Grumman American Avn. Corp. AA 1C N9923U accident near Hemet, California

Probable cause

The airplane’s hard landing due to the pilot’s failure to maintain sufficient airspeed while on approach after shutting down the engine because of the smoke in the cockpit from a burnt wire that originated from the alternator field terminal and extended to the cockpit.

NTSB analysis

The pilot reported that, while on the downwind leg of the airport traffic pattern, smoke entered the cockpit and that his passenger thought the engine was on fire. He immediately shut down the engine and opened the canopy a little, which cleared most of the smoke. He then transmitted on the common traffic advisory frequency that he had smoke in the cockpit and was going to make an emergency landing. As the pilot turned the airplane toward the runway, he observed a helicopter on it, and he transmitted his intention to land a second time. The pilot slowed the airplane and then saw the helicopter depart. As the helicopter lifted off, the pilot "tried to make the runway." The pilot reported that, during the approach to landing, the airplane was "too low and too slow," and, subsequently, the airplane landed hard. Postaccident examination of the airplane revealed a burnt wire that originated from the field terminal of the voltage regulator and extended into the cabin through the engine firewall. It is likely that the burnt wire created the smoke that entered the cockpit. The reason for the burnt wire could not be determined.

Text from the NTSB. Open the NTSB docket for WPR13LA432 for the full record.