Accident Details
On September 23, 2023, about 1914 central daylight time, a Beech C23 airplane, registration N18994, was substantially damaged during an accident near Gonzales, Texas. The pilot, who was the sole occupant, received minor injuries. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
The pilot reported that he intended to land at Roger M Dreyer Memorial Airport (T20) in Gonzales. During the final approach to runway 15, he encountered wind shear and elected to perform a go-around. He applied full throttle and began to climb, at which point the engine experienced a loss of power. The pilot executed a forced landing to a field off the left side of the runway, during which the airplane collided with a fence and a tree. The impact separated the right wing near the wing root.
Postaccident Examination
Postaccident examination revealed substantial damage to the wings and fuselage. The exhaust system, which appeared undamaged externally, was inspected internally using a flashlight and a lighted borescope, revealing a blockage in the tailpipe. The muffler was removed and cut open, exposing a flame tube that was blocking at least 95% of the tailpipe exit path. The lodged fragment exhibited a degraded and corroded fracture surface. Additionally, a 3-inch crack was noted on the muffler endcap opposite the separated flame tube. No other mechanical malfunctions or failures were identified that would have prevented normal operation.
Maintenance History
The aircraft maintenance logbooks showed that during an inspection on December 24, 1997 (at 3,523.42 hours total time), the exhaust system was inspected and found satisfactory. A subsequent inspection on January 2, 1999 (3,556.5 hours) made no mention of the exhaust system. On March 21, 2000, the muffler was repaired by an authorized repair station, including replacement of the outer shell, caps, flame tubes, elbows, beaded ends, end plates, and tailpipe. The repaired muffler was reinstalled on April 1, 2000 (3,603.36 hours). No further muffler-related entries were found.
The most recent 100-hour/annual inspection was completed on November 23, 2022, at 4,052.8 hours total time. During that inspection, eight exhaust clamps were replaced and a new exhaust stud was installed on the No. 4 cylinder, but there was no specific mention of the muffler. Federal Aviation Administration (FAA) regulations (14 CFR Part 43 Appendix D) require inspection of exhaust stacks for cracks, defects, and improper attachment during annual and 100-hour inspections.
At the time of the accident, the airplane's total time was 4,108.2 hours, as recorded by the installed Dynon Avionics. The muffler had been installed for 504.84 hours. Beech maintenance documents recommended overhaul or replacement of the exhaust system every 800 hours or when condition warrants, and inspection of the muffler and shroud every 100 hours.
Additional Information
The FAA Aviation Maintenance Technician Handbook – Powerplant states that internal muffler failures, such as dislodged baffles or diffusers, can cause partial or complete engine power loss by restricting exhaust gas flow. Erosion and carburization from extreme thermal conditions are primary causes. FAA Advisory Circular 91-59A also notes that loose internal components can block exhaust outlets, leading to power loss.