N700AK

On September 17, 2022, about 1202 eastern daylight time, a Rockwell International 700 multi-engine airplane, N700AK, was substantially damaged when it was involved in an accident at Gatlinburg-Pigeon Forge Airport (GKT), Sevierville, Tennessee. One passenger sustained minor injuries, while the commercial pilot and two of the passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot stated that before departure from Marianna Municipal Airport (MAI), Marianna, Florida, he purchased fuel from the airport’s self-serve fuel pump. He reported that he filled both of the airplane’s wing fuel tanks to about 1 and 1/2 inches below the top of the tanks for a total of 166 gallons (83 gallons per side). Receipts provided by the airport confirmed the pilot purchased about 98 gallons of fuel.

A review of ADS-B flight tracking data revealed the flight originated at MAI at 1007; the airplane’s last ADS-B-reported position was at 1201 (1 hour 54 minutes), when the airplane was about 0.62 miles from the approach end of runway 28 at GKT.

The pilot said the flight to GKT was normal until the airplane was on final approach when the right engine fuel boost pump light illuminated. The right engine began to sputter; fuel flow dropped and began to fluctuate between 0 and 75 pounds per hour (pph). The pilot brought both throttles, propeller, and mixture controls full forward and cleared a set of powerlines located about .6 miles off the end of the runway. Once the airplane reached the end of the runway, the right engine lost power completely. The pilot said he applied full left rudder pedal to compensate for the asymmetric thrust, but the rudder became “ineffective.” The airplane made a hard right turn even after he reduced power to the left engine., The pilot said in hindsight he may have kept power on the left engine too long and did not “account for the loss of wind going over the rudder.” The airplane struck a taxiway and runway light as it veered to the right. The pilot reported that after the airplane left the grass infield, the airplane became airborne again. As the airplane flew away from the runway environment, he tried to avoid hitting parked aircraft and gas tanks. The pilot reported that the airplane then stalled and collided with two hangars, resulting in substantial damage to both wings and the fuselage. There was no postimpact fire. The pilot, a witness who was in the hangar, students from the local flight school who arrived shortly after the accident, and the responding police and fire departments reported there was no evidence of a fuel spill and no smell of fuel.

Examination of the airplane revealed the fuel lines to each fuel tank were impact separated from each wing and both tanks were empty of fuel. The fuel caps were secure to each wing and their respective flapper seals functioned properly. There was no evidence of a fuel leak or fuel staining anywhere on the airplane.

Each engine was equipped with an engine-driven fuel pump. The engine-driven pump is the primary pump that pumps fuel from the fuel tanks to the engine when the engine is operating. The engine-driven fuel pumps were removed from the right and left engines and less than a drop of fuel was observed in each. The couplings were intact. When manually rotated, the pumps rotated freely and produced a pumping action (air in and out). No mechanical deficiencies were noted.

The right engine was also examined. When the crankshaft was manually rotated, compression for each cylinder was established. The top spark plugs were removed and exhibited normal wear and the bottom plugs were oil soaked. No mechanical deficiencies or malfunctions were observed with the right engine that would have precluded normal operation at the time of the accident.

The pilot was a flight test pilot for the United States Army. He held a Federal Aviation Administration (FAA) commercial pilot certificate for airplane single and multi-engine land airplanes, and rotorcraft-helicopter. Most of his flight time was operating military helicopters. He reported a total of 10,047 flight hours, of which 46 hours were in multi-engine airplanes. The pilot had recently purchased the accident airplane and his flight logbook revealed that within the last 11 months he had flown the airplane 9 times for a total of 14.6 hours, which included the 2-hour accident flight.

A review of the airplane’s maintenance records revealed the last annual inspection was completed two days before the accident. No major work was done to the right engine or fuel system. The pilot said he flew the airplane for a 1-hour return-to-service flight after the annual inspection was completed and he reported no issues. He also reported there had been no previous problems with the airplane’s fuel system.

The airplane was equipped with an electric low (LO) fuel boost pump and an in-line high (HI) pressure fuel boost pump that serviced each fuel tank/engine. The HI boost pump is used during takeoff and landing only or in the case of an emergency if the engine driven fuel pump failed. The LO boost pump is used during normal flight and runs continuously. It also assists the HI boost pump in the case of an emergency. Per the airplane’s pilot operating handbook (POH), if either the LO boost pump or HI boost pump become inoperative, the engine-driven fuel pump still has the capacity to provide fuel to the engine. If a LO boost pump fails, a L FUEL BOOST or R FUEL BOOST light will illuminate on the annunciator panel. The annunciator light is activated by a pressure switch downstream of the pump. If there is no fuel pressure, the light will illuminate. The fuel capacity of the airplane was 210 gallons with 2 gallons of unusable fuel.

The airplane was equipped with an engine data monitor that recorded engine data for the entire flight from engine start to the time of the accident. The engine monitor indicated that the right engine was operating for about 2 hours 3 minutes and the left engine was operating for about 2 hours 4 minutes. The data for right engine showed the EGT dropping from between 1,300° to 1,400°F to about 250°F before the monitor stopped recording. The data for left engine shows the EGTs dropping from between 1,300° to 1,400°F to about 1,200° momentarily, and then less than 600°F before the monitor stopped recording.

The pilot reported to the NTSB that the fuel on board the airplane at the last takeoff was 87 gallons. In a telephone interview with FAA inspectors, the pilot reported that he filled both of the airplane’s wing fuel tanks to about 1 and 1/2 inches below the top of the tanks for a total of 166 gallons (83 gallons per side). The pilot reported that the normal fuel flow for the airplane was 160 – 170 pph (26.6 – 28.3 gph). Later in the same interview, the pilot stated that the normal fuel flow for cruise setting was 120 - 130 pph (20 – 21.6 gph); fuel flow at full power was 170 pph (28.3 gph). Apart from the fuel flow estimates, the pilot did not provide any additional flight planning information.

According to the airplane’s POH, a fuel flow of 160 pph during cruise flight equates to a cruise power setting of 55% power at 2,200 rpm. If the airplane was flown at that power setting during cruise flight, the airplane would have used about 70 gallons of fuel during the flight. Had the pilot used a 75% cruise power setting (75% power at 2,400 rpm), the fuel flow would have been about 256 pph, which would increase the fuel used during the flight to about 100 gallons.