The pilot was accompanied by two friends on a local flight to view a property in the South West Rocks area. About twenty minutes after take off, the engine commenced to run roughly and lose power. The pilot carried out a trouble check which revealed the left magneto had failed. Whilst the pilot was attempting a forced landing the engine stopped, the aircraft collided with trees before coming to rest in a semi-inverted attitude. The pilot and passengers were able to vacate the aircraft without assistance. Post accident testing of the ignition system revealed that both magnetos were unserviceable because of age deterioration of the insulation around the transformer coils. The failure of both magnetos resulted in the loss of engine power. A service bulletin was issued by the magneto manufacturer in 1973 which recommended replacement of the transformer coils in the type of magneto fitted to VH-DLT. The aircaft maintenance records show the magnetos were repaired and tested in 1985 but the transformer coils were not replaced as recommended by the service bulletin.
