Grumman American Avn. Corp. AA-5 N6552L accident near Fredericksburg, Texas

Probable cause

The pilot's failure to maintain adequate airspeed following a partial loss of engine power during initial climb, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall. Also causal was the mechanic's inadequate inspection of the airplane fuel system, which resulted in the partial loss of engine power due to fuel contamination.

NTSB analysis

The private pilot reported that his passenger, an aviation mechanic, had completed an annual inspection of the airplane immediately before the flight. The pilot did not identify any anomalies with the airplane during his preflight inspection following the annual inspection nor did he observe any fuel contamination in the samples that he collected from the airplane's four fuel drains. Additionally, he reported that the engine operated normally during a before-takeoff runup. Although the pilot did not recall all portions of the flight, he remembered that the engine lost power shortly after takeoff and had a brief memory of the airplane pointing nose-down toward the ground. The pilot did not recall any corrective actions that he made following the loss of engine power. The pilot reported that, while he was being treated at the hospital, he had apparently told his wife that the engine had lost power shortly after takeoff and that he had lowered the nose to regain airspeed. An onsite examination established that the airplane impacted the ground in a nose-low attitude, and the lack of an appreciable debris path was consistent with an aerodynamic stall. It is likely that the pilot did not maintain adequate airspeed following the loss of engine power, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall at a low altitude.

Postaccident examination revealed water and particulate contamination within the fuel distribution system, which likely resulted in a partial loss of engine power during initial climb. Based on the amount of fuel contamination observed after the accident, the mechanic did not adequately inspect the entire fuel system during the annual inspection that he completed immediately before the flight. According to the airplane's maintenance manual, during an annual inspection, the auxiliary electric fuel pump should be disassembled and its filter inspected/cleaned, the fuel tanks and sumps inspected, and the engine carburetor bowl drained. Had the mechanic examined the auxiliary electric fuel pump, he would have noted the extensive water and particulate contamination. The maintenance logbooks did not contain an entry for the annual inspection or any work associated with the inspection.

Text from the NTSB. Open the NTSB docket for CEN15FA269 for the full record.