N486KC – Mooney M20M – Amisville, VA

On March 3, 2012 a Mooney M20M airplane, federally registered as N486KC, crashed near Amisville, Virginia, seriously injuring the pilot and passenger. The pilot reported a total loss of engine power while the airplane was in cruise flight at 5000 feet MSL. Visual meteorological conditions (VMC) existed and an instrument flight plan was filed for the flight to Hagerstown Regional Airport (HGR) in Hagerstown, Maryland. The flight had departed Georgetown County Airport, Georgetown, South Carolina. After the engine quit, the pilot was attempting to glide to a field when the airplane struck a fence and trees. The NTSB preliminary report states that the agency has retained the airplane engine.

While investigators will properly focus their attention on the airplane’s engine while seeking to determine the cause of this crash, it is worth noting that Mooney airplanes have a little known problem with contamination occurring in the fuel tanks that cannot be detected and removed by pre-flight draining of the fuel sumps. I’ve owned a Mooney; I know from personal experience. And our firm successfully represented the estate of a pilot who was killed when his Mooney airplane crashed due to fuel exhaustion and engine failure because fuel could not properly flow between the tanks due to this same problem.

Mooney airplanes are manufactured using integral fuel tanks (the fuel tanks are incorporated into the aluminum structure of the wing), rather than using rubber bladder tanks inserted into the wing. In the internal structure of each Mooney airplane wing are holes located along the stringers at the bottom of the fuel tanks. These holes are intended to port fuel between the integral wing tanks and too allow contaminated fuel to reach the fuel sumps (the lowest part of each wing) from which the pilot can drain contaminants before flight.

A sealant is applied along the inside seams of the fuel tanks to prevent leakage. When the airplane’s fuel tanks are sealed at the factory and particularly when resealed in the field, it is common to have sealant block several of the holes in the stringers, which in turn traps contaminants in the Mooney airplanes’ fuel tanks and prevents fuel from flowing properly to the engine pick up located at the inner most tank near the fuselage. This is a recipe for eventual engine failure due to either contaminated fuel or inadequate (blocked) fuel flow.

It is important to rule out all probable causes of an airplane crash. With engine failure in a Mooney airplane, it is essential to look beyond the engine and to the airframe fuel tanks and the fuel lines and pumps.