MELBOURNE — Australia’s fleet of Black Hawk combat helicopters returned to the skies Jan. 24 after being temporarily grounded Jan. 20 over safety concerns surrounding fractured bolts.
The defect was found during routine maintenance of an Army S-70A-9.
The defective bolts were found on the drive shaft between the engine and transmission, and a fleetwide suspension of flying was ordered following concerns that all power could have been lost to the engine if the bolts failed entirely.
The Black Hawk is a twin-engined helicopter.
The only helicopters allowed to operate during the period were three assigned to Joint Task Force 631 in Timor Leste to provide emergency aero-medical evacuations for International Stabilization Force personnel if required.
The Royal Australian Navy’s 16 S-70B-2 Seahawks were not affected by the grounding order.
Speaking at the time, Col. Stephen Evans, acting director general Aviation, said, “The precautionary suspension will remain in place to allow an investigation into the cause of the fracture to be completed.”
During the investigation, Chris Clapperton, director of Maritime and Asia Strategies for Sikorsky Aerospace Services, noted, “The bolt that failed is a general aviation hardware bolt that is not manufactured by Sikorsky; we are assisting the Australian Army with their investigation into the cause of the failure.”
In an announcement that flying would resume Jan. 24, Maj. Gen. Michael Slater, commander of Forces Command (Army Operational Airworthiness Authority), said, “The engineering investigation has indicated the defective bolts were confined to a single manufacturer’s batch and were not a fleetwide issue. The defective batch of bolts has been quarantined from use.
“The precautionary suspension has been lifted following airworthiness advice from the Technical Airworthiness Authority. The suspension demonstrates Army’s commitment to safety. The temporary safety precaution was affected while a thorough engineering investigation was carried out following discovery of the defective bolts.”
Australia has 34 Black Hawks, including the three in Timor Leste, but the type is being replaced by the European MRH 90 Multi-Role Helicopter, being assembled in Australia by Eurocopter subsidiary Australian Aerospace.