Sparta, TN, USA
N7254L
AMERICAN AVIATION AA-1A
An annual inspection had just been completed on the airplane, and the following day the pilot conducted a test flight directly over the airport. Shortly after takeoff, the pilot climbed to 6,500 ft mean sea level (msl) while conducting rectangular patterns directly over the airport for several minutes and then initiated a descent to 4,500 ft msl. During the descent, without any warning, the airplane sustained a loss of engine power. The pilot was unsuccessful in his attempts to restart the engine, resulting in the need to conduct a forced landing. As he entered the airport traffic pattern, the airplane was too high to land on the runway, so he conducted a side slip to lose altitude, but over-corrected and was too low to reach the desired runway. Unable to glide to the runway, the pilot landed short of the runway on rough, hilly terrain, which resulted in substantial damage to the airframe. Postaccident examination of the engine, fuel system, and induction system revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The weather conditions reported at the time of the accident were conducive to serious carburetor icing. Examination revealed that the carburetor heat was not in use when the airplane impacted the ground based on damage signatures to the bottom side of the heat box; the carb heat butterfly valve was in the “cold air” position and could not be activated due to the deformation of the box. The pilot also did not report that he used the carburetor heat. Based on the temperature and dew point at the altitude about where the loss of engine power occurred, the conditions were favorable for serious carburetor icing at the glide power setting and very close to the cruise power setting; therefore, it is likely that carburetor ice accumulated while descending and resulted in a loss of engine power.
On November 4, 2022, about 1715 central standard time, an American Aviation AA-1A, N7254L, was substantially damaged when it was involved in an accident near Sparta, Tennessee. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. The pilot stated that, during an annual inspection the day before, he had discovered and repaired an irregularity with an air intake hose. The accident flight was a post-maintenance test flight. He performed a thorough preflight inspection and engine run-up before takeoff with no anomalies observed. Shortly after takeoff, the pilot climbed the airplane to about 6,800 ft mean sea level (msl) while conducting rectangular patterns directly over the airport, then initiated a descent to 4,500 ft msl. During the descent, without any warning, the airplane “completely” lost all engine power. The pilot reported that he never reduced power during the descent; he maintained takeoff power or cruise power for the entire duration of flight, even during the descent. The pilot’s attempts to restart the engine were unsuccessful. As the airplane continued to descend, he approached the airport on the downwind leg of the traffic pattern abeam the runway 22 numbers at 4,000 ft msl (2,075 above ground level). The pilot decided the airplane was too high to land on the runway and he conducted a slip to lose altitude. Upon completion of the slip, the pilot realized he had over-corrected and was too low to reach the runway. He elected to perform a forced landing in a field about 1/2 mile before the runway. The pilot flew below powerlines and landed hard on rough, hilly terrain. The airplane impacted a fence and brush before coming to rest. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the left and right wings were crushed at multiple locations, and the fuselage was buckled under the engine compartment. A subsequent examination by the FAA inspector and a mechanic revealed that the engine air inlet was packed with dirt, but the induction system components were otherwise intact and not obstructed. The carburetor heat butterfly valve was in the open (cold) position, fuel was present in the carburetor and the fuel pumps operated and showed no anomalous behavior. Engine crankshaft continuity was established, and the spark plugs showed normal coloration. The recorded temperature and dew point near the accident site was about 71°F and 50°F, respectively. On the carburetor icing probability chart, those temperatures were in the “serious icing – glide-power” range; however, at altitude about 6,000 ft msl, near where the loss of engine power occurred, weather sounding data revealed temperature and dewpoint was about 49°F and 35°F, respectively, which bordered on the serious icing at a cruise power setting.
A total loss of engine power due to an accumulation of carburetor ice, resulting in an off-airport landing and substantial damage to the airplane.
Source: NTSB Aviation Accident Database
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