Piper PA 28R-200 N5469T accident near Santa Maria, California

Probable cause

The engine failure due to oil starvation, which resulted from the installation of an unapproved oil quick drain valve that subsequently led to the inadvertent draining of the oil when the nose landing gear was retracted. Contributing to the accident was the lack of required warning placards on the engine mounts.

NTSB analysis

The pilot reported that, during climbout, while the airplane was about 3,500 ft mean sea level, the engine lost partial power. He then turned the airplane back toward the airport. Shortly thereafter, the engine lost all power, and the pilot chose to initiate a forced landing to a nearby field about 4 miles southeast of the airport.

During postaccident examination of the engine, two cracks were observed on the upper portion of the engine crankcase near the No. 2 cylinder mounting surface. The crankshaft would not rotate by hand. Oil residue was observed on the left lower portion of the engine cowling and on the airplane's belly. A minimal amount of oil was observed in the oil filter and oil sump.

Review of the airplane's maintenance records revealed that an oil quick drain valve was installed on the engine 2 days before the accident. An aircraft manufacturer service letter (SL) and an airworthiness directive (AD) had been issued about 14 years before the accident to inform maintenance personnel about which oil quick drain valve should be installed on the accident make and model airplane. The SL provided a sketch of both the incorrect and correct oil quick drain valves, and the AD provided the approved part number. Examination of the engine revealed that the incorrect oil quick drain valve was installed on the engine. When the nose landing gear (NLG) assembly was actuated into its up-and-locked position, the bolt connecting the NLG assembly struck the oil quick drain valve, and several impact marks were present. It is likely that this damage resulted in the loss of oil and subsequent oil starvation to the engine.

The AD also required that two warning placards be installed, one on each side of the engine mounts, stating that unapproved oil quick drain valves can cause inadvertent draining when the gear is retracted and to use only the manufacturer-approved part to prevent the loss of oil due to the installation of an incorrect oil quick drain valve. No placards were observed on the engine mounts.

Text from the NTSB. Open the NTSB docket for WPR15LA141 for the full record.