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N8980D accident description

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Tail numberN8980D
Accident dateSeptember 14, 2002
Aircraft typePiper PA-18A-150
LocationTucson, AZ
Near 39.033333 N, -111.466667 W
Additional details: None

NTSB description

HISTORY OF FLIGHT

On or about 0900 mountain standard time on September 14, 2002, a Piper PA-18A-150, N8980D, collided with the ground in a flat desert area 19 miles south west of the Ryan Airport, Tucson, Arizona. The airplane was owned and operated by the pilot under the provisions of 14 CFR Part 91 of the Federal Aviation Regulations, and was destroyed in the impact sequence. The commercial pilot/airplane owner and a passenger, who also holds a private pilot certificate, sustained fatal injuries. Visual meteorological conditions prevailed and no flight plan was filed for the presumed local area personal flight that departed from the Ryan Airport at 0740.

No witnesses to the accident were identified. Several pilots on the Ryan airport reported that they heard what they believed to be an ELT going off about 0936 on the morning of September 14; however, the signal stopped shortly thereafter.

According to information from the Federal Aviation Administration (FAA), Pima County Sheriff's investigators, Tucson Airport Authority Police, and Officers from the Arizona Department of Public Safety (DPS), the passenger's family reported the airplane overdue on the morning of the 15th when the passenger failed to return home. The FAA issued an ALNOT for the missing airplane and it was found by (DPS) search helicopter at 1641 that afternoon. Information developed by Pima County Sheriff's investigators revealed that the pilot and passenger intended a short duration local area flight.

Sheriff's investigators and Tucson Airport Authority police officers interviewed persons at the Ryan airport who are pilots and stated that they knew the pilot. The witnesses stated that the pilot liked to land in the open desert on "sand dunes" on the large sized tundra tires he had equipped the airplane with that were designed to be used on soft unimproved surfaces.

PERSONNEL INFORMATION

According to identifications made by the Pima County Medical Examiners Office and Sheriff's investigators, the aircraft owner occupied the front seat while the passenger was in the rear seat of the two-place tandem airplane. Examination of the airplane disclosed that full flight controls were installed at both seat locations.

Front Seat Occupant

Review of FAA airman and medical records files disclosed that the airplane owner held a commercial pilot certificate with ratings for airplanes single engine land and instruments. His certificate was also endorsed for private privileges in airplanes single engine sea. The most recent issuance of his commercial pilot certificate was dated July 12, 1999. The pilot also held a Second class medical certificate issued on March 6, 2001, with the limitation that correcting lenses be worn. A Statement of Demonstrated Ability for defective color vision was issued to the pilot on March 2, 1999, on the basis of his passing a practical color vision test. The pilot's personal flight record log book was recovered in the wreckage and examined. The last entry was dated September 3, 2002, and noted a 1.7-hour local flight from Ryan airport. In the remarks section of that entry the pilot wrote, "Practice dirt landings." The entry prior contained in the remarks section the notation, "Practice short and soft landings in dirt." The pilot's total flight time recorded as of the September 3 entry was 839 hours, with 305 in the PA-18. The most recent flight review was conducted on May 14, 2001.

Rear Seat Occupant

The rear-seated passenger held a recently issued private pilot certificate. His original student certificate was issued on February 16, 2000. A third class medical certificate was issued to the pilot on the same day without limitations. No personal flight records were recovered for the passenger and his total flight time and time in the PA-18 series airplanes could not be determined

Both the pilot and the rear-seated passenger held FAA-issued airframe and power plant mechanic certificates and were the holders of Inspection Authorizations.

AIRCRAFT INFORMATION

The aircraft was a Piper PA-18A-150, serial number 18-6424, which was manufactured in 1958. According to the maintenance records, the airframe had accumulated a total time in service of 3,360 hours. The most recent annual inspection was completed on March 30, 2002, 40 hours prior to the accident. Comparison of the Airworthiness Directive compliance listing in the log book against a list of AD's applicable to the aircraft's serial number revealed that all had been endorsed as complied with.

Review of all records related to the airplane disclosed that the left wing and landing gear had been damaged in a ground loop accident in January of 1999. The pilot purchased the airplane in the damaged condition in March of that year and repaired the airplane by replacing the damaged components with new parts. A FAA form 337 was filed covering the repair and listing the work accomplished.

From his purchase of the airplane in 1999 until 2003, the pilot made numerous modifications to the airplane, all with approvals endorsed on FAA 337 forms covering the work performed. The fuel system was modified to incorporate fuel tank inlet ports at both the forward and aft portions of the tank.

The power plant, a Lycoming O-320-A2B, serial number L-49404-27A, is a four cylinder, air cooled, direct drive, horizontally opposed, normally aspirated (carburetor), internal combustion engine rated at 160hp @ 2700rpm. Review of the maintenance records and FAA forms 337 disclosed that the engine had been converted on April 3, 2000, from the factory rated 150hp (O-320-A2C) to 160hp (O-320-A2B) in accordance with STC # SA315NM. The maintenance records listed a total time for the engine of 854 hours, with 305 since major overhaul.

METEOROLOGICAL INFORMATION

The closest official weather observation station is the Tucson International Airport, which is located 23 miles east of the accident site. At 0855 on the morning of September 14, the airport was reporting clear sky conditions and winds from 160 degrees at 5 knots. Throughout the morning hours, the conditions remained clear with generally southerly winds at less than 10 knots. No unusual meteorological phenomena were reported during this time.

WRECKAGE AND IMPACT

The accident site is in flat desert terrain composed of firm sandy soil and populated by scrub type trees up to 10 feet tall. Examination of the trees surrounding the accident site revealed no evidence of disturbance to any upper branches or trunks.

Initial assessment of the accident site disclosed extensive longitudinal crush and collapse of the fuselage back to within 3 feet of the horizontal stabilizers. Ground scar impressions were noted about 15 feet from the wreckage that dimensionally and geometrically resembled the nose of the airplane and the left wing tip. No other ground disturbances were observed in the vicinity. The engine was in a shallow crater formed in the impact sequence with the engine's longitudinal axis at a 30-degree angle to the horizontal.

The airplane was equipped with the large tundra tires. Approximately 15-gallons of fuel was found in each fuel tank and the cockpit throttle control was in the full open position. The carburetor heat and mixture controls were in the cold and full rich positions, respectively.

The empennage fixed and movable control surfaces remained attached to the fuselage and were undamaged.

The left wing remained attached to the fuselage attach points; however, it was extensively buckled and had collapsed in a span wise direction. The leading edge tip was crushed and displaced upward and rearward. The aileron and flap remained secured to their respective hinge and hangar assemblies and were buckled and bent in a manner consistent with the deformation to the wing. At a point about 3 feet inboard from the tip, the leading edge was found wrapped around a dead tree stump.

The right wing remained attached to the fuselage attach points. Leading edge crush and accordioning damage was noted along the outboard one third of the span at a 30-degree angle to the lateral axis. The aileron and flap remained secured to their respective hinge and hangar assemblies and were bent and distorted in a manner consistent with the deformation patterns to the wing.

About 1/2 mile further southwest of the wreckage, a large flat clear area was noted with multiple tire tracks crossing the field. The tire tracks were dimensionally similar to the main gear tires on the airplane and were approximately spaced about the wheel width of the PA-18 series airplanes. Two sets of tracks were found with a center track approximating the geometry and dimension of the airplane's tail wheel; these tracks started, went for a distance estimated about 500 feet, where they turned around and proceeded back the opposite way until they disappeared. Two additional tracks were observed without the center track trace; these tracks were shorter in length at about 200 feet. No footprints could be discerned around any of the tracks. Assuming that the tracks represent an airplane landing or taking off, the accident site was noted to be in a location consistent with the approximate traffic pattern distance from a typical 2,000-foot landing strip at either a base-to-final or crosswind-to-upwind turn point.

TESTS AND RESEARCH

The airframe wreckage and engine were examined October 2, 2002, at the facilities of Air Transport, Phoenix, Arizona.

The engine remained attached to the airframe by the engine mount. The engine had been displaced aft and upward from the normal position due to the absorption of impact energy. The engine had sustained moderate impact energy damage at the forward lower section due to the absorption of impact energy. The propeller was displaced from the crankshaft flange. Visual examination of the engine revealed no evidence of pre-impact catastrophic mechanical malfunction or fire.

The crankshaft was rotated by hand at the flange and was free and easy to rotate in both directions. "Thumb" compression was observed in proper order on all four cylinders. The complete valve train was undamaged and was observed to operate in proper order. Normal lift action was observed at each rocker assembly. Clean, uncontaminated oil was observed at all four rockerbox areas. Mechanical continuity was established throughout the rotating group, valve train and accessory section during hand rotation of the crankshaft.

The cylinder(s) combustion chamber was examined through the spark plug holes utilizing a lighted bore scope. 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. The oil soaking observed within the cylinders 2 & 4 was attributed to the engine positioning at the mishap site and post recovery. There was no oil residue observed in the exhaust system gas path. Ductile bending and crushing of the exhaust system components was observed.

The left and right magnetos remained securely clamped at their respective mounting pads. The ignition harness was attached at the respective magneto(s) and each spark plug, and exhibited minor impact related damage. Magneto to engine timing could not be ascertained, due to the destruction of the flywheel. The magnetos were removed for examination. Each magneto produced spark at the distributor block post(s), during hand rotation of the drive. The drives of each magneto remained intact and undamaged.

The fuel system utilizes gravity fed fuel. There were no discrepancies noted. The fuel selector valve was positioned on the left tank. About 15 gallons of fuel were found in the left and right tanks.

The carburetor was a Precision model MA-4SPA. The bowl was displaced from the carburetor and destroyed. The portion of the carburetor that remained attached at the mounting pad was secure. The fracture surface signatures were grainy and angular, consistent with overload. The throttle/mixture controls were found securely attached at their respective control arms on the carburetor and continuity to the cockpit was established. The engine compartment fuel lines were found to be in place and secure at their respective fittings. The fuel bowl of the carburetor was shattered, thus compromising the fuel system. There was no fuel observed. The metal float pontoons exhibited moderate hydrodynamic crushing.

The two bladed fixed pitch McCauley 1A175GM8244 propeller, serial number VF23078, was displaced from the crankshaft flange at the mechanical attachments. The fracture surfaces exhibited grainy and angular signatures consistent with overload. The propeller blades displayed leading edge gouging, torsional twisting, and chordwise striations across the cambered surface in addition to trailing edge "S" Bending. Rotational scoring was noted on the cowl directly behind the propeller's plane of rotation.

The spark plugs were secure at each position with their respective spark plug lead attached. The top spark plugs were removed, examined and photographed. The spark plug electrodes remained mechanically undamaged, and according to the Champion Spark Plugs Check-A-Plug chart AV-27, the spark plug electrodes displayed coloration consistent with normal operation.

There was no contamination found in the oil pressure screen or rocker box areas during the examination.

Examination of the airframe found control continuity from the cockpit controls to all control surfaces. The flaps were in a retracted position. The horizontal stabilizer trim was found in a mid-range position.

MEDICAL AND PATHOLOGICAL INFORMATION

The pilot and passenger sustained fatal injuries in the accident and the Pima County Medical Examiners Office conducted autopsies on both individuals. Toxicological specimens were retained from both occupants and were submitted to the FAA Civil Aeromedical Institute in Oklahoma City, Oklahoma, for testing.

The results of the toxicological tests on the specimens from the pilot were negative for alcohol and all screened drug substances.

The test results on the specimens for the passenger were negative for all screened drug substances. Ethanol was present in urine and brain tissue at respective levels of 11 mg/dl and 97 mg/dl. Acetaldehyde and N-propanol was also detected in brain tissue at respective levels of 11 mg/dl and 4 mg/dl. Ethanol was also found in muscle tissue at a level of 45 mg/dl.

ADDITIONAL INFORMATION

The wreckage was released to representatives of the pilot's estate on October 7, 2002, at the conclusion of all follow-on examinations. No parts or components were retained.

(c) 2009-2011 Lee C. Baker. For informational purposes only.