MILFORD, UT, USA
N531J
CESSNA T337G
AT 1325 MDT, THE PILOT REPORTED AN ENCOUNTER WITH ICING CONDITIONS WHILE IN CRUISE FLIGHT AT FL190. ATC CLEARED HIM TO DEVIATE FROM COURSE AND ASSIGNED A BLOCK ALTITUDE OF FL190 TO FL210 SO THAT HE COULD CHANGE ALTITUDE. WHEN QUERIED, THE PILOT STATED THAT ABOUT 1/4 INCH OF RIME ICE HAD ACCUMULATED. AT 1332 MDT, THE PILOT TRANSMITTED AN UNINTELLIGIBLE REMARK ABOUT HIS GYRO INSTRUMENTS AND SAID HE WAS TURNING 'SOUTH TOWARD ST GEORGE.' SHORTLY THEREAFTER, HE TRANSMITTED THAT HE HAD LOST CONTROL AND THE AIRPLANE WAS GOING DOWN. THE AIRPLANE BROKE UP IN FLIGHT, AND WRECKAGE WAS FOUND SCATTERED OVER ABOUT A 1.2 MILE AREA. PIECES OF THE LEFT AILERON AND THE OUTER PORTION OF BOTH WINGS WERE FOUND AT THE FARTHEST POINT FROM THE RESTING PLACE OF THE MAIN WRECKAGE. AN EXAMINATION REVEALED THAT THE OUTER PORTION OF BOTH WINGS HAD SEPARATED IN A POSITIVE AND AFT DIRECTION. EXAMINATION OF THE AIRFRAME AND ENGINES DID NOT DISCLOSE ANY MECHANICAL PROBLEMS.
HISTORY OF FLIGHT On October 3, 1994, at 1340 mountain daylight time, a Cessna T337G, N531J, was destroyed following a loss of control near Milford, Utah. The instrument rated commercial pilot and his two passengers, one of which was a rated pilot, were fatally injured. Instrument meteorological conditions prevailed at the site. A weather briefing was received and an instrument flight plan was air-filed for the personal flight. According to friends of the pilot, the airplane departed the Lincoln Municipal Airport (051) at 1228 on a flight to the Green River Municipal Airport (U34), Green River, Utah. According to air traffic control (ATC), the airplane was in cruise flight at FL190, when the pilot advised ATC that he was picking up ice. Salt Lake City Center issued the pilot a clearance to maintain a block altitude of FL190 to FL210. Approximately 30 seconds later the pilot transmitted "lost control, going down." A rancher on horseback near the accident site reported hearing the sound of the airplane as it descended above him in the clouds, and later observed the airplane coming out of the overcast and impacting close to his location in a nearly inverted attitude. AIRCRAFT INFORMATION The 1973 pressurized airplane was purchased in September 1993 by a private partnership which included the pilot and two other owners. Prior to departure from the Lincoln Airport, the airplane was topped off with 89.1 gallons of 100LL aviation gasoline. The aircraft was last weighed on September 24, 1993. An estimate of the weight of the airplane at the time of accident places the airplane within its limits. A review of the airframe and engine records did not reveal any anomalies or uncorrected maintenance defects prior to the flight. Examination of the airframe and engines at the accident site did not disclose any mechanical problems. METEOROLOGICAL INFORMATION The weather at the accident site was reported by an eyewitness to be "stormy, with a low overcast, windy, and very cold." The nearest available recorded weather was from Cedar City, Utah, which is located approximately 35 miles south of the accident site. The area of the flight was influenced by a cold front centered over southern Idaho. The weather outlook for central and eastern Nevada called for scattered clouds between 10,000 and 12,000 feet with a broken layer at Flight Level (FL) 180, with isolated rain showers and thunderstorms in southern Nevada, with tops to FL350. The weather outlook for southern Utah until 1600 mountain daylight time called for broken to overcast ceilings at 10,000 feet with isolated rain showers and thunderstorms, with tops to FL350. AIRMET Tango (with update 3), valid until 1400 mountain daylight time for Utah and Nevada, forecasted moderate turbulence between FL180 and FL360 due to weather associated with the upper low and the jetstream. AIRMET Zulu (with update 2), also valid until 1400 mountain daylight time, forecasted moderate mixed icing Utah between 9,000 feet and FL180 over Utah. During the weather briefing, the pilot was briefed on the possibilities of moderate icing at those altitudes, and also told to expect increasing rain showers and thunderstorm activity as the day continued. No pilot reports (PIREPS) were available to be issued to the pilot at the time of the briefing. According to the winds aloft forecast for the route of flight, the temperatures at FL180 were forecasted to be in the freezing range (minus 14 degrees centigrade). A copy of the recorded weather reports and forecasts for the area is enclosed in this report. COMMUNICATIONS A copy of the transcripts of the weather briefing received by the pilot, as well as the transcripts of all the ATC radio communications is enclosed in this report. WRECKAGE AND IMPACT INFORMATION The wreckage was located on a high desert pasture scattered for over a mile from the initial point of impact. Ground scars were found at the initial point of impact on a measured heading of 172 degrees. The main wreckage came to rest on a measured heading of 260 degrees. The landing gears were found in the extended position with the flaps extended approximately 20 degrees. All aircraft components were located at the site. Flight control continuity was established. The left aileron, fractured in 4 pieces, and the outer portion of both wings, were found at the farthest point from the resting place of the main wreckage, at a distance of approximately 1.2 miles. Physical evidence demonstrated that the outer portion of both wings had separated in a positive and aft direction. A sunvisor; several pieces of windshield plexiglass; the oil cap access door; a partially buried (upside down) magnetic compass, a propeller governor control arm; and several small engine parts were found located at the initial point of impact for the main wreckage. Both engines were found separated from their respective mounts. Both propellers were found separated from their respective engines at the propellers flange. The right tail boom exhibited paint transfers and evidence of propeller slashes from the aft engine. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy and toxicological tests were ordered and performed. The autopsy was performed by the Office of the Medical Examiner of the State of Utah on October 5, 1994. Toxicological tests were negative. TEST AND RESEARCH Both vacuum pumps were examined at the site. One vacuum pump was destroyed by impact damage, and the second one was found undamaged. Internal examination of the undamaged vacuum pump revealed that the rotor was intact and no anomalies were found. No evidence or signatures of pre-impact electrical failure was found. ADDITIONAL DATA The wreckage was released to the owners representative following the conclusion of the investigation.
THE PILOT'S CONTINUED FLIGHT INTO ADVERSE WEATHER CONDITIONS, WHICH RESULTED IN AIRFRAME (STRUCTURAL) ICE, A LOSS OF CONTROL, AND SUBSEQUENT IN-FLIGHT BREAKUP OF THE AIRPLANE. A FACTOR RELATED TO THE ACCIDENT WAS: THE ICING/WEATHER CONDITION.
Source: NTSB Aviation Accident Database
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