KELLOGG, ID, USA
N7659C
PIPER PA-32-260
WHILE EN ROUTE ON A VFR FLIGHT PLAN, THE PILOT CONTACTED SEATTLE ARTCC & OBTAINED AN IFR CLEARANCE. SUBSEQUENTLY, HE REQUESTED & WAS CLEARED TO CLIMB TO 15,000' MSL. DURING THE CLIMB, ARTCC TEMPORARILY LOST RADAR CONTACT WITH THE PLANE & ASKED THE PILOT TO REPORT AT 15,000', WHICH HE DID AT 1329 PDT. ABOUT 1 MINUTE LATER, THE PILOT SAID HE LOST 'GYRO SUCTION' & WOULD BE USING 'PARTIAL PANEL.' ALSO, HE REPORTED THERE WAS STILL SOME IMC CONDITIONS, THAT HE WAS IN & OUT OF CLOUDS & THAT HE HAD ENCOUNTERED SOME LIGHT RIME ICING CONDITIONS. SOON THEREAFTER, ARTCC LOST RADIO & RADAR CONTACT WITH THE AIRPLANE. A WITNESS HEARD THE SOUND OF THE ENGINE REVVING JUST BEFORE THE PLANE CRASHED. AN EXAM OF THE WRECKAGE REVEALED THE WINGS & EMPENNAGE HAD SEPARATED IN FLIGHT. THERE WAS EVIDENCE THE WINGS HAD FAILED DOWNWARD. THE FUSELAGE SKIN FORWARD OF THE EMPENNAGE WAS RIPPED & TORN WITH NUMEROUS RIVETS TORN THROUGH THE SEAMS. A CHECK OF THE VACUUM PUMP REVEALED EVIDENCE OF SEIZURE AFTER LONG-TERM ENGINE OIL CONTAMINATION & WEAR.
HISTORY OF FLIGHT On April 24, 1994, approximately 1335 Pacific daylight time (PDT), a Piper PA-32-260, N7659C, impacted the terrain after experiencing an inflight breakup about seven miles northwest of Kellogg, Idaho. The private pilot, who was the sole occupant of the aircraft, received fatal injuries, and the airplane was destroyed. The FAR Part 91 business flight, which departed Kelwona Airport, Kelwona, British Columbia, about an hour and forty-five minutes earlier, was in instrument meteorological conditions at the time of the accident. The pilot, who had filed a VFR flight plan from Kelwona to Missoula, Montana, picked up an IFR clearance while about 75 miles northwest of Spokane, Washington. There was no report of an ELT activation, and no evidence of any inflight or post-impact fire. The first reported contact between the pilot of N7659C and Seattle Center took place at 1226 PDT, about one hour before the accident. At that time, the pilot contacted the center, advised the controller that he was on a VFR flight plan "...out of Kelwona, British Columbia...", and requested "...an IFR clearance into Spokane...", and additional routing along Victor two into Missoula, Montana. Center then cleared the flight to Missoula "...via direct Spokane, Victor Two...", and cleared the pilot to climb to and maintain 13,000 feet, as per his request. At 1232, center updated the routing by directing the pilot to turn left to 100 degrees, and proceed direct to the Mullan Pass VOR, with the rest of the route unchanged. At 1317 the pilot requested and received a clearance to climb to 15,000 feet. At 1325 Center advised the pilot that they had lost his transponder, and asked what altitude he was at. He reported that he was passing through 14,000 feet, and recycled his transponder as requested by Center. After the recycle, Center reported that they still were not picking up the transponder, and asked the pilot to report level at 15,000 feet, which he did at 1329. About one minute after reporting level at 15,000, the pilot advised Center that he had lost his "gyro suction", and that he was "...going to be partial panel..." About two minutes later, Center asked the pilot to "ident", and then advised him that they were now receiving his transponder. About thirty seconds later, Center asked the pilot what his flight conditions were at 15,000 feet, and he responded that he was on top of most of it, but that there were still some IMC conditions that he was going through, and that "...we're in and out of clouds..." He also advised Center that he "...picked up some light rime icing climbing to one five thousand...", but that he seemed "...to be out of it now..." Center responded by advising the pilot that "...light rime icing is reported along your route of flight whenever you're in the clouds." The pilot acknowledged that transmission, and neither center nor the pilot made any more transmissions for about three minutes. At 1337:35, Center attempted to advise the pilot that they had again lost his transponder, but he did not respond to this or any further transmissions. An individual who lived about three miles southeast of the accident site reported that, approximately the same time as the aircraft was lost from radar, he had heard a "normal sounding" aircraft engine overhead. He said that it sounded as if the aircraft was getting lower, and then he heard the engine "rev up", followed closely thereafter by the sound of the impact. After hearing the impact, he immediately called the Sheriff's office. METEOROLOGICAL INFORMATION The 1346 PDT observation taken at Mullan Pass, which is located about 25 miles east of the accident site, showed an estimated ceiling of 6,000 broken, 7,500 overcast, visibility seven miles, light drizzle, wind calm, and an altimeter setting of 29.95 inches. The 1355 PDT Automated Weather Observation System (AWOS) surface weather observation for Coeur D' Alene, Idaho, which is located about 28 miles west of the accident site, showed a measured 4,200 overcast, 10 miles visibility, temperature 52, dewpoint 45, winds 010 degrees at 10 knots, and an altimeter setting of 29.52 inches. At 1315, an aircraft climbing from 10,000 feet to 13,000 feet, about 20 miles south of Coeur D' Alene, reported light rime icing in the climb. At 1318, an aircraft over Mullan Pass VOR, at about 13,000 feet, reported trace to light rime ice. WRECKAGE AND IMPACT INFORMATION The aircraft fuselage impacted the terrain about the 3,200 foot level of a clear-cut area on the Barrymore Creek drainage. It was found laying inverted on a heading of 235 degrees magnetic, and was missing both wings and the entire empennage. The fuselage skin just forward of the empennage was ripped and torn and numerous rivets along the seams had torn through the skin. From the cabin aft, the fuselage had been forced downward by the impact so that there was between six inches and a foot separation between the floor and the roof. Both the flap actuator torque tube, and the lower portion of the wing spar carry-through, were found bent in a continuous arc, with their outboard ends in the downward direction. The engine compartment was essentially intact, and the nose gear strut was still attached to the firewall. Both propeller blades where still attached to the hub, and both displayed a small amount of chordwise scarring near their tips. These scars ran from the leading edge to about one inch into the chord of the blade. One blade, which was found embedded almost straight into the ground, showed a small amount of spanwise scarring. The other blade, which had not penetrated the terrain, had soot smeared spanwise along its inboard half where it had contacted a burned tree trunk which was laying on the ground at the point of impact. One side of the spinner was crushed toward the hub, but the other side and the nose of the spinner was not damaged. Both blades had torn about one-half inch into the spinner, in the direction against rotation, around the edge of the cutout where they exit the spinner sides. There was also a single two inch scratch, running opposite the direction of rotation, where the spinner had been forced against the starter engagement gear housing. Both of the aircraft's wings were found about one-half mile up a 12 degree slope from the fuselage on a heading of 035 degrees. They were about 100 feet apart, just beyond the edge of the clear-cut, within a dense coniferous forest made up of trees about 100 feet in height. Both wings had retained their main landing gear strut, flap and aileron. There was very little impact scarring, and no evidence of damage to any of the trees was found. Both wings were missing their wing-tip fuel tanks, and both had the outboard two-thirds of their upper surface bent downward both forward and aft of the main spar. The main spar carry-through was still connected to the left wing, and was found to be bent downward near its outboard ends. Control continuity was unable to be positively established because of the separation of the wings and the impact damage to the fuselage. The Shoshone County Sheriff's office and the Civil Air Patrol conducted a search for the empennage, but it was unable to be located. TESTS AND RESEARCH The vacuum pump, attitude indicator, heading indicator, and turn and slip indicator were removed from the aircraft for further inspection. The vacuum system filter was inspected at the scene, and found to be clean and free from blockage. The gyroscopes in the attitude indicator, heading indicator, and turn and slip indicator were removed from their gimbals, and the gyroscopic wheels were removed from their housings. The housings were inspected under 10 power magnification, and then cut in half in order to facilitate further examination of their interior walls. The interior walls of the housings and the exterior surface of the rotating wheels on all three gyroscopes were inspected for signs of rotational contact. The heading indicator gyro housing showed no rotational scarring or evidence of gyro wheel contact. The heading indicator gyro wheel had no surface scarring, and the area of black paint, which ran about half way around its circumference, showed no smearing or rubbing. The attitude gyro housing showed three scars on its interior wall, all of which were about 13 millimeters from the bottom of the housing. The first two were about 60 degrees apart, and the third was about 180 degrees from a point midway between the first two. The first scar, which was located about 20 degrees forward of the two air intake holes, was approximately one-half millimeter wide and six millimeters long. Its longitudinal axis ran parallel to the circumference of the housing wall, but the fine scratch lines which made up the scar ran 45 degrees to the plane of the gyro wheel's rotation. The second scar, which was about 40 degrees behind the air intake holes, was about one millimeter wide and five millimeters long. Its longitudinal axis was also parallel to the circumference of the housing wall, but the series of gouges and scratches which made up the scar were 45 degrees to the direction of gyro wheel rotation, and 90 degrees to the scratches which constituted the first scar. The third scar, which was made up of two sub-scars, also had its longitudinal axis parallel to the circumference of the housing. The bottom half of this scar was about one centimeter wide and five centimeters long, while the top half was less than one-half centimeter wide and about 10 centimeters long. The scratches and gouges that made up the lower portion of the scar were approximately 80 to 85 degrees from the plane of gyro rotation, and the scratches that made up the top half were about 50 degrees from the rotational plane (see attachment #1). The gyro wheel from the attitude indicator had thin stain lines around its circumference, near the top and bottom of the wheel, but there were no circumferential scratches, gouges, or paint rub lines anywhere on its surface. The interior surface of the electrically driven turn and slip indicator housing was inspected, and four clear circumferential scars were identified. One scar, which ran through approximately 180 degrees of the circumference, was located about two centimeters from the bottom of the housing. This scar, which varied from about one to two millimeters wide, was made up entirely of fine scratches which ran parallel to the plane of rotation of the gyro wheel. The second scar, which began about 20 degrees clockwise to the one gimbal attach point that had fractured, was about two millimeters wide and 11 millimeters long. It also was composed entirely of scratches and gouges that ran parallel to the plane of gyro wheel rotation. The third scar, which began about six millimeters counterclockwise from the intact gimbal attach point, was about six millimeters long and two to three millimeters wide. This was the deepest of the four scars, and was clearly defined by gouges in the plane of gyro rotation. The fourth scar was located 90 degrees to the gimbal attach points, and measured one by three millimeters. This scar was defined by scratch lines running parallel to the lines in the other three scars. The steel gyro wheel from the turn and slip indicator was examined, and three areas of clear circumferential scarring were found. The first area was along the bottom millimeter of the wheel, where a series of fine scratches ran around approximately 180 degrees of the wheel. The second area was the top one-quarter of the wheel, a surface machined at 45 degrees to the rest of the wheel exterior. Half of this surface had been painted with black paint, and almost the entire area covered by the paint was either scratched, rubbed or smeared by rotational contact. The non-painted half showed a considerable amount of rotational smearing of the paint that had been rubbed from the painted half. In addition, there was a series of scratches located about half way up the side wall of the wheel. These scratches ran about 90 degrees around the gyro in its plane of rotation. The Airborne dry vacuum pump was disassembled by the IIC, and along with a substantial amount of wear of the internal housing wall, a considerable build-up of carbon powder mixed with an oily residue was noted. After the initial inspection by the IIC, the vacuum pump was sent to the FAA Flight Standards District Office in Cleveland, Ohio. After being received by that office, an FAA Airworthiness Inspector took the pump to Parker Hannifin Corporation, Airborne Division, where he supervised an inspection teardown of the unit. The conclusions from that inspection stated that, "Heavy oil leakage from the engine seal allowed oil to enter the pump through the pump's drive, thus contaminating the unit." The report also stated that, "The wear signatures on the attached portion of the drive coupling center indicates the pump seized prior to the pump breaking away from the engine." The report further indicated that, "The buildup of material in the pump's porting indicates that the oil contamination took place over a long period of time..." After the inspection at Parker Hannifin was completed, the pump was forwarded to the laboratories of Artech Corporation, Chantilly, Virginia. At that location, the oily residue in the pump was analyzed by means of a Fourier Transform Infrared Spectrophotometer (FTIR) and a Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM/EDS). The results of this testing showed residues typical for hydrocarbon engine oils. Their report stated that the elements in these residues "...are commonly found in engine oil residues as either wear metals or oil additives and modifiers. ADDITIONAL INFORMATION An autopsy was performed by Pathology Associates Inc., of Spokane, Washington, and the cause of death was determined to be blunt impact damage to the head, chest, abdomen, and extremities. A toxicological examination was performed by the Armed Forces Institute of Pathology, and no ethanol, cyanide, elevated carboxyhemoglobin, or screened drugs were found. The aircraft was released to Midwest Aviation Adjustment Company, a representative of the owner, at Kellogg, Idaho, on May 6, 1994.
FAILURE OF THE PILOT TO MAINTAIN AIRCRAFT CONTROL, DUE TO SPATIAL DISORIENTATION, WHILE FLYING WITH PARTIAL PANEL, AND THE DESIGN STRESS LIMITS OF THE AIRCRAFT BEING EXCEEDED. FACTORS RELATED TO THE ACCIDENT WERE: FAILURE OF THE VACUUM SYSTEM, WHICH RESULTED IN AN INOPERATIVE ATTITUDE INDICATOR, AND THE ADVERSE WEATHER CONDITIONS.
Source: NTSB Aviation Accident Database
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