Accident Summary
On June 4, 2022, at 0900 central daylight time, a Beech A36, registration N9087S, was involved in an accident near Amarillo, Texas. The airplane was operating under Title 14 Code of Federal Regulations Part 91 as a personal flight. The pilot reported that during an RNAV approach to runway 35 at the destination airport, he noticed the airspeed decreasing and attempted to apply full engine power. He realized the engine had lost power and was unsuccessful in regaining it. He performed a forced landing on a pasture about 2 to 3 miles from the airport. The airplane sustained substantial damage, including damage to the right wing. The pilot and a pilot-rated passenger were uninjured.
Postaccident Examination
Postaccident examination of the airplane revealed a blue stain on the left side of the engine cowl, consistent in color with 100 low lead aviation fuel, extending aft. An attempt to run the engine postaccident could not be completed due to fuel leaking from the fuel control assembly. The fuel control assembly was removed for bench testing, but that test also could not be performed because of fuel leaking from the control arm shaft. The safety wire on the fuel control assembly bore a metal stamp with “TCM,” indicating the last assembly was performed by Teledyne Continental Motors (TCM). Disassembly of the fuel control assembly showed the leak originated at the mixture control arm shaft O-ring. The O-ring was intact and did not exhibit separation, but its outside diameter was less than the diameter of the mixture control shaft.
Maintenance History
TCM records indicated that in 1996 the engine and its accessories, including the fuel control assembly, were overhauled. An engine logbook entry dated July 15, 1996, stated the engine was installed onto the airplane. Another entry dated April 1, 2013, recorded a tachometer and engine total time of 772.0 hours, with time since major overhaul (TSMOH) listed as “NA.” That entry noted that all work was performed in accordance with the TCM IO-520 overhaul manual and that an annual inspection was completed, but it did not state that an engine overhaul was performed. Subsequent logbook entries referenced the TSMOH from the April 1, 2013, entry. No evidence was found to indicate that the fuel control assembly had been overhauled since 1996. TCM’s recommended time between overhaul, per Continental Motors Aircraft Engine Service Information Letter SIL98-9C, was 12 years. Several sections in TCM’s Standard Practice Manual stated that engine accessories must be overhauled at the time of engine overhaul.