What happened
On 26 August 1999, a Piper PA-44-180 Seminole, registration G-TWIN, was conducting a refresher flying session at Bournemouth International Airport. The flight involved two crew members and resulted in no injuries.
The aircraft had been involved in a previous incident where the left main landing gear failed to indicate as locked down, necessitating an emergency landing. Although maintenance personnel had performed retraction tests and released the aircraft as serviceable, the same issue recurred during the subsequent flight. After takeoff, the gear retracted normally, but during the approach for landing, the left main gear light remained extinguished and the gear unsafe light illuminated.
The pilot attempted several troubleshooting steps, including checking for bulb failures, cycling the gear, and resetting circuit breakers. After consulting with the maintenance organisation and performing the manual gear extension procedure, the cockpit indications did not change. Although an air traffic controller reported that the wheels appeared visually down during a fly-past, the pilot proceeded with the landing.
To mitigate potential damage, the pilot shut down the left engine and motored the propeller in line with the wing. Upon touchdown, the left gear initially supported the aircraft's weight, but as the speed decreased, the gear collapsed. This caused the aircraft to slew off the left side of the runway, with the left wingtip eventually making contact with the tarmac, causing damage to the wingtip, aileron, and flap.
The investigation
The investigation focused on why the landing gear indication failed despite recent maintenance checks. Investigators examined the landing gear mechanism and identified the specific components responsible for the malfunction.
Findings
- The investigation established that the landing gear indication failure was caused by a seized bush and bushing bracket.
- A contributing factor was a blocked grease nipple, which prevented proper lubrication of the assembly.