Aviation Accident Summaries

Aviation Accident Summary ERA13LA365

Numidia, PA, USA

Aircraft #1

N598LF

FETTERMAN LANNY R FIRESTAR II

Analysis

The pilot reported that, just after takeoff in his experimental light-sport airplane, the engine began to "surge," so he chose to return to the airport to perform a precautionary landing. On final approach to the turf runway, the pilot reduced the engine power to idle, and the engine subsequently experienced a total loss of power. Upon touchdown, the right main landing gear (MLG) wheel separated from the gear leg, the gear leg dug into the turf, and the airplane nosed over and came to rest inverted, which resulted in substantial damage to the airframe and left wing. Examination of the right MLG and wheel axle revealed that the wheel had separated from the gear leg due to the fatigue failure of the axle attachment bracket.

Factual Information

On August 16, 2013, approximately 1815 eastern daylight time, an experimental light sport Fetterman Firestar II, N598LF, was substantially damaged during a forced landing at Numidia Airport (8PA0), Numidia, Pennsylvania. The certificated sport pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was originating at the time of the accident. The flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. The pilot stated that prior to departing on the accident flight, he drained the airplanes fuel tank and added 8 gallons of 92-octane automotive fuel, premixed with oil to manufacturers specifications. He subsequently drained fuel from the gascolator to check for the presence of water, and stated that the sample contained none. The pilot performed a run-up check of the engine by increasing power to 4,000 rpm for about four minutes. During this time, he stated that the engine sounded "terrific," and that a magneto check revealed no anomalies. He then taxied the airplane to the end of the turf runway, performed a second run-up, and stated that all engine indications were within parameters. The pilot applied engine power to initiate the takeoff, and the airplane lifted off the runway and climbed to about 300 feet above ground level. The engine subsequently began to "surge," fluctuating between 6,200 rpm and about 4,500 rpm, and the pilot elected to return to the airport. On final approach, the pilot reduced engine power to idle and the engine subsequently experienced a total loss of power. Upon touchdown on the runway, the right main landing gear wheel departed from the gear leg, the gear leg dug into the turf, and the airplane nosed over and came to rest inverted. The pilot held a sport pilot certificate with a rating for airplane single engine land. He reported 238 total hours of flight time, of which 72 hours were in the accident airplane make and model, and reported that he had flown the accident airplane 3 hours in the year previous to the accident. The airplane was manufactured in 1997, and was issued a Federal Aviation Administration airworthiness certificate in 2006. It was equipped with a Rotax 503 DIDC, 52 hp reciprocating engine. Its most recent annual inspection was completed on May 3, 2013. At the time of the accident, the airplane and engine had accrued 72 total hours of flight time. Postaccident examination by a Federal Aviation Administration inspector revealed substantial damage to the airframes tubular structure, as well as the tail boom and left wing. Examination of the right main landing gear wheel revealed a fracture of the bracket that connected the wheel axle to the landing gear leg. Continuity was confirmed from the cockpit area to the flight control surfaces. No examination of the engine was performed. The pilot reported that he believed the engine surging was the result of a fuel flow issue. He stated that several weeks after the accident, he examined the engines carburetor bowls, and found that neither contained any fuel. The fractured wheel axle bracket was sent to the NTSB Materials Laboratory for analysis. Examination indicated that the bracket fractured near a weld. The fracture surface displayed a flat, thumbnail-shaped region near one of the toes of the weld; a signature consistent with a fatigue crack. The fatigue crack was approximately 0.2 inches in the circumferential direction and extended through approximately 70 percent of the wall thickness at the joint.

Probable Cause and Findings

A fatigue failure of the right main landing gear wheel axle attachment bracket, which resulted in a nose-over during a precautionary landing.

 

Source: NTSB Aviation Accident Database

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