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On August 12, 2001, at 0003 Pacific daylight time, a Piper PA-28-180, N8098W, collided with power lines and poles 1 mile east of the runway 27 approach end at the Boulder City, Nevada, airport. The airplane was owned and operated by the pilot under 14 CFR Part 91 of the Federal Aviation Regulations. The airplane was destroyed in the collision sequence and postcrash fire. The instrument rated private pilot and one passenger sustained fatal injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight that is believed to have originated at an undetermined time from the Bullhead City, Arizona, airport.
An individual who identified herself as the girlfriend of the passenger was contacted and interviewed by telephone. She reported that both her and the passenger were friends with the pilot. The pilot had invited them to go on flights previously, however, their schedules and his had never allowed them to accept his invitation. She stated that she was back east on a business trip when the accident happened; however, had come to find out from other friends that the pilot and passenger had dinner together at a local Boulder City restaurant the night of the accident. The friends reported that the two had consumed alcoholic beverages during dinner. Following dinner, the pair walked to a nearby park to join an outdoor party, where they were observed to consume other alcoholic beverages. She said she knows that the two returned to her apartment sometime after that because the passenger had left some personal possessions there that he normally carries with him at all times. She believes the two decided to go flying after that and that the flight departed from the Boulder City airport, where the airplane is based, and was local in nature, though she could not rule out a flight to Bullhead City.
An airborne witness was piloting an emergency medical services helicopter (based at the Boulder City Airport), which was returning from a mission and inbound to the airport from the south. He observed the position lights of the accident airplane approach the airport from the west through "Railroad Pass," which crosses the mountains between the valley where Boulder City is located and the greater Las Vegas metropolitan area. The position lights were roughly at the same elevation as his helicopter, 4,000 feet msl. He attempted to contact the airplane on the Common Traffic Advisory Frequency, but got no response. As he continued inbound to the airport, he monitored the position of the airplane and saw it on a wide arcing flight path to the south of the airport. As he was beginning a final descent to land at their parking spot, the airplane's pilot came on the CTAF and announced that he was going to make a "teardrop approach" to runway 27 left. The witness said the pilot's voice had an unusual quality. When asked for details, the witness reported that he could not say the pilot was ill or disoriented, but the voice sounded very strange. The witness said the pilot's comment about a teardrop approach confused him momentarily because he knew that there was no such instrument approach to the airport. He then observed the airplane continue the wide arcing and descending left-hand flight path to runway 27. The witness had landed and was shutting the helicopter down when he looked up and observed the navigation lights of the airplane on final approach. He thought to himself that the airplane was very low, then he saw the bright flash of arcing electricity as the airplane contacted the power lines.
The witness stated that the airplane's position lights were visible from the first time he noticed the airplane until the flash associated with the crash. He did not see a landing light, rotating beacon or strobe lights from the airplane at any time.
The power lines contacted by the airplane are the most eastern of four sets of high tension power lines running perpendicular to the approach end of the runway. The lines contacted by the airplane were reported by the power company to be 66 feet above ground level.
Safety Board investigators arrived at the accident site 2 hours after the accident. The sky was clear and the winds calm. The most western set of the three power line sets were marked by red obstruction lights, which were functioning at the time they were observed by the investigators.
According to the Federal Aviation Administration (FAA) Airman and Medical records files, the pilot held a private pilot certificate with airplane ratings for single engine land and instruments. The most recent issuance of the certificate was the addition of the instrument rating, which occurred on July 17, 2001. The pilot held a third-class medical certificate, which was issued without limitations on December 14, 2000.
The pilot's personal flight records were not located and information contained in the FAA records disclosed that the pilot had self reported a total flight time of 400 hours, which was accrued over a 4-year period.
No airplane or engine maintenance records were located. A review was conducted of the material maintained by the FAA in the Aircraft and Registry files for this airplane. The Piper PA-28-180 airplane, serial number 28-2193, was manufactured in February 1965, and purchased by the pilot on December 20, 1999. According to the original application for a normal category airworthiness certificate completed by the Piper factory, a Lycoming O-360-A3A engine, serial number L-7723-36A, was installed at the time of manufacture (the data plate on the engine in the wreckage listed the same serial number).
While no formal maintenance logbooks as such were located, two hand written sheets of paper were found in the wreckage that contained notations of maintenance activities, the dates these were performed, and the tach times. No signatures or return to service endorsements were contained on any entry. The first entry was dated December 18, 1999, and noted a tach time of 3576.00. An entry dated December 3, 2000, noted the completion of an annual inspection at a tach time of 3717.96. The last entry was dated July 15, 2001, at a tach time of 3780 and noted the addition of 1 quart of oil. A notation in the margin of the first page states "IFR cert due 8/21/01."
The closest official weather observation station is the McCarren International Airport, which is 19 miles northwest of the accident site. The airport's 2350 weather observation noted in part, a visibility of 10 miles with few clouds at 25,000 feet and variable winds at less than 4 knots.
The airborne witness who was landing at the Boulder City Airport at the time of the accident reported in an interview that the sky was clear with unrestricted visibilities and calm winds. No unusual meteorological phenomenon was observed.
A Safety Board investigator arrived at the accident site about 2 hours after the accident. The atmospheric conditions were observed to be clear with unrestricted visibilities and calm winds.
A Safety Board computer program was used to determine the position and illumination of the moon. At the time of the accident, the moon was 3.8 degrees above the eastern horizon on a magnetic bearing of 062.5 degrees. The program listed the disk illumination as 50 percent. A north-south oriented range of mountains were noted to the east of the accident site on the general 060 bearing line, with elevations that reach 5,400 feet msl.
The airport is located on the south side of the city. When Safety Board investigators arrived at the site at about 0230, it was noted that there were no ground reference lights over an arc from the southwest through south to the east northeast of the accident site. The only ground lights were noted to the west (airport) and north (city).
AERODROME AND GROUND FACILITIES
The Boulder City airport is an uncontrolled civil facility at an elevation of 2,201 feet msl. While the airport has three asphalt-surfaced runways (15-33, 09L-27R, and 09R-27L) only 09R-27L is lighted. The 4,800-foot-long by 75-foot-wide runway 27L is equipped with Medium Intensity Runway Lights (MIRL), Runway End Identifier Lights (REIL), and a Precision Approach Path Indicator (PAPI), which is aligned for a 3-degree glide slope. The traffic pattern for this runway is left traffic, with a standard pattern altitude of 800 feet agl. The MIRL, REIL and PAPI light systems are available after normal hours and can be turned on by pilots through microphone keying on the CTAF. In his interview with Safety Board investigators, the EMS pilot witness stated that he activated the lights using the CTAF while inbound to the airport and he observed that all the light systems were functioning. According to the witness, these runway lights were on at the time of the accident.
WRECKAGE AND IMAPCT
The accident site is in level desert terrain about 1 mile east of the Boulder City Airport, and at approximately the same elevation. The fuselage wreckage mass was upright and found oriented on a 115-degree magnetic bearing. A path of wreckage debris, ground scars and flash-burn sooting was noted extending on a 090-degree magnetic bearing 440 feet and culminated at the base of a concrete and steel power pole. The pole exhibited impact marks near the top and the two uppermost conductor lines were damaged and disconnected from the insulator hangers on the pole.
Nevada Power employees were present at the pole and preparing to begin repairs to the power lines when Safety Board investigators arrived. They reported that the system monitoring equipment recorded a ground fault on the line at 0003 hours. The pole was identified as number X-4329, which is part of the Las Vegas No. 3 line and supplies power to Boulder City. With reference to system drawings, the power company personnel reported that the height of the pole was 66 feet above ground level. Seven wires are attached to the pole. A stranded steel static line is attached to the very top, and, three pairs of phase lines are strung on insulated hangars (one line of each pair on each side of the pole) and separated by a vertical distance of 4 feet (at the pole connection) from either the top static line or the next phase line pair. The damaged phase lines are 4 feet below the static line. The phase lines carry 69,000 volts when charged and are constructed of stranded aluminum wrappings around a stranded steel core.
At the request of Safety Board investigators, the power company employees surveyed the top of the pole. They reported that on the east side of the pole about 3 feet below the static line, a damage area was found. The damage consisted of sooting and electrical arcing pits. Some abrasion was noted to the static line's under surface about 5 feet north of the pole.
A helicopter from the Air Unit of the Las Vegas Metropolitan Police responded to the accident. At the request of investigators, they hovered directly over the pole. According to the onboard GPS unit readings, the pole was 1.1 nautical miles from the end of runway 27L. The pilot reported that the pole was on the extended runway centerline for 27L. As the investigation progressed during the morning hours, three airplanes landed on runway 27L and each passed directly overhead of the accident site while on final approach.
The outboard half of the left wing (separation from the inboard section occurred at the flap/aileron juncture just outboard of the fuel tank) was found 45 feet southwest of the damaged power pole. A semicircular impression with an 11-inch radius was noted in the wing leading edge at the separation point (the power company noted the pole diameter just below the static line is 22 inches). The impression in the wing leading edge exhibited electrical arc pitting and sooting, with a faint color transfer similar to the power pole. The axis of the impression in the leading edge was observed to be perpendicular to the wing in both a lateral and chordwise direction.
The top 10 inches of the vertical stabilizer was found 132 feet from the pole on the 270-degree wreckage distribution bearing. A strand-like abrasion pattern was noted in the leading edge at the separation line; the strand-like pattern in the paint and underlying metal was consistent with the static line both in dimension and pattern.
A path of ground scars, wreckage debris, and flash burn sooting was noted beginning at a point 321 feet from the damaged power pole along the 270-degree bearing and continued to the resting point of the fuselage. The debris in this area consisted of the tail cone, a portion of the engine cowling, and fiberglass and Plexiglas fragments.
The airplane was upright with the nose oriented on a 115-degree magnetic bearing. The entire cabin from the firewall aft to the aft baggage compartment door frame was thermally destroyed. All flight and engine instruments, along with the cockpit system switches, were thermally destroyed. Disassembly of the thermally damaged fuel selector valve revealed an internal valve body position consistent with selection of the RIGHT TANK. A surviving remnant of center front windshield post was noted to have a pattern of stranded abrasion markings consistent with the steel static line.
The right wing remained with the fuselage in the normal orientation. The inboard half was burned at the root bulkhead while the outboard portion was extensively crushed, distorted, and fragmented. No fuel was found in the right tank; however, the lower inboard aft corner was compromised. The sandy soil beneath the tank was moist to a depth of 3 inches and smelled of gasoline.
The inboard half of the left wing remained with the fuselage; however, the forward attach points were failed and the wing was displaced aft about 30 degrees from it's normal orientation. The left fuel tank was bulged, distorted and burned, with heat signatures both inboard and outboard of the fuel cell location.
Flight control continuity was established from the wing roots to the respective left and right wing aileron bell cranks. The aileron on the right wing remained attached to it's hinges. The left aileron was found with the separated left outer wing section.
The empennage control surfaces remained attached to the fuselage. Control cable continuity was established from these control surface bell cranks to the cabin center section. The horizontal stabilizer trim mechanism was found in a near neutral position.
Control continuity from the cabin center section to the cockpit flight controls could not be established due to thermal fusion of the cables into resolidified puddles of once molten aluminum and thermal destruction of the cockpit components.
The flap actuator mechanism and bell cranks were found set to a 25-degree extension.
The landing light filament was broken at the posts. The filament itself was intact and there was no evidence of stretch.
TESTS AND RESEARCH
An examination of the engine was conducted on August 13, 2001, at the facilities of Air Excel, Inc., Boulder City Airport, Boulder City, following recovery from the accident site.
The engine remained attached to the airframe by the engine mount. The engine sustained impact and fire damage. The impact energy damage signatures were observed at the forward bottom section of the engine, encompassing the exhaust system and carburetor. The fire damage was most prominent at the rear of the engine, encompassing the rear-mounted accessories, fluid lines/hoses and the electrical harness. The propeller remained attached at the crankshaft flange. Visual examination of the engine revealed no evidence of pre-mishap catastrophic mechanical malfunction or fire.
The top spark plugs were removed, examined and photographed. The vacuum pump, magnetos, and fuel pump was removed, and the crankshaft was rotated by hand utilizing the propeller. The crankshaft was free and easy to rotate in both directions. "Thumb" compression was observed in proper order on all four cylinders; however, the number one cylinder compression appeared weaker when compared to the others. A hissing sound could be heard emanating from the exhaust port of the subject cylinder. A lighted borescope examination of the cylinder revealed that carbon debris had become affixed to the valve seat, preventing proper mechanical seating of the valve. The complete valve train was observed to operate in proper order, with equal lift action at each rocker assembly. Clean, uncontaminated oil was observed at all four rocker box areas. Mechanical continuity was established throughout the rotating group, valve train and accessory section during hand rotation of the crankshaft.
The bottom spark plugs were removed, examined, and photographed. The cylinder(s) combustion chamber was examined through the spark plug holes utilizing a lighted borescope. The combustion chambers remained mechanically undamaged, and there was no evidence of foreign object ingestion or detonation. The valves were intact and undamaged. There was no evidence of valve to piston face contact observed. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration consistent with normal operation. There was no oil residue observed in the exhaust system gas path. There was significant ductile bending of the exhaust system components. The exhaust system appeared free of obstructions.
The magnetos were thermally damaged and remained secure at their respective mounting pads. Due to the extent of the thermal and impact damage, the magnetos could not be functionally tested. Magneto to engine timing could not be ascertained. The magnetos were disassembled and examined. There was no evidence of internal mechanical malfunction observed.
The carburetor was detached from the engine and the portion that remained attached at the mounting pad was secure. The fracture surface signatures were consistent with overload. The throttle/mixture controls were found securely attached and continuity to the cockpit was established. All engine compartment fuel lines appeared to be in place and secure. The thermally damaged carburetor was disassembled and examined. The composite floats sustained heat deformation and cracking. The fuel inlet filter screen was intact and remained free of visible contaminates. No evidence of induction system or airflow obstruction was observed. Investigators noted that the throttle control at the instrument panel was captured near the idle position. The exposed portion of the control rod measured approximately 3 inches. The mixture and carburetor heat controls were found in the full rich and cold positions, respectively.
The fuel pump was securely attached at the mounting flange and had sustained fire damage at the area of the pump casting that would contain fuel. The fuel pump actuator arm plunger rod was observed to move normally during the hand rotation of the propeller.
The Champion REM-38E SI 1042 spark plugs were secure at each position with their respective spark plug lead attached. The spark plugs electrodes were undamaged, and according to the Champion Spark Plugs Check-A-Plug chart AV-27, displayed coloration consistent with normal operation. The oil soaking of the No. 1 bottom and No. 2 top and bottom spark plugs was noted to be consistent with the engine at rest position at the accident site.
The ignition harness was attached at the respective magneto(s) and each spark plug. The ignition harness had been subjected to post mishap ground fire and had sustained thermal damage.
The alternator was securely attached at the mounting pad, with the electrical connections secure at each post.
The rear-mounted vacuum pump was secure at the mounting pad. The pump was removed, and disassembled for examination. The drive was intact. The rotor/vane assembly was intact and undamaged.
The oil suction screen was found secure and uncontaminated. The oil filter was destroyed by fire. There was no evidence of any pre-accident lubrication system contamination.
There was no evidence of pre-mishap mechanical malfunctions observed during the examination of the engine and airframe.
The two bladed fixed pitch propeller remained attached at the crankshaft flange. The spinner was attached to the propeller. The propeller blades remained attached to the propeller hub. The propeller blades displayed leading edge damage geometrically and dimensionally consistent with the damaged high tension power line that was damaged and separated. Moderate torsional twisting and trailing edge "S" bending were observed at one of the blades. The opposing blade was bent aft about 40 degrees at about the midspan of the blade.
MEDICAL AND PATHOLOGICAL INFORMATION
The pilot and passenger sustained fatal injuries in the accident and autopsies were conducted by the Clark County, Nevada, Coroners Office, with specimens retained for toxicological examination. The toxicological tests were performed by the FAA Civil Aeromedical Institute. No carbon monoxide was detected in samples from either the pilot or passenger.
According to the toxicological report, ethanol, acetaldehyde and tetrahydrocannabinol carboxylic acid were detected in the tissue, urine, and blood samples from the pilot. Ethanol was found in the following levels: 124 mg/dl in blood, 74 mg/dl in brain, and 214 mg/dl in urine. Acetaldehyde was found in these levels: 12 mg/dl in blood, 2 mg/dl in brain, and 3 mg/dl in muscle. Tetrahydrocannabinol carboxylic acid was found at 0.006 ug/ml in blood, and 0.04 ug/ml in urine.
The wreckage was released to insurance company adjusters representing the estate of the pilot at the conclusion of the examinations. No components were retained by the Safety Board.