly failed, with the left wing hitting the ground, resulting in a ground loop. The pilot was uninjured.
An Australian Transport Safety Bureau short investigation subsequently identified the lower tube of the left shock strut assembly had failed at a fatigue crack.
Examining the damaged strut assembly at its technical facilities in Canberra, the ATSB determined the fatigue crack had initiated from the hole where the lower tube attached to the slider plate, and had propagated around the circumference of the tube.
“It is very likely this lower tube was a part that Thrush Aircraft – then Ayres Corporation – had instructed owners and operators to replace or modify in 1994, in accordance with a service bulletin,” ATSB Director Transport Safety Stuart Macleod said.
Thrush Aircraft informed the ATSB that writing on the lower tube which fractured was consistent with a part from pre-1994, and that the failure in this accident was consistent with the failures which prompted the service bulletin.
“Manufacturers issue service bulletins to inform owners and operators about critical and useful information on aircraft safety, maintenance, or product improvement,” Mr Macleod said.
The reason the part was not replaced or modified on the accident aircraft, in accordance with the service bulletin, was not identified.
Mr Macleod said the ATSB strongly encourages compliance with service bulletins that effect aircraft safety.
“Additionally, on acquisition of an aircraft, it is important to review maintenance documentation to determine whether all the appropriate manufacturer issued instructions have been addressed,” he concluded.
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