What happened
On 30 May 2020, a Mooney M2/M20K, registration G-OSUS, was conducting a private flight when the aircraft's baggage door became detached during level flight. Approximately 15 minutes into the flight, while passing over Membury Airfield in Berkshire, a loud impact occurred, causing the aircraft to pitch nose-down and roll to the right. The detached door had struck the right tailplane and remained wedged against the leading edge near the tip, creating significant drag and control difficulties.
The pilot declared a MAYDAY and performed an emergency landing at Membury Airfield. To maintain control despite the aerodynamic interference, the pilot flew at a higher speed than usual. The aircraft landed on Runway 13 and, despite an extended ground roll, the pilot successfully steered the aircraft into a clear area and brought it to a stop without further incident. There were no injuries to the two occupants.
The investigation
The AAIB examined the aircraft and found substantial damage to the right tailplane, including twisted structure and popped rivets. The investigation focused on the mechanism of the baggage door, which is secured by shoot bolts operated by an internal emergency handle.
Analysis of photographs taken prior to the flight revealed that the internal handle was actually in a partially open position while the aircraft was parked at a previous location. Investigators also examined the assembly of the secondary locking clip intended to prevent accidental operation of the internal handle. The investigation also reviewed maintenance records, noting that the interior trim had been removed for repainting in 2019, which required the disassembly of the handle mechanism.
Findings
- The safety clip for the internal emergency handle was incorrectly installed under the handle rather than over it, failing to secure the mechanism.
- The locking clip was bent, suggesting the handle had been forced into place over the clip.
- The clevis pin was loose in its mounting, making proper installation of the clip difficult.
- The internal handle was positioned such that it was not fully closed, which likely allowed the shoot bolts to disengaged during flight, possibly due to light turbulence.
- It could not be determined when the incorrect installation occurred or why the partially open handle was not detected during pre-flight checks.