Aviation Accident Summaries

Aviation Accident Summary CHI05LA138

Jefferson City, MO, USA

Aircraft #1

N231HX

Mooney M20K

Analysis

The airplane was substantially damaged during a forced landing following a loss of engine power. The pilot reported that the airplane fuel tanks were filled prior to the flight and that the fuel burn during the flight was between 11 and 11.3 gallons per hour, which agrees with data obtained from the Pilot Operating Handbook (POH). The duration of the flight was about 3 hours and 47 minutes. The POH listed the airplane fuel capacity was 72 gallons of useable fuel. The pilot further stated that he alternated burning fuel from each tank during the flight and that he had noticed that the fuel quantity indication did not agree with what he had expected. He stated that for between 30 and 45 minutes he had been planning for alternate airports due to weather and fuel concerns. While burning fuel from the left fuel tank, the engine lost power and the pilot switched to the right fuel tank. The engine re-started and the pilot diverted to an airport about 5 to 6 miles away. The pilot stated that he circled to lose altitude and executed an approach to the runway. He stated that when he turned onto final approach he realized that he was too high and executed a go-around. He reported that the engine again lost power as he was turning onto the downwind leg of the traffic pattern. During the off-airport landing the airplane impacted the ground in a wings level attitude with the landing gear extended. The pilot stated that, although he closed the gascolator fuel drain from within the cockpit, he believed that the fuel drain remained open allowing approximately 30 gallons of fuel to be lost during the flight. The preflight checklist procedures specify draining the gascolator prior to the external airplane examination. According to the airplane manufacturer, a leaking gascolator drain should be detectable during the external examination.

Factual Information

On June 13, 2005, at 1202 central daylight time (cdt), a Mooney M20K, N231HX, piloted by a private pilot, sustained substantial damage during a forced landing following a loss of engine power. The airplane was attempting a precautionary landing to runway 12 (6,001 feet by 100 feet, asphalt), at the Jefferson City Memorial Airport (JEF), Jefferson City, Missouri, when the accident occurred. The 14 CFR Part 91 flight was being operated in visual meteorological conditions on an instrument flight rules flight plan. The pilot was not injured. The passenger received serious injuries. The flight originated from the McGhee Tyson Airport (TYS), Knoxville, Tennessee, about 0815 cdt. The intended destination was the Kansas City International Airport, Kansas City, Missouri. In a written report, the pilot stated that the airplane fuel tanks were filled prior to the accident flight. He stated that, although he closed the gascolator fuel drain from within the cockpit, he believed that the fuel drain remained open allowing approximately 30 gallons of fuel to be lost during the flight. In a separate written statement, the pilot stated that he personally witnessed the fueling of the airplane and that his fuel burn during the flight was between 11 and 11.3 gallons per hour as indicated on the aircraft fuel flow meter. He stated that after departure from TYS he was initially assigned a cruising altitude of 10,000 feet above mean sea level (MSL). He stated that his altitude assignment was ultimately changed to 12,000 feet MSL about 30 to 40 miles after departure. He stated that during the flight he alternated fuel tank selection several times and that while burning fuel from the left tank, the engine stopped running. He stated that he switched to the right tank and the engine restarted. He stated that he had noticed that the fuel gauges had been indicating lower quantities than he expected. He stated that he did not see or smell any evidence of fuel leaking. He stated that he had been planning for alternate airports for about 30 to 45 minutes due to weather and fuel concerns. He stated that when the engine re-started, he diverted to JEF, which was about 5 to 6 miles northwest of his position. He stated that he planned to fly to the east end of the airport and circle to lose altitude and then land. He stated that when he turned onto final approach for runway 12, he was too high and executed a go-around. He stated that while turning to a left hand downwind leg of the traffic pattern, the engine again quit running. He stated that the airplane impacted the ground wings level with the landing gear in the down position. A post accident examination of the airplane revealed no anomalies that could be associated with a pre-impact condition. The fuel tanks were found to be empty. No evidence of a fuel leak was found. The airplane came to rest in a bean field about 100 yards from the airport. A fuel receipt was obtained that indicated that 14 gallons of fuel had been added prior to the accident flight. Examination of excerpts from the Pilot Operating Handbook (POH) showed that the best economy fuel burn for a 75% power setting at 12,000 feet altitude was 11.2 gallons per hour. The POH listed a total useable fuel capacity of 72 gallons. The fuel system is comprised of two wing fuel tanks that feed into a fuel selector valve and then to the engine through a gascolator. There are drains at the fuel tanks, and a drain at the gascolator. The gascolator drain is actuated remotely from within the cockpit. The "Preflight Inspection" checklist from the POH listed in step one, "Fuel selector - R; pull gascolator ring (5 seconds)" and "Fuel selector - L; pull gascolator ring (5 seconds)." Step one of the checklist is followed by procedures for external examination of the airplane. According to a telephone conversation with a Technical support representative for the airframe manufacturer, a leak from the gascolator drain should be visible during the external examination.

Probable Cause and Findings

The pilot's delay in diverting to an alternate destination due to low fuel indications which led to the fuel exhaustion, loss of engine power and the subsequent forced landing. Factors were the pilot's improper preflight inspection which resulted in an undetected fuel drain leak and his misjudged glidepath during the precautionary landing which led to a go-around and the subsequent fuel exhaustion.

 

Source: NTSB Aviation Accident Database

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