On October 13, 2003, a Domeier RV-7A (registration N707DD) was involved in an aviation accident near Augusta, MO. Investigators recorded the probable cause as: The failure of the supercharger and alternator drive belts which resulted in foreign object damage to the valve timing system and subsequent loss of engine power, and the unsuitable terrain encountered by the pilot during the forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An airplane equipped with a converted Subaru engine nosed over during a forced landing after a complete loss of engine power. Postaccident examination revealed broken timing-belt cover and alternator and supercharger belts, with valve impact damage.
Accident Overview
The airplane sustained substantial damage when it nosed over during a forced landing. The forced landing was necessitated by a complete loss of engine power. The pilot reported that during the landing, the nose landing gear dug into soft sandy soil, causing the airplane to nose over.
Engine Details and Examination
The airplane was powered by a Subaru automobile engine that had been converted for aircraft use. A postaccident examination of the engine revealed several mechanical failures. The plastic timing-belt cover was broken, and both the alternator belt and the supercharger belt were found broken. Pieces of the alternator belt were discovered within the remaining portion of the timing-belt cover. Additionally, the engine's intake and exhaust valves had struck the top of the cylinders, indicating significant internal contact.
Conclusion
The investigation documented the physical evidence of belt and cover failures, as well as valve-to-cylinder contact, but did not assign a specific probable cause for the loss of engine power.