CEN17FA035

The private pilot was departing on a local flight in the experimental airplane that he had built when the right gull-wing cabin door rotated open upon liftoff. A witness saw the pilot reaching for the fully open door as the airplane continued to overfly the runway at a low altitude. The airplane subsequently entered an aerodynamic stall at a low altitude and descended into terrain about 1,675 ft past the end of the runway and 183 ft left of the extended runway centerline. A postimpact fire destroyed the airframe. The right gull-wing cabin door was found in a ravine about 600 ft from the main wreckage. Although the door had separated from the fuselage while the airplane was in flight, there was no evidence that the door had struck any portion of the airplane. The door latch handle and associated latch pins were found in a partially secured position. A functional test of the door latch mechanism did not reveal any anomalies. Testing of the door latch indicator system was not possible due to extensive postimpact fire damage to the fuselage and instrument panel. Based on the witness description and the physical evidence, it is likely that the pilot failed to ensure that the right gull-wing cabin door was properly latched before takeoff. The pilot likely became distracted by the open door and, as a result, did not maintain adequate airspeed after takeoff, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall at a low altitude.

A search of the National Transportation Safety Board (NTSB) accident database revealed another Van's Aircraft RV-10 airplane accident that involved an inflight separation of a gull-wing cabin door. In this accident (NTSB identification number NYC07LA237), the airplane was established in cruise flight at an altitude of 4,500 ft mean sea level and an airspeed of 145 knots when the right cabin door began to vibrate. As the pilot reached to grip the door handle, the door opened upward and separated from the fuselage. The separated door subsequently impacted the right horizontal stabilizer. Although the pilot declared an emergency, he was able to maintain control of the airplane and make an uneventful landing at the departure airport. A search for the separated door was unsuccessful, and a postaccident examination of the airplane was inconclusive in determining the cause of the inflight door separation. The airplane, serial number 40146, was a single-engine, low-wing, monoplane of conventional aluminum construction. The airplane was powered by an experimental, 260-horsepower Aero Sport Power IO-540-D4A5 reciprocating engine, serial number 1542. The engine provided thrust through a constant-speed, three-blade, Whirl Wind Aviation 375RV composite propeller, serial number 375-106. The four-seat airplane was equipped with a fixed tricycle landing gear, wing flaps, and had a maximum allowable takeoff weight of 2,700 pounds. The pilot had assembled the airplane from a kit purchased from Van's Aircraft. The airplane was issued a special airworthiness certificate on April 23, 2016. The airplane's hour meter was destroyed during the postimpact fire, which precluded a determination of the airplane's total service time at the time of the accident. According to available information, the airplane likely had accumulated 10 to 12 hours since receiving the airworthiness certificate and had not completed the Phase I flight test requirements. The last condition inspection of the airplane was completed on April 23, 2016. A postaccident review of available maintenance records found no history of unresolved airworthiness issues. The airplane had a total fuel capacity of 60 gallons distributed between two wing fuel tanks. A review of fueling records established that the fuel tanks were topped-off before the accident flight. The airplane was equipped with two upward-opening gull-wing cabin doors. Each door was affixed to the roof of the cabin with two steel hinge assemblies. The upper fuselage cabin and both doors were constructed of composite material. Each door lock assembly consisted of a rack and pinion latch mechanism, and two latch pins were set into the lower section of the door panel. Each door was locked by rotating a door handle affixed to the pinion gear, and as the gear rotated, the latch pins extended through a polyethylene pin block and into pin sockets recessed into the forward and aft cabin doorjambs. The doors were not equipped with an additional safetylatch mechanism provided by the airframe kit manufacturer. Alternatively, the doors were equipped with an aftermarket center latch system, which consisted of a rotating semicircular cam that worked in conjunction with the rack and pinion latch mechanism. As the door handle rotated into a locked position, the center cam rotated against a polyethylene block installed in the lower doorjamb to provide an additional center latch point. The gull-wing cabin doors were fitted with a latch indicator system supplied by the airplane kit manufacturer. The system consisted of four magnetic reed switches located near the doorjamb pin sockets. A cylindrical magnet was installed into the end of each latch pin, and the locations of the reed switches were adjusted such that they would activate when the latch pins extended into the doorjamb. The latch circuit was designed so that the instrument panel indicators extinguished when the latch pins were extended into the locked position. DUB, a public airport located about 3 miles northwest of Dubois, Wyoming, was owned and operated by the Town of Dubois. The airport field elevation was 7,297 ft mean sea level. The airport had a single asphalt runway, runway 10/28, that was 6,700 ft by 75 ft. The airport was not equipped with an air traffic control tower. On November 5, 2016, about 0756 mountain daylight time, an experimental, amateur-built Stamper RV-10 airplane, N924WY, impacted terrain following a loss of control shortly after takeoff from the Dubois Municipal Airport (DUB), Dubois, Wyoming. The private pilot was fatally injured, and the airplane was destroyed. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Day visual meteorological conditions prevailed, and no flight plan was filed for the local test flight, which was originating at the time of the accident. A witness reported that he saw the airplane takeoff from runway 28 and that the airplane's right gull-wing cabin door rotated open upon liftoff. The witness saw the pilot reach for the fully open door with his right hand and heard a momentary reduction of engine power. He then saw the airplane descend momentarily before he heard an increase in engine power and saw the airplane level-off over the runway. He reported that the pilot continued to reach for the open cabin door as the airplane overflew the remaining runway about 35 ft above ground level. The witness then saw the airplane's left wing and nose drop suddenly, which he described as an aerodynamic stall. The airplane descended into terrain, and there was a large explosion upon impact. The Regional Medical Examiner's Office, Loveland, Colorado, performed an autopsy on the pilot. The cause of death was attributed to extensive thermal injuries and blunt force injuries sustained during the accident. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology tests on specimensobtained during the autopsy. The pilot's toxicology results were negative for carbon monoxide, ethanol, and all tested drugs. A postaccident review of available meteorological data established that day visual meteorological conditions prevailed at the accident site. At 0755, about 1 minute before the accident, the DUB automated surface observing system reported: wind 270° at 6 knots, 10 miles surface visibility, a clear sky, temperature 0°C, dew point -8°C, and an altimeter setting of 30.29 inches of mercury. According to Federal Aviation Administration (FAA) records, the 44-year-old pilot held a private pilot certificate with ratings for airplane single-engine land, airplane single-engine sea, and instrument airplane. His most recent FAA second-class medical certificate was issued on September 17, 2015, with no limitations. The pilot's flight history was established using his logbook. The final logbook entry was dated October 10, 2016, at which time he had accumulated 1,482.1 total hours of flight experience. According to his logbook, the pilot had flown 119.3 hours, 81.6 hours, 30.6 hours, and 1.3 hours during the year, 6 months, 90 days, and 30 days before the accident, respectively. There was no record that he had flown during the 24 hours before the accident. The pilot had logged 1.8 hours in the accident airplane. His most recent flight review, as required by 14 CFR 61.56, was completed on March 17, 2016. According to the company that insured the airplane, in October 2016, the pilot reported having a total flight experience of 1,500 hours of which 40 hours were in Van's Aircraft RV-6 airplanes and 4 hours were in Van's Aircraft RV-10 airplanes. The pilot reported having flown 2 hours in the accident airplane. The initial point-of-impact was in an open field about 1,675 ft past the runway 28 departure threshold and 183 ft left of the extended runway centerline. The debris path was 67 ft long oriented on a 210° magnetic heading between the initial point-of-impact and the main wreckage. A ground impact crater, containing propeller fragments, was located about 44 ft from the initial point-of-impact. The main wreckage consisted of the fuselage, wings, and empennage. The cabin, including the cockpit instrument panel, was destroyed during the postimpact fire. Both wings exhibited damage consistent with ground impact. The empennage was relatively undamaged. A flight control continuity check was not possible due to the extent of damage; however, all observed flight control separations were consistent with fire and impact damage. The right gull-wing cabin door was found in a ravine about 600 ft northeast of the main wreckage. The door was located about 1,500 ft past the runway 28 departure threshold and 200 ft right of the extended runway centerline. The door had separated from the fuselage hinges. There was no evidence that the door had struck any portion of the airplane after it separated. Before the door was recovered from the ravine, the doorlatch handle was observed to be about 20° from a vertical position or about 110° from the fully latched position. The forward and aft door latch pins were found extended about 1/8 inch outside the door. The curved portion of the semicircular center latch was found facing aft. A functional test of the door latch mechanism did not reveal any anomalies. The door latch handle rotated 180° between the open and latched positions. When the handle was in the latched position, the forward and aft door latch pins extended about 1 1/4 inches outside the door, and the curved portion of the semicircular center latch faced down. A functional test of the door latch indicator system was not possible due to the postimpact fire damage to the fuselage and instrument panel. The engine remained partially attached to the firewall by its mounts. Internal engine and valve train continuity were confirmed as the engine crankshaft was rotated. Compression and suction were noted on cylinder Nos. 1, 2, 3, and 5 in conjunction with crankshaft rotation. Further examination of cylinder Nos. 4 and 6 revealed thermal damage to their valve springs that precluded compression. The engine was equipped with one traditional magneto and an electronic ignition system. The traditional magneto exhibited extensive thermal damage and could not be tested. The electronic ignition control module was not recovered and was likely destroyed during the postimpact fire. The upper spark plugs were removed and exhibited features consistent with normal engine operation. A borescope inspection revealed no anomalies with the cylinders, valves, or pistons. The propeller hub remained attached to the engine crankshaft flange. Two of the three composite blades were destroyed during the impact sequence. The remaining composite blade exhibited thermal damage from the postimpact fire.