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ch 750 forced landing ntsb report
14 CFR Part 91: General Aviation
Accident occurred Thursday, April 14, 2011 in Winchester, CA
Aircraft: ZENITH CH-750, registration: N632DR
Injuries: 1 Minor.
On April 14, 2011, about 0940 Pacific Daylight Time, a Zenith CH-750 experimental amateur-built airplane, N632DR, was substantially damaged in a forced landing following a complete loss of engine power near Winchester, California. The pilot/owner, the sole person on board, received minor injuries. The personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91, as part of the Phase 1 flight test program for the airplane. Visual meteorological conditions prevailed, and no flight plan had been filed.
According to the pilot, the accident flight was the third flight for the airplane. He spent about 30 to 40 minutes conducting a pre-flight inspection, and added 4 gallons of fuel, to bring the total takeoff fuel quantity to about 13 gallons. He started the engine, warmed it up, and then conducted an uneventful engine run-up. After takeoff, the pilot headed east towards a nearby lake, and climbed to an altitude of about 5,000 feet above mean sea level (msl). While over the lake, he conducted turns and familiarized himself with the airplane's handling and operating characteristics. After about 40 minutes, the pilot decided to return to the airport. He turned west, reduced power to about 3/4 throttle, and began a descent. When the airplane was at an altitude of about 3,000 feet msl, the engine suddenly lost power.
The pilot made three or four restart attempts; each time, the engine would catch and turn about 10 revolutions, and then stop. After a few minutes, the pilot realized that he would not reach the airport, and executed a 180-degree turn to head for a straight, empty road he knew of in the area. After another minute or two, he noticed power lines between his position and the road, and pushed the nose down to fly under the power lines. After that maneuver, the airplane did not have enough altitude to reach the road, and touched down in a field, where it nosed over into the inverted position. The pilot extracted himself from the airplane, and first responders observed that fuel was leaking from the tanks.
At the time of the accident, the hour meter registered a total of 4.8 hours, of which the pilot estimated 1 hour was initial ground and taxi test time, and the remainder was flight time. The airplane was equipped with a modified Chevrolet Corvair engine, which was assembled by the pilot with components and guidance from an engine modification company based in Florida. The engine was equipped with a Marvel-Schebler aviation carburetor. The pilot had conducted the initial ground and taxi runs with automotive gasoline, but then switched to 100LL aviation fuel for the flight test phase. The pilot was uncertain whether the automotive gasoline contained ethanol. The airplane was equipped with two interconnected wing tanks, which were not individually selectable.
Automated weather observations from three airports within a 20-mile radius of the accident location included light winds; clear skies; temperatures between 15 and 18 degrees C; and corresponding dew points between 5 and 9 degrees C.
Comment
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Comment by david a mcphee on May 5, 2011 at 9:03pm
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There's an SAIB on the MS carburetors calling for replacement of the white internal floats with metal or solid plastic. The carb data plate should have had an "M" stamped on the data plate if the plastic white float was replaced with metal...(should have a "V" stamped as well for the single piece venturi as well). A leaky, sunk float would cause the carb to go to a over-rich situation causing it to stop from idle..a full throttle may have helped, carb heat normally adds more air and may have helped from a mixture sense as well. It's amazing Precision Airmotive and I'll bet Tempest is still using white plastic floats.
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Comment by Bob Pustell on May 3, 2011 at 6:51pm
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Geoff has an interesting point - carb heat. The corvair, when modified into a flight engine, has a carb that is not bolted to the warm oil pan. It is on the end of an intake tract, not attached to the warm mass of the engine. This is just the same as small Continental engines and Franklins. They all need carb heat anytime the power is pulled back, unless you have a carb temp gage and watch it carefully. I am not saying for sure that was the problem, but it certainly could be.
I am glad the owner/pilot is unharmed and the airplane is repairable.
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Comment by Geoff Klestadt on April 30, 2011 at 5:32pm
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Any landing you walk away from......
Was Carb Heat available?
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