Pilot Debrief

MOONEY AIRCRAFT CORP. M20 near Skiatook, OK — 2017-08-02

Final reportGAA17CA472
Sign in to save
Date
2017-08-02
Location
Skiatook, OK, USA
Airport
2F6
Aircraft
MOONEY AIRCRAFT CORP. M20
Registration
N95442
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The pilot's improper decision to conduct the flight despite the fuel gauges indicating that there was insufficient fuel for the flight, which resulted in the low amount of fuel in the right tank becoming unported during the multiple turns, and his subsequent improper decision to switch to the nearly empty left tank, which led to a loss of engine power due to fuel starvation.

NTSB narrative

The pilot reported in a written statement that the airplane had just been released from a repair shop after the engine exhaust system had been rebuilt. He added that the engine was tested before being released from the repair shop, and no mechanical anomalies were noted. According to the pilot, while completing the preflight run-up, the engine quit running when it was at 1,800 rpm. He got out of the airplane and did a walk-around and noticed nothing abnormal. He then attempted multiple engine starts, and "the engine would try to start but would not keep running." Subsequently, he was able to get the engine started. The pilot reported that he conducted a preflight but did not visually check or measure the fuel in either tank during the preflight, but before flight, he believed the left fuel tank was empty. He then took off and circled the airport in a right traffic pattern, flew down the runway at 2,000 ft mean sea level, then proceeded on-course to his destination. The pilot further reported that, when he departed, the left tank low fuel light was on, the right fuel tank light was off, and the fuel level in the right tank was between 1/8 and 1/4 full. The fuel selector was selected to the right fuel tank. He added that, about 7 nautical miles from the destination airport, the right tank low fuel light illuminated for about 3 to 5 seconds and then extinguished. As he turned the airplane onto final, he added power and "pumped [the] throttle several times with no response from [the] engine." He added that when the engine lost power, he switched the fuel selector from the right tank to the left tank out of habit. The pilot reported that the airplane continued to sink and that he made a slight right turn to avoid power lines and a street with several cars and landed hard in a large yard. The right wing sustained substantial damage. A Federal Aviation Administration aviation safety inspector reported that, after the accident, he and the pilot drained the fuel from the airplane. He reported that they sumped about 3.25 to 3.50 gallons of fuel from the right tank and about 1 gallon of fuel from the left tank. The Airplane Flight Manual (AFM) stated that the airplane had a total unusable fuel volume of 3 gallons and was equipped with left and right fuel low annunciation lights that indicated when 2.5 to 3 gallons of usable fuel remained in the respective tanks. The AFM further stated, "switch to fuller tank." According to Title 14 Code of Federal Regulations Part 91.151 Fuel requirements for flight in VFR [visual flight rules] conditions: (a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed - (1) During the day, to fly after that for at least 30 minutes. Estimated fuel requirements for the flight, based on the pilot's statement that the airplane normally burned "28-30 gph [gallons per hour] on takeoff power and 18-19 gph on cruise power" and the reported flight profile, indicated that a minimum of 8.7 gallons were required for the flight. When an additional 30-minute reserve was added, a total of 17.96 gallons were required for the flight. As noted previously, the pilot reported that, before flight, the fuel gauges read 1/8 (4.7 gallons) to 1/4 (9.4 gallons) full on the right fuel tank, and he believed the left fuel tank was empty. It is likely that the engine was starved of fuel after the pilot completed multiple turns in the traffic pattern with low fuel in the right fuel tank, and that, subsequently, when the pilot switched the fuel selector to the left fuel tank, which contained only about 1 gallon of fuel, fuel starvation occurred.

Analysis

Primary failure mode
Fuel management
First missed decision gate
Pilot did not visually check fuel levels before flight despite low fuel indications.

NTSB coding

Evidence available

  • Photos
  • 7 docket documents
View NTSB final reportView NTSB docket

Docket documents7

Related mishaps