AUBURN, WA, USA
N531PC
Cessna 172P
The pilot reported that shortly after takeoff from a touch-and-go landing, the engine began to lose power and eventually quit. A forced landing was made to a field. During the landing roll, the airplane was substantially damaged. An engine inspection found that the number one intake valve was stuck open. Further inspection found that the number one exhaust cam follower head broke in three pieces. Debris from the exhaust cam follower was found jammed between the cam and the cam follower to the number one intake plunger assembly of that cam follower. A section of the engine casing also broke away from around the number one intake cam follower. Maintenance records indicate that the engine total time was beyond manufacturer's recommendation for time between overhaul.
On July 3, 1999, approximately 1650 Pacific daylight time, a Cessna 172P, N531PC, registered to Auburn Flight Service of Auburn, Washington, was substantially damaged in a forced landing following a loss of engine power during climbout from a touch-and-go landing at the Auburn airport. The solo student pilot was seriously injured in the accident. Visual meteorological conditions were reported at Renton, Washington, at 1653, and no flight plan was filed for the 14 CFR 91 local instructional flight. In a written statement, the pilot reported that after departing from his third touch-and-go landing on runway 16, he noticed a slow reduction in engine RPM at approximately 200 feet above ground level (AGL). He stated that he pulled the carburetor heat control out, but did not notice any change, and that he then tried closing the throttle and jamming it forward. He reported that he thought this improved engine performance to about 600 feet AGL, at which point the engine quit. The pilot landed straight ahead in a field. A Federal Aviation Administration Inspector from the Renton, Washington, Flight Standards District Office responded to the accident site. The inspector reported that the carburetor heat control was found on and functional, and the mixture and throttle controls were found fully in. Fuel was found in the aircraft's fuel tanks and gascolator. The magneto switch and fuel selector were secured to the off position prior to the inspector's arrival at the accident scene. At 1653, the Renton airport, located nine miles to the north of Auburn, reported the temperature as 64 degrees F and dewpoint as 48 degrees F. On July 9, 1999, a test run of the aircraft's Lycoming O-320-D2J engine was conducted at Wings Aloft, Boeing Field/King County International Airport, Seattle, Washington. The inspector who supervised the test run reported to the Safety Board that during the run, the engine operated to a maximum of 1,700 to 1,800 RPM, but ran very rough. Compression tests on the engine cylinders disclosed zero compression on the number 1 cylinder. Further investigation of this condition revealed that the number 1 intake valve was mechanically blocked open, with no movement of the rocker arm during engine rotation. Further disassembly revealed that the number one intake valve was stuck open approximately 3/8 inch. The mechanic assisting in the engine examination reported on Malfunction or Defect Report, FAA Form 8010-4, that "the valve was not stuck in the guide." The cam follower (body hydraulic tappet) head was found broken in three pieces and had broken off of the number one exhaust valve. Debris from the exhaust cam follower was found jammed between the cam and the cam follower to the number one intake plunger assembly of that cam follower, and broke the number one intake cam follower out of the case. The owner of the aircraft reported the engine's total time since new was 2,268 hours, and that the engine had not been overhauled since new. Textron Lycoming service instructions give the recommended time between overhauls for O-320 engines as a maximum of 2,000 hours.
Total mechanical failure of the hydraulic tappet. A factor was an overdue major overhaul per manufacturer's recommendations.
Source: NTSB Aviation Accident Database
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