ANC18FA024

Chuckanut Mountain, which was located along the intended route of flight, was visible as elevated terrain on the Seattle VFR Sectional chart. Its highest elevation (1,900 ft) was not depicted; however, the elevation of a higher mountain 2 miles southeast of Chuckanut was noted as 2,320 ft. A flight time and fuel log was recovered from the wreckage. The fuel quantity logged at the end of the previous flight was 35 gallons, which would have been enough for over 2 hours of flight at an average fuel burn rate of 13 gallons per hour. Fueling receipts corresponded to the last recorded fueling. The accident flight was about 30 minutes. Bellingham International Airport is a part-time tower-controlled (Class D) airport located at an elevation of 171 ft msl. Runway 16/34 is 6,700 ft long and 150 ft wide. Runway 34 did not have an approach lighting system, but was equipped with runway end identifier and precision approach path indicator (PAPI) lights. The airport lights were operating the night of the accident. On February 12, 2018, about 1913 Pacific standard time, a Mooney M20K airplane, N123JN, was destroyed when it was involved in an accident near Chuckanut, Washington. The private pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The co-owner of the airplane stated that the purpose of the flight was to re-position the airplane from Harvey Field (S43), Snohomish, Washington, to Bellingham International Airport (BLI), Bellingham, Washington, for maintenance. Federal Aviation Administration (FAA) radar and automatic dependent surveillance-broadcast (ADS-B) data revealed that the flight departed S43 at 1851 and climbed to 4,300 ft mean sea level (msl) on a north-northwesterly course. About 1907, the airplane began a slow descent at 275 ft per minute (fpm). At 1911, the pilot contacted the BLI air traffic control tower and reported his position 14 miles south of the airport and requested a straight-in approach. The tower controller issued a clearance for a visual approach to runway 34 and instructed the pilot to report 3 miles from the airport. There were no further radio communications from the pilot. Flight track data indicated a gradual increase in the descent rate to about 700 fpm at the last recorded position. During the last 2 minutes of the flight, the airplane's groundspeed slowed from 153 to 146 knots. The airplane's last recorded position was at 1913:08, about 9 miles south-southeast of the airport near the accident site and on a northwesterly course at an altitude of 1,975 ft msl. (See figure 1.) At 2122, the FAA issued an alert notice (ALNOT) and the airplane was subsequently located about 2200 on the north side of Chuckanut Mountain in Larrabee State Park. Figure 1. OpsVue flight path and wreckage location on a Google Earth image. The Whatcom County Medical Examiner, Bellingham, Washington, performed an autopsy of the pilot. The pilot's cause of death was massivetrauma. Toxicology testing of the pilot was performed at the FAA Forensic Sciences Laboratory. Fluid and tissue specimens tested negative for ethanol and other drugs. Astronomical data from the US Naval Observatory indicated that sunset on the day of the accident occurred at 1726. Moon set was at 1437. The pilot's third class medical certificate was converted to a time-limited special issuance medical certificate on October 4, 2017, due to hypertension, cardiac disease, and sleep apnea; it was due to expire on October 31, 2018. The pilot's family indicated that he was physically active and was managing his health well. The accident site was located on the north face of the mountain in an area of dense forest with no lighted structures. Aerial photographs indicated that the initial impact point was a section of tall trees (about 50 to 75 ft tall) on a ridge (elevation 1,900 ft msl) above the wreckage. All major components were located at the site. Large portions of the fragmented airplane were scattered along a 1,200-ft-long debris path, which started on the ridgeline and continued on a heading of 344° through large trees down to an elevation of 1,589 ft. (See figures 2 and 3.) Figure 2. Aerial image of initial impact tree strikes on south side of Chuckanut Mountain. (Image courtesy of US Customs and Border Patrol.) Figure 3. Fragmented wreckage on the north side of Chuckanut Mountain with flight track path in red. The outboard wing sections and flaps were separated and located at the top of the debris field. The wings exhibited 12- to 18-inch-wide semicircular indentations in the leading edges consistent with high-speed tree strikes in level flight. The fuel tanks were breached and no measurable fuel was present. The speed brakes were retracted. A portion of the empennage, separated rudder, and horizontal stabilizers were located downhill and exhibited leading edge tree strike damage similar to the wings. The main fuselage and center wing section came to rest midway in the debris field. The flap control actuator indicated that the flaps were in the retracted position. The propeller was separated from the engine. One propeller blade indicated chordwise scrapes and leading edge nicks. Propeller strikes and cuts were evident in nearby tree debris. Two cockpit sections were downhill of the main wreckage and exhibited substantial deformation. The altimeter setting was 30.40, which was .06 higher than the local pressure setting of 30.34 at BLI at the time of the accident. The engine came to rest at the far north end of the debris field against a tree. A detailed examination of the engine established mechanical continuity throughout the engine, valve train, and accessory section. Thumb compression was obtained on all cylinders and a borescope examination revealed no preaccident anomalies with the cylinder barrels, pistons, cylinder heads, and valves. The magnetos produced ignition spark at the leads when the crankshaft was manually rotated. The fuelmanifold valve was disassembled; residual fuel was found in the housing and the screen was unobstructed. The turbocharger was partially disassembled and revealed no preaccident anomalies. The vacuum pump was removed and disassembled. The shear coupling was intact but displayed torsional twisting and a semi-circular score mark indicative of rotation at the time of impact. An examination of the flight control system revealed control pushrod fractures and separations consistent with impact damage and tension overload at the attachment fittings. Full flight control functionality could not be established due to fragmentation and deformation in the forward fuselage. The stabilizer trim jack screw was fractured at the actuator box and not recovered. The forward (cockpit) pitch trim actuator was bent within the trim assembly and the travel lug was in the full forward position, which is beyond the normal range of measurement in the full nose-down direction. A JPI EDM-830 engine data monitor was recovered from the wreckage and downloaded by the NTSB. Data from the last 7 flights, including the accident flight, were recorded at 6-second intervals; this data included exhaust gas temperatures, cylinder head temperatures, RPM, and manifold pressure. The turbocharger inlet temperature (TIT) sensor did not record data. The engine data for the accident flight indicated that the engine was running about 2,400 rpm and 24-inches manifold pressure during the final descent until the last 3 data points, during which all parameters, except engine rpm, indicated a decrease. There were no engine performance anomalies indicated in the data.