Incident Details
On November 4, 2023, at 1200 Pacific standard time, an Arrow Falcon Exporters UH-1H (registration N3053Q) sustained substantial damage during startup near Firebaugh, California. The helicopter was being operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot, who was uninjured, reported that he believed the helicopter might not have flown for the preceding two weeks. He conducted a preflight inspection and initiated startup without noting any anomalies. While activating the GPS system and putting on his helmet, the pilot observed and smelled smoke in the cockpit. Upon looking outside, he saw smoke emanating from the upper engine compartment. He promptly secured the helicopter, shut it down, and contacted emergency services. The local fire department extinguished the fire.
Postaccident Examination
A postaccident examination revealed significant thermal damage to the left side of the cockpit and cargo areas adjacent to the engine, resulting from the on-ground fire. The engine remained attached to the upper engine compartment, and the engine-side fuel filter was in its normal position with fuel lines still attached. The area where the airframe-side fuel shutoff valve was located had been thermally destroyed, and the fuel lines in that region were consumed by the fire. Maintenance personnel concluded that the fire originated on the airframe side at a fuel inlet line leading to the fuel shutoff valve.
Maintenance History
A review of the maintenance logbooks indicated that an annual inspection had been completed on July 18, 2023, approximately three and a half months before the incident. According to the director of maintenance, the fuel line fittings would have been checked for tightness during that inspection.