On May 29, 1996, a Schweizer G164B (registration N48559) was involved in an aviation accident near Moscow, ID. Investigators recorded the probable cause as: inflight loss of an unsecured access plug from the engine crankcase, which resulted in a loss of engine oil and a forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an agricultural application flight, the windscreen became obscured by smoke and oil. The pilot attempted a forced landing on a ridge top, resulting in substantial damage. Investigators found a missing access plug on the engine crankcase.
Accident Overview
A pilot conducting an agricultural aerial application flight reported that the windscreen suddenly became obscured by smoke and oil. Operating over hilly terrain with poor forward visibility through the windscreen, he attempted a forced landing on a ridge top. The airplane sustained substantial damage during the forced landing.
Pilot Report
The pilot stated that the windscreen obscuration occurred unexpectedly while flying over hilly terrain. With limited forward visibility, he chose to attempt a forced landing on a ridge top. The outcome of the landing resulted in substantial damage to the aircraft.
Examination Findings
FAA inspectors examined the airplane after the accident. They reported finding an access plug missing from the front of the crankcase of the aircraft's Pratt & Whitney R-1340 radial engine. No further information about the cause or circumstances was provided by the source.