What happened
The pilot reported experiencing a partial electrical system failure that progressed to a total loss of electricity while the aircraft was in cruise flight. With no power available for systems or instruments, the pilot initiated an off-airport emergency landing on a wet, grassy field. During the rollout, the pilot was unable to bring the aircraft to a stop before it slid into a nearby culvert.
The investigation
A physical examination of the airplane revealed that both belts for the accessory drive were missing from the engine area. The absence of these critical components caused the electrical system failure that precipitated the emergency landing sequence.
Findings
The investigation determined that the loss of both accessory drive belts was the primary mechanical issue. This failure resulted in the total electrical outage, which limited the pilot's options and contributed to the difficulty of stopping the aircraft on the wet surface.