What happened
On 6 January 2001, a Piper PA-28RT-201, registration N83196, was returning to Shoreham Airport following a local flight. During the approach, the pilot attempted to extend the landing gear but noted that the green light for the left main gear failed to illuminate. Despite following established checklist procedures and cycling the gear, the indication remained missing. After performing a low fly-by of the control tower, the pilot received visual confirmation from the tower that the gear appeared to be in the normal position.
Upon landing on Runway 21, the left main landing gear collapsed. This caused the left wing tip to strike the runway, resulting in the aircraft veering off the left side of the runway and coming to a stop on the soft grass. There were no injuries to the pilot. The aircraft sustained damage to the left aileron and flap, and the airfield fire crew attended the scene to apply foam to the left wing.
The investigation
Investigators examined the aircraft's hydraulic landing gear system, which utilizes an electrically powered pump and downlock switches to indicate the gear is locked. During the recovery process, the aircraft was jacked, and the gear was manually locked. However, subsequent testing replicated the failure, as the left main gear would not lock in the down position.
An inspection of the downlock and squat switches revealed slightly corroded terminals. While new terminals were installed, further investigation into the landing gear control circuit wiring identified a broken wire located within the fuselage. This break specifically affected the circuit connecting the left landing gear downlock switch to the hydraulic pump.
Findings
- The primary cause of the gear failure was a broken wire in the landing gear control circuit located inside the fuselage.
- This electrical break caused the hydraulic pump to shut off prematurely once the nose and right main gears had successfully locked, preventing the left gear from completing its extension.
- Corroded terminals were also present on the downlock and squat switches.