Introduction
On September 21, 2015, about 0645 mountain daylight time, a Cessna T206H (registration N7269T) experienced an in-flight fire during initial climb from Idaho Falls Regional Airport, Idaho Falls, Idaho. The airplane was registered to TK Leasing LC and operated by Aero-Graphics Incorporated as an aerial survey flight under 14 CFR Part 91. The flight instructor and passenger/camera operator sustained minor injuries related to smoke inhalation. The airplane sustained minor damage. The flight departed at about 0640 under visual meteorological conditions; no flight plan was filed.
Event Sequence
The pilot performed a preflight inspection, and the passenger checked external camera equipment. No anomalies were noted, and the engine run-up was normal. During initial climb, after flap retraction and reaching about 200 ft above ground level, the passenger observed smoke. The pilot initiated a turn to the crosswind leg, and smoke rapidly filled the cabin. The passenger opened the side window; the pilot asked him to close it, concerned it might fan the smoke source. The pilot donned his oxygen cannula, but it provided no relief, and he had difficulty breathing due to smoke density. The smoke obscured the instrument panel, but he could partially see the runway and immediately turned toward it. He opened his side window and put his head outside for better visibility, but wind made breathing difficult. He pushed the nose down, initiating a steep dive to the runway. He could not recall the final landing stages, but upon touchdown, he applied full brakes, locking the wheels. After stopping, he shut off the fuel mixture control, and both occupants rapidly egressed.
Post-Flight Examination
Thermal damage was observed on the right side of the firewall, upper and lower engine cowlings, and the forward right fuselage section, which had burned through to the cabin at the air inlet door. The fire location relative to the air inlet caused smoke to be forced directly into the fresh air intake system. Examination revealed that the wastegate overboard exhaust tailpipe had separated from the turbocharger housing. The turbocharger housing outlet was aligned with the battery mounting tray on the right firewall. The battery had partially melted, and both positive and negative electrical cables had partially melted, exhibiting globular damage consistent with arcing and an electrical short circuit.
Service Bulletin Information
Cessna Service Bulletin SB99-71-06, released December 6, 1999, recommended installation of a tailpipe lanyard to ensure positive turbocharger exhaust tailpipe retention. No lanyard was found on the airplane, and no maintenance logbook record indicated compliance. The bulletin affected 111 Cessna T206H airplanes; Cessna records showed that in the two years following issuance, 91 subassembly components were sold, with sales averaging about three per year through 2015. Federal Aviation Administration regulations do not require compliance with service bulletins for Part 91 operations.
Previous Event
The airplane experienced a similar tailpipe separation during takeoff on April 28, 2015. Smoke again entered the cockpit, and damage was limited to the battery and its cables. Maintenance records indicated that the tailpipe clamp and gaskets were replaced after that event.
The pilot noted that a fire extinguisher was installed, but his focus was on flying, and the rapid pace of events prevented its use until after landing.