What happened
On Saturday, December 18, 2010, an instructor and a student prepared for a local flight at Lyon Bron Airport. During the startup sequence, the instructor performed three fuel injections, but the engine failed to start. A second attempt involving two additional injections also proved unsuccessful, and a third attempt failed as well. Noticing a low battery charge, the instructor decided to cancel the flight.
Upon exiting the Reims Aviation F152, the occupants discovered that the engine compartment was on fire. The instructor immediately closed the fuel valve, disconnected the battery, and retrieved a fire extinguisher from a nearby hangar to extinguish the flames. The aircraft sustained heavy damage.
The investigation
The investigation focused on the startup procedures used during the sub-zero temperatures recorded at the time (-5 °C). The instructor stated that he followed the cold-weather startup procedures outlined in the flight manual (Section 4.22), which recommend manual propeller pulling and performing two to four simultaneous fuel injections.
Investigators determined that during the repeated failed start attempts, fuel had accumulated within the heater box and the engine cowling. This accumulation was likely ignited by an exhaust backfire.
Findings
- The primary cause of the accident was the incomplete application of the cold-weather startup procedure, specifically the failure to manually pull the propeller.
- Fuel accumulation in the engine compartment and heater box provided the fuel source for the fire.
- An exhaust backfire likely acted as the ignition source.