Aircraft and Flight Details
The aircraft, a Piper PA-31 (registration G-OPRA), was manufactured in 1967 and powered by two Lycoming TIO-540-A1B piston engines. It was operating a public transport (passenger) flight with one pilot and two passengers on board. The pilot held a Commercial Pilot's Licence with an Instructor Rating and had accumulated 2,017 flying hours, including 545 hours on type.
Incident Sequence
On 5 April 1999 at approximately 1446 hrs UTC, while on approach to Blackpool Airport with about 10 nautical miles to run, the pilot selected the landing gear down. The nose and right main landing gear indicated green (down and locked), but the left gear showed a red 'gear unsafe' light. The pilot attempted to reselect the gear up, but the handle could not move past the horizontal (neutral) position.
A flypast of the tower confirmed that the left main landing gear inboard door was down, but the left gear leg had not extended. After several unsuccessful attempts to raise the gear, the pilot initiated the emergency gear lowering procedure. Further flypasts and two touch-and-go circuits were conducted in an effort to unlock the left gear leg.
Emergency Landing
With fuel quantity decreasing and following engineering consultation, the pilot decided to land. He shut down the left engine, feathered the left propeller, and used the starter motor to align the blades horizontally. An asymmetric circuit was flown, and before landing, the pilot instructed the passengers to brace. The touchdown occurred on the right main and nose wheels; the pilot shut down the right engine and held the left wing tip up as long as possible. Eventually, the left wing contacted the runway, and the aircraft was steered onto the grass.
Engineering Investigation
Post-accident engineering examination revealed that the left main landing gear oleo had deflated due to a seal that had rolled instead of sliding down the fescalised portion of the ram. The reduced length of the oleo prevented the uplock mechanism from releasing. The oleo seal had been changed approximately one month before the incident.
Outcome
No injuries were reported among the pilot or passengers. The aircraft sustained damage to the left wing and landing gear door.