What happened
On July 12, 2002, at approximately 18:00 local time, a PIPER PA-28RT-201, registration EC-HXO, was conducting a flight training mission at Son Bonet Aerodrome, Balearic Islands. The aircraft was occupied by an instructor, a student pilot, and a passenger. After performing several maneuvers and takeoff/landing cycles on runway 24, the crew prepared for a final approach to accommodate following traffic.
During the approach, the student pilot performed the landing checklist, which included the gear down command. However, as the aircraft touched down on the runway, the landing gear collapsed. The aircraft remained aligned with the runway centerline but slid approximately 30 meters along the asphalt before coming to a complete stop. The impact caused significant damage to the propeller, engine, lower fuselage, and the landing gear mechanisms and doors. All three occupants were uninjured.
The investigation
Investigators examined the aircraft's hydraulic system and landing gear functionality. They discovered that the hydraulic pump responsible for operating the landing gear had failed. When a replacement pump was installed, the gear functioned correctly. Tests simulating the failure confirmed that if the pump loses pressure while the gear is in transit, the gear remains in an intermediate position without locking down.
The investigation also revealed that the aircraft's automatic gear extension system was habitually disabled by the operator to prevent constant flashing of the 'override engaged' light. To further avoid the visual distraction, the bulb for the yellow warning light had been removed, and there was no documentation indicating this modification. Furthermore, while the instructor and student performed the checklist, they failed to verify the presence of the three green lights indicating the gear was down and locked.
Findings
- The primary cause of the incident was the failure of the hydraulic pump while the landing gear was in the middle of its extension cycle.
- The landing gear checklist was not executed correctly; specifically, the crew failed to verify that the three green lights were illuminated.
- The aircraft was being operated with the automatic extension system permanently disabled, a practice that was not documented in the aircraft's technical records.
- The removal of the 'override engaged' warning bulb was undocumented and contributed to a lack of situational awareness regarding the gear's status.
- The instructor's use of engine power during the final approach likely masked the audible gear warning horn during the critical moment of the failure.