Accident Overview
On November 15, 2021, at approximately 1012 eastern standard time, a Mooney M20M, registration N21890, was substantially damaged when it ditched near Tampa, Florida. The private pilot and one passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight Sequence
The pilot reported an uneventful 15-minute flight earlier that day from Peter O Knight Airport (TPF), Tampa, to Lakeland Linder International Airport, Lakeland, Florida. After picking up a passenger, the pilot departed for Gainesville Regional Airport, Gainesville, Florida. While at 3,000 ft mean sea level (msl) with the mixture full rich and engine operating at 32 inHg and 2,400 rpm, the turbine inlet temperature (TIT) was in the red range. Simultaneously, the pilot noticed liquid on the bottom portion of the windshield. Reducing engine power decreased the TIT reading, but liquid remained on the windshield.
At 4,000 ft msl, the pilot advised air traffic control of the high temperature and diverted back to TPF. While maintaining 4,000 ft msl until the downwind leg of the traffic pattern, the pilot reduced power, extended the landing gear, and lowered the first notch of flaps. On the base leg at about 1,200 ft above ground level, before turning onto final, the pilot added throttle but the engine did not respond. Pushing the mixture, propeller, and throttle controls full forward activated the auxiliary fuel pump (as designed at full throttle), but the propeller windmilled. At 800 ft msl, realizing the runway was unreachable, the pilot informed the passenger of the impending ditching. He retracted the landing gear and maintained a nose-up, wings-level attitude for the ditching. Both occupants exited the airplane and were transported to land. The underside of the fuselage was substantially damaged during the ditching.
Post-Accident Examination
After recovery, examination of the fuel lines in the engine compartment revealed that the inlet fuel line at the manifold valve was 7.5 flats of the b-nut from being hand tight against the inlet fitting. There was no provision for safety wiring the b-nut, and no torque stripe was present on the b-nut or inlet fitting. Pressure testing of the fuel supply system with the b-nut in the as-found position showed fuel leakage at the b-nut. After the b-nut was tightened, no leakage was observed. Inspection of the threads of the fitting and flexible fuel hose revealed no discrepancies. Torque stripes were noted on the fuel injector nuts at the manifold valve.
Maintenance Background
Review of maintenance records indicated that nearly two months before the accident, fuel system components—including the engine-driven fuel pump, servo fuel injector, manifold valve, and fuel injectors—were removed for testing and overhaul. These components were installed, and according to the pilot, the airplane had been operated about 12 hours over three or four flights since installation. There was no record of any subsequent engine work after the overhauled components were installed.
The mechanic who installed the components reported that the airplane owner assisted with the installation. The mechanic indicated that he normally would have applied a torque stripe to the inlet hose at the manifold valve.