Accident Details
Probable Cause and Findings
The excessive wear of one magneto’s wiring harness, which resulted in a loss of engine power during takeoff. Contributing to the accident was the pilot’s failure to maintain airspeed following the loss of engine power, which resulted in exceedance of the critical angle of attack and a subsequent aerodynamic stall.
Aircraft Information
Registered Owner (Historical)
Analysis
On May 15, 2020, about 1357 Pacific daylight time, an American Aviation AA-1A airplane, N12YT, was substantially damaged when it was involved in an accident near Blythe, California. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
According to the pilot, he was on a cross-country trip from California to Tucson, Arizona, and landed at Blythe Airport (KBLH) to refuel. He reported that while descending into the airport, the engine was running unevenly, requiring him to adjust the mixture. The landing was uneventful, and he refueled the airplane to a full fuel load of about 24 gallons and proceeded to take off on runway 8. The pilot stated that the wind was light and variable as he began his takeoff.
Shortly after takeoff about 50 ft above ground level, the airplane would not climb, and he noticed a loss of airspeed and partial power. The pilot confirmed that the throttle and mixture levers were full forward. The airplane experienced an aerodynamic stall, and the pilot pushed the nose down to gain airspeed, but shortly thereafter, the airplane’s left wing dropped and struck terrain. The airplane subsequently impacted the ground just past the end of the runway, spun, and came to rest about 150 ft from the initial point of impact.
A weather study revealed no significant weather in the immediate vicinity of the airport. At 1352, the weather observation for KBLH reported true wind from 140° at 9 knots gusting to 16 knots, visibility 10 miles or more, sly clear below 12,000 ft above ground level, temperature 91° F, dew point temperature 35° F, and altimeter 29.78 inches of mercury. At these conditions, the calculated density altitude was 2,759 ft mean sea level (msl). For takeoff on runway 8, there was a headwind component of 6 to 10 knots based on the peak reported gust.
According to the pilot’s operating handbook for the airplane, at gross weight, at 2,500 ft msl and 50° F, the airplane was capable of a 645 ft per minute rate of climb. The pilot’s operating handbook did not provide a correction factor for higher-than-standard day temperatures.
During postaccident examination of the airframe, flight control continuity was established. Examination of the engine revealed that it rotated by hand, and rotational continuity was established throughout the engine. A borescope examination of the cylinders revealed normal operational conditions. The left magneto’s wiring harness had excessive wear from being twisted and zip-tied near the distributor cap. All four wires were noted to have exposed center conductors that contacted their shielding. When tested, the wires intermittently failed to conduct current and sporadically arced.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# WPR20LA148