What happened
On December 1, 2007, a Reims Aviation F 177 RG (registration F-BVIY) was on long final approach to runway 23 at Bordeaux Mérignac airport. During the landing sequence, the pilot deployed the landing gear, but the green indicator light failed to illuminate. After consulting with air traffic control, who suggested the gear appeared to be down, the pilot attempted to cycle the gear while flying a downwind leg. However, the green light remained unlit, and only the amber warning light functioned.
After an unsuccessful attempt to swap the indicator bulbs, the pilot declared a precautionary landing. During the touchdown, the nose gear retracted, causing the propeller to strike the runway. The aircraft slid approximately 100 meters along the runway before coming to a halt. There were no fatalities or injuries to the two occupants, but the aircraft sustained significant damage to the nose gear, propeller, and engine.
The investigation
The investigation focused on the mechanical failure of the nose gear and the failure of the cockpit warning systems. Investigators found that the linkage connecting the nose gear strut to the gear door had become detached. Specifically, the attachment point on the gear door was heavily worn and had broken. Additionally, it was discovered that the gear door had been obstructed by a grease fitting on the strut during the extension sequence.
Regarding the cockpit instrumentation, the investigation established that both the green and amber lights were functional. However, a broken ground wire prevented the green light from illuminating during the pilot's test. While the audible warning alarm was operational, its volume was noted to be insufficient for easy detection.
Findings
- The primary cause of the gear collapse was the mechanical failure of the linkage attachment point due to excessive wear.
- The pilot misdiagnosed the nature of the gear malfunction, failing to utilize the emergency gear extension procedure.
- Maintenance oversight contributed to the accident, as the maintenance manager had identified abnormal play in the linkage but had only scheduled its inspection for a future 50-hour maintenance interval.
- The existing maintenance protocol, which relies on visual inspections, was insufficient to detect the internal wear of the attachment point without removing the lower engine cowling.
- The aircraft had flown 1,275 hours since the last time any components of the gear mechanism had been replaced.