NTSB Factual Report

HISTORY OF FLIGHT

On July 31, 2014, about 1930 central daylight time, an amateur-built Ketterling FEW P-51 Mustang airplane, N116LK, impacted an agricultural field following a loss of control near Lisbon, North Dakota. The pilot, who was the sole occupant, was fatally injured. The airplane was destroyed by impact forces and a post-impact fire. The aircraft was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from the Lisbon Municipal Airport (6L3), Lisbon, North Dakota, at an unconfirmed time.

A witness that lived near the accident site reported seeing the accident airplane fly over the tree line northwest of their house. She told authorities that the airplane barely cleared the trees, and then shortly afterward there was silence. She and her husband then saw smoke and notified authorities. She stated that the airplane sounded very loud.

Another witness reported hearing the accident airplane and reported to authorities that the engine sounded as if it were speeding up and slowing down.

Another witness reported that he heard a loud unusual engine noise. He then saw a light colored low wing airplane at about 500 to 750 feet in the air traveling toward the south. He stated that the airplane's engine was making an abnormal on/off sputtering type noise that continued throughout the remainder of the flight. The airplane continued south while losing altitude. The airplane then nosed up slightly, rolled, and then began a slow spin toward the ground. The airplane then went out of sight behind a tree line. The engine sounds were heard for a few more seconds and then stopped. He then saw a large black plume of smoke coming from the direction where he last saw the airplane.

PERSONNEL INFORMATION

The pilot, age 64, held a private pilot certificate with a single-engine land airplane rating. He was issued a third-class special restriction airman medical certificate on April 22, 2014. The medical certificate listed the following limitations: Must wear corrective lenses for near and distant vision. Not valid for night flight or color signal control.

The pilot's logbook was not reviewed during the investigation, however, he reported having 700 hours total flight experience and 30 hours in the six months preceding his most recent medical examination.

AIRCRAFT INFORMATION

The accident airplane was a 2/3 scale replica of a World War II North American P-51D fighter airplane. It was constructed of predominately composite materials and employed a retractable conventional (tailwheel) landing gear arrangement. It could seat two people in a tandem seating arrangement. A Chevrolet Corvette LS-1 engine powered the airplane through a propeller reduction drive.

According to kit manufacturer information, the airplane had the following specifications:

Airframe specifications:

All composite 7781 pre-preg airframe.

Wingspan . . . . . . . . . . . . . . 25 ft 5in

Length . . . . . . . . . . . . . . . . 18 ft 6in

Wing loading . . . . . . . . .22.5 lb/sq ft

Fuel capacity . . . . . . . . . . . . . 60 gal

Max gross weight . . . . . . . . .2500 lb

Typical empty weight . . . . . . 1800 lb

Full fuel payload . . . . . . . . . . . 700 lb

Full fuel payload . . . . . . . . . . . 349 lb

Seat capacity . . . . . . . . . . . . . . . . . .2

Cabin width . . . . . . . . . . . . . . . . 24 in

Baggage capacity . . . . . . . . . . . 50 lb

Performance specifications:

Cruise speed . . . . . . . . . . . . . 250 kts

w/ LS-376, 480 hp, 18 gph

(7000ft @ 70% max continuous)

Max rate of climb . . . . . 3000+ft/min

Stall speed (landing config) . . . 51kts

Stall speed (clean) . . . . . . . . . . 65kts

Take off distance . . . . . . . . . 1000 ft

Landing distance . . . . . . . . . .1650 ft

Firewall forward specifications:

GM LS-376 V-8 Alum Crate Engine

480 hp normal fuel injected

super charged available!!!

Cam 500 geared PSRU

MT-16, 86 in, 4 blade, paddle prop

Due to differences in construction, the accident airplane may not have had the same specifications as listed above.

METEOROLOGICAL INFORMATION

Weather conditions recorded by the Gwinner Airport-Roger Melroe Field (GWR), Gwinner, North Dakota, Automated Weather Observing System (AWOS), located about 14 miles south of the accident site, at 1029, were: wind from 330 degrees at 5 knots, clear skies, temperature 27 degrees Celsius, dew point 15 degrees Celsius, and altimeter 30.04 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

The airplane impacted a level wheat field about 3 nautical miles north of 6L3. All of the airplane's flight control surfaces were located in the immediate area of the wreckage site. The tail surfaces were separated from the fuselage but remained predominately intact. The left elevator was separated from the horizontal stabilizer. The right elevator and rudder remained attached to the horizontal and vertical stabilizers respectively. The right wing and fuselage forward of the empennage was almost completely consumed by fire. The left wing was intact and exhibited crushing of the leading edge and fire damage to the root end of the wing. Examination of the airplane's flight control system did not reveal any anomalies or defects attributable to a pre-impact failure or malfunction. The airplane's landing gear was in the retracted position. The flap position could not be conclusively determined, but the flap surfaces appeared to be retracted. The engine's crankshaft could not be fully rotated due to crushing damage to the oil pan and windage tray. However, partial rotation confirmed crankshaft and camshaft continuity. The engine used automotive components for the ignition and fuel injection systems. Testing of these systems was not possible due to extensive fire and impact damage.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy of the pilot was performed by the University of North Dakota-School of Medicine and Health Science-Department of Pathology, Grand Forks, North Dakota, on August 1, 2014. The pilot's death was attributed to injuries received in the accident.

Toxicology testing was performed by the FAA Civil Aerospace Medical Institute. Testing results showed:

Amlodipine detected in Liver

Amlodipine detected in Kidney

Atorvastatin detected in Liver

Amlodipine is a calcium channel blocker heart medication commonly used in the treatment of hypertension (high blood pressure). Atorvastatin, sold under the trade name Lipitor, is a member of the drug class known as statins, commonly used for lowering blood cholesterol.

ADDITIONAL INFORMATION

The accident airplane was equipped with a Dynon SV-D700 primary flight display. The unit was removed from the aircraft and sent to the National Transportation Safety Board Recorder Laboratory for examination and download of any pertinent data. The data downloaded included flight parameters from the unit's altitude and heading reference system (AHRS), as well as global positioning system (GPS) data. No engine parameters were recorded by the unit. GPS data was determined to be unreliable; however, AHRS data was recovered. The data showed that the airplane took off from a pressure altitude of 1,097 ft and performed several maneuvers in excess of two g's in the first three minutes of the flight. Roll reached extents of 80 degrees to the left and the right during this time. Recorded vertical acceleration force during this time ranged from 0.2 to 3.1 g.

About 2 minutes before the end of the recorded data, the aircraft was in relatively stable flight at about 2,500 ft pressure altitude and 150 knots on a westerly heading. At a recorded time of about 19:30:41, the longitudinal acceleration began to go negative, indicative of a deceleration force on the aircraft, and lateral and vertical acceleration both experienced a transient change. Shortly afterward, the airspeed began to decrease, and it stabilized at around 83 knots. As the airspeed decreased, the aircraft began a turn to the left, ending on a southerly heading. Altitude stayed steady following the deceleration for about 15 seconds, and then decreased between 500 and 1000 feet per minute for the rest of the recording.

The recording ended with the aircraft at 1,815 ft pressure altitude, decreasing at 626 feet per minute, and at a speed of 78 knots.

According to the manufacturer, in the case of a sudden power interruption, the unit has the possibility of losing as much as the previous 30 seconds of data due to data buffering prior to writing the log files.

NTSB Probable Cause

The partial loss of engine power for a reason that could not be determined because of extensive impact and postcrash fire damage, and the pilot's failure to maintain adequate airspeed, which resulted in the airplane's wing exceeding its critical angle-of-attack and a subsequent aerodynamic stall/spin.