On March 4, 1995, at 0838 Pacific standard time, a Mooney M20J, N11385, collided with trees while attempting a forced landing in a recreation area near Pacoima, California. The forced landing was precipitated by a loss of engine power while in cruise. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The aircraft incurred substantial damage. The private pilot and his one passenger sustained minor injuries. The flight originated at El Monte, California, on the day of the accident at 0830 as a personal cross-country flight to Santa Barbara.

The Lycoming IO-360-A3B6D engine, serial number L-22634-51A, underwent a major overhaul during the period from January 18 to March 2, 1995. It was reinstalled on the airframe on March 3, 1995, by an aircraft maintenance facility co-located with the engine overhaul shop. According to maintenance records and work orders, the engine was test run on the ground and an oil leak was discovered in the area of the propeller governor oil pressure line fitting, which is adjacent to the propeller governor on the engine accessory case. The line fitting was tightened and the engine further test run to include a test flight. The total engine run time since engine reassembly was about 40 minutes. The aircraft was then returned to the owner/pilot's hangar and parked inside.

The applicable return to service provisions of Lycoming's Engine Overhaul Manual pertinent to the engine and Lycoming Service Instruction 1427B were reviewed. The publications state a requirement for a cumulative 2 hour and 25 minute engine run-in period after an overhaul prior to the engine's return to service.

Examination of the engine and airframe logbooks revealed no notation of the engine major overhaul or endorsement for return to service by the engine overhaul shop. The engine logbook contained a record of the engine removal and reinstallation by the aircraft maintenance facility co-located with the overhaul shop. In addition to the notation concerning the reinstallation of the engine, an entry was found annotating a 100-hour inspection and sign-off for the engine, which was dated March 3, 1995. The airframe logbook contained an annual inspection and sign-off entry dated March 3, 1995.

According to the owner/pilot's written and oral statements, on the morning of March 4 he preflighted the aircraft for a personal flight to Santa Barbara. In his report, the pilot noted that he checked the oil level and determined that 8 quarts were in the engine. After an engine runup, the pilot departed the El Monte airport. During the initial climb, controllers in the Federal Aviation Administration (FAA) Air Traffic Control Tower (ATCT) noticed that the aircraft appeared to be trailing smoke. The controller notified the pilot and suggested that the fuel mixture may be rich. The pilot leaned the mixture and continued on his flight.

The pilot said that he was performing a shallow climb to cruise altitude and began to detect a "peculiar odor" which he could not identify. The engine temperature and pressure gages appeared to be normal and he continued on the climb. As the aircraft was passing through 3,500 feet msl, the engine began to run rough, then vibrate and rattle. The oil pressure dropped to zero, then the engine seized. The aircraft collided with trees during an attempted forced landing in the Hansen Dam recreation area.

The aircraft and engine were examined over March 15 through 17, 1995, after recovery from the accident site. A streak of oil was observed from the firewall aft along the bottom of the fuselage, principally on the left side, to the area of the tailcone. No oil was found on the external engine cowling, windshield, or fuselage sides. Internally, the engine top and bottom cowls exhibited only minor splashes of oil. The upper rear cooling baffle was found installed bent aft. A film of oil was found distributed evenly on the firewall. In addition, a coating of oil was noted on the accessory case. About 1 quart of oil was found in the oil sump when it was removed from the engine.

All external engine oil hoses and fittings were secured, with no evidence of oil leakage noted. The engine oil dipstick and filler cap was secured in place. The oil breather tube was found routed correctly in the engine compartment, secured at both ends, and the relief hole was intact.

The oil pump was free to rotate by hand. Disassembly revealed the presence of small metal flakes and a quantity of oil. No internal scoring or heat distress was observed.

The crankshaft could not be rotated; however, valve and gear train components were found intact. Connecting rods 2, 3, and 4 were found separated from the crankshaft. The number 2 journal was dry and exhibited heat distress. The number 3 journal was dry and had failed bearing material attached. The number 4 journal was discolored. The number 1 connecting rod remained attached to the crankshaft and the bearing insert was wet with oil. The front and main bearing journals were wet with oil. The crankshaft and crankcase halves oil passages were clear. All piston rings were intact, with no evidence of oil staining or blow-by signatures on the pistons or in the cylinders.

The propeller governor was removed for examination. During removal, only one MS9144-01 governor gasket was found installed between the governor and the engine accessory case governor pad plate. The gasket was found loose and raised on the pad between the left top and bottom studs, around the left side screen cut out area and oil passage hole. A gasket scraper could easily be inserted in the raised area. Detailed examination of the gasket revealed a channel and trail of oil leading from the oil passage hole in the governor to the side.

The Lycoming IO-360-A Series Parts Catalog (PC-406-1), and Lycoming Service Instruction 1438 were reviewed. The publications state that for the IO-360-A1B6D and -A3B6D engines, a LW-12347 governor pad plate and a 72053 governor gasket must be installed in addition to the MS9144-01 gasket to prevent oil leakage between the governor and the accessory case governor pad. Detailed examination of the parts catalog revealed that the seal and gasket set for this engine includes a 72053 gasket, but not the LW-12347 plate, which must be ordered separately.

The owners of the overhaul facility and the co-located aircraft maintenance company were interviewed on April 6, 1995.

The owner of the overhaul facility stated that after the accident he was surprised by the unique requirement for two gaskets and a plate on this particular engine. He said that he routinely orders the seal and gasket set for each engine in overhaul, but does not review all service instructions. In his statement he said he considers service instructions as product improvements versus a mandatory requirement. He further stated that if this engine has a unique gasket stack on the governor he should not have to dig through many publications to find such critical information.

The owner of the co-located aircraft maintenance facility said that he received the engine from the overhaul shop without gaskets on the governor pad. He reported that he installed the governor on the engine using the Mooney maintenance manual which makes no mention of a unique gasket requirement. He put the MS9144-01 gasket on the governor pad and was totally unaware of a Lycoming requirement for another gasket and a plate. He further stated that he does not routinely check or refer to the Lycoming Overhaul Manual to install an engine in an airframe and has no requirement to use that publication.

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