Piper Aircraft Crash Due to Carburetor Heat Valve Failure and Frost (N8184Y)

What happened

The aircraft departed runway 27 and crashed on the north boundary of the airport within minutes. Dense ground fog was present at the crash site. Approximately one and a half hours after the accident, examination revealed very heavy frost on all parked aircraft adjacent to where the subject aircraft had been parked for two days. A witness who drove the pilot to the airport reported that there was frost on the aircraft upon arrival. The witness did not see the pilot remove frost from any part of the aircraft except the windshield.

The investigation

Examination of the wreckage found the carburetor heat valve jammed in the full hot position. Engineering data obtained from Piper indicated that the heat rise of the carburetor heat system is 129 degrees Fahrenheit at 75% power with a 28-degree Fahrenheit ambient air temperature. The power loss due to carburetor heat is 1% for each 10-degree heat rise.

Findings

The primary factors contributing to this accident were the pilot's failure to remove frost from the aircraft prior to flight and the jammed carburetor heat valve. These conditions led to a significant loss of power during the critical initial climb phase.