What happened
On 16 October 2004, a Mooney M20J, registration G-EKMW, departed Jersey Airport for a private flight. Shortly after takeoff from Runway 27, the pilot reported an engine emergency, noting that the engine was running rough. During the subsequent attempt to turn back to the airfield, the aircraft experienced a loss of power, entered a nose-low attitude, and impacted the ground in a shallow valley near the airfield boundary. The impact caused the aircraft to catch fire, and the single fatality was the pilot.
The investigation
The AAIB investigation focused on the engine's performance and recent maintenance history. The aircraft had undergone a 500-hour inspection six days prior to the accident. Investigators examined the wreckage and found that the engine's dual magneto system had been recently refitted. Examination of the engine components revealed that the magneto's cam retaining screw had not been properly tightened. Furthermore, the investigation identified that the maintenance organisation was using an outdated version of the service manual, which contained errors and omissions regarding the reuse of certain components.
Findings
- The engine malfunction was caused by a failure in the ignition system.
- A loose cam retaining screw within the magneto led to incorrect ignition timing, causing the engine to misfire.
- The maintenance technician likely missed the final tightening of the screw due to a lack of pre-planned process sheets and potential distraction.
- The use of an outdated maintenance manual prevented the identification of incorrect procedures during the 500-hour inspection.
- The aircraft's impact speed was significantly higher than its stall speed, and the terrain offered no suitable area for an emergency landing.