Aviation Accident Summaries

Aviation Accident Summary SEA07FA134

Wilbur, WA, USA

Aircraft #1

N9434N

Cessna 185

Analysis

Based on all the available evidence, it is believed that shortly after taking off from his private grass airstrip, the pilot encountered an undetermined problem that caused him to attempt a precautionary or forced landing in the only nearby level flat open area available. During that attempt, with the airplane in the landing configuration, and at a very low airspeed, the airplane's left wing came in contact with the level terrain. When the wing contacted the terrain, the airplane cart wheeled nose-first into the ground, and came to a stop about 12 feet beyond where the nose impacted the field. The investigation did not reveal any anomalies in the airplane's airframe, engine, or flight controls that would explain the necessity for the forced landing or would have contributed to the wing tip coming in contact with the terrain. It could not be determined if the pilot lost control of the airplane during the last part of the landing sequence, or whether he inadvertently allowed the wing tip to touch the ground during a low level turn to align the airplane's heading parallel to an upcoming ditch just prior to touchdown.

Factual Information

HHISTORY OF FLIGHT On May 28, 2007, approximately 1515 Pacific daylight time, a Cessna 185, N9434N collided with the terrain about four miles north of Wilbur, Washington. The airline transport pilot, who was the sole occupant, was killed, and the airplane, which was owned and operated by the pilot, sustained substantial damage. The local 14 CFR Part 91 personal pleasure flight, which was being conducted in visual meteorological conditions, is believed to have departed the pilot's private airstrip less than one minute prior to the accident. No flight plan had been filed. The ELT was activated by the impact sequence, and the transmissions of the ELT were what lead to the discovery of the wreckage about four hours after the accident. According to family members, the pilot and his wife returned from a two-day camping/vacation trip on the morning of the accident. Then, according his wife, some time after 1430, the pilot said that he was going to go fly around the local area for a while. Although no one reported seeing the actual takeoff from the private airstrip, the pilot's wife said that she thought it was a little after 1510 when she heard the sound of the aircraft's engine at the west end of the strip (near the house). There were no reports of anyone seeing the aircraft after takeoff, and no reports of anyone hearing or seeing the accident sequence. Some time around 1700, Emergency Locator Transmitter (ELT) signals were detected by a satellite, and a search for an active ELT in the general area was initiated. Around 1930, the wreckage was spotted from the air by the pilot of a helicopter that was participating in the search for the source of the ELT signals. The wreckage was located in a level open field of wheat, about 700 yards north of the east end of the pilot's airstrip. The area of impact was the only flat level area within about one-half mile of the east end of the airstrip. Although the time of impact could not be positively determined, the accident is assumed to have happened almost immediately after takeoff. This assumption is based upon the fact that no one saw the aircraft flying around the area that afternoon, the wife did not hear the aircraft return to the area, and because the data retrieved from the onboard Global Positioning System (GPS), which recorded the date, initiation time, and duration of the pilot's last known seven flights, did not record a flight on the day of the accident. PERSONNEL INFORMATION The 44 year old pilot held an Airline Transport Pilot rating for Airplane Multiengine Land, with commercial privileges for Airplane Single Engine Land. He held a Type Rating for the Boeing 737. His last medical was a First Class, which was issued on December 7, 2006. His medical certificate listed the limitation of "The Holder Shall Wear Corrective Lenses. At the time of the accident he held the position of Captain (Boeing 737) for a major FAR Part 121 air carrier. METEOROLOGICAL INFORMATION The 1452 surface aviation weather observation (METAR) for Moses Lake, Washington, which is located about 50 miles south of the accident site, recorded winds from 170 degrees magnetic at seven knots, 10 statute miles visibility, few clouds at 9,500 feet, a temperature of 23 degrees Celsius, a dew point of zero degrees Celsius, and an altimeter setting of 30.04 inches of mercury. The 1456 METAR for Spokane International Airport, which is located about 55 miles east of the accident site, reported winds from 130 degrees at nine knots, 10 miles visibility, scattered clouds at 2,400 feet, broken clouds at 9,000 feet, a temperature of 12 degrees Celsius, a dew point of 06 degrees Celsius, and an altimeter setting of 30.11 inches of mercury. Individuals who were in the general area of the accident on the afternoon of May 28, reported that is was "breezy," but that it was consistent with how the winds had been in the days prior to the accident. WRECKAGE AND IMACT INFORMATION The initial point of ground contact was in a level area of immature wheat that averaged about 18 inches in height. The impact scar was about two feet long, six to eight inches wide, and about two inches deep at its center. The forward three-quarters of the left wing tip was located about two feet past the point of initial impact. From that point to the next major impact scar, which was located about 37 feet further down-track, the wheat had been crushed flat in a swath about six inches wide, but the soil was essentially undisturbed. The next impact scar was about five feet long and three feet wide, and was six to eight inches deep at its center. Near the center of this scar was a portion of a wing root fresh air ventilation vent, and two pieces of the airplane's windscreen, both of which measured less than six inches at their widest point. Adjacent to the dirt berm that had been thrown up on the down-track end of this scar were three larger pieces of the windscreen. Two of the pieces measured about eight inches at their widest point, and the third, which was from near the top edge of the windscreen, was a triangular shape, with each side being about 18 inches long. The remainder of the wreckage was located about 12 feet beyond this last impact scar, at 47 degrees, 49.65 minutes North, 118 degrees, 39.99 minutes West. The magnetic heading from the initial impact scar to the last impact scar was 030 degrees magnetic. The nose of the airplane itself was pointing back up the impact track on a heading of about 210 degrees. About 220 feet past the remainder of the wreckage, on the same heading as the impact track, there was a rough/uneven drainage channel/area that was about 20 feet wide and about one foot deep. About 115 feet past the drainage area was the first of four multi-wire high-tension power line tower rows (a total of 18 wires), which ran approximately perpendicular to the impact path. The lowest of the wires was estimated to be about 100 feet above ground level (agl). The aircraft was laying on its right side, with the left wing and left main landing gear sticking into the air. The outboard half of the left wing, from just outboard of the lift strut attach fitting, was bent upward about 90 degrees, and was partially torn from the inboard portion. The most outboard four feet of the wing had been crushed aft, creating a diagonal ridge/crease that ran from just aft of the rear spar at the wing tip, to a point about four feet inboard of the tip on the leading edge. The fuel filler neck cap was in place, and there was no sign of leakage or staining from fuel dripping or flowing over the skin near the cap. Both the forward and aft fuel tank outflow lines had been breeched, and the position of the wing was such that all the fuel in the left main tank, including that designated as unusable in flight, would have drained onto the ground through one of the two lines. The right wing was torn from the fuselage at the wing root, and was lying horizontally, with its top surface up, along side, and about 90 degrees to the fuselage. Except for leading edge diagonal crushing outboard of the lift strut attach point, the right wing had maintained its basic structural form. The diagonal crush line/crease ran from the leading edge just outboard of the lift strut attach fitting, to the tip of the wing just forward of the aft wing spar. The fuel filler neck cap was in place, and there was no sign of leakage or staining from fuel dripping or flowing over the skin near the cap. The forward fuel outflow line had separated from the right fuel tank, which was undamaged, and due to the right wing's position on the ground, all but the fuel designated as unusable in flight would have drained from the tank. Approximately one cup of blue colored fuel was recovered from the right wing, and no visual evidence of water or other contamination was noted. The fuselage maintained its basic structure aft of the front seats, with the left side being wrinkled and dented in several locations, and with the right side remaining essentially undamaged. The left empennage horizontal surfaces, left vertical stabilizer, and the rudder were undamaged. The right horizontal empennage surfaces were bent up and over nearly 180 degrees, at a point about one-half their span. The flap handle was engaged in the third notch of deployment (a normal landing position), and the flaps were in a position approximating the flap handle engagement. The elevator trim was slightly nose-down of the takeoff position. The cowl flaps were open. The auxiliary fuel pump was in the "OFF" position. The engine, firewall, and instrument panel had been pushed directly aft into the forward part of the pilot area. Both sides of the cowling showed substantial aft crushing and accordion folding. All four engine mount legs had fractured. The propeller remained attached to the crankshaft, and the propeller spinner was crushed directly aft to a point where it was tightly formed around the propeller structure behind it. The spinner displayed a substantial amount of rotational twisting and scarring. All three propeller blades remained attached to the hub. The outboard portion of all three blades displayed deep burnishing of the paint near the tip of their forward facing surface and along the outboard portion of their leading edge. One of the blades exhibited "S" bending and blade twisting, another was bent aft about 30 degrees about mid-span, and the third blade was twisted in the hub, and bent forward about 90 degrees about eight inches outboard of the propeller hub. After the on-site inspection was complete, the airplane was recovered to Discount Aircraft Salvage, in Deer Park, Washington, for further teardown and analysis. The engine, to which all accessories remained attached, was removed from the fuselage, and the crankshaft was rotated by a hand tool attached to the propeller flange. Mechanical continuity from the crankshaft to the valve/rocker area and to the engine accessories was established. Compression was established at all six cylinders by rotating the crankshaft and holding a thumb over the hole from which a spark plug had been removed. The induction manifolds and the exhaust headers were correctly and securely attached. The top spark plugs were removed and inspected. They exhibited normal wear and deposit accumulation, with no evidence of in-flight malfunction. The magnetos were removed from the engine and impulse-coupling engagement was confirmed on both magnetos through hand rotation. Spark was obtained at all six lead terminals when the left magneto was rotated by hand. None of the lead terminals on the right magneto produced spark during the initial hand rotation test. The ignition harness cap, along with its attached leads, was then removed from the magneto, and when the magneto was rotated by hand, spark was obtained at all six body-to-lead distribution points. The ignition harness cap was then reinstalled, and rotation produced spark at all six lead terminal ends. The magneto was subsequently shipped to Teledyne Continental Motors (TCM), where the Federal Aviation Administration (FAA) monitored/observed further inspection/testing of the unit. No further anomaly or malfunction was noted. The engine-driven (mechanical) fuel pump and the fuel manifold valve were removed from the engine. The fuel pump drive coupling was intact, and the drive shaft rotated freely. The manifold valve showed no indication of leakage or plugged lines, and the injector nozzles were free of debris. The fuel pump and manifold valve, along with the fuel control throttle body, the fuel distribution lines, and the injectors nozzles were sent to TCM for further FAA directed/observed testing and inspection. No anomaly or malfunction was noted in any of these fuel system components. The engine-driven oil pump was removed, disassembled, and inspected. The oil pump gears, which were oil-coated, rotated freely, and there was no evidence of internal damage or contamination. The external oil filter was removed and cut open, and the filter element material was spread flat in order to check for contamination of debris. None was found. The components internal to the cylinders were inspected with a lighted bore scope. The faces of all intake and exhaust valves exhibited normal operational signatures, with no indication of burning or cracking. All piston domes showed normal operational signatures, with no indication of abnormal deposits or detonation. All intake and exhaust rocker assemblies and valve springs were oil coated, and operated normally when the crankshaft was rotated. Inspection of the airframe revealed that the seats, seat bases, and the occupant restraint system components remained intact, and were still attached to their respective connecting points. The seat positioning pins for both front seats remained in the position holes on their respective rails, and the secondary seat stop attached to the inboard rail of the front left seat was still in place. Control continuity was established by tracing the cables past the cable overload failures and the cable cuts made by recovery personnel. One anomaly was found while tracing the cables of the right wing aileron control system. The anomaly consisted of a chafed, frayed, and partially separated aileron interconnect cable at a point just inboard of the flap pushrod. Three of the cable's seven primary strands had been worn through where they passed through a wing rib by way of an aftermarket non-Cessna cable guide made of Phenolic sheet. As part of the continuity check, the right aileron was deflected to its full up and full down position by hand-manipulation of the control cables just inboard of the aforementioned cable anomaly. That test, which did not have the mechanical advantage provided by the arm of the control yoke, determined that any resistance was unnoticeable by feel, and that no control interference would have been presented by the anomaly. Both fuel bladders were intact, their outlet finger screens did not contain any debris, and their filler cap gaskets were still pliable. The bottom surface of the left fuel bladder contained a number of wrinkles approximately one-quarter inch in height, and there was a thin line of discoloration along the outboard edge of most of the surface of the wrinkles. The fuel selector valve was in the "BOTH" position. The fuel quantity sending units were removed from the tanks, and tested for variable resistance with an ohmmeter. The right unit functioned normally, and was used along with the aircraft battery to check the operation of the cockpit fuel gauges. The left unit indicated an open circuit when tested with the ohmmeter. After disassembly, it was determined that the wiper arm was resting on the back (wrong) side of the Phenolic sheet that the resistive coil was wound around. Scratch marks on the sheet and the windings indicated that the wiper arm had moved past the limits of the windings, and then off the end of the sheet, ending up on the backside of the winding sheet. The fuel lines were visually checked for blockage, and those that could not be inspected visually had compressed air blown through them. There was no indication of blockage or debris in any of the lines. The fuel strainer screen and bowl where also clear of contamination. The auxiliary fuel pump (electrical) and the engine-driven fuel pump (mechanical) were tested for function and freedom of flow. The auxiliary pump was spun via connection to the aircraft battery, and the engine-driven pump was rotated by hand. Both pumps produced suction at one orifice, and expelled air or residual fuel at the other orifice. MEDICAL AND PATHOLOGICAL INFORMATION According to the autopsy provided by the Spokane County Medical Examiner, the manner of death was determined to be accidental due to an aircraft crash, and the cause of death was determined to blunt force impact to the head, chest, and abdomen. In addition, the FAA's Forensic Toxicology Laboratory at the Civil Aeromedical Institute performed a forensic toxicology examination on specimens taken from the pilot. That examination proved negative for cyanide, ethanol, carbon monoxide, and all drugs for which the examination screened. ADDITIONAL DATA AND INFORMATION A review of t

Probable Cause and Findings

In-flight collision with terrain shortly after takeoff for undetermined reasons.

 

Source: NTSB Aviation Accident Database

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