What happened
On 14 September 2008, a DH82A Tiger Moth, registration G-AHVV, was operating at Dunkeswell Airfield in Devon. During the flight, the aircraft experienced issues related to the engine's ignition system. The pilot reported irregularities in the engine's performance involving the magnetos.
The investigation
Following the incident, the operator conducted an internal investigation. Testing of the magnetos revealed significant faults. One magneto ceased producing sparks entirely when the timing was advanced, while the second magneto exhibited inconsistent performance, fluctuating between zero and three sparks. A detailed strip examination of both components determined that the failures were caused by oil contamination and the breakdown of the coils due to heat exposure.
Findings
- The primary cause of the ignition failure was oil contamination within the magnetos.
- Heat-induced breakdown of the magneto coils contributed to the malfunction.
- The investigation established that the timing advancement directly impacted the spark output of the faulty units.