NTSB Factual Report

On March 25, 2004, at 0945 Pacific standard time, a Cessna 188B, N478Q, collided with terrain during a forced landing following a loss of engine power in the vicinity of Planada, California. T-Craft, Inc., was operating the airplane under the provisions of 14 CFR Part 137. The pilot was not injured, and a post crash fire destroyed the airplane. Visual meteorological conditions prevailed, and a flight plan had not been filed. The flight originated at Chowchilla, California, about 0900.

The pilot stated in his written report that he was applying fertilizer to an agriculture field. He was in a climbing turn after making a pass, and the engine began to run rough. He said that it sounded like the propeller was surging. He was unable to maintain altitude, and he was only about 150 feet above ground level (agl). He said that manifold pressure and rpm seemed good at 25 inches and 2,500 rpm, respectively. He advanced the throttle, but did not feel or hear the engine respond. He did not recall the fuel pressure, oil pressure, or cylinder head temperature.

He was over an orchard, fighting the stall buffet, and directed the airplane towards one of the fields he was working. The pilot said that he was over that field when the airplane gave up flying, spun over to the right inverted, and nosed down to the ground 50 feet below. The airplane flipped back onto the gear upon ground contact. The pilot observed fire on the right side in the fuel tank area, and expedited his egress.

A Federal Aviation Administration (FAA) inspector performed a post accident examination of the airplane's engine at the operator's facility. He reported that the engine was a Continental IO-520-D that had folded under the wreckage against the ground, which provided protection from the post accident fire. The propeller had been completely sheared from the propeller hub retaining bolts. The engine's crankshaft rotated freely and the valve train operated in conjunction with compression on all cylinders. The magnetos were removed and examined. Extensive heat damage was identified around cylinder number 5, which included local melting of the aluminum around the rocker cover and intake manifold. The number 5 cylinder fuel injector line was broken free of the fuel injector nozzle and the fuel distribution manifold. The number 5 cylinder injector fuel line b-nut was finger tight.

Examination of the airplane's maintenance logbook revealed that the engine oil cooler had been removed and replaced on March 12, 2004, approximately 36 flight hours prior to the accident. The FAA inspector said that a common practice used by mechanics was to move or adjust the number 5 cylinder fuel injector line in order to install or uninstall the engine oil cooler.

NTSB Probable Cause

the partial loss of engine power due to the separation of the number 5 cylinder fuel injector supply line. The fuel line separation was due to company maintenance personnel's failure to secure the b-nut fitting following maintenance. Factors in the accident were the unsuitable nature of the terrain where the engine problem developed and the pilot's failure to maintain airspeed while attempting to reach a suitable forced landing spot, which led to an inadvertent stall.