Primary finding
Probable cause
the in-flight separation of a portion of one wooden propeller blade due to undetected dry rot in the wood fibers.
Investigator assessment
Analysis narrative
According to the flight instructor, the aircraft was in cruise when a sudden severe vibration went through the airframe. The pilot shut down the engine and noted that the brass abrasion strip and part of one wooden blade had separated. The pilot landed in a field, but could not stop the aircraft before it went down an embankment and into a ravine. An airframe and powerplant mechanic who recovered the aircraft reported that he saw evidence of dry rot in the remaining wooden blade section.
Source record
Factual narrative
On March 23, 1996, at 1545 hours Pacific standard time, a Taylorcraft DC-65, N36354, collided with ground obstructions during a forced landing in hilly terrain near Fremont, California. The forced landing was precipitated by the separation of a portion of one of the wooden propeller blades during cruise flight. The aircraft was owned and operated by Amelia Reid Aviation of San Jose, California, and was engaged in a local area instructional flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft sustained substantial damage. The commercial pilot/flight instructor and the private pilot undergoing conventional gear aircraft training sustained minor injuries. The flight originated from the Reid-Hillview airport, San Jose, on the day of the accident at 1515. According to the flight instructor, the aircraft was in cruise when a sudden severe vibration went through the airframe. The pilot shut down the engine and noted that the brass abrasion strip and part of one wooden blade had separated. The pilot landed in a field, but could not stop the aircraft before it went down an embankment and into a ravine. An airframe and powerplant mechanic who recovered the aircraft reported that he saw evidence of dry rot in the remaining wooden blade section. -