On June 4, 2006, a Piper PA-28R-200 (registration N4438T) was involved in an aviation accident near Alpine, CA. Investigators recorded the probable cause as: a loss of engine power due to the aviation maintenance technician's failure to install the correct oil sump quick drain, which resulted in the inadvertent draining of engine oil during flight. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an instructional flight, the engine lost oil pressure and RPM fluctuated. The instructor shut down the engine and performed a forced landing. Investigation revealed an unapproved oil sump quick drain valve with excessive extension.
Accident Details
Approximately 50 minutes into a local instructional flight, the instructor and student experienced a decrease in oil pressure accompanied by fluctuating engine revolutions per minute (RPM). The instructor shut down the engine and executed a forced landing. The airplane sustained damage during the encounter with rough terrain.
Background and Maintenance
The oil sump quick drain valve had been replaced on the day of the accident. On the first flight following the replacement, 2 quarts of oil were lost. An aviation maintenance technician subsequently retorqued the valve, and a maintenance test flight was completed successfully before the accident flight.
Findings
Examination revealed that the installed oil sump quick drain valve, a Safe-Air 5000, had an extension of 1.9 inches. The approved Piper quick drain valve (Piper part number 492-172V) has an extension of 0.21 inch. Airworthiness Directive 81-11-02 R1 specifies that unapproved drain valves can cause inadvertent draining of oil when the landing gear is retracted and mandates that only Piper approved parts be used for the oil sump quick drain installation on this airplane model.