NTSB Factual Report

HISTORY OF FLIGHT

On August 17, 2012, about 1425 Pacific daylight time, a Cessna T210N, N6493N, experienced an in-flight fire shortly after departing from Meadows Field Airport, Bakersfield, California. The airplane was substantially damaged by the fire. The pilot was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certified flight instructor and two passengers were not injured. The local personal flight was departing at the time of the accident with a planned destination of Redlands Municipal Airport, Redlands, California. Visual meteorological conditions prevailed, and no flight plan had been filed.

The pilot reported that following departure, he banked the airplane to adjoin the right crosswind of the traffic pattern for runway 30R. The pilot observed smoke entering the cockpit and the engine began to only produce partial power. The pilot elected to return back to the airport and configured the airplane for landing on runway 30R. With the degradation of power, he was unable to make it to the runway and landed in a field outside the airport's perimeter.

The pilot further stated that the fire was a result of a clamp failure on the turbocharger which is where the origin of the fire appeared to be. The firewall was damaged by fire.

AIRCRAFT INFORMATION

The Cessna T210N, serial number (s/n) 21063067, was manufactured in 1978. The airplane was equipped with a Teledyne Continental Motors TSIO-520R9B engine. A review of the maintenance logbooks revealed that the last annual inspection was dated as having being completed on May 1, 2012 at a tachometer time of 3,931.0 hours.

TESTS AND RESEARCH

The turbocharger clamp pieces were collected and sent to the National Transportation Safety Board Material laboratory for further examination. The V-band exhaust clamp had a 2-segment retainer (''V" portion of the clamp) and was installed on the turbocharger exhaust gas outlet on the accident airplane. The band (flat outer strap) was fractured near the end of the wrap for the t-bolt assembly. Two circumferential cracks were also observed in the retainer extending from the gap opposite from the t-bolt. Each retainer segment contained one circumferential crack. The clamp was generally covered in oxides and sooty deposits.

The fracture occurred at the edge of a spot weld attaching the band to the retainer and the fracture surface was on slant planes. Slant-plane fracture features were observed from the edges of the spot weld out to the edges of the band and were consistent with ductile overstress fracture. Reduced width of the band associated with necking deformation was observed adjacent to the fracture. In addition, the edges of the band were deformed radially inward. Similar necking deformation with edges deformed radially inward was observed at the mirror opposite side of the band.

In the vicinity of the spot weld, fracture occurred in part in a flat transverse plane. However, slant-plane fracture was also observed at this location. The flat plane fracture was located near the middle of the thickness, and a slant fracture was observed near the outer surface. Slant fracture was also observed at the inner edge of the band across most of the spot weld except for an area near the middle of the weld that appeared to have a granular appearance but was not in the transverse plane.

A piece of the band containing the t-bolt side of the fracture was separated from the rest of the clamp by cutting the band at the wrap for the t-bolt assembly. The flat fracture region had an intergranular appearance mixed with ductile tear ridges. A piece of the band away from the fracture was cut to facilitate hardness testing. The testing did not reveal any anomalies.

No part number or identifying information was found on the v-band clamp. According to the Parts Catalog for the Cessna model 210 and T210 airplanes, one of two part number clamps may be used.

NTSB Probable Cause

A partial loss of engine power during the initial climb due to an in-flight fire of undetermined origin.