Accident Summary
On August 20, 2018, at 0620 central daylight time, a Beech B36TC single-engine airplane, registration N6860W, was destroyed when the engine lost power and the pilot executed a forced landing in a wooded area approximately 1/4-mile southeast of La Porte Municipal Airport (T41), La Porte, Texas. The aircraft was registered to and operated by RD Airways of Channelview, Texas, under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which was originating from T41 at the time of the accident.
Pilot Report
The pilot reported that after takeoff and during the initial climb, the airplane began to emit a "weird very loud sound" and the engine started losing power. The pilot verified that the throttle, mixture, and propeller controls were positioned full forward. The engine noise escalated, and power diminished substantially. Activating the auxiliary fuel pump caused the engine to become "real loud [and] sounded very deep." The pilot recognized the descent and executed a forced landing near a housing development on unsuitable terrain. Both wings separated from the fuselage during the landing. The pilot sustained no injuries.
Examination and Findings
A Federal Aviation Administration inspector examined the wreckage and noted that the exhaust section appeared to have been experiencing issues over an extended period, and the condition of the v-band clamp was described as disturbing. The inspector referenced Airworthiness Directive (AD) 2018-06-11, issued in June 2018, which introduced a life limit for the exhaust tailpipe v-band clamp that secures the exhaust tailpipe to the turbocharger and requires annual visual inspection of the clamp.
The engine was subsequently removed and sent to Continental Motors in Mobile, Alabama. On March 13, 2019, under the oversight of an FAA inspector, the engine underwent functional testing and operated without any anomalies. According to Continental Motors, the v-band may have been loose enough to permit manual rotation of the turbo outlet collar. Additionally, a hose connecting the aftermarket intercooler was found oil-soaked and did not appear to have been freshly torn. If such a hose failed in flight, manifold pressure would have dropped immediately, and the unusual sound could have been attributed to turbo discharge pressure escaping through the tear. With the loss of turbo pressure, the fuel pump would have continued to deliver fuel, resulting in a rich mixture; activating the auxiliary fuel pump would have further enriched the mixture.
No probable cause was determined by the investigation.