Incident Report
During a short cross-country flight, the pilot reported that the flight was normal until he descended and leveled off at 3,500 feet. At that point, he noticed the oil pressure gauge indicating zero. After crosschecking instruments, the cylinder head temperature and oil temperature were within normal ranges, and the engine continued to run smoothly. The pilot began searching for possible landing sites and turned east toward fields seen in the distance.
Approximately two minutes later, the engine experienced an rpm surge, which the pilot interpreted as a sign of true oil loss. Within a minute, the engine stopped. The pilot executed an emergency landing in a field, during which the aircraft collided with logging debris.
Investigation Findings
An FAA inspector and an A&P mechanic examined the engine and discovered that a flexible oil gauge pressure line, running from the engine to the firewall, had separated. The oil line was found to have been installed with only about three-quarters of its length inserted into the fitting, leaving just three threads to secure the ferrule and B-nut. The B-nut socket showed no signs of wear.
Further review of maintenance records indicated the oil gauge pressure line had been replaced on July 20, 2001, at an engine tachometer time of 5,694.15 hours and a Hobbs time of 1,067.9 hours. The line had accumulated approximately 63.05 service hours before failure.