What happened
On July 12, 2007, an Aerospatiale AS 350B1 helicopter, registered as EI-IHL, crashed in a field near Ballynacally, County Clare. The aircraft, operated by Irish Helicopters Ltd, was performing routine aerial work involving the inspection of a gas pipeline under contract for a gas supplier. While flying at a low altitude, the helicopter struck the ground in farmland located west of the village. The accident resulted in one fatality among the two crew members on board; the observer seated in the left-hand position died, while the other crew member survived.
The investigation
The Air Accident Investigation Unit (AAIU) recovered the wreckage and transported it to their facility in Gormanston, County Meost. As part of the technical analysis, the aircraft's single Arriel 1D turbine engine was sent to the manufacturer's facility in Tarnos, France, for specialized inspection under AAIU supervision. Investigators examined the transmission shaft and the accessory gearbox, where they discovered that a bevel gear within the accessory drive train had disintegrated.
Findings
Technical examination established that the disintegration of the bevel gear within the accessory drive train was the primary mechanical failure. This structural failure had the immediate consequence of cutting off the fuel supply, which led to the engine stopping within seconds of the event. While the specific reason for the gear's disintegration remains under investigation, its impact on the engine's operation was the direct catalyst for the crash.
Safety action
Recognizing the heightened risks inherent in low-altitude aerial work, the AAIU issued Interim Safety Recommendation SR No. 13 of 2007. This recommendation calls upon the Irish Aviation Authority to evaluate whether single-engine helicopters are appropriate for low-level operations when conducting aerial work under specific permits.