NTSB Factual Report

On February 17, 2001, at 1235 central standard time, a Piper PA32-R-301T single-engine airplane, N8355L, was substantially damaged during a forced landing following a loss of engine power near Haslet, Texas. The airplane was registered to a private individual and operated by Hest Aviation of Temple, Texas. The commercial flight instructor and pilot-rated passenger were seriously injured, and one passenger sustained minor injuries. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The flight originated from Killeen, Texas, at 1145, and was destined for the Fort Worth Alliance Airport, Fort Worth, Texas.

According to the pilot's written statement, the airplane was approximately 40 minutes into the flight and 4 miles south of the destination airport, when the "propeller increased to maximum RPM. Shortly thereafter, the oil pressure light illuminated." The pilot added that he noticed the oil pressure gauge was indicating "zero." The pilot performed the emergency checklist and notified air traffic control of the emergency. Subsequently, the engine "seized," and the pilot elected to land in a field approximately 2 miles south of the runway 34L threshold. The airplane touched down on the soft ground, separating its landing gear. The airplane came to rest upright.

Examination of the airplane by the FAA inspector, who responded to the accident site, revealed that the fuselage was buckled and both wings were damaged. The engine was checked for oil and none was found. The wreckage was taken to Air Salvage of Dallas, Lancaster, Texas, for further examination.

On April 26, 2001, the NTSB investigator-in-charge and an engine manufacturer representative examined the Lycoming TIO-540-S1AD engine (serial number L-7631-61A). During the examination of the engine, it was noted that the engine oil dipstick did not indicate an oil quantity and the propeller could not be rotated. The oil filter and the oil filter converter plate were removed, and it was noted that the oil filter's interior element was collapsed inward, and the oil filter converter plate gasket was found separated from the plate and broken in half. The oil filter, oil filter converter plate, and the oil filter converter plate gasket were sent to the engine manufacturer's facility for further examination.

According to the engine manufacturer, the oil converter plate gasket part number could not be determined; however, their materials laboratory determined that the rubber gasket material was "non-conforming." It was also noted that the gasket "had not been glued to the surface of the oil filter converter plate." According to Textron Lycoming Service Instruction (SI) 1453, dated May 9, 1991, the oil filter converter plate gasket must be bonded to the converter plate using 3M Scratch Grip Industrial Adhesive No. 847. The manufacturer reported that it was possible that the collapsed oil filter element could have occurred "due to a sticking oil filter bypass valve."

On July 11, 2001, an NTSB investigator and an engine manufacturer representative examined the engine's oil filter bypass valve. The valve was removed and examined. It was noted that the valve was installed incorrectly. According to Textron Lycoming SI 1442, the oil filter bypass valve is composed of 5 pieces; a spacer (part number 55K21022), a spring (part number 55C21021), a seat (part number 76539), a sleeve (part number LW-10320), and a ring (part number MS16625-1100), installed in that order. During the examination, the seat was found located in front of the spacer, which according to Lycoming, would have prevented the proper operation of the oil filter bypass valve. According to Textron Lycoming, if the oil filter bypass valve fails to operate, the oil filter element could collapse during a cold weather and/or high RPM start with cold oil.

According to the aircraft maintenance records, the engine was field overhauled and re-installed on the accident airplane on June 25, 1992, at a tachometer time of 1,317.2 hours. On February 3, 1997, the oil filter converter plate gasket was replaced at a tachometer time of 2,017.0 hours (699.8 hours since the 1992 overhaul). At the time of the accident, the engine had accumulated approximately 981 hours since its last overhaul.

NTSB Probable Cause

the improper installation of the oil filter bypass valve by an unknown person, which resulted in the loss of engine oil and subsequent loss of total power during a normal descent. A contributing factor to the accident was the lack of suitable terrain for the forced landing.