*** Final Report ***
N52854 Cessna T206H Austin Texas 16 JUN 2022
1 Serious Injury
Pilot Flight Time: 17000 hours (Total, all aircraft), 3500 hours (Total, this make and model)
The pilot reported that the accident flight was the first flight following a 100-hour maintenance inspection. The pilot departed from the Austin-Bergstrom International Airport (AUS), Austin, Texas, and shortly after takeoff reported to air traffic control that there was smoke in the cockpit and he wanted to return to AUS. Shortly thereafter, the smoke increased, and the pilot was not able to see his instrument panel. He attempted to increase engine power and discovered that the engine had stopped producing power. After opening the airplane’s side windows, he could see a body of water below him and ditched the airplane into Lady Bird Lake, near Austin.
Postaccident examination revealed that the V-band exhaust coupling securing the turbocharger exhaust fractured.
The General Aviation Joint Steering Committee issued a “Best Practices Guide for Maintaining Exhaust System Turbocharger to Tailpipe v-band Couplings / Clamps”, which recommended life limits for the various styles of clamps including a 500-hour life limit on spot welded v-band couplings such as the failed coupling from the accident airplane.
The Federal Aviation Administration issued a Special Airworthiness Information Bulletin (SAIB), CE-18-07, on December 14, 2017, which described several accidents that resulted from v-band clamp failures. The SAIB recommended detailed inspections of v-band exhaust couplings be performed at 100-hour intervals. It also identified areas of concern and locations on the v-band exhaust couplings for focused inspection.
In April 2018, the General Aviation Joint Steering Committee issued a “Best Practices Guide for Maintaining Exhaust System Turbocharger to Tailpipe V-band Couplings / Clamps”, which went into further detail concerning the various designs of exhaust system couplings, and inspection of those couplings. The guide also recommended life limits for the various styles of clamps including a 500-hour life limit on spot welded v-band couplings such as the failed coupling from the accident airplane.
According to maintenance records, the airplane’s most recent annual inspection was completed on December 13, 2021, and indicated that an exhaust system inspection was included in the inspection process. A 100-hour inspection was completed on June 15, 2022, and indicated that an exhaust system inspection had been performed. Neither entry specifically noted inspection of the v-band exhaust couplings and the investigation was unable to determine if a specific inspection of the v-band clamp was accomplished. The total time in service of the clamp was not determined.
Probable Cause and Findings:
A total loss of engine power due to an engine fire that resulted from failure of the turbocharger exhaust clamp, which allowed hot exhaust gases to damage other vital engine components.
