On June 4, 2005, a Grumman G-164B (registration N6832K) operated by O'brien Flying Service, Inc. was involved in an aviation accident near Lake Charles, LA. Investigators recorded the probable cause as: Failure of the propeller governor pilot valve, resulting in an internal oil leak and failure of the propeller governor. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot with 19,000 hours reduced propeller RPM after takeoff, causing the propeller to go to full coarse and lose drive. During a forced landing, the airplane struck a power line and impacted terrain. Investigation revealed a failed propeller governor pilot valve.
Incident Overview
Following takeoff and after initiating a left turn to return to the field being sprayed, the pilot—who had accumulated 19,000 flight hours—reduced the propeller RPM. Subsequently, the two-bladed propeller "went to the full coarse setting and lost drive."
Forced Landing and Impact
During the ensuing forced landing, the airplane struck a power line and then impacted terrain. The sequence of events directly resulted from the loss of propeller drive.
Examination Findings
A post-incident examination of the propeller governor by a repair facility revealed that the "propeller governor pilot valve had failed, causing an internal oil leak, which resulted in the failure of the propeller governor." No other causal factors were identified in the available information.
Probable cause
Failure of the propeller governor pilot valve, resulting in an internal oil leak and failure of the propeller governor.