ANC15FA066

A witness stated that he saw the accident airplane operating at a low level over the beach. When the airplane was directly in front of him, it pitched up to about 45 degrees and climbed to about 100 ft above the trees located on the bluff overlooking the water. After lowering the nose to a level pitch attitude, he heard a reduction in engine power followed by a sound consistent with an engine misfiring. The airplane disappeared from view, and the engine noise ceased. Immediately after, a loud sound consistent with an impact was heard and a postimpact fire consumed the wreckage. Based on the witness statement, in combination with the absence of power signatures on the propeller in the wreckage, it is likely the engine was not producing rated power at the time of the accident. A NTSB postaccident examination of the airframe and engine revealed no mechanical malfunctions or anomalies that would have precluded normal operation. An engine test run was conducted following the replacement of impact- and thermal-damaged components. The engine experienced a normal start and accelerated normally without any hesitation, stumbling, or interruption in power, and demonstrated the ability to produce rated horsepower.

The model specification for the Continental Motors O-470-L requires a minimum fuel pressure at the carburetor inlet of +1.5 to +9.0 psi for all operating conditions. The airplane was a Cessna 180, manufactured in 1954, and equipped with a Continental Motors O-470 series engine. The tachometer at the time of the last annual inspection, completed on December 15, 2014, read 4,526.6 hours and the total time in service was 8,231.5 hours. On August 22, 2015, about 2020 Alaska daylight time, a tailwheel-equipped Cessna 180 airplane, N3043E, sustained substantial damage after impacting terrain while maneuvering low level about 5 miles southwest of Kasilof, Alaska. The private pilot and passenger sustained fatal injuries. The airplane was registered to, and operated by, the pilot under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on August 23, 2015, an airframe and powerplant mechanic rated witness stated that he saw the accident airplane operating low level over the beach along the Turnigain Arm waterway. He began watching the airplane about 1 mile from his location and estimated the altitude to be about 20 feet above ground level (agl), with a loud engine sound. When the airplane was directly in front of him, it pitched up to about 45 degrees and climbed to about 300 feet agl, about 100 feet above the trees located on the bluff overlooking the water. After lowering the nose to a level pitch attitude, he heard a reduction in engine power, followed by a sound consistent with an engine misfiring. The airplane disappeared from view, and the engine noise could no longer be heard. Immediately after, a loud sound consistent with an impact was heard. When he approached the site, about .1 miles from his previous location, a post-impact fire had consumed the wreckage, and ammunition could be heard exploding. A second witness, who could not see the airplane, said he heard an aircraft overhead about the time of the accident that was making noises consistent with an engine sputtering. A third witness told the NTSB IIC that he observed the accident airplane flying down the coastline in a southwesterly direction, and heard a sound consistent with an abrupt increase in engine power just prior to the impact. A postmortem examination was conducted under the authority of the Alaska State Medical Examiner, Anchorage, Alaska, on August 25, 2015. The cause of death for the pilot was attributed to multiple blunt force injuries. Additionally, the autopsy identified dilated cardiomyopathy and coronary artery disease with 40% narrowing of the left circumflex coronary artery and 80% narrowing of the proximal left anterior descending and the right coronary arteries. However, the investigation revealed no evidence of pilotimpairment during or after the abrupt maneuver preceding the accident sequence. The FAA Bioaeronautical Laboratory identified tetrahydrocannabinol (THC) in blood and its inactive metabolite tetrahydrocannabinol carboxylic acid (THC-COOH) in blood (0.0031 ug/ml) and liver (0. 856 ug/g). THC is the psychoactive compound found in marijuana. Therapeutic levels may be as low as 0.001 ug/ml (1.0 ng/ml). THC has mood altering effects including euphoria, relaxed inhibitions, sense of well-being, disorientation, image distortion, and psychosis. According to the toxicologist from the FAA Bioaeronautical Laboratory, the level of THC in the blood was below the calibration curve of 1 ng/ml. A copy of the NTSB's Medical Officer's Factual Report is available in the public docket for this accident. The closest weather reporting facility is Soldotna Airport, Soldotna, Alaska, about 15 miles northeast of the accident site. At 2016, an aviation routine weather report (METAR) from the Soldotna Airport reported in part: wind from 290 degrees at 8 knots; sky condition clear; visibility 10 statute miles; altimeter 29.85 inHg. The pilot, age 69, held a private pilot certificate with an airplane single engine land rating. His most recent third-class medical certificate was issued on May 23, 2013, and contained the limitation "MUST HAVE GLASSES FOR NEAR VISION." This medical certificate expired May 31, 2015. No personal logbooks were located for the pilot and the aeronautical experience listed on page 3 of this report was obtained from a review of the airmen FAA records on file in the Airman and Medical Records Center located in Oklahoma City. On the pilot's application for medical certificate, dated May 1, 2013, he indicated that his total aeronautical experience was about 1,678 hours, of which 20 were in the previous 6 months. Engine On October 21, 2015, an engine examination was performed by Continental Motors, Mobile, Alabama, under the supervision of the NTSB. Present for the examination was the NTSB IIC, another NTSB investigator, and an air safety investigator from Textron Aviation. Due to limited damage, an engine test run was conducted following the replacement of impact and thermal damaged components. The engine was fitted with a test club propeller for the O-470 series engine. The engine experienced a normal start on the first attempt without hesitation or stumbling in observed rpm. The engine rpm was advanced in steps for warm-up in preparation for full power operation. The warm-up sequence was completed over a span of 15 minutes before the engine throttle was advanced to the full open position and held for 5 minutes to stabilize. Throughout the test phase, the engine accelerated normally without any hesitation, stumbling, or interruption in power, and demonstrated the ability to produce rated horsepower. During the engine test, the magnetos were checked and a drop of 93 rpm was noted for the left magneto and a drop of 95 rpm was noted for the right magneto.The NTSB IIC reached the accident site on the morning of August 23. All of the airplane's major components were found at the main wreckage site. The wreckage was located in an area of densely populated spruce and birch trees, on its left side at an elevation of about 45 feet mean sea level (msl). Portions of the fragmented airplane were scattered along a debris path oriented along a magnetic heading of 037 degrees, with the airplane facing 217 degrees. (All headings/bearings noted in this report are magnetic). An area believed to be the initial impact site was marked by broken limbs atop an estimated 50-foot-tall birch tree. The distance between the initial impact site and the main wreckage was about 25 feet. Only one tree branch was located that exhibited an angular cut. All other tree branches and limbs exhibited damage consistent with a break. Following the impact sequence, a post-crash fire consumed the fuselage from the firewall (fuselage station (FS) 0) aft to just aft of FS 172.0. The left wing exhibited extensive thermal damage. All wing components and structure aft of the forward wing spar were consumed by post-crash fire. The left leading edge exhibited aft crushing beginning at WS 23.62 and extended outboard to WS 100.5. A portion of the right wing, beginning about 2 feet aft of the leading edge at the wing root and extending chordwise to the trailing edge and spanwise about 3 feet was consumed by post-crash fire. The wing remained attached to the airplane by the wing strut. The leading edge exhibited aft crushing beginning at wing station (WS) 100.5 and extended outboard to WS 154.0. The vertical stabilizer and rudder remained attached to the empennage, and were relatively free of impact damage but exhibited signatures consistent with thermal damage. The left and right horizontal stabilizer remained attached to the empennage and exhibited signatures consistent with thermal damage. The left and right elevators remained attached at the respective attach points. The engine remained attached to the firewall by the engine mounts and came to rest on its left side. The #1 rocker cover exhibited signs consistent with impact damage and contained an estimated 3-inch hole on the face of the cover. Fragments of metal and aluminum were located inside the rocker cover. The propeller and hub remained attached to the engine crankshaft. Both propeller blades remained attached to the propeller hub assembly. One blade exhibited slight aft bending and about a ½ inch gouge on the trailing edge beginning about 6 inches from the tip and extending inboard about 1 inch. Both blades were relatively free of chordwise scratches and striations. The propeller spinner separated from the hub and was located in two pieces about 15 feet from the main wreckage. The wreckage was examined at a private warehouse in Kasilof on August 27, 2015. In attendance for the examination was the NTSB IIC, an FAA aviation safety inspector, and an air safety investigator from TextronAviation. Flight control continuity was confirmed through multiple cuts and fractures for the aileron and rudder control systems and the lower elevator control cable. The upper elevator control cable exhibited multiple separations, the mode of which could not be determined at the examination. Portions of the cable were sent to the NTSB Materials Laboratory in Washington, DC for further analysis. A NTSB mechanical engineer and metallurgist examined the fractured cable surfaces and determined the cable failed in a manner consistent with overstress fracture. The elevator trim actuator was measured and found to be extended about 7.7 inches, which equates to about 5 degrees nose down. A materials laboratory factual report is contained in the public docket for this accident.