Blythe, CA, USA
N12YT
AMERICAN AVIATION AA-1A
The pilot was departing for a personal cross-county flight. Shortly after takeoff and about 50 ft above ground level, the engine lost partial power, and the airspeed decayed. Despite the pilot attempts to gain airspeed by confirming that the throttle and mixture levers were full forward, he did not lower the airplane’s nose at the first indication of an engine power loss to maintain airspeed. As a result, the airplane’s critical angle of attack was exceeded, and the airplane subsequently stalled and struck terrain. Review of performance data in the pilot’s operating manual for the airplane indicated that given the accident conditions, the airplane should have had the performance to adequately climb. A weather study revealed no significant weather in the immediate vicinity of the airport. Postaccident examination of the engine revealed that 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, which likely resulted in the loss of engine power after takeoff.
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.
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.
Source: NTSB Aviation Accident Database
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