N69PWCessna 172M · 1975

The pilot reported he was landing the airplane when a strong gust of wind pushed the airplane to the right about halfway down the runway. The pilot reported that after he initiated a go-around, the airplane became uncontrollable which resulted in an aerodynamic stall and impact with the ground. The impact resulted in substantial damage to the left wing and fuselage.

Initially the pilot reported that there were no mechanical malfunctions related to the airplane so the airplane was released to the owner. Later, the pilot reported that he did not hear the stall horn and suspected it was inoperable. He also stated that the flap switch physically stuck in the up position which retracted the flaps fully and contributed to the stall.

The pilot was asked to describe the normal operation of the flap switch. He stated that holding the switch up raises the flaps, holding the switch down lowers the flaps, and letting go of the switch shuts off the flap motor.

When follow up was conducted on the reported mechanical issues, the airplane was found stripped of parts, thus examination of the stall horn was not possible. The flap switch was removed and examined.

The flap switch specifications and the Pilot Operating Handbook both stated that the switch would remain in the up position until the switch was physically moved to the center (off) position, thus if the pilot let go of the switch while raising the flaps, the switch would stay in the up position and continue to raise the flaps to zero. During a go around, the flaps should have initially been retracted to 20 degrees which would require the pilot to move the flap switch back to the neutral position after the flaps reached 20 degrees. After the airplane was established in a climb, the remaining flaps would be retracted by returning the flap switch to the up position.

The switch was found to operate normally with no defects found. Based on the pilot’s description of the flap switch operation it is likely he did not know how the switch functioned.