NTSB Factual Report

HISTORY OF FLIGHT

On February 21, 2018, at 1615 central standard time, a Piper PA-28-140, N3568K, was destroyed when it impacted terrain while landing at Tri-County Airport (1J0), Bonifay, Florida. The commercial pilot was fatally injured. The airplane was privately owned and the pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Day visual meteorological conditions prevailed and no flight plan was filed for the local flight, which originated from 1J0 about 1600.

The owner stated that he had flown the airplane before the accident flight. He departed runway 19, climbed to 1,800 ft mean sea level, and maneuvered within 3 to 4 nautical miles of the airport for a few minutes. He then reentered the traffic pattern and completed a touch-and-go landing. He stated that the engine operated normally during this portion of the flight; however, during the initial climb after the touch-and-go landing, the airplane "seemed like it didn't want to fly." The owner verified that the throttle, mixture, and carburetor heat were "full forward." He stated that the engine was not popping or shaking and was not running rough, but the engine would not produce full power. The owner declared an emergency, made a 180° turn back to the airport, and landed uneventfully. He then performed an engine run-up and observed no abnormalities. He subsequently taxied the airplane to his hangar and reported the anomaly to his mechanic.

The owner said that the mechanic immediately boarded the airplane, started the engine, and performed a run-up, during which the engine sounded normal. The mechanic informed the owner that he was going to take the airplane for a test flight and asked the owner to join him multiple times. The owner declined and watched as the airplane departed runway 19. The airplane made a left turn and entered the downwind leg of the traffic pattern at a normal traffic pattern altitude. The owner then observed the airplane descend on the downwind leg and turn onto a left base leg before it disappeared behind trees. A few moments later, he saw a plume of smoke and rushed to the accident site, where he observed the airplane engulfed in flames.

A witness stated that he was outside of his home located on the approach to runway 19. He said that the airplane "didn't sound right" as it flew over his home and that the engine sounded as if it were making "little explosions" or "backfires." The witness observed the airplane's main landing gear brush a tall tree on his property then continue south out of view. Shortly thereafter, he heard an impact and saw a fireball.

PILOT INFORMATION

In addition to holding a mechanic certificate with airframe and powerplant ratings, the mechanic held a commercial pilot certificate with ratings for airplane single- and multi-engine land and instrument airplane. A review of his logbook revealed that he had accrued a total of 816.2 hours of flight experience (30.3 hours were in the accident airplane) as of February 14, 2017, when he completed his last flight review. There were no flights logged after this date. His most recent Federal Aviation Administration (FAA) second-class medical certificate was issued on June 26, 2016.

AIRCRAFT INFORMATION

The low-wing, four seat airplane was equipped with a Lycoming O-320-E2A engine and a two-bladed Sensenich propeller. A review of maintenance records revealed that the last annual inspection was conducted on June 5, 2017, by the pilot, at a tachometer time of 3,951.77 hours, with 715.3 hours since engine overhaul. The airframe total time was 5,207.57 hours. The owner reported that the airplane had only flown a few hours since the annual inspection and that he had not had any problems with the engine before the day of the accident.

The owner purchased 20 gallons of 100LL aviation gasoline before his flight and stated that the total fuel onboard before departure was 50 gallons (48 usable).

METEOROLOGICAL INFORMATION

1J0 was not equipped with weather reporting equipment. A witness reported that the wind was 10-20 knots from the south, visibility 10 statute miles, and the sky condition was scattered to overcast at the airport at the time of the accident.

At 1556, reported weather at Cairns Army Airfield (OZR), Fort Rucker/Ozark, Alabama, about 27 nautical miles north of 1J0, included wind from 140° at 8 knots, visibility 10 miles, scattered clouds at 5,000 ft, broken clouds at 6,000 ft, temperature 28°C, dew point of 17°C, and an altimeter setting of 30.28 inches of mercury.

WRECKAGE INFORMATION

Examination of the area surrounding the accident site revealed damage that was consistent with the airplane striking a 60-ft-tall tree located about 1/4 mile from the runway. before it impacted the ground, and collided with the airport's chain-link perimeter fence. The airplane came to rest upright just north of the runway threshold on a heading of 35°. A postimpact fire consumed most of the wreckage; however, all major components of the airplane were accounted for at the accident site.

Flight control continuity was established from all flight controls to the cockpit area. The flaps were in the fully retracted position and the fuel selector was set to the right tank.

The engine remained secured to the airframe and the engine cowling had burned away. The engine-driven fuel pump remained attached to the engine but was destroyed by fire. Both magnetos remained attached to the accessory housing. The left and right magnetos and their associated ignition harnesses were destroyed by fire and could not be tested.

Fuel lines, including the firewall-mounted fuel strainer, from the wings to the carburetor were destroyed by fire. The carburetor was thermally damaged and removed from the engine. The carburetor, which was equipped with composite floats, was disassembled and the bowl was empty. The inlet fuel screen was absent of debris.

The engine, with the propeller still attached, was removed from the airframe and examined. The top spark plugs and the rocker covers were removed. The spark plugs displayed a low service life and a color consistent with normal combustion per the Champion Check-a-Plug chart. The No. 2 cylinder bottom spark plug could not be removed due to the deformation of the exhaust header pipe. The No. 4 cylinder bottom spark plug had dislodged from the cylinder and was not recovered.

The engine was manually rotated via the propeller. Compression and valve train continuity was established for all but the No. 4 cylinder. The cylinder was removed and the exhaust valve was found seized in the valve guide in the open position; the valve face exhibited some deformation. The valve and the face of the piston displayed a substantial amount of carbon deposits. The No. 4 cylinder barrel bore also appeared worn and the piston rings were heat-compressed in the ring lands.

MEDICAL AND PATHOLOGICAL INFORMATION

The District 14 Medical Examiner, Panama City, Florida, performed an autopsy of the pilot. The cause of death was determined to be "airplane crash."

The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on specimens of the pilot. The results were negative for carbon monoxide, ethanol, and all tested-for drugs. Friends of the pilot reported that the pilot was diabetic and was having issues controlling his blood glucose. Additional testing revealed that glucose at 18 mg/dl in vitreous, 22 mg/dl in urine, and a hemoglobin A1C of 8.2%.

After death, "normal" glucose levels in vitreous are below 200 mg/dl. Levels below 150 mg/dl are normal in urine. Hemoglobin A1C is a measure of the percentage of hemoglobin molecules that have a glucose molecule attached to them. It is used as a measure of average blood glucose over the preceding several weeks. Non-diabetic levels are below 5.4%. Between 5.5% and 6.4% is considered "pre-diabetes" and above 6.5% indicates diabetes. For diabetic individuals, levels below 7.0% are considered "good control." Levels above 9% are considered "poor control."

ADDITIONAL INFORMATION

Valve sticking in Lycoming reciprocating aircraft engines is addressed in Lycoming Mandatory Service Bulletin 388C and Lycoming Service Instruction 1485A. Mandatory Service Bulletin 388C, which, according to FAA regulations, is not mandatory for aircraft operated under 14 CFR Part 91, calls for all Lycoming reciprocating aircraft engines to be inspected at 400-hour intervals or earlier if valve sticking is suspected. If the valve and guide do not pass the inspection, then corrective action is to be taken as defined in Service Instruction 1485A. Once the guides are replaced with the newer Hi-Chrome guides, inspection is called for every 1,000 hours, half of the published TBO, or when valve sticking is suspected, whichever occurs first.

Review of the airplane maintenance logs revealed that the valve guides and stems had not been inspected in accordance with Lycoming Mandatory Service Bulletin 388C at the recommended 400-hour interval.

NTSB Probable Cause

A partial loss of engine power due to a stuck exhaust valve. Contributing to the accident was the pilot's decision to operate an airplane with a known mechanical deficiency and his failure to fly an appropriate traffic pattern that would have allowed the airplane to reach the runway.