Accident Overview
On September 17, 2022, at about 1202 eastern daylight time, a Rockwell International 700 multi-engine airplane, registration N700AK, was substantially damaged in an accident at Gatlinburg-Pigeon Forge Airport (GKT) in Sevierville, Tennessee. The commercial pilot and two passengers were not injured; one passenger sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pre-Flight Fueling and Flight
The pilot reported that before departing from Marianna Municipal Airport (MAI) in Marianna, Florida, he purchased fuel from the airport's self-serve pump, filling both wing fuel tanks to about 1 1/2 inches below the top, totaling 166 gallons (83 gallons per side). Receipts from the airport confirmed the purchase of about 98 gallons of fuel. ADS-B flight tracking data showed the flight departed MAI at 1007; the last ADS-B-reported position was at 1201, about 0.62 miles from the approach end of runway 28 at GKT. The flight duration was 1 hour 54 minutes.
Events During Approach and Landing
The pilot stated the flight was normal until the airplane was on final approach, when the right engine fuel boost pump light illuminated. The right engine began to sputter, and fuel flow dropped, fluctuating between 0 and 75 pounds per hour (pph). The pilot advanced both throttles, propeller, and mixture controls full forward and cleared a set of powerlines about 0.6 miles off the runway end. Once the airplane reached the runway end, the right engine lost power completely. The pilot applied full left rudder to compensate for asymmetric thrust, but the rudder became “ineffective,” and the airplane made a hard right turn even after reducing power to the left engine. The pilot later stated that in hindsight he may have kept power on the left engine too long and did not account for the loss of wind over the rudder.
The airplane struck a taxiway and runway light while veering right. After leaving the grass infield, the airplane became airborne again. The pilot tried to avoid parked aircraft and gas tanks, but the airplane stalled and collided with two hangars, causing substantial damage to both wings and the fuselage. There was no post-impact fire. Witnesses, including a person in a hangar, students from a flight school, and responding police and fire departments, reported no evidence of a fuel spill or fuel smell.
Post-Accident Examination
Examination of the airplane revealed that the fuel lines to each fuel tank were impact-separated from each wing, and both tanks were empty. The fuel caps were secure, and their flapper seals functioned properly. No evidence of a fuel leak or staining was found anywhere on the airplane. The engine-driven fuel pumps from both engines were removed; less than a drop of fuel was observed in each, and they rotated freely and produced pumping action with no mechanical deficiencies. The right engine was manually rotated, establishing compression for each cylinder; top spark plugs exhibited normal wear, and bottom plugs were oil-soaked. No mechanical deficiencies or malfunctions were observed that would have precluded normal operation.
Pilot Experience and Maintenance
The pilot, a U.S. Army flight test pilot, held an FAA commercial pilot certificate for airplane single- and multi-engine land and rotorcraft-helicopter. Most of his flight time was in military helicopters. He reported 10,047 total flight hours, including 46 hours in multi-engine airplanes. He had recently purchased the accident airplane and had flown it 9 times for a total of 14.6 hours within the last 11 months, including the 2-hour accident flight. The airplane's last annual inspection was completed two days before the accident, with no major work done to the right engine or fuel system. The pilot performed a 1-hour return-to-service flight after the inspection with no issues and reported no previous fuel system problems.
Fuel System and Engine Monitor Data
The airplane was equipped with an electric low (LO) fuel boost pump and an in-line high (HI) pressure fuel boost pump for each fuel tank/engine. Per the pilot operating handbook (POH), if either pump becomes inoperative, the engine-driven fuel pump can still provide fuel. The annunciator light for LO pump failure activates if there is no fuel pressure. The airplane's fuel capacity was 210 gallons with 2 gallons unusable.
The engine data monitor recorded the flight from engine start to the accident: the right engine operated for about 2 hours 3 minutes, the left engine for about 2 hours 4 minutes. Right engine exhaust gas temperature (EGT) dropped from between 1,300° and 1,400°F to about 250°F before stopping. Left engine EGT dropped from between 1,300° and 1,400°F to about 1,200°F momentarily, then less than 600°F before the monitor stopped.
Pilot Fuel Statements and Fuel Consumption
The pilot reported to the NTSB that the fuel on board at the last takeoff was 87 gallons. In a telephone interview, he reported filling the tanks to 1 1/2 inches below the top for a total of 166 gallons. He stated that normal fuel flow was 160–170 pph (26.6–28.3 gph), later saying cruise fuel flow was 120–130 pph (20–21.6 gph) and full power fuel flow was 170 pph (28.3 gph). According to the POH, a fuel flow of 160 pph during cruise corresponds to 55% power at 2,200 rpm, which would use about 70 gallons during the flight. At 75% cruise power (2,400 rpm), fuel flow would be about 256 pph, using about 100 gallons. The pilot provided no additional flight planning information.