On September 21, 2015, about 0645 mountain daylight time, a Cessna T206H, 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 the provisions of 14 Code of Federal Regulations Part 91. The flight instructor and passenger/camera operator sustained minor injuries related to smoke inhalation. The airplane sustained minor damage. The local flight departed Idaho Falls about 0640; visual meteorological conditions prevailed, and no flight plan had been filed.The pilot reported that he performed a preflight inspection, and the passenger checked the external camera equipment prior to flight. No anomalies were noted, and the engine run-up was normal.
During the initial climb, the pilot retracted the flaps, and having reached about 200 ft above ground level the passenger began to see smoke. The pilot initiated a turn to the crosswind leg, and smoke rapidly filled the cabin. The passenger opened the side window, and concerned that it may fan the source of the smoke, the pilot asked him to close it. The pilot then put on his oxygen cannula but it did not provide relief, and by now he was having trouble breathing due to the smoke density. The smoke was now obscuring the instrument panel, but he could partially see the runway and immediately turned the airplane towards it. He opened his side window and put his head outside for a better view, however, the force of the wind made breathing difficult. The pilot then pushed the airplane's nose down, initiating a steep dive to the runway. He could not recall the final stages of the landing, but as soon as the airplane touched the ground, he applied full brake action, locking up the wheels. Once they had come to a stop, the pilot shutoff the fuel mixture control and they rapidly egressed.
The airplane sustained thermal damage to the right side of the firewall, the upper and lower engine cowlings, and the forward right section of the fuselage skin, which had burned through to the cabin at the air inlet door. The fire location relative to the air inlet resulted in smoke being forced directly into the airplane's fresh air intake system.
Subsequent examination revealed that the wastegate overboard exhaust tailpipe had come away from turbocharger housing. The turbocharger housing outlet was directly in line with the battery mounting tray on the right side of the firewall. The battery had partially melted, and both its positive and negative electrical connecting cables had partially melted. Both cables exhibited globular damage to their copper conductors consistent with arcing and an electrical short circuit.
Cessna Service Bulletin SB99-71-06, released December 6, 1999, recommended the installation of a tailpipe lanyard to, "provide a safety link ensuring positive turbocharger exhaust tailpipe retention should the clamp become loose." No lanyard was found on the airplane, and there was no record in the maintenance logbooks indicating that the service bulletin had been complied with. The service bulletin affected 111 Cessna T206H airplanes, and records provided by Cessna revealed that in the 2-year period following issuance of the service bulletin, 91 of the service bulletin's sub assembly components were sold, with sales then averaging about 3 per year through to 2015.
Federal Aviation Administration regulations do not require compliance with service bulletins for aircraft operating under the provisions of 14 Code of Federal Regulations Part 91.
The airplane experienced a similar separation of the tailpipe during takeoff on April 28, 2015. On this occasion smoke was again drawn into the cockpit, but damage was limited to the battery and its associated cables. Maintenance records indicated that the tailpipe clamp and gaskets were replaced following the event.
The pilot stated that the airplane was equipped with a fire extinguisher, however, his primary focus was with flying the airplane, and the event transpired at such a rapid pace that it wasn't until landing that he and the passenger remembered it was installed.