CEN22LA253

The pilot reported that shortly after takeoff he experienced smoke in the cockpit. The pilot reported to air traffic control that he wanted to return to the airport; however, the amount of smoke continued to increase and the engine stopped producing power. The pilot opened the side windows and located a lake below him into which he ditched the airplane. Postaccident examination revealed that the v-band clamp securing the turbocharger exhaust fractured and allowed hot exhaust gas to blow over the accessory section of the engine. The hot exhaust gases caused damage to several components, resulting in a fire and total loss of engine power. The Federal Aviation Administration issued a Special Airworthiness Information Bulletin (SAIB), CE-18-07, recommending detailed inspections of v-band exhaust couplings be performed at 100-hour intervals. The accident occurred on the first flight following a 100-hr inspection that indicated an examination of the exhaust system. The investigation did not determine the total time in service of the clamp or whether a specific examination of the v-band clamp was accomplished.

On June 16, 2022, about 1400 central daylight time, a Cessna T206H, N52854, was substantially damaged when it was involved in an accident near Austin, Texas. The pilot was seriously injured. The airplane was operated as a public use flight. 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. Figure 1. Photo of failed V-band exhaust coupling. 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.