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Final report

Summary

What happened

On 9 December 2013, the pilot/owner of an amateur-built Stoddard-Hamilton Glasair III aircraft, registered VH-USW and operated in the ‘experimental’ category, was conducting a local flight from Jandakot Airport, Western Australia with a passenger on board.

Shortly after take-off, when about 2 km from the airport, the aircraft’s engine stopped without warning. During the ensuing forced landing onto a sports oval, the aircraft’s left wing detached from the fuselage after striking a metal goal post. Fuel from the ruptured left wing fuel tank ignited as the aircraft tumbled across the ground.

The pilot and passenger sustained serious burns and were taken to hospital. The aircraft was destroyed by impact forces and an intense post-impact fuel-fed fire.

Photograph of Stoddard-Hamilton Glasair III, VH-USW

Stoddard-Hamilton Glasair III, VH-USW

 

 

 

 

 

Source: Aircraft owner

What the ATSB found

During the aircraft’s construction, modification of the electronic ignition system incorporated a single point of failure in the intended dual system, increasing the risk of the simultaneous failure of both systems and a total loss of engine power. In addition, the connector plug used for the modification was inappropriate for the in-line installation, increasing the risk of its disconnection and disabling the ignition system.

Examination of the engine found that the single wiring harness for the ignition system was disconnected from the connector plug. However, due to the level of impact and fire damage sustained by the aircraft, the ATSB was unable to conclusively establish if this occurred inflight, resulting in the total engine power loss, or during the early stages of the impact sequence.

Safety message

The aviation industry has long recognised the need for redundant systems, particularly those relating to safety-critical components. The ATSB cautions that, even if unintended, the incorporation of a single point of failure into such systems during construction or modification can eliminate all levels of redundancy. In this case, damage to the aircraft’s modified single wiring harness resulted in the failure of an otherwise redundant system, with near-fatal consequences.

 

The occurrence

Context

Safety analysis

Findings

Sources and submissions

 
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