What happened
On January 30, 2012, a Cessna 150, registration F-OGVK, departed from the Saint-François aerodrome in Martinique for a flight instruction session. During the initial climb, at an altitude of approximately 300 feet, the instructor noticed a drop in engine RPM followed by fluctuations. The instructor took control of the aircraft but determined that environmental conditions were unsuitable for a landing aligned with the runway centerline. Consequently, the instructor initiated a right turn to establish a suitable landing pattern.
While on the downwind leg, the engine power decreased further, prompting the instructor to attempt a landing against the wind. The aircraft touched down mid-runway. Despite the instructor applying maximum braking, the aircraft overran the runway longitudinally. Upon reaching the grassy area, the aircraft crossed a ditch and subsequently capsized. The student occupant sustained slight injuries, while the aircraft was heavily damaged.
The investigation
The investigation focused on the mechanical state of the engine and the airfield environment. Investigators noted that the instructor was unaware of the ditch's location, which was situated 83 meters from the runway threshold, outside the runway safety area designed to mitigate damage during excursions. While the instructor had approximately 3,870 total flight hours, the investigation could not confirm if a full engine run-up had been performed prior to the flight.
Technical examinations of the engine revealed significant electrical issues. Specifically, the magneto cables showed unsatisfactory continuity and physical condition. Furthermore, the spark plugs were found to be malfunctioning, exhibiting abnormal wear in the form of ovalization on the center electrodes.
Findings
- The primary cause of the power loss was a malfunction within the engine's ignition system.
- The ignition system defects, including faulty magneto cables and worn spark plugs, had not been detected during the previous 100-hour inspection, which had been completed only six days prior to the accident.
- The presence of a ditch outside the runway safety area contributed to the severity of the accident when the aircraft overran the paved surface.