Accident Overview
On August 1, 2012, at approximately 1120 central daylight time, a Beech H35 airplane, registered as N4684D, sustained substantial damage when it struck trees following a loss of engine power near Holly Lake Ranch, Texas. The pilot, who was also the sole occupant, received serious injuries. The flight was conducted under 14 Code of Federal Regulations Part 91 as a business flight in visual meteorological conditions. No flight plan was filed. The flight originated from Wood County Airport (JDD) in Mineola, Texas, at about 1100 and was destined for Gilmer Municipal Airport (JXI) in Gilmer, Texas.
Pilot Report
The pilot reported that a pre-flight run-up was performed with no anomalies noted. After departing JDD, the airplane climbed to an altitude of 7,500 feet en route to JXI. During the descent to JXI, at approximately 6,500 feet, the engine experienced a total loss of power. The pilot turned the airplane toward Holly Lake Ranch Airport (16TE) and attempted an engine restart, which was unsuccessful. The airplane subsequently struck trees off the end of runway 27 at 16TE.
Engine Examination
Post-accident examination of the engine revealed that the idler gear pin was missing from the rear of the engine, and both nuts and washers were missing from the idler gear pin attachment studs. The idler gear pin was later found in a plastic trash bag containing smaller parts recovered from the wreckage. The idler gear had fallen into the rear crankshaft gear, damaging the gear teeth. Additionally, the nut was missing from the forward left side lower through bolt on the crankcase half, and the nut was missing from the forward left side engine mount bolt.
Maintenance Records
A review of the maintenance records uncovered a piece of paper attached to the log book indicating that the engine had been disassembled and inspected following a propeller strike. The crankshaft was turned 0.010 inches undersize, and the engine was reassembled. This entry was dated July 25, 2012, and was signed by the pilot, who held a mechanic certificate with airframe and powerplant ratings issued by the Federal Aviation Administration.
According to manufacturer drawings, the aft crankshaft gear engages the idler gear, which in turn engages both magneto drive gears. Without the idler gear in place, the magnetos would cease to operate.