Eldon, MO, USA
N144AC
LOEHR THOMAS H ZENITH STOL CH701
Shortly after takeoff, at 300 feet above ground level, the engine "revved excessively and power was lost to the propeller." The pilot performed an off airport forced landing. During the forced landing, the airplane impacted terrain and sustained substantial damage to the forward fuselage. Examination of the airplane revealed that both engine-to-propeller drive belts failed, which led to the reported engine overspeed and lack of propeller drive. A representative of the manufacturer stated that the belt failure during the accident was caused by loose belts or a lack of proper tension on the belts and that the belt tension should have been checked during a preflight inspection.
On March 22, 2010, at 1854 central daylight time, a Loehr Zenith STOL CH701 experimental airplane, N144AC, sustained substantial damage during takeoff from the Eldon Model Airpark (H79), Eldon, Missouri. The non-certificated pilot, who was the sole occupant and registered owner, was not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The local flight was originating at the time of the accident. According to the pilot, shortly after takeoff at 300 feet above ground level (agl), the engine "revved excessively and power was lost to the propeller." The pilot performed an off airport forced landing. During the forced landing, the airplane impacted terrain and sustained substantial damage to the forward fuselage. Examination of the airplane by a Federal Aviation Administration inspector revealed that both engine to propeller drive belts failed which led to the reported engine overspeed and lack of propeller drive. The belts displayed missing drive lugs. The nut which retained the propeller pulley was found loose. The pilot reported the airplane underwent its most recent conditional inspection on September 30, 2009. The airplane had accumulated 122 total hours. According to the manufacturer of the engine to propeller drive system, Valley Engineering, L.L.C., the pilot had flown the airplane to their facility a couple months prior to the accident. Their inspection of the airplane revealed the drive belts were out of adjustment and needed servicing. During a telephone conversation between the NTSB investigator-in-charge and the manufacturer, the manufacturer reported that the belt failure during the accident was caused by loose belts or a lack of proper tension on the belts. The representative stated that belt tension should have been checked during a preflight inspection. On the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1), Recommendation section, the pilot reported, "A more thorough look at belts from temperature change of extreme cold to warm."
A loss of engine thrust during takeoff due to the failure of the engine-to-propeller drive belts as a result of improper belt tension. Contributing to the accident was the non-certificated pilot's improper preflight inspection.
Source: NTSB Aviation Accident Database
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