What happened
On September 26, 2010, at 18:00 UTC, a Westland Gazelle HT.Mk2, registration G-TIZZ, was preparing for a visual flight from Loulé to Almancil. The pilot had personally refueled the aircraft prior to departure. During the takeoff roll at the Miguel Barros Heliport, the helicopter ascended several meters; however, while the pilot was performing a hover to transition toward the destination, the engine suffered a sudden and complete failure. This loss of power caused the aircraft to descend rapidly, resulting in a severe landing.
There were no injuries to the pilot or any third parties, and no damage was caused to property on the ground. The aircraft sustained significant damage to its landing gear structure.
The investigation
The GPIAAF investigation focused on the circumstances surrounding the engine failure. During the post-incident inspection of the aircraft, investigators identified that the fuel tank filler cap was missing. The fuel filler neck is located in an area positioned slightly forward and below the engine's turbine air intake.
Investigators examined the possibility that the pilot had either failed to replace the cap after refueling or had failed to tighten it sufficiently. While the investigation considered whether foreign object debris (FOD) from the rotor blades could have been the cause, no impact damage from external objects was found on the main rotor.
Findings
- The engine failure was caused by the ingestion of fuel into the turbine air intake.
- It is determined that fuel had spilled near the filler neck during the refueling process.
- The suction force generated by the turbine air intake during takeoff power application drew the spilled fuel into the engine, leading to a compressor stall and subsequent engine shutdown.