Background
The helicopter, an AS 350 B1 registered D-HAUX, was based at Covilhã aerodrome. During the night of 1–2 August 1996, a scheduled 200-hour inspection was performed by a qualified mechanic. On the morning of the accident, the pilot, who had accumulated approximately 51 flight hours in the current firefighting campaign, conducted a 10-minute ground run-up after the inspection. At around 09:30, a fire call was received, and firefighters boarded the helicopter. After completing pre-departure checks and receiving a positive indication from the mechanic after a 360° external inspection, the pilot departed for a forest fire on the northwest slope of Serra da Estrela, near Sabugueiro.
The Flight
Upon arrival, the pilot began firefighting operations, replacing another helicopter that had left for refuelling. Water was initially obtained from a small lake, then from a canal approximately 50 metres from the fire. The pilot hovered while a firefighter helped fill the bucket. During these bucket runs, a firefighter reported a dark stain on the right side of the helicopter. The pilot decided to land near the canal to inspect. When attempting to release the empty bucket, the electrical release system failed because the mechanic had placed adhesive tape over the electrical connectors as a temporary solution. The pilot performed a partial landing on the sloping ground. After learning that the stain was on the right fuselage below the main transmission fairing, and uncertain of its origin, the pilot aborted the mission, loaded the firefighters, and initiated a return to Covilhã.
Emergency and Crash
About five minutes after departing the fire site, and two minutes from landing at Covilhã, with the aerodrome in sight, the red engine oil pressure warning light (ENG.P) illuminated. The pilot immediately declared an emergency to the forest fire support radio station at Covilhã. Halfway to the aerodrome, the turbine lost power. Caution and warning lights for low rotor RPM and low hydraulic pressure came on, accompanied by an audio alarm. The pilot entered autorotation toward a suitable area but, after a trajectory correction, the helicopter struck the roof of a vehicle parking and repair facility. The accident occurred at 11:05 local time. The roof was made of asbestos tiles.
Investigation
The investigation established the sequence of events as described in the official report. No probable cause was stated in the available report.