N39AE

On September 20, 1999, about 1139 hours Pacific daylight time, a Cessna 177A, N39AE, ditched in Big Bear Lake after losing power near Big Bear City, California. The aircraft sustained substantial damage; however, the certificated airline transport pilot, the sole occupant, was not injured. The aircraft was being operated under the provisions of 14 CFR Part 91 by the pilot as a maintenance test flight when the accident occurred. The flight originated from the Big Bear City Airport about 1130. Visual meteorological conditions prevailed at the time and no flight plan was filed.

The pilot reported that the aircraft had been parked outside, on the ramp, for nearly 7 months. The owner had reported that the left main tank had been "seeping." At the time the aircraft was parked, both fuel drains were removed and all fuel was drained from the tanks. At the end of the period of inactivity, an airframe and powerplant mechanic (A&P) replaced the fuel drain in the aircraft's right tank and added fuel to prepare the aircraft for a ferry flight to Corona, California. After sitting for most of a day, no leaks were noted. The mechanic then added enough additional fuel to bring the level up to 20 gallons. The pilot performed a preflight and before takeoff checks; however, the engine stalled once during taxi.

On the first flight, the pilot had climbed to 8,000 feet msl when he found that the engine began to miss and run roughly. After returning, the pilot again drained the fuel sumps and obtained a "small amount of water" from the gascolator. He then drained an additional gallon of fuel from the tank, and at that time, did not find any additional water or sediment. The pilot's procedures were observed by the mechanic.

Prior to takeoff on the accident flight, the pilot again performed the same preflight and before takeoff checks. This time the checks were performed without incident. The mechanic did not perform or offer to perform any additional troubleshooting procedures between the first and second flight.

The pilot reported that he took off with about 18 gallons of fuel in the right main tank. After takeoff, he climbed to 7,500 feet msl heading east of the airport and over the lake. After reaching 7,500 feet, the engine began surging and then quit. He turned on the electric fuel boost pump, pushed the mixture handle into the "full rich" position, and "pumped" the throttle. When his attempts to restart the engine failed, he turned back toward the airport but was unable to reach the runway. He ditched the airplane in about 1.5 feet of water, 50 yards from the south shore of the lake, west of the Stanfield cutoff. After touching down, the aircraft nosed over and came to rest on its back. The pilot turned off the electric fuel pump and master switch, and crawled out of the cockpit and onto the wing. He waited there until rescued by boaters who had witnessed the accident.

On November 1, 1999, a Safety Board investigator examined the engine and airframe at Action Towing and Recovery in Fresno, California. A cold compression check of the Nos. 1 through 4 cylinders revealed the following readings: 62, 61, 61, and 63 psi, respectively. All four top spark plugs were removed and examined. The tips of all four plugs were covered with a similar looking brownish substance consistent with the color and texture of rusted metal.

The inside of the gascolator was found to be coated with an apparently insoluble greenish-brown film. The left wing fuel quantity transmitter was removed and examined. It was coated with material that was similar in appearance to silicon sealant. The material was decomposing and readily flaked off when touched. The fuel reservoir drain plug was removed and approximately 10cc of liquid was recovered. The liquid precipitated into a lower layer and upper layer in a manner similar to the precipitation that follows the mixture of water and gasoline. The sample also contained some heavier sediment that was similar in color and consistency as to the sealant-like material found on the fuel quantity transmitter.

The above noted discrepancies were located in areas that are not accessible or serviceable by a pilot performing a preflight inspection or before takeoff checks.