Alpine, TX, USA
N60HG
CESSNA 421B
Shortly after departure, when the airplane was about 400 feet in the air, the right engine stopped producing power. The pilot conducted a forced landing in a nearby field. An on-site inspection revealed that the airplane fuel tanks contained plenty of fuel. A post accident examination of the engines was conducted. An engine monitor was downloaded; a sudden decrease in cylinder head (CHT) and exhaust gas (EGT) temperature readings were observed for the right engine. A visual inspection of the engine revealed that the idler gear support pin, located on the rear of the engine, had backed out. The idler pin's retaining hardware (two nuts and lock-washers) were missing. The idler pin's movement allowed the idler gear to drop and become disconnected from the magnetos drive gear, resulting in a loss of engine ignition. Additionally, due to the mis-located idler gear, the accessory drive gears on the cam and crankshafts were either ground down or broken. Disassembly of the engine, found numerous metal pieces in the engine's oil sump.
On May 8, 2009, approximately 1030 central daylight time, a twin-engine Cessna 421B, N60HG, was substantially damaged during a forced landing following the loss of engine power shortly after takeoff, near Alpine, Texas. The commercial pilot, sole occupant, received minor injuries during the forced landing. The airplane was registered and operated by O'Hara Flying Service, Amarillo, Texas. Visual meteorological conditions prevailed and a flight plan was not filed for the Title 14 Code of Federal Regulations Part (CFR) 91 positioning flight destined for the Rick Husband Amarillo International Airport (AMA), Amarillo, Texas. The pilot reported that, shortly after takeoff when the airplane was about 400 feet in the air, the right engine stopped producing power. As the pilot reached up to feather the right engine, the left engine "surged and sounded like it was going to quit." The pilot moved the engine controls forward, and looked for a place for a forced landing. The pilot added that he felt he did not have full power on the left engine. The airplane impacted several small bushes during the off-airfield landing. A Federal Aviation Administration (FAA) inspector who responded to the site reported that the airplane had plenty of fuel and that it appeared consistent with 100LL aviation grade fuel. An examination of the aircraft wreckage was conducted by the NTSB Investigator-in-Charge (IIC), along with technical representatives from the airframe and engine manufacturers, at Air Salvage of Dallas (ASOD) on 28 May, 2009. A JPI engine monitor was downloaded; a sudden decrease in cylinder head (CHT) and exhaust gas (EGT) temperature readings were observed for the right engine. A visual inspection of the engine revealed that the idler gear support pin, located on the rear of the motor, had backed out. The idler pin's retaining hardware (two nuts and lock-washers) were missing. The idler pin's movement allowed the idler gear to drop, and become disconnected from the magneto drive gears, resulting in a loss of engine ignition. The idler gear teeth were severely worn. Additionally, the accessory drive gears on the cam and crankshafts were either ground down or broken. Disassembly of the engine, found numerous metal pieces in the engine's oil sump. Examination of the left engine and engine monitor readings, revealed no apparent abnormalities. The engine was rotated to obtain thumb compression and drive train continuity. Each cylinder was borescoped; the sparkplugs were light gray in color and appeared "normal." The magnetos were removed and rotated by hand, producing spark at each terminal. The engine's oil filer was cut open, inspected, and was found to be clear of any metal.
The loss of engine power due to disengagement of the magneto idler gear support pin.
Source: NTSB Aviation Accident Database
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