Incident Summary
On 13 January 2005 at 1623 UTC, a Piper PA-24-260 Comanche, registration G-BRXW, sustained damage to its underside, landing gear, and propeller during a landing at Coventry Airport, West Midlands. The aircraft was on a private flight with one pilot and one passenger; neither was injured. The damage was described as possibly beyond economic repair.
Aircraft and Pilot Details
The aircraft was manufactured in 1964 and powered by a single Lycoming O-540-E4A5 piston engine. The pilot, aged 72, held a Private Pilot's Licence and had 181 hours of flying experience, all on type. His flying in the previous 90 days totaled four hours, with none in the last 28 days.
Sequence of Events
The pilot had flown to Leicester earlier that day without issues. While returning to Coventry, he selected landing gear DOWN on approach, but the gear stopped when approximately half-extended. The landing gear motor circuit breaker had tripped; each reset attempt caused it to trip again. A fly-by of the control tower prompted the controller to report that the nose gear did not appear in the locked-down condition.
The pilot proceeded to the Visual Reference Point at Draycot Water to deploy the manual free-fall mechanism, but that was also unsuccessful. He then spoke with his usual engineer via radio, who offered no further advice. After orbiting Draycot Water for about 50 minutes to burn fuel and allow the low sun glare to diminish, he positioned for an approach to Coventry Airport. Air Traffic Control had suggested landing on the grass section of the northern taxiway. With full flap and some power applied, upon touchdown all three landing gears collapsed, and the aircraft slid to a stop. The pilot and passenger evacuated normally without injury; there was no fire and no apparent fuel leaks.
Examination of Aircraft
The PA-24 uses a single electric motor connected to a transmission that converts rotary motion to linear movement, acting on Bowden-type cables for the main gears and a rod for the nose gear. A manual release lever is provided to disconnect the transmission from the motor, allowing gear free-fall. Investigation revealed that the landing gear motor relay had developed an internal short circuit, causing the circuit breaker to trip and stopping the motor. The actuating system sustained considerable damage due to landing loads feeding back into it; the manual release mechanism could not be operated. The maintenance company opined that the unusual semi-extended gear position may have generated forces that made mechanical release difficult or impossible.
The circumstances resembled those of a previous PA-24 incident (G-BUTL, 15 October 1998, reported in AAIB Bulletin 5/99). In that case, the motor circuit-breaker also tripped with gear partially extended, and free-fall was unsuccessful. The earlier investigation suggested a restriction in a main gear operating cable might have caused high forces stalling the motor and preventing free-fall; it was not known whether the motor relay was checked then, though the motor was found serviceable.