History of Flight
On July 27, 2012, at 1830 Pacific daylight time, an Interplane Skyboy EX, registration N582YB, experienced a partial loss of engine power and collided with a fence during an off-field landing near Sandy River Airport (03S) in Sandy, Oregon. The private pilot operated the aircraft under Title 14 Code of Federal Regulations Part 91. The pilot and single passenger were not injured, and the airplane sustained substantial damage. Visual meteorological conditions prevailed for the local flight, and no flight plan had been filed.
The pilot reported that after about 1 hour of flying, he landed, shut down the engine, changed passengers, and restarted after approximately 5 minutes. The engine run-up and takeoff were normal. After takeoff, at about 300 to 400 feet above ground level (agl), the engine began to lose power. The pilot executed a hard right turn and landed in an open field. During the landing rollout, the airplane impacted a fence post with its right wing.
Personnel Information
The pilot, aged 41, held a private pilot certificate for airplane single-engine land issued January 17, 2012, and a second-class airman medical certificate issued June 22, 2011, with a limitation to wear corrective lenses. He reported 338.1 total flight hours and 1.2 hours in the accident airplane make and model.
Aircraft Information
The two-seat, high-wing, fixed-gear experimental category airplane, serial number 06192001735, was manufactured in 2001. It was powered by a Rotax 582, 64-horsepower engine, equipped with a Powerfin 3-bladed fixed-pitch propeller. The pilot reported 159.6 hours total time; the most recent annual inspection was completed on July 9, 2012. The engine was not equipped with a carburetor heat system. The engine manufacturer stated in the installation manual that a heating system must be fitted if operating where carburetor icing is likely.
Meteorological Information
A Remote Automated Weather Station (RAWS) 1.7 miles south of Sandy River Airport recorded at 1848 on July 27: ambient temperature 63°F, dew point 55°F, relative humidity 76%. On August 9 at 1248, conditions were 62°F, dew point 56°F, relative humidity 81%. The ambient conditions at the time of engine examination on August 9 closely matched those at the time of the accident. At the manufacturer's facility in Vernon, British Columbia, on November 12, 2012, conditions were 32°F, dew point 31°F, relative humidity 91%.
Wreckage and Impact Information
Post-accident photographs showed damage to the leading edge of the right wing outboard of the lift strut attach point. The left main landing gear mount and nose wheel were collapsed. The windscreen exhibited a crack across its entire face. No damage to the engine or propeller was evident.
An FAA inspector, assisted by an A&P mechanic, examined the airplane and engine on August 9, 2012. The engine, still attached, was test run multiple times. Fuel, oil injection, and engine controls appeared to operate properly. Pistons viewed through exhaust ports showed normal wear with no sign of seizure. The engine started and accelerated to 5,900 rpm; after about 1.5 minutes, rpm degraded by approximately 1,000, then stabilized around 5,000 rpm. After replacing carburetor fuel jets with smaller orifice size and replacing spark plugs, results were consistent. Carburetor fuel pressure was 3 psi after shutdown. The engine was removed and shipped to Rotech facility in Vernon, British Columbia, for further examination.
On November 13, 2012, the engine was examined at Rotech under NTSB supervision. After removal from a sealed crate, static examination revealed no anomalies. Oil was present in the gearbox, carburetors closely synchronized, fuel filter held 15 kPa vacuum, spark plug gaps 0.032 inches, piston heads with normal combustion signatures. The engine was run on a test stand: first 8 minutes at 3,000 rpm, then max power at 5,500 rpm. Test propeller repitched to 12 degrees to produce max power rpm. Engine ran at 6,250 rpm for 2 minutes, 6,000 for 5, 4,900 for 5, shut down, inspected, restarted, then idle 1 minute, 6,200 for 2, 4,800 for 10. Acceleration tests from 3,150 to 5,800 rpm performed twice, then 3,150 for 2 minutes, shut down for 1 hour. Fuel transducer removed, engine restarted, new max 6,480 rpm. The engine ran approximately 28 minutes without losing power or rpm, shut down for 1 hour, then restarted and maintained normal power rpm.
Additional Information
The carburetor icing chart indicated the possibility of serious carburetor icing at the reported atmospheric conditions. The Pilot's Handbook of Aeronautical Knowledge states that the first indication of carburetor ice in an airplane with a fixed-pitch propeller is a decrease in engine rpm, and that when conditions are conducive to carburetor icing, carburetor heat should be applied immediately and left ON until certain all ice is removed. Applying partial heat or insufficient time might aggravate the situation.