SEA95FA025

The airplane was level at FL220 at night when vertical fluctuations in altitude up to 500 feet above altitude were noted by the Salt Lake Center controller. Immediately thereafter, the aircraft began a descent and transponder targets were lost. A trajectory study showed the aircraft descending in a tight right turn. Examination of the wreckage revealed that the right elevator separated in negative overload with both wings separating negatively. Wreckage distribution established separation of the empennage and its associated control surfaces before the separation of the wings. A preimpact fire was witnessed and the main fuselage was destroyed by an intense postcrash fire. The initiating event which resulted in the altitude divergence and descending turn could not be determined.

History of flight

On November 29, 1994, at 1950 mountain standard time, a Piper PA-31T1 Cheyenne, N22CN, being flown by a multi-engine, instru- ment rated, private pilot, broke up in flight and then collided with terrain during an uncontrolled descent. The aircraft was destroyed and a pre/post impact fire occurred. The pilot and passenger were fatally injured. The aircraft crashed 15 nautical miles southwest of Brockway, Montana. Dark night and variable meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was in effect at the time. The flight, which was business in nature, was to have been operated under 14CFR91, and originated from Lacrosse, Wisconsin approximately 1632.

At 1930:59, N22CN requested a descent from flight level (FL) 240 to FL 220 and this request was granted by the Salt Lake Air Route Traffic Control (ARTCC) sector controller. Radar data showed the aircraft at FL 220 shortly thereafter.

The Salt Lake ARTCC sector controller reported in a statement that "after working the sector for about 10 minutes I saw N22CN's altitude go up 500 feet. I was getting ready to tell him, when I saw his target disappear and the data block went into coast track." The controller's attempts to contact the aircraft were unsuccessful (refer to attached statement).

The mode "C" altitude readout from the aircraft showed a consistent altitude of FL 220 with only minor 100 foot deviations on four occasions during the 12 second interrogations by the Salt Lake ARTCC radar between 1935:53 until shortly after 1944:18.

At 1944:30, small up and down fluctuations of altitude up to 300 feet were noted on the mode "C" radar returns. At 1949:31, the mode "C" altitude peaked at 500 feet above FL 220, followed by a readout of 100 feet above FL 220 at 1949:43, and a final mode "C" readout of 100 feet below FL 220 at 1949:55. The mode "C" readout and transponder target were then lost. Salt Lake ARTCC radar recorded 23 additional primary (non transponder) targets before losing the aircraft (refer to ATTACHMENT RD-I).

The next and last known radio contact received from the aircraft was an unintelligible transmission received at 1950:39.

Witnesses reported observing a fireball descending steeply in an easterly direction (refer to attached witness statements).

Personnel information

A personal friend of the pilot reported that the pilot had logged approximately 1,200 hours of total flight time of which an esti- mated 300-400 hours were in the Beech Duke aircraft and approxi- mately 170 hours were in the PA-31T1. He indicated that the pilot had been flying N22CN on a weekly basis since its purchase.

The pilot received ground and flight instruction from an individual providing contractual training during the month of June of 1994. No unusual attitude recovery training was conducted. The contractor, who travelled to Jefferson City, reported that he provided 24 hours of ground school instruction and approximately 10 hours of flight training (conducted in N22CN) over a three-day period, and that the pilot had no previous turbine experience at that time. The contractor signed off the pilot on June 22, 1994.

As the aircraft was reported to have departed approximately 0800 from Jefferson City, the pilot would have been engaged in flight/ crew duty conditions for a period of time exceeding 12 continuous hours.

Aircraft information

The aircraft's airframe and powerplant logbooks were reported to be on board the aircraft at the time of the accident. No evidence of their remains was discovered during the on-site examination.

According to FAA records, the aircraft was purchased by and registered to the pilot on July 20, 1994. Maintenance documen- tation retained by Jefferson City Flying Service, Inc., showed a pre-purchase inspection dated May 31, 1994, at an aircraft total time of 3223 hours (158.5 hours Hobbs time). Additional records from the same source showed 27 write ups on the aircraft with corresponding action taken. These writeups were dated September 6, 1994, coincident with the date on which a Piper programmed inspection 100-hour cycle checklist was signed off. Aircraft total time noted on the first page of the check sheet was 3330.9 hours with a corresponding Hobbs time of 264.2 hours noted. The most recent maintenance record was a single writeup corrected on November 16, 1994, at a recorded Hobbs time of 338.9 hours.

A passenger occupying the front right seat of the aircraft on the morning of November 29th, while the aircraft was en route to Appleton, Wisconsin, reported the following event: "While en route and prior to our descent, we were on auto- pilot. The plane suddenly went into a hard right bank. (The pilot) turned off the auto-pilot and manually corrected back on course." "After the correction we (the pilot and front right passenger) commented that it had never done that before. (The pilot) put on the auto-pilot again and shortly it began a right bank. (The pilot) turned off the auto-pilot for a short time and again activated it with the same results commenting he would have it looked at" (refer to statement TB attached).

Meteorological information

Winds aloft for Glasgow, Montana, were recorded as follows:

Observation time: 1900 hours mountain standard (11/29/94)

altitude speed direction (true) 18,000' 60 kts 310 deg 19,000' 60 kts 308 deg 20,000' 62 kts 306 deg 21,000' 62 kts 305 deg 22,000' 68 kts 309 deg 23,000' 80 kts 317 deg 24,000' 93 kts 320 deg

The Glasgow radiosonde launch point bears 322 degrees magnetic and 74 nautical miles from the accident site.

Communications

No abnormal communications were noted until 1950:39 hours when Salt Lake ARTCC received an unintelligible radio transmission associated with N22CN (refer to attached communication transcripts).

Wreckage and impact information

The ground impact site of the fuselage was established by a hand- held global positioning system (GPS) receiver as 47 degrees 05.184 minutes north latitude and 105 degrees 56.595 minutes west longitude at an elevation of approximately 2,975 feet above mean sea level. This location was 15 nautical miles south-southwest of Brockway, Montana. The terrain at the site was characteristic of gently rolling agricultural farmland. Fragments of wreckage were recovered during the on-site phase of the investigation and were distributed along an approximate 090 degree magnetic bearing line.

The fuselage was observed to be inverted and oriented along a 245/065 degree magnetic bearing line (nose southwest). The nose cone/radar, empennage and associated control surfaces aft of the aft pressure bulkhead, and left/right wing sections outboard of the flaps, were absent. The fuselage was extensively fire damaged consequently Supplement "D" was not completed (refer to photo- graphs 1 through 4). The nose baggage door was observed detached from the fuselage and lying on the ground approximately 15 feet west of its baggage compartment and was observed to be free of any sooting or fire damage. Both engines were found within their respective nacelles with their respective propeller assemblies and spinners attached. All three blades of the right propeller remained attached to the spinner and were in a near feathered position (refer to photograph 5). One of the three blades of the left propeller was separated and observed lying next to the fuselage. The two remaining blades were in a near feathered position (refer to photographs 6/7). Several ground slash marks consistent with a propeller blade strike were observed in the soil 11 feet southwest of the right propeller spinner (refer to page 3, Supplement I).

Twenty-four additional pieces of wreckage from the aircraft were locate