Heber City, UT, USA
N289WB
Cessna T310R
Radar data depicted the airplane reverse course from a southerly track to a northerly track. The pilot reported to air route traffic control center (ARTCC) that he had just lost manifold pressure in the left engine and that he needed to go lower. The controller cleared the pilot to descend from 16,000 feet mean sea level (msl) to 14,000 feet msl. The center controller asked the pilot if he had reversed course due to his engine problem and the pilot acknowledged in the affirmative. The controller assigned the pilot another frequency and the pilot acknowledged the frequency change. No further transmissions were made from the pilot on either frequency and radar contact was lost at an encoded altitude of 11,400 feet msl. The wreckage was located in mountainous, down sloping, snow covered, forested terrain. The airplane was destroyed. An examination of the airframe, engines, and airplane systems revealed no anomalies. Radar echoes and satellite data indicated that the accident airplane most likely entered clouds approximately 1010. Based upon the current icing potential algorithm, there was a high likelihood of icing and supercooled large water droplets at 14,000 to 16,000 feet msl in the accident area. Based on area forecasts, PIREPS, and weather advisories, the accident airplane most likely encountered moderate to severe turbulence and moderate to severe mixed icing during the final few minutes before the accident.
HISTORY OF FLIGHT On April 17, 2006, at 1026 mountain daylight time, a Cessna T310R, N289WB, owned and piloted by a private pilot, was destroyed when it impacted mountainous terrain 15 nautical miles (nm) east of Heber City, Utah. A post impact fire ensued. Instrument meteorological conditions prevailed at the time of the accident. The personal business flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91 and an instrument flight rules (IFR) flight plan had been filed. The pilot was fatally injured. The cross-country flight departed Billings, Montana, approximately 0730, and was en route to Cedar City, Utah. The pilot was traveling to Palm Springs, California, for a medical conference. At 0955:22, a Salt Lake City (SLC) Air Route Traffic Control Center (ARTCC) controller rerouted the flight to MEGIE intersection then direct to Cedar City, due to poor weather in the Salt Lake area. National Track Analysis Program (NTAP) radar data depicted the airplane reverse course from a southerly track to a northerly track at 1023:54. At 1024:04, the pilot reported to SLC ARTCC that he "just lost manifold pressure in [his] left engine" and that he needed to "go lower." The controller cleared the pilot to descend from 16,000 feet mean sea level (msl) to 14,000 feet msl. At 1025:07, the center controller asked the pilot if he had reversed course due to his engine problem and the pilot acknowledged in the affirmative. The controller assigned the pilot another frequency and the pilot acknowledged the frequency change. No further transmissions were made from the pilot on either frequency and radar contact was lost at 1026:05, at an encoded altitude of 11,400 feet msl. An alert notification (ALNOT) was issued by the Federal Aviation Administration (FAA) at 1057 on April 17. The airplane was located approximately 1630 by the Wasatch County Search and Rescue Team, Heber City, Utah, on April 18 in the Uinta National Forest. PERSONNEL INFORMATION The pilot, age 60, held a private pilot certificate with airplane single and multi-engine land, and instrument ratings, initially issued in June of 1986. The instrument rating was added to the certificate in February 1988, and the airplane multi-engine privileges were added in February 2005. The pilot held a third class airman medical certificate issued on September 21, 2005. The certificate contained the limitations "must wear corrective lenses [and] possess glass for near [and] [intermediate] vision." According to the pilot's FAA Airman Certificate and/or Rating Application (Form 8710-1) for the multi-engine certificate check ride, he reported a total time of 677 hours; 52.3 hours of which were logged in multi-engine airplanes and 104 of which were solely by reference to the instruments. The pilot's flight logbook was located within the wreckage. A review of the logbook by the National Transportation Safety Board (Safety Board) Investigator-in-Charge (IIC) indicated that the pilot had logged no less than 737 hours total time: 154 of which was logged in multi-engine airplanes. The pilot had logged no less than 107 hours in the accident airplane and no less than 23 hours in instrument meteorological conditions. AIRCRAFT INFORMATION The accident airplane, a Cessna T310R (serial number 310R0817), was manufactured in 1977. It was registered with the FAA on a standard airworthiness certificate for normal operations. The airplane was equipped with two Teledyne Continental Motors (TCM) TSIO-520-B engines rated for 285 horsepower at 2,700 rpm. Each engine was equipped with a McCauley 3-blade, controllable pitch propeller. The airplane was registered to and operated by the accident pilot, and was maintained under an annual inspection program. A review of the maintenance records indicated that an annual inspection had been completed on January 12, 2006, at an airframe total time of 8,834.6 hours. In September of 2005, the pilot experienced low oil pressure and subsequent engine failure, on the left engine, while flying in Reno, Nevada. The engine was removed and inspected, at which time the bearings, gaskets, seals, and o-rings were replaced. The engine was returned to service in November of 2005. On April 14, 2006, the left wing fuel transfer pump was replaced at an airframe total time of 8,845.0. According to the aircraft maintenance log, on April 14, 2006, maintenance had been completed on the avionics system in the airplane. The Bendix IN 152A radar indicator and GA 56 GPS antenna were removed. An Avidyne EX 500 multi function display (MFD) was installed, as per Supplemental Type Certificate (STC) SA0016BO, interfaced to the Garmin GNS 530/430, NSD 360A bootstrap heading output, and the XM076 XM weather uplink. In addition, a heads-up technology XMD076 XM weather uplink receiver with a Comant Combination CI 401-420 XM/GPS antenna with a Comant CI 511 GPS attenuator was installed. METEOROLOGICAL INFORMATION On April 16, 2006, at 1200, the pilot logged into the Direct User Access Terminal System (DUATS) and obtained a low altitude weather briefing for his proposed route of flight. On April 17, 2006, at 0645, the pilot logged into DUATS and obtained a low altitude weather briefing for the same route of flight. The pilot also filed two IFR flight plans; one from Billings to Cedar City and the other from Cedar City to Palm Springs. On April 17, at 0900, a Surface Analysis chart, prepared by the National Weather Service, National Center for Environmental Prediction, depicted a cold front extending through northwestern Utah. Doppler weather radar (approximately 76 nautical miles northwest of the accident location) scanned the accident area at 1017:33, 1023:04, and 1027:28. The nominal beam center ranged between 14,600 feet and 15,800 feet msl. Data indicated reflectivity values of 21 to 22 dBz in the accident area around the accident time. Aviation area forecasts were issued for Utah by the Aviation Weather Center (AWC) in Kansas City, Missouri, the day of the accident, starting at 0515. The forecast for the north third of Utah was as follows: sky conditions, broken at 12,000 feet msl with tops at flight level 240; occasional, overcast at 8,000 feet msl with scattered light rain showers. Starting at 0700, AWC forecasted the sky condition overcast at 6,000 feet, visibility 4 statute miles with light rain and snow. Starting at 1000, AWC forecasted visibility 3 statute miles with light rain and snow showers, isolated snow, rain, and thunderstorms with cumulonimbus tops at flight level 300. Airman's Meteorological Information (AIRMET) for instrument flight rules (IFR) and mountain obscuration (SIERRA), turbulence (TANGO), and icing (ZULU) were all issued by AWC for areas in Utah, including the accident airplane's route of flight. AIRMET SIERRA for IFR stated to expect occasional ceilings below 1,000 feet above ground level (agl), visibility below 3 statute miles due to clouds, precipitation, fog, and mist. AIRMET SIERRA for mountain obscuration stated to expect mountains occasionally obscured by clouds, precipitation, and mist. AIRMET TANGO stated to expect occasional moderate turbulence below flight level 180 due to strong low and middle level winds. AIRMET ZULU stated to expect occasional moderate rime and mixed icing between 8,000 feet msl and flight level 200. No significant meteorological information (SIGMET) or center weather advisories were issued by the Salt Lake City Center Weather Service unit for the time of the accident. Multiple pilot reports (PIREPS) had been issued for the Salt Lake City area regarding icing and turbulence. Reports given for icing included light to moderate mixed icing, and light to moderate rime icing, from 9,000 feet msl to 19,000 feet msl. Reports given for turbulence included light to moderate turbulence and continuous light to severe turbulence from 4,000 feet msl to 19,500 feet msl. The closest official weather observation station was Heber Valley Municipal Airport (36U), Heber City, Utah, located 15 nm west of the accident site. The elevation of the weather observation station was 5,637 feet msl. The routine aviation weather report (METAR) for 36U, issued at 1055, reported winds, 010 degrees at 6 knots, gusting to 16 knots; visibility, 1 statute mile, light snow; sky condition, 600 feet overcast; temperature 02 degrees Celsius (C); dewpoint, 0 degrees C; altimeter, 29.71 inches. The METAR for Provo (PVU), Utah (located 32 nm southwest of the accident site, at an elevation of 4,497 feet msl) issued at 1035, reported, winds, 320 degrees at 23 knots, gusting 29 knots; visibility, 9 statute miles; sky condition, 900 feet scattered, 2,300 feet broken, 7,500 feet overcast; temperature, 03 degrees C; dewpoint, minus 02 degrees C; altimeter, 29.78 inches. WRECKAGE AND IMPACT INFORMATION The Safety Board IIC arrived on scene approximately 1100 on April 20, 2006. The accident site was located in mountainous, down sloping, snow covered (ranging in depth from 8 to 10 feet), forested terrain. A global positioning system receiver reported the coordinates of the main wreckage as 40 degrees 28 minutes 23.5 seconds north latitude, and 111 degrees 8 minutes 7.1 seconds west longitude. The accident site was at an elevation of 9,350 feet msl and the airplane impacted on a magnetic heading of 340 degrees. The Safety Board IIC identified the initial point of contact upslope and south of the main wreckage. Tree branches had been torn and broken in the direction of flight and were pointing towards the main wreckage. A ground crater 50 feet in length, 12 feet in width, and 5 feet deep, preceded the main wreckage. Insulation, miscellaneous airplane debris, and personal effects were scattered within the crater. The main wreckage consisted of wing assemblies (to include both engines), the empennage, and fuselage, and was located at the north end of the ground grater. Portions of the empennage and fuselage were visible at the top of the crater. The remainder of the wreckage was crushed, torn, and compressed beneath the snow. The left engine and portions of the left wing were recovered from 8 feet of snow. The right engine and wing were not visible. MEDICAL AND PATHOLOGICAL INFORMATION The autopsy was performed by the Utah State Medical Examiner's office on April 19, 2006, as authorized by the Wasatch County Coroner's office. The autopsy revealed the cause of death as "blunt force trauma." Toxicology was performed by the FAA's Civil Aerospace Medical Institute, Oklahoma City, Oklahoma (CAMI Reference #200600080001). Tests for carbon monoxide, and cyanide were not performed. Tests for ethanol were negative. Dextromethorphan was detected in the liver and kidney and dextrorphan was detected in the liver. TESTS AND RESEARCH The empennage, portions of the fuselage and left wing, the left engine, and one propeller blade were recovered on April 20, 2006, and relocated to a hangar in Spanish Fork, Utah, for further examination. The remainder of the wreckage, to include portions of the fuselage, the right engine and propeller assembly, and portions of the left and right wing, were recovered on June 27, 2006, and relocated to a hanger in Spanish Fork for further examination. The Safety Board IIC and representatives from Cessna Aircraft Company, and Teledyne Continental Motors, examined the wreckage on April 21, and July 18, 2006. A representative from Kelly Aerospace was present on July 18, 2006. Airframe Investigators examined the airframe and noted that not all of the torn metal from the accident airplane could be readily identified. The manufacturer's representative was able to positively identify the torn pieces of metal by comparing the part numbers identified on each piece with the Cessna Aircraft parts catalogue. The fuselage of the airplane, to include the cabin area and instrument panel, was fragmented and destroyed. The top aft skin and floor of the fuselage exhibited forward to aft accordion crushing. The pilot seat cushion exhibited thermal damage. The right and left wing assemblies, to include both engine assemblies, ailerons, and flaps, were fragmented and destroyed. The de-icing boots were torn, and fragmented, and could not be functionally tested. Torn metal from the leading edge exhibited forward to aft accordion crushing. A portion of the wing skin from the right wing, identified as mid section skin, exhibited thermal damage. This portion of the skin was located on scene under the cabin seats that also exhibited thermal damage. Aileron and flap continuity was not established. The empennage, to include the elevator, rudder, and horizontal and vertical stabilizers sustained extensive impact damage. The leading edge of both the vertical and horizontal stabilizers exhibited accordion crushing. The horizontal stabilizer was crushed aft to the front of the forward spar. Flight control continuity to the rudder and elevator was not established. Both fuel transfer pumps were removed from the airframe for further examination under the auspices of the FAA. No anomalies were noted during the electrical current and flow tests. Engines Investigators removed and examined the left and right engines (serial number 176100-70-B and 145381-6-B). The engine assemblies, to include the cylinders, oil sump, and various accessories exhibited extensive impact damage. Due to impact damage, engine continuity, tactile cylinder compression, and ignition spark could not be readily verified. The cylinder walls, sparkplugs, intake and exhaust valve faces, piston heads, connecting rods and bushings, camshaft, and crankshaft exhibited normal operating signatures. Examination of both engine's respective vacuum pumps, fuel pumps, and engine magnetos revealed no anomalies. The fuel injector nozzles and oil sump screens were removed from both engines and found to be free of debris or contamination. Turbochargers Both engines turbocharger assemblies were removed from the engine and examined by a representative from Kelly Aerospace, under the auspices of the Safety Board IIC. Both assemblies were partially disassembled revealing normal signs of wear and operation. The unit housing of both assemblies exhibited rotational scoring and the turbine vanes were bent or broken aft, opposite the direction of rotation. Propellers Both propeller assemblies were shipped to McCauley Propellers in Wichita, Kansas, for further examination. The assemblies were disassembled and examined under the auspices of the FAA on September 18, 2006. The propeller blades (positively identified by serial number) were labeled "L" and "R" to signify left and right assemblies, and were arbitrarily labeled "A", "B", and "C", for identification purposes only. All three blades from the left propeller assembly separated from the spinner and hub. Blade L-A, was bowed aft and exhibited chordwise scratching along the face of the blade, and leading edge polishing. The de-icing boot was torn, and the tip of the blade curled approximately one inch, opposite of the direction of rotation. Blade L-B was bowed aft and exhibited slight leading edge polishing. Blade L-C exhibited slight leading edge polishing. According to McCauley, the number 2 and number 3 hub sockets exhibited counterweight impact marks whose relative position indicated blades were at, or very near, the feather position at impact. Blade R-A, exhibited S-shape bending from tip to hub. Blade R-B was bent aft 90 degrees about one third of the span inboard from the blade tip. The blade face and back exhibited longitudinal, 90 degree and 45 degree, chordwise scratching. A 2 inch by 1 inch nick was located 12 inches outboard of the blade hub. Blade R-C separated from the propeller hub and spinner, and exhibited leading edge and trailing edge nicks, scratches, and polishing. According to McCauley, the blade bending is indicative of power at impact. ADDITIONAL INFORMATION In a telephone conversation with the pilot's multi-engine flight instructor, he stated that during the pilot's training, he never seemed stressed in instrument or icing conditions. The instructor stated that the training was in-depth and covered all the airplane's systems, to include the icing systems and the alternate air. The
the pilot's loss of aircraft control due to the loss of engine power due to induction icing. Contributing factors include the in-flight encounter with structural icing, the severe turbulence, and the pilot's increased workload.
Source: NTSB Aviation Accident Database
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