What happened
On 2ly September 2001, during the Newcastle Airshow, a LET L-29 Delfin (registration ZU-AUW) was involved in an accident approximately 1.2 nm southwest of Newcastle aerodrome. While performing aerobatic maneuvers, the pilot encountered acrid smoke filling the cockpit. In response to the emergency, the pilot attempted to land on Runway 29. However, due to the smoke obscuring visibility and the aircraft's excessive airspeed upon touchdown, the pilot initiated a go-around to avoid potential collisions with other aircraft on the field.
As the aircraft climbed to roughly 200 ft AGL, the pilot jettisoned the forward canopy to alleviate breathing difficulties. Immediately following the removal of the canopy, a fire broke out in the forward nose section. The pilot was forced to perform an emergency landing in an open field. During the descent, the aircraft struck a tree and severed electrical lines before coming to a halt 202m past the impact point. The aircraft sustained substantial damage to the nose, empennage, and right-hand wing. The pilot survived the crash but sustained serious burn injuries.
The investigation
Investigators examined the aircraft's nose compartment to determine the origin of the fire. The inquiry focused on the electrical systems and the movement of components within the forward section of the LET L-29 Delfin.
Findings
- The primary cause of the in-flight fire was an air-recharge hose migrating from its protective bag.
- This movement caused the hose to create a short-circuit across the exposed terminals of one of the two 12V batteries located in the nose.
- The resulting short-circuit generated intense heat, which burned the hose's sleeve material.
- This heat likely caused secondary damage to nearby wiring and components, and potentially heated hydraulic couplings, which may have released flammable hydraulic fluid into the fire.