N2435KSilvaire LUSCOMBE 8E · 1947

On May 29, 2012, about 1220 Pacific daylight time, a Luscombe 8E, N2435K, sustained substantial damage following a forced landing due to a loss of engine power near the Twentynine Palms Airport (TNP), Twentynine Palms, California. The pilot/owner, who was the sole occupant, was not injured. Visual meteorological conditions prevailed for the planned personal cross-country flight, which was conducted in accordance with 14 Code of Federal Regulations (CFR) Part 91, and no flight plan was filed. The flight departed TNP about 1215, with Big Bear City (L35), California, as the planned destination.

In a report submitted to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that prior to taking off, he filled the right tank with 11.34 gallons of 100LL aviation fuel; the left fuel tank contained 12.5 gallons at the time of takeoff. The pilot stated that after takeoff and while in a shallow climb at full power at about 800 feet above ground level (agl) and about 4 nautical miles (nm) from the departure airport, the engine lost power. The pilot reported that he switched the fuel selector from the left tank to the right tank and back to the left tank, [checked] each magneto individually, [confirmed] the mixture was FULL RICH, and moved the throttle aft and then full in; there was no change in the power. The pilot revealed that he then selected a dirt road on which to make an emergency landing and applied brakes upon touchdown. After slowing to about 10 miles per hour a bumpy surface was encountered, which resulted in the airplane nosing over and coming to rest inverted.

At the request of the IIC, a Federal Aviation Administration (FAA) Aviation Safety Inspector performed a post-accident examination of the airplane on the day following the accident. The inspector reported to the IIC that upon his arrival there was no presence of fuel at the accident site. The inspector further reported that the right wing and fuselage had sustained substantial damage, and that the left wing’s leading edge was damaged at the tip. The inspector revealed that there was a buckle in the fuselage aft of the right hand door post near the bottom. Continuity of all flight controls was confirmed. Both magnetos were secured to the accessory section. The engine crankshaft was rotated by hand, at which time it was verified that both magnetos were firing by checking for spark on the top four high tension leads. The magneto impulse couplings engaged and thumb compression was noted by resistance while blocking the spark plug holes. A borescope of the four cylinder walls appeared normal. All spark plugs and high tension leads were secured. The carburetor was completely separated from the intake manifold. An engine run was precluded due to being unable to replace the manifold. There was no obvious visual damage noted to the carburetor.

The inspector stated that all 4 valve covers were removed, the engine was rotated by hand, and all valves were observed to operate normally; no grinding or other defects were noted. There was no visual damage to the fuel strainer, and no fuel was observed coming out of the drain valve when it was opened; it was dry. Additionally, no fuel was observed to exit the strainer when positive air pressure was blown into the fuel lines at the wing roots with the fuel selector set to either the left or right wing tanks and the fuel strainer drain valve in the OPEN position; only air was emitted. The inspector also revealed that the fuel selector moved freely and that all detents were felt as it turned; the fuel selector valve appeared to be operating normally. The inspector subsequently inspected the carburetor bowl, the needle, the screen, the float and the oil filter. No anomalies were noted. The inspector further reported that the screen had a small amount of fuzz (similar to pocket lint) that covered less than 5 percent of the screen. He concluded that such an amount would not have blocked the fuel from passing through the screen. The float had no apparent cracks and did not have any fuel present. The oil filter was clear of any foreign objects. The inspector reported no anomalies with either the airframe or the engine that would have precluded normal operation.

The FAA inspector contacted the company that provided the fueling documentation for TNP. When asked by the inspector how many aircraft had refueled there on the day of the accident, the employee reported that the only airplane that refueled that day was N61188N. When asked if this number could have been mistaken for N6118B, the employee said no, as the receipt was easy to read, and that the pump would accept any number that is entered, right or wrong. The pilot reported that on the day of the accident while refueling [at TNP] he used the fleet card from his business. The registration number for the purchase of fuel was N6118B, which corresponds to the Cessna 182 he uses for business trips; however, he can never get the keypad to register the B. When asked by the inspector what time the fueling took place, the employee reported 1258; a fuel receipt confirmed the time as 1258. During the investigation fueling documentation was provided by the vendor that revealed the sitemeter program for the self-serve fueling station at TNP was 1 hour and 15 minutes off of the correct time. FAA records revealed that the accident was reported to the regional office at 1220. The pilot reported that he refueled at 1215, and local law enforcement records indicate that an officer arrived at the accident site at 1219, which was 39 minutes prior to the reported time of the refueling as noted on the fuel receipt as 1258.

In a statement submitted to the IIC, a Luscombe expert with 40 years of experience in doing restorations and modifications to Luscombe airplanes, reported that in his professional opinion that when the accident airplane flipped over, any fuel on board would have run to the low point (fuel cap area) in the wing, and then drained into the sand or dirt under the airplane wing through the vented cap within a matter of a few hours. The expert added that the tank configuration would allow for virtually all of the fuel to escape in this position/condition. The expert stated that he would expect that if the airplane was recovered in a few hours there might be some evidence of fuel, but after a day or more in the desert, fuel traces would be unlikely in evidence at/on the airplane OR in the porous soil.

The closest weather reporting facility to the accident site was the Palm Springs International Airport (PSP), Palm Springs, California, which was located about 31 nautical miles southwest of the TNP. At 1253, the facility reported temperature 36 degrees Celsius (C), dew point minus 3 degrees C, and an altimeter setting of 29.85 inches of mercury. A review of the carburetor icing probability chart, located in the FAA's Special Airworthiness Information Bulletin CE-09-35, dated 6/30/2009, revealed that the airplane was not operating in an area favorable for the formation of carburetor icing.

The investigation did not reveal the cause for the loss of engine power.