Accident Overview
The private pilot was conducting a personal cross-country flight. Shortly after takeoff, the pilot informed an air traffic controller that he needed to return to the airport due to an attitude heading reference system (AHRS) "miscommunication."
Flight Path
Air traffic control radar data showed the airplane was about 1.75 miles north of the airport on a southeasterly course at approximately 2,000 ft mean sea level. About 20 seconds after the pilot requested to return, the airplane began to descend. It then entered a right turn that continued until the final radar data point. The airplane subsequently struck power lines about 3/4 of a mile from the airport while maneuvering within the traffic pattern. The power lines were about 75 ft above ground level.
Examination
A postaccident examination of the airframe and engine revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. Although the pilot reported a flight instrumentation issue, the investigation was unable to confirm whether such an anomaly occurred based on component testing and available information. Examination of the standby airspeed indicator showed that the link arm had separated from the pin on the rocking shaft assembly; however, it likely separated during the accident sequence. Functional testing indicated that the standby airspeed indicator was likely functional and providing accurate airspeed information throughout the flight. Additionally, examination of the left and right annunciator panel bulb filaments associated with the left fuel pump advisory revealed that they were stretched, indicating the left fuel pump advisory indication annunciated at the time of the accident. This likely occurred during the accident sequence as a result of an automatic attempt to activate the left fuel pump due to loss of fuel pressure immediately after the left wing separated.
Toxicology
Toxicology testing of the pilot detected low levels of three different sedating antihistamines. However, antemortem levels could not be determined, nor could the underlying reason(s) for the pilot's use of these medications. Consequently, it could not be determined whether pilot impairment occurred due to the medications or the underlying condition(s) themselves.
Analysis
Although the pilot reported a flight instrumentation issue, this problem would not have affected his ability to control the airplane. Further, the pilot should have been able to see the power lines given the day/visual weather conditions. It is possible that the pilot became distracted by the noncritical anomaly, which resulted in his failure to maintain clearance from the power lines.