Accident Details
On May 29, 2012, at about 1220 Pacific daylight time, a Luscombe 8E, registration N2435K, sustained substantial damage following a forced landing due to a loss of engine power near Twentynine Palms Airport (TNP) in Twentynine Palms, California. The pilot/owner, the sole occupant, was not injured. Visual meteorological conditions prevailed for the planned personal cross-country flight, which was conducted under 14 CFR Part 91; no flight plan was filed. The flight departed TNP at about 1215, with Big Bear City, California as the intended destination.
Pilot Report
According to a report submitted to the National Transportation Safety Board (NTSB) investigator-in-charge, the pilot stated that before takeoff he filled the right fuel tank with 11.34 gallons of 100LL aviation fuel; the left tank contained 12.5 gallons at takeoff. After takeoff, while in a shallow climb at full power at about 800 feet above ground level and approximately 4 nautical miles from the departure airport, the engine lost power. The pilot reported switching the fuel selector between left and right tanks, checking each magneto individually, confirming the mixture was FULL RICH, and moving the throttle aft and then full in, with no change in power. He then selected a dirt road for an emergency landing and applied brakes upon touchdown. After slowing to about 10 mph, a bumpy surface caused the airplane to nose over and come to rest inverted.
Post-Accident Examination
A Federal Aviation Administration (FAA) Aviation Safety Inspector examined the airplane the day after the accident. The inspector reported no presence of fuel at the accident site. Substantial damage was noted to the right wing and fuselage, with left wing leading edge damage at the tip and a buckle in the fuselage aft of the right door post near the bottom. Flight control continuity was confirmed. Both magnetos were secured, and when the crankshaft was rotated by hand, both magnetos fired with spark on the top four high tension leads. Impulse couplings engaged, and compression was noted. A borescope of the four cylinder walls appeared normal. All spark plugs and high tension leads were secure. The carburetor was completely separated from the intake manifold, precluding an engine run, but no obvious visual damage was observed.
All four valve covers were removed; the engine was rotated by hand, and all valves operated normally with no defects. No visual damage was found on the fuel strainer, and no fuel came out of the drain valve when opened; it was dry. Positive air pressure blown into the fuel lines at the wing roots with the fuel selector set to either tank and the drain valve open produced only air. The fuel selector moved freely with all detents felt, appearing to operate normally. Inspection of the carburetor bowl, needle, screen, float, and oil filter revealed no anomalies. The screen had a small amount of fuzz (less than 5% coverage) that, according to the inspector, would not have blocked fuel flow. The float had no cracks and no fuel inside. The oil filter was clear. The inspector reported no anomalies with either the airframe or engine that would have precluded normal operation.
Fuel Documentation
The FAA inspector contacted the company providing fueling documentation for TNP. The employee reported that on the day of the accident, only one aircraft (N61188N) refueled. When asked if the number could have been mistaken for N6118B, the employee responded no, as the receipt was legible and the pump accepts any entered number. The pilot reported using his business fleet card to refuel that day, entering the registration N6118B (a Cessna 182 used for business), though he noted difficulty entering the 'B' on the keypad. The employee reported fueling at 1258, and a receipt confirmed that time. The fuel vendor's sitemeter program was 1 hour and 15 minutes off. FAA records show the accident was reported at 1220; the pilot reported refueling at 1215; local law enforcement records indicate an officer arrived at the accident site at 1219—39 minutes before the receipt time of 1258.
Expert Statement
A Luscombe expert with 40 years of experience stated that when the airplane flipped over, any fuel would have drained to the low point (fuel cap area) in the wing and escaped through the vented cap into the sand within a few hours. He noted that tank configuration would allow virtually all fuel to escape in that position. He expected that if the airplane was recovered within a few hours, some fuel evidence might remain, but after a day or more in the desert, fuel traces would be unlikely.
Weather Conditions
The closest weather reporting facility, Palm Springs International Airport (PSP), about 31 nautical miles southwest of TNP, reported at 1253: temperature 36°C, dew point -3°C, altimeter 29.85 inHg. A review of the carburetor icing probability chart indicated the airplane was not operating in an area favorable for carburetor ice formation.
Investigation Outcome
The investigation did not reveal the cause for the loss of engine power.