N6289ZPiper PA-25 · 1959

On August 13, 2015, about 0930 Pacific daylight time, a Cessna T182T, N6289Z, was destroyed when it impacted terrain while maneuvering near Oroville, Washington. The pilot, who was the registered owner of the airplane, and a pilot-rated passenger sustained fatal injuries. The flight was operated under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal cross-country flight. Visual meteorological conditions (VMC) prevailed at the time of the accident, and no flight plan had been filed. The flight originated from Dorothy Scott Airport (0S7), Oroville, about 0920, with an intended destination of Spokane International Airport (GEG), Spokane, Washington.

About 0945, the Okanogan County Sheriff's department received a notification of a forest fire near Oroville. Upon arrival to the scene, Sheriff's department personnel discovered an airplane that was destroyed. The airplane was not positively identified at that time.

On August 14, 2015, at 0031, an Alert Notification (ALNOT) was issued for an airplane after family members of the pilot became concerned when he did not arrive at his intended destination. Later that day, the airplane wreckage found by the sheriff's department was identified as the missing airplane.

There were no reported witnesses to the accident sequence.

It could not be determined which pilot occupied which seat, and which pilot was manipulating the flight controls when the accident occurred.

The pilot/owner, age 88, held a private pilot certificate with airplane single-engine land, and instrument airplane ratings. A third-class airman medical certificate was issued on February 17, 2015 with the following limitation: must use hearing amplification. On his most recent medical certificate application, the pilot reported that he had accumulated 1,701 total flight hours. The pilot's personal logbook was not obtained during the investigation.

The pilot-rated passenger was a Canadian citizen and flight information was not provided.

The four-seat, single-engine, high-wing, fixed landing gear airplane, serial number T18208870, was manufactured in 2008. It was powered by a Lycoming TIO-540-AK1A engine, serial number L-13038-61A, rated at 235 horse power. The airplane was also equipped with a McCauley three bladed constant speed propeller; the model and the serial number could not be determined. A review of maintenance records showed that the most recent annual inspection was completed July 14, 2015, at a total airplane time and a tachometer time of 295.5 hours.

An NTSB staff meteorologist prepared a factual report for the area and timeframe surrounding the accident.

The National Weather Service (NWS) Surface Analysis Chart for 0800 depicted a low pressure center in southern Washington, with a north/south-oriented trough stretching from British Columbia to the south. Station models generally depicted calm and light and variable winds throughout the region.

A weather observing station at Osoyoos (CWYY), British Columbia, Canada, reported at 0900 wind calm, temperature of 23 degrees C, and dew point temperature of 14 degrees C. Remarks: site does not have a precipitation sensor, sea level pressure of 1,014.1 milibars (Mb), temperature of 23.1 degrees C, and dew point temperature of 13.5 degrees, 3-hour pressure tendency: increasing, then decreasing 0.2 Mb.

A North American Mesoscale (NAM) model sounding identified relatively light and variable winds below about 6,000 feet. Above this level, the wind became southwesterly with magnitudes between 15 and 20 knots through 10,000 feet. The entire atmosphere was dry, with relative humidity at or below 41 percent. The RAwindsonde Observation Program did not identify any significant levels of turbulence. The freezing level was identified as being at 14,300 feet.

There were no publicly disseminated pilot reports made within 2 hours of the accident time in the vicinity of the accident site.

The Geostationary Operational Environmental Satellite (GOES-15) visible imagery revealed mostly clear of cloud conditions above the surface.

There were no Airmen's Meteorological Information (AIRMET) advisories active for the accident location at the accident time.

There were no convective or non-convective Significant Meteorological Information (SIGMET) advisories active for the accident location at the accident time.

The four-seat, single-engine, high-wing, fixed landing gear airplane, serial number T18208870, was manufactured in 2008. It was powered by a Lycoming TIO-540-AK1A engine, serial number L-13038-61A, rated at 235 horse power. The airplane was also equipped with a McCauley three bladed constant speed propeller; the model and the serial number could not be determined. A review of maintenance records showed that the most recent annual inspection was completed July 14, 2015, at a total airplane time and a tachometer time of 295.5 hours.

The accident site was located on the side of a hill at an elevation of 3,093 ft msl. The airplane wreckage was spread along a 68 ft-long up-sloping path through a forest of Pinus Ponderosa on a 168-degree magnetic heading.

The first identified point of impact was a Ponderosa pine tree that was broken off about 70 ft above the ground. The tree damage exhibited a 45-degree angle cut.

The airplane's right wing tip, a section of the right wing, the right aileron, and the right flap were found about 43 ft southeast of the first impact point resting on the ground. All of the components exhibited signatures consistent with impact damage, and were charred, melted, and consumed by the fire.

The terrain from the first point of impact to where the airplane's main wreckage came to rest was up-sloping at an angle of 4 degrees. The main wreckage, which consisted of the airplane's engine, propeller, cabin, left wing, both main landing gear, baggage compartment, aft fuselage, and empennage rested inverted with the nose of the airplane oriented to the south-east on a magnetic heading of about 128 degrees. These components were charred, melted, and consumed by fire.

The fuel selector valve was submitted to the Materials Laboratory for examination. A black, rigid material was observed inside the inlet of the fuel selector valve. Using the spectrum of the unknown material, a comparison search including a mixture analysis search was performed in a special library database. The search did not find a strong spectral match for either a single material or a mixture. Due to the high elemental carbon content of the unknown sample, it is likely that the material was exposed to high temperatures and was decomposed to element carbon and water. The identity of the original material in the inlet could not be determined. The complete email examination report is appended to this accident in the public docket.

The airport manager observed the airplane depart from runway 33. He noted that the airplane did not fly southbound through the valley which was the most commonly used route to depart the area. Instead, the pilot turned eastbound towards rising terrain. At that time, the airplane was at about 400 agl. He also stated that when he previously flew with the owner/pilot, he had a tendency to engage an autopilot right after the takeoff. The pilot/owner was not familiar with the instrumentation panel; he did not know how to set up a vertical speed on the autopilot.

A family member disclosed that, in the recent years, the owner/pilot did not fly by himself and that he conducted about two flights per year. A family friend stated that the owner/pilot purchased the airplane about 3 years prior to the accident and that it was "too much of the airplane" for him.

An autopsy was performed on the pilot and the passenger August 25, 2015, by the Okanogan County Coroner's Office, Okanogan, Washington. The cause of death for the pilot and the passenger was determined to be "blunt force trauma and thermal injuries due to aircraft collision with ground".

The FAA Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma performed toxicology on specimens from the pilot and the passenger. The test on the pilot's specimen did not detect a presence of volatiles in blood; however, it detected the following drugs: diphenhydramine and propranolol. The tests for cyanide and carbon monoxide were not performed. The test on the passenger's specimen detected a presence of ethanol in muscle; however it did not detect a presence of drugs in muscle. The tests for cyanide and carbon monoxide were not performed.

The airframe was examined at the accident site on August 15, 2015, by a representative from Textron Aviation and the NTSB IIC.

Most of the airplane was consumed by the post-crash fire. The right wing flap exhibited signatures consistent with thermal damage. The flap actuator extension was measured at 3/16 inches, and investigators determined that the flaps were in a full up position. The wing flap control cables remained attached at both wing bellcranks, and separated at the wing root. The cable separations exhibited signatures consistent with a tension overload. Both right wing aileron cables remained attached to the right wing bellcrank, and were found separated at mid wing. The push-pull rod remained attached to the aileron.

The left wing was located at the main wreckage, and was mostly consumed by the postimpact fire. The left wing aileron cables remained attached to the left wing bellcrank.

Aileron flight control cable continuity was confirmed from the cockpit to each flight control surface via aileron control cable separations in the cockpit area and the right wing mid-section. The aileron control cable separations exhibited signatures consistent with tension overload.

The McCauley three blade propeller remained partially attached to the crankshaft. The propeller hub exhibited signatures consistent with impact and thermal damage. The propeller blades No. 1 and No. 3 were separated and located at the main wreckage. Blade No. 2 remained attached to the hub.

The No. 1 blade exhibited blade tip twisting/curling toward the non-camber side. No. 2 blade and No. 3 blade exhibited no significant twisting, but displayed nicks along the leading edge.

The fuel selector valve exhibited thermal damage consistent with the postimpact fire. The unit was removed from the wreckage and disassembled. The valve was found ported to the left wing fuel tank. The fuel selector valve right wing fuel port was obstructed with an un-identified charred substance and was sent to the NTSB Materials Laboratory for analysis.

The elevator trim actuator extension was measured and found to be about 1 ¾ inches, which corresponded to 15 degrees trailing edge up.

No evidence of pre impact mechanical anomalies or malfunction was observed with the airframe.

The engine remained attached to the airframe. The engine exhibited thermal damage consistent with the postimpact fire. The bottom section of the engine was thermally damaged exposing the engine's internal components.

The engine was examined at the facilities of AvTech, Auburn, Washington, on September 10, 2015, by representatives from Lycoming Engines and the FAA under the supervision of the NTSB IIC.

All six cylinders remained attached to their respective mounts with rocker box covers intact with the exception of cylinder No. 6 which broke off at the piston head. The top sparkplugs on all cylinders except No. 6 remained secured to their respective cylinder location. The bottom sparkplugs on cylinders 1, 3, 4, and 5 remained secure to their respective cylinder location. The bottom sparkplug on cylinder No. 2 exhibited extensive thermal damage, and was not able to be removed from the cylinder. The bottom sparkplug on cylinder No. 6 was missing.

Top and bottom sparkplugs were inspected. The spark plugs exhibited varying degrees of coloration with the exception of top No. 2 and bottom No. 1, which were contaminated with engine oil. All sparkplugs exhibited some corrosion. The electrodes displayed no mechanical deformation. A borescope inspection revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head.

Both magnetos remained attached at their mounts; however, the testing of magnetos for spark was not possible due to extensive thermal damage. The drive of each magneto remained secure.

The crankshaft was not able to be manually rotated.

The turbocharger compressor shroud and the turbocharger compressor wheel were thermally damaged. The exhaust clamps at the exhaust bypass valve and the turbocharger turbine tail pipe were secured. The exhaust bypass valve actuator was thermally damaged; the valve was intact. The turbocharger turbine impeller showed no signs of foreign damage. The turbine blades exhibited no signs of erosion or foreign object ingestion.

No evidence of pre impact mechanical anomalies or malfunction was observed with the engine.

The complete engine and airframe examination reports are appended to this accident in the public docket.