Willow, AK, USA
N78831
PIPER PA-11
Witnesses near the accident site saw the accident airplane flying about 100 feet above a river and towards their location on the river bank. As they watched the airplane fly past, there appeared to be nothing wrong with the airplane or its engine. Review of a digital video taken by one of the witnesses showed the airplane flying in a straight and level attitude over the river at a low altitude. Within 2 minutes of the airplane passing the witnesses, they heard an unusual sound, possibly that of the airplane crashing. Associates of the pilot and passenger said that the pilot told them they intended to scout for wildlife during the flight to their intended destination. Numerous moose hoof prints were seen near the accident site. Examination of the wreckage revealed impact damage consistent with a stall and/or spin. No evidence of any preimpact mechanical anomaly was discovered during the postaccident examination of the airplane and engine.
HISTORY OF FLIGHT On August 24, 2010, about 1945 Alaska daylight time, a Piper PA-11, N78831, sustained substantial damage when it impacted terrain about 25 miles southwest of Willow, Alaska. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed, and a visual flight rules flight plan was filed for the personal flight. The private pilot and passenger were killed. The cross-country flight departed from Lake Hood Strip Airport (LZ1), Anchorage, Alaska, about 1915 with an intended destination of Rainy Pass Lodge Airport (6AK), Rainy Pass, Alaska. Two witnesses on a hunting trip were about one mile southeast of the accident site near the bank of the Susitna River when they heard an airplane flying towards their location. One of the witnesses, who was familiar with small airplanes, said that the airplane was flying over the river at less than 100 feet. The witness added that as they watched the airplane fly past their position along the river, there appeared to be nothing wrong with the airplane and that the engine seemed to be running smoothly. About a minute or two after the accident airplane flew past them, they heard a "strange noise" like something had "flapped the water." The witnesses said that earlier in the day, prior to drifting down river in their boat, they had been watching a small moose near the accident site. A digital video recorded by one of the witnesses showed the accident airplane flying in a straight and level attitude over the Susitna River at a low altitude. The sound of the engine could be heard with no irregularities noted. A witness, who was flying from Skwentna, Alaska to Anchorage, Alaska, reported to the Safety Board investigator-in-charge (IIC), that around 1945, he saw dark smoke rising above a tree line, and he flew towards the smoke. He flew over a sandbar on the Susitna River about 400 to 500 feet above ground level, and saw an object engulfed in flames. He made three or four passes over the area at a lower altitude, and determined that it was the wreckage of an aircraft. The witness said he immediately notified the FAA Kenai Flight Service Station of the location of the wreckage. Information provided by the Alaska State Troopers revealed that friends and family of the pilot and passenger reported that the pilot said they intended to scout for wildlife during the flight to their intended destination. There were no known witnesses to the accident sequence. PERSONNEL INFORMATION The pilot, age 28, held a private pilot certificate with airplane single-engine land and sea ratings. A second-class Federal Aviation Administration (FAA) airman medical certificate was issued on July 09, 2010, with no limitations. The pilot reported on his most recent medical certificate application that he had 230 total flight hours. The pilot's personal logbooks were not located during the course of the investigation. AIRCRAFT INFORMATION The two-seat, high-wing, fixed-gear airplane, serial number (S/N) 11-1605, was manufactured in 1947. It was powered by a Teledyne Continental Motors (TCM) C-90 engine, serial number 45610-7-12 rated at 95 horsepower, and equipped with a Sensenich model M76AK-4 fixed pitch propeller. Review of copies of maintenance logbook records showed an annual inspection was completed on December 14, 2009, at a recorded tachometer reading of 473.5 hours, airframe total time of 3,755.5 hours, and engine total time of 3,098.5 hours, and engine time since major overhaul of 1,298.5 hours. The tachometer was observed at the accident site; however, damage precluded determining the current readings. METEOROLOGICAL INFORMATION A review of recorded data from the Ted Stevens Anchorage International Airport (ANC), Anchorage, automated weather observation station, about 30 miles southeast of the accident site, at 152 feet above mean sea level (MSL), reported at 1953, weather conditions were wind from 240 degrees at 5 knots, visibility 10 statute miles, few clouds at 5,000 feet above ground level (agl), scattered clouds at 7,500 feet agl, temperature 17 degrees Celsius, dew point 8 degrees Celsius, with an altimeter setting of 29.98 inches of Mercury. WRECKAGE AND IMPACT INFORMATION The accident site was on the northwestern edge of a sandbar along the Susitna River. Examination of the accident site by the IIC and an FAA inspector the day following the accident revealed that the airplane came to rest in a near vertical attitude on a heading of about 291 degrees magnetic, about 53 feet MSL. No ground impressions or wreckage debris path was observed surrounding the main wreckage within about 300 feet. Examination of the area surrounding the accident site revealed what appeared to be fairly recent moose hoof prints in the sandbar about 200 feet south of the main wreckage. The fabric covering of the left and right wings, fuselage, and empennage was consumed by fire. All major structural components of the airframe remained attached to the fuselage. The engine was partially embedded in soft terrain, and remained partially attached to the airframe. Examination of the airframe and flight control system disclosed no evidence of preimpact mechanical malfunction. The wreckage was moved to a secure location for further examination. MEDICAL AND PATHOLOGICAL INFORMATION The Alaska State Medical Examiner conducted an autopsy on the pilot on August 25, 2010. The medical examiner determined that the cause of death was “...multiple blunt force injuries.” The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had positive results for Acetone within the blood vitreous, ethanol within the urine and vitreous, and methanol within the muscle, brain, vitreous, and urine. The toxicology report stated that the ethanol found was from sources other than ingestion. For specific test levels, see the toxicology report in the public docket for this report. SURVIVAL ASPECTS The Terminal Radar Approach Control (TRACON) facilities at ANC reported that the Rescue Coordination Center (RCC) received two reports of Emergency Locator Transmitter (ELT)121.5 MHz signals received by military aircraft who were in the area of the accident site on an unrelated training mission about 1945. The accident airplane was equipped with a 121.5 MHz emergency locator transmitter (ELT). As of February 1, 2009, the 121.5 MHz ELT satellite monitoring (SARSAT) was terminated. According to the National Oceanic and Atmospheric Administration (NOAA) Satellite and Information Service, "NOAA, along with the U.S. Coast Guard, U.S. Air Force, and NASA (the four Federal Agencies who manage, operate, and use the SARSAT system) are strongly advising users of 121.5/243 MHz beacons to make the switch to 406." The National Transportation Safety Board issued Safety Recommendation A-07-51, on September 4, 2007. The recommendation, addressed to the FAA administrator, states in part "Seek authority from Congress to require the installation of Technical Standard Order C126 [406 megahertz (MHz)] emergency locator transmitters (ELTs) in all applicable aircraft at the earliest possible opportunity. Further, the Federal Aviation Administration should strongly consider establishing a compliance date for upgrading to 406-MHz ELTs on or before the date that COSPAS-SARSAT will cease satellite processing of 121.5-MHz signals." As of March, 2011, the FAA has not sought to mandate the use of 406MHz ELTs, and the Safety Board has classified the FAA’s response to Safety Recommendation A-07-51 as: "Open-Unacceptable." TESTS AND RESEARCH The recovered engine was examined on September 23, 2010, by the Safety Board IIC. Examination of the engine revealed that all four cylinders remained attached to the engine crankcase. The right magneto remained partially attached to its mounting pad. The left magneto remained attached to its mounting pad. The carburetor was displaced from the engine just below the mount pad. The oil sump was intact and had impact damage. The exhaust system was impact damaged. One of the two exhaust stacks was flattened near the exhaust tip. Thermal and fire damage was observed to the engine crankcase, cylinders, and all engine accessories. The top spark plugs, left and right magneto, carburetor, propeller, and rocker box covers were removed from the engine. The engine crankshaft was manually rotated by hand using a hand tool attached to the crankshaft propeller flange. Rotational continuity was established throughout the engine and valve train. Thumb compression was noted on all four cylinders. Equal movement was noted on all of the intake and exhaust rocker arms. The left and right magnetos were removed from the engine. The impulse couplings on both magnetos were intact. Both magnetos drive shafts would not rotate by hand. The magnetos were disassembled and inspected. The internal components of both magnetos had thermal and fire damage. The Sensenich fixed pitch propeller was removed from the engine. Both propeller blades exhibited twisting and bending opposite the direction of normal rotation. Leading edge and forward blade face polishing was seen on both propeller blades. One propeller blade tip had leading edge gouges. No mechanical anomalies were noted with the airframe or engine that would have precluded normal operation.
The pilot’s failure to maintain adequate airspeed, which resulted in an aerodynamic stall/spin and impact with the ground.
Source: NTSB Aviation Accident Database
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