On September 27, 1990, a Mooney M20E (registration N7197U) operated by Lloyd Crandall was involved in an aviation accident near Morrison, IL. Investigators recorded the probable cause as: Failure of a propeller blade due to a fatigue crack that originated from a reworked leading edge. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During cruise flight, a propeller blade failed, causing severe vibration. After engine shutdown, the airplane made a forced landing; the landing gear collapsed and the airplane slid into a dirt bank. Fatigue crack found on remaining blade portion.
Accident Overview
An airplane experienced an inflight failure of a propeller blade while operating at cruise. According to the pilot, a severe vibration began, and reducing engine power did not alleviate it. The vibration ceased only after the pilot shut down the engine and raised the nose to stop the windmilling propeller.
Forced Landing and Damage
The pilot conducted a forced landing. Upon touchdown, the landing gear collapsed, and the airplane slid into a dirt bank.
Post-Accident Examination
Examination of the remaining portion of the failed propeller blade revealed a fatigue crack on the fracture surface. The crack extended from the leading edge to a point 3-1/4 inches measured in the chordwise direction. The leading edge of the blade had been reworked by filing or grinding.
Probable cause
Failure of a propeller blade due to a fatigue crack that originated from a reworked leading edge.