Accident Sequence
On January 28, 2023, at about 1310 eastern standard time, a Mooney M20C, registration N5587Q, was destroyed in an accident at Calhoun, Georgia. The pilot was seriously injured, and the flight instructor-rated passenger received minor injuries. The flight was operated as a Title 14 Code of Federal Regulations Part 91 personal flight and had departed from Tom B David Field Airport (CZL) for a local flight.
According to the pilot, the preflight check and runup were normal except for a magneto drop. The right magneto initially dropped 150 rpm. After leaning the fuel mixture and running the engine at about 1,700 rpm for about one minute, repeated a couple of times, both magnetos dropped 125 rpm. Subsequent magneto checks each resulted in a 125-rpm drop with normal engine operation.
After the runup, the flight proceeded to runway 17. Full throttle was applied, with oil temperature and pressure in the green and the engine sounding normal. Just after liftoff, the pilot retracted the landing gear. Moments later, at about 70 ft above the runway, a popping noise occurred, the engine lost power, engine rpm dropped to nearly zero, and the airplane began losing altitude.
Because they had not cleared the south end of the runway, the pilot lowered the landing gear, pitched down, and descended. The airplane touched down at the very end of the runway, and the pilot applied wheel brakes. There was insufficient runway to stop; the airplane skidded off the end into the grass and slid into an earth embankment. It then became airborne briefly, rotated 90° to the left, and came to rest after a few hundred feet.
The flight instructor unbuckled his lap belt, saw flames near the pilot’s feet, and advised the pilot of the fire. Both egressed and moved away from the airplane in a westerly direction.
A witness, who was moving airplanes in a hangar about 4,000 ft from runway 17, reported hearing sputtering around the time the airplane passed him, though it did not sound like a complete engine failure. The witness observed the landing gear retract and then extend when the engine roughness and power loss occurred. He then saw the airplane hit the displaced threshold, heard the tires chirp, and watched the airplane bounce, skid through the grass, hit an embankment about 100 ft off the end of the runway, become airborne momentarily, cartwheel into the ground, and come to rest. Both pilots were out of the airplane when he arrived; it was becoming engulfed in flames.
Investigation Findings
Examination of the displaced threshold revealed four propeller strike marks, with spacing indicating that the propeller was rotating on impact.
The wreckage examination showed the cabin was destroyed by fire. Flight control continuity was established from the flight control surfaces to the cabin. The fuel selector valve was in the right-wing fuel tank position; when an air source was applied to the port for the right tank, no blockages were discovered.
Examination of the 4-cylinder, horizontally opposed, air-cooled, carbureted engine revealed that the No. 3 bottom spark plug was not in the spark plug hole and was hanging from the ignition cable. The No. 3 bottom spark plug hole thread insert (Helicoil) was partially pulled from the spark plug hole, with the lower three threads displaying an absence of rust. The threads above the lower three threads were rusty, and the bottom portion of the Helicoil was still intact.
No other anomalies were discovered that would have resulted in a preimpact failure or malfunction that would have precluded normal operation.
Maintenance History
Review of maintenance records disclosed that the most recent engine overhaul was completed on March 9, 1993, about 30 years before the accident.
The most recent annual inspection was completed on December 1, 2022. The logbook entry for that inspection indicated the engine had accumulated 838.24 hours of time in service and that the spark plugs had been removed, cleaned, inspected, and installed.
As of the last entry in the engine logbook, dated January 14, 2023, the engine had accumulated 839.24 hours since overhaul. That entry stated that the No. 2 cylinder spark plug was replaced. The pilot stated that this maintenance was a result of the engine running rough during a magneto check. The investigation was unable to determine if the No. 3 spark plug was removed and reinstalled at that time.