Accident Details
On March 13, 2016, about 0800 mountain daylight time, a tailwheel-equipped Cessna 180, registration N4696B, was substantially damaged when it failed to accelerate and overran the end of a private airstrip located about 2 nautical miles west of Boulder, Utah. The commercial pilot, who owned the airplane, and his two passengers were not injured. Visual meteorological conditions prevailed for the planned local flight, which was conducted under 14 CFR Part 91. No flight plan was filed. The flight was originating at the time of the accident.
Pilot Report
The pilot reported that before departure, he allowed the engine to warm up for about 15 minutes, rechecked the magnetos, and listened to the engine at higher power settings. Due to the dirt airstrip, he did not check carburetor heat; normal oil pressure was observed. After applying full power for the takeoff roll on the 2,100-foot unimproved dirt strip, the pilot noted acceleration felt slightly slow but thought it might be due to soft dirt or vegetation. He glanced at the tachometer, which read 2,600 rpm (redline), but did not recall checking manifold pressure. The engine did not run rough or backfire. About halfway down the runway, the tail lifted, and he added one notch of flaps. Approaching the end, he pulled back on the control yoke, increasing angle-of-attack. The airplane lifted about two feet before settling into sagebrush. When the pilot attempted to reduce power by retarding the throttle, the engine continued at high output. The airplane rolled through vegetation, then impacted a 10-foot-diameter tree and came to rest upright about 50 yards from the stump. The pilot suspected the engine was not generating full power and noted he could have aborted the takeoff. Winds were from the northwest at 5 knots.
Postaccident Examination
A postaccident examination revealed substantial damage to both wings and the elevator. The airplane was recovered for further examination.
Engine Examination
On April 27, 2016, under NTSB supervision, a Continental Motors field technician examined the engine at Air Transport in Phoenix, Arizona. The engine remained attached to the airframe with no external damage. Top spark plugs were removed, showing grey combustion deposits and normal electrode wear. Borescope inspection of cylinder combustion chambers revealed no anomalies. Crankshaft rotation by hand produced thumb compression on all six cylinders, with magneto impulse couplings audible and spark on all six top plug leads. An external fuel supply was connected for an engine test run. After warm-up, a magneto check showed each magneto dropped about 75 rpm at 1,600 rpm. At full throttle, the engine achieved 2,600 rpm and 22 inches manifold pressure. Throttle and mixture controls operated without binding. The engine run was repeated with fuel from the left wing root line, then the "both" selector position, all normal. When switched to "off," the engine ran rough; returning to left restored smooth operation.
Airframe Examination
On April 27, 2017, at the same facility, the NTSB IIC examined the airframe and found no anomalies.
Conclusion
The postaccident examination of the engine and airframe failed to reveal any anomalies that would have precluded normal operation.