Aviation Accident Summaries

Aviation Accident Summary ANC16FA057

Chugiak, AK, USA

Aircraft #1

N9541S

CHAMPION 7ECA

Analysis

According to multiple witnesses at the airport, they observed the airplane perform several touch-and-go landings throughout the late morning and early afternoon on the day of the accident. They added that the pilot then landed and taxied to a local fuel vendor's facility and refueled. The pilot then departed. Two witnesses who were near the departure runway reported that, after the airplane departed, they heard the engine making a "pop pop" sound and that it then appeared to lose power. Another witness near the runway reported hearing the engine "sputtering" and added that the airplane appeared to stall. All the witnesses reported that they observed the airplane turn right steeply, that its right wing and nose dropped abruptly, and that it then descended in a steep, nose-down attitude, consistent with an aerodynamic stall. A postimpact fire immediately ensued, which destroyed the airplane. A postaccident examination of the airframe and engine revealed no mechanical malfunctions that would have precluded normal operation. The witnesses reported hearing noises consistent with an engine misfiring and it was likely losing power; however, the reason for the loss of engine power could not be determined based on the postaccident examination. After the loss of engine power, the pilot attempted a steep turn at low altitude, during which he failed to maintain proper airspeed and exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall and a loss of control at too low of an altitude to recover.

Factual Information

On August 13, 2016, about 1330 Alaska daylight time, a Champion 7ECA (Citabria) airplane, N9541S, impacted terrain following a loss of engine power just after takeoff from Birchwood Airport, Chugiak, Alaska. The private pilot sustained fatal injuries, and the airplane was destroyed. The airplane was registered to the pilot and a co-owner and operated by the pilot as a 14 Code of Federal Regulations Part 91 visual flight rules personal flight. Visual meteorological conditions existed near the accident site at the time of the accident, and no flight plan was filed for the intended local flight. According to multiple witnesses at Birchwood Airport, they observed the airplane perform several touch-and-go landings throughout the late morning and early afternoon on the day of the accident. They said that, just after 1300, the pilot made a full-stop landing and then taxied to a local fuel vendor's facility. During a postaccident interview, one of the witnesses stated that the accident airplane had been for sale and that the accident pilot had met him and a friend at Birchwood Airport about 1315 to show the potential buyer the airplane. The potential buyer reported that he "walked around the airplane" and noticed no mechanical problems and that the pilot told him that there were no mechanical problems with the airframe and engine. The pilot asked the potential buyer if he would like to go for a ride in the airplane, and the potential buyer declined and said he would only go for a ride if he offered to purchase the airplane. The pilot then started the airplane and departed from runway 2R, which was 2,200 ft long and 50 ft wide. The potential buyer said he watched the airplane as it departed and that, as it neared the departure end of the runway, it turned "steeply to the right about 90 degrees," followed by a nose-and-right-wing-low descent. The airplane subsequently descended behind a stand of trees and hangars and out of view. Two other witnesses, who were located near the departure end of runway 2R, reported that, after the airplane departed, they heard the engine making a "pop pop" sound and that it then appeared to lose power. Another witness reported hearing the engine "sputtering" and stated that the airplane appeared to stall. All the witnesses reported that they saw the airplane turn steeply to the right, the airplane's right wing and nose drop abruptly, and the airplane continue to descend nose down behind several hangars and impact terrain. A postimpact fire ensued, and the airplane was destroyed. A witness who was flying a helicopter about 1/2 mile east of Birchwood Airport before the accident reported hearing a male voice on the airport's common traffic advisory frequency (CTAF) stating that he was taking off from runway 2R and would make a right turnout. The helicopter pilot reported that he saw the accident airplane and that it appeared "lower than what I would expect." The airplane began an early right crosswind turn near the airport. The helicopter pilot noticed that the bank of the right turn appeared steep considering the low altitude of the airplane. The helicopter pilot reported that, about 90° into the right turn, he heard a male voice transmit on the CTAF, "oh [expletive]." Immediately after the radio transmission, the airplane "appeared to stall and enter a very nose down attitude." The helicopter pilot saw the airplane descend until it disappeared below the tree line. PERSONNEL INFORMATION The pilot held a private pilot certificate with an airplane single-engine land rating. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on June 1, 2015, and contained no limitations. On the medical certificate application, the pilot reported a total time of 206 hours, with 0 hours in the last 6 months. A review of the pilot's personal logbook revealed that he had a total of 194.2 flight hours, all of which were in single-engine airplanes. AIRCRAFT INFORMATION The two-seat, tailwheel-equipped airplane was equipped with a 115-horsepower Lycoming O-235-C2C engine. The engine was equipped with a two-bladed McCauley metal propeller. According to the airplane's maintenance logbook, the engine was installed on June 14, 1974. The last annual inspection of the airframe and engine was performed on April 2, 2016, at which time the engine total time was 1,313.02 hours, including 383.8 hours since its last major overhaul, and the airframe total time was 1,913.8 flight hours, including 383.8 hours since the last major overhaul. METEOROLOGICAL INFORMATION The official weather observation station located at the Birchwood Airport was not reporting full METAR data at the time of the accident. The closest official weather observation station was located at the Wasilla Airport, Wasilla, Alaska, about 9 miles north of the accident site. At 1336, a METAR reported, in part, wind 090° at 5 knots; visibility 10 statute miles; clouds and sky condition, few clouds at 8,000 ft; temperature 64°F; dew point 48°F; altimeter setting 29.56 inches of mercury. WRECKAGE AND IMPACT INFORMATION The accident site was about 1,725 ft northeast of the departure end of runway 2R on the north side of a "t" intersection of Birchwood Spur Road and Stoltze Drive (A terrain image of the accident site location in relation to the departure runway is available in the public docket for this accident). The accident site was bordered on the north side by a wooded area and was about 260 ft east of airport hangars. The initial impact point was on about a 351° heading, and the airplane was resting upright on sloping terrain (about 45°), with the left wing closest to Birchwood Spur Road, and the right wing closest to the bottom of the sloping terrain at the "t" intersection. No wreckage path was present at the accident site. Ground scarring was limited to the planform area of the airplane. The wreckage was recovered and transported to a secure facility for examination. The airplane exhibited about a 45°-nose-down crushing of its firewall with the vertical stabilizer displaced left about 10°. The airplane was destroyed by postimpact fire. The responding firefighting personnel reported that foam was used to extinguish the fire. All of the major airplane components were found at the accident site. The fuselage was twisted, and the empennage was displaced forward and to the left near the left wing. Various tube attachment points were separated due to impact forces. The majority of the airplane's fabric was melted by the postimpact fire except for several feet on the left wing's outboard section. All the windscreens were missing. The cockpit and instrument gauges were consumed by the postimpact fire, and no readings/positions could be determined. The cockpit structure was crushed from downward impact forces. Flight control continuity was established from the control surfaces to the cockpit. The propeller was separated from the crankshaft flange at the mechanical attachment point on the hub. All the propeller bolts were in place within the propeller hub. Neither of the propeller exhibited S-shaped bending and/or chordwise gouging/scratching. The engine's top spark plugs were removed, and the engine was rotated by hand. During the rotation, air was drawn in and expelled through each top spark plug hole. Engine and valve train continuity was confirmed. Borescope inspection of the cylinders revealed no mechanical anomalies. No liquid was found in the fuel system due to impact damage and the postimpact fire. The fuel selector was in the "on" position, and the selector manifold and selector valve did not contain debris upon disassembly. The carburetor heat was found in the "off" position. The throttle was found in the "full forward" position. The carburetor was found displaced from the engine, and the throttle/mixture controls were attached to their respective control arms of the carburetor. The fuel inlet screen did not contain debris. The carburetor fuel hose was consumed by the postimpact fire. The carburetor was opened, and the fuel bowl had no visible contaminants. The float assembly hinge remained secure at the mounting and was not damaged. The float pontoon and float arm were consumed by postimpact fire. During the engine examination, no evidence of anomalies, contamination, or malfunctions were found in any of the engine accessories, including the magnetos, ignition harness, induction system, spark plugs, oil pump, oil cooler, and oil filter. The cylinders, pistons, valve train, crankshaft, and other internal components showed no evidence of anomalies or malfunctions. MEDICAL AND PATHOLOGICAL INFORMATION The Alaska State Medical Examiner, Anchorage, Alaska, performed an autopsy of the pilot. The autopsy report attributed the pilot's cause of death to multiple blunt force injuries with a contributing cause of thermal injuries. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology tests on the pilot's specimens. The results were negative for carbon monoxide, cyanide, ethanol, and drugs. TESTS AND RESEARCH Fuel Testing The pilot purchased 10.45 gallons of 100 low-lead fuel at 1316. A fuel sample from the fuel facility was tested by the owner with the National Transportation Safety Board investigator-in-charge present, and no fuel contamination was found. There were no reports of fuel contamination or operating anomalies from pilots of other airplanes that were fueled before or after the accident from the fuel pump at the airport.

Probable Cause and Findings

The pilot's failure to maintain proper airspeed and his exceedance of the airplane's critical angle of attack during a steep low-altitude turn following a loss of engine power, which resulted in an aerodynamic stall and subsequent loss of control at too low of an altitude to recover. The reason for the loss of engine power could not be determined because postaccident examination revealed no mechanical malfunctions that would have precluded normal operation.

 

Source: NTSB Aviation Accident Database

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