N8431T

On September 4, 1994, at 1637 hours Pacific daylight time, a Cessna 182B, N8431T, crashed short of a privately owned dirt airstrip near Twentynine Palms, California, while executing an emergency landing. The emergency landing was precipitated by a loss of engine power. The airplane, registered to and operated by the pilot's father, sustained substantial damage. The certificated private pilot did not sustain any injuries; however, his passenger received minor injuries. Visual meteorological conditions prevailed. The flight originated at Torrance Airport, Torrance, California, at 1545 hours.

The pilot said that he circled the airport, a privately owned dirt airstrip known as Dale's Sky Ranch, and entered the right traffic pattern for the westerly runway. While on the downwind leg, just before turning onto the base leg, the engine began popping and backfiring. The pilot turned the airplane toward the runway, but the airplane's power and altitude were insufficient to make the runway. The pilot landed the airplane about 100 feet east of the runway.

During the ground rollout, the airplane struck a berm located about 30 feet from the approach end of the runway. After striking the berm, the airplane's nose and left main landing gears separated and the airplane became airborne. The airplane then landed on the runway.

National Transportation Safety Board investigators examined the engine, a Continental O-470-L, on November 23, 1994, at Lynn's Aircraft Engines, El Monte, California.

External examination:

During the compression check, Safety Board investigators established continuity of the gear and valve train assembly. The following are the differential compression check data:

Cylinder Number Differential Compression 1 75/80 PSI 2 60/80 PSI 3 72/80 PSI 4 69/80 PSI 5 65/80 PSI 6 75/80 PSI

Both magnetos produced spark upon rotation of their respective drive shafts. The right magneto timing was found set at 24 degrees and the left magneto was set at 23 degrees. The manufacturer's service limits are 22 degrees.

The upper spark plugs, except the No. 4 spark plug, exhibited normal operating signatures. Both the No. 4 upper and lower spark plugs were oil soaked.

The carburetor, a Marvel-Shevler MA-4-5, housing did not contain any fuel. The pilot told Safety Board investigators that the carburetor contained fuel when he removed it from the engine. The pilot did not check the fuel for any contaminates before discarding the fuel. The carburetor contained the metal float and its finger screen was free of contaminates.

The oil pump housing displayed rotational score marks emanating from a piece of metal going throughout the system.

The oil pan was found free of contaminates, but the oil had been drained. The pilot told Safety Board investigators that he drained the oil when he removed the engine from the airframe. The pilot also removed the oil filter.

Oil pressure relief valve - normal signatures.

Disassembly Examination:

The crankcase through bolts breakaway torque were found between 600- and 700-foot pounds. The crankcase halves did not display any fretting or abnormal wear signatures.

The hydraulic lifters displayed extensive galling areas beyond their respective housing and the camshaft contact area displayed galling. According to Lynn's Aircraft Engines maintenance personnel, the lifters would not meet the manufacturer's service limits. The lifters housing tolerances were found within the recommended manufacturer's service limits.

The camshaft displayed extensive corrosion on all of the lobes. According to Lynn's Aircraft Engines maintenance personnel, the cam exceeded the manufacturer's service limits specifications. The cylinders, pistons, piston rings, and the main bearings displayed normal operating signatures. The exhaust valves, however, displayed lean mixture signatures. The valve clearances were found within the manufacturer's service limits.