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On April 17, 1994, about 1408 hours mountain standard time, a Piper PA24-180, N6331P, crashed after departure from runway 03, about 3/4 mile northeast of Nogales International Airport, Nogales, Arizona. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight to Phoenix, Arizona, when the accident occurred. The airplane, co-owned and operated by the pilot, was destroyed by impact. The certificated private pilot (first pilot), a pilot-rated passenger and co-owner (second pilot), and two passengers received fatal injuries. Visual meteorological conditions prevailed. The flight originated at the Nogales Airport as part of an intermediate stop from Guaymas, Sonora, Mexico. A VFR flight plan was filed from Guaymas to Nogales. No flight plan was filed from Nogales.
At 1324 hours, the aircraft arrived at Nogales after departure from Guaymas at 1125 hours. The pilot proceeded to the U.S. Customs Office to comply with international cross-country flight requirements. The customs inspector on duty reported that the pilot exited and reentered the aircraft from the left front seat. The pilot received a telephone call from the Prescott Automated Flight Service Station (AFSS) with a reminder of the need to close his flight plan from Guaymas to Nogales. After clearing customs, the aircraft was observed to depart on runway 03. The customs inspector did not report hearing any unusual engine sounds.
Witnesses observed the airplane flying slow about 100 feet above the ground with the landing gear down and headed in a northeast direction. The wings appeared to wobble and the airplane did not appear to be climbing. The airplane then began a left turn toward the north. During the turn, the nose of the airplane suddenly dropped and the aircraft descended to the ground in a near vertical nose-down attitude. About 10 minutes after the crash, witnesses reported the accident to the U.S. Customs Office at the airport.
The accident occurred during the hours of daylight at latitude 31 degrees, 25.67 minutes north and longitude 110 degrees, 50.59 minutes west.
The pilot held a private pilot certificate with an airplane single-engine land rating. The most recent third-class medical certificate was issued to the pilot on October 4, 1993, and contained the limitation that the pilot must wear correcting lenses.
No personal flight records were located for the pilot and the aeronautical experience listed on page 6 of this report was obtained from a review of the airmen Federal Aviation Administration (FAA) records on file in the Airman and Medical Records Center located in Oklahoma City.
According to the pilot's application for a medical certificate on October 4, 1993, his total aeronautical experience consisted of about 305 hours, of which 30 were accrued in the preceding 6 months.
Examination of photographs taken at the accident scene by the Santa Cruz County Sheriff's Department, revealed that the left front seat was occupied by the first pilot. The Director General of Civil Aviation in Mexico reported that the first pilot signed the accident flight plan. The right front seat of the aircraft was occupied by the co-owner (second pilot) who also held a pilot certificate. Family members reported that the second pilot flew the aircraft into Mexico on April 16, 1994. The first pilot was to fly the return flight on April 17, 1994.
The airplane had accumulated a total time in service of 4,191.38 flight hours. Examination of the maintenance records revealed that the most recent annual inspection of the airframe and engine was accomplished on October 7, 1993, 91.58 flight hours before the accident.
According to the maintenance records, the engine had accrued a total time in service of 868.38 hours of operation since being installed in the aircraft in October, 1980.
National Transportation Safety Board investigators were unable to determine the amount of fuel on board the aircraft when it departed Guaymas. The U.S. Customs data indicated that the flight time from Guaymas to Nogales was about 2 hours.
The aircraft owner's manual indicates that the standard empty weight of the aircraft is 1,455 pounds. A standard fuel load is 50 gallons. The aircraft's fuel consumption is 10 gallons per hour. The total weight of the passengers was 647 pounds. The total weight of the baggage was 77.5 pounds. Based on the above data, Safety Board investigators calculated the aircraft weight at the time of the accident was about 2,359.5 pounds. The maximum gross weight for the airplane is 2,550 pounds.
The closest weather observation equipment to the accident is located at Nogales, Arizona, which is 3/4 nautical miles southwest of the accident site. At 1418 hours, an Automated Meteorological Observation Station (AMOS) was reporting in part: Sky condition and ceiling, not reported; visibility, not reported; temperature, 87 degrees F; dew point, 25 degrees F; wind, 210 degrees at 5 knots; peak wind, 14 knots; no report of rain.
Aerodrome and Ground Facilities
The Nogales International airport is owned and operated by the County of Santa Cruz. The published elevation of the airport is 3,932 feet mean sea level. The airport was not attended on the accident date and airport traffic communications are conducted on a common traffic advisory frequency (CTAF). The airport is situated in a small valley with higher rolling terrain surrounding the field.
The airport is equipped with a single hard-surfaced runway oriented on a 210/030 degree magnetic heading. Runway 03 is 6,020 feet long by 90 feet wide. The runway slopes uphill on a 1.63 percent grade. The density altitude was calculated to be about 6,500 feet.
Wreckage and Impact Information
Safety Board investigators examined the airplane wreckage at the accident site on April 18, 1994. All of the airplane's major components were found at the main wreckage area at an elevation of about 4,050 feet mean sea level. The area consists of rolling, desert brush and tree covered terrain. A path of wreckage debris and ground scars from the initial point of ground contact to the airplane's point of rest were observed on about a 258 degree heading. (All heading/bearings noted in this report are oriented toward magnetic north.) The airplane came to rest next to a fence about 50 feet south of the south curb of Arizona State Highway 82. The tail of the airplane was resting on a cattle guard at a gate opening in the fence with the nose and wings oriented on about a 078 degree heading.
The first evidence of ground impact was pieces of the red position light lens from the left wing tip that were located at the base of a mesquite tree about 35 feet from the airplane's point of rest. The nose section of the airplane, the engine, and the instrument panel were crushed aft and downward, below the lower edge of the fuselage at the leading edge of the wings. The fuselage roof section separated at the lower edge of the windshield and was peeled and crushed aft over the rear cabin area.
The wings exhibited extensive spanwise leading edge aft crushing and folding with more damage evident on the lower surface. The left wing exhibited aft crushing and upward curling about 3 feet inboard from the tip. The left wing aileron remained attached to the wing; however, the outboard attach point hinge was broken. Extensive aft crushing from the leading edge to the wing spar was evident just outboard of the left landing gear. The right wing aileron remained attached to the wing; however, the outboard attach point hinge was broken. Both the left and right flaps remained attached to their respective wings. Both fuel tanks were ruptured.
The empennage was twisted and folded about 90 degrees to the right and was oriented about parallel with the right wing. It came to rest on a steel fence support next to the cattle guard. The vertical stabilizer, rudder, horizontal stabilizer, and trim tab remained attached to the airplane. The right stabilizer was bent about midspan and curled upward about 270 degrees.
Due to the impact damage, Safety Board investigators were unable to operate the flight controls by their respective control mechanisms; they were, however, able to establish continuity of the flight control cables to the cabin/cockpit area.
The propeller assembly separated from the engine and was located about 20 feet from the initial point of ground contact. Both blades were loose in the hub and exhibited slight aft bending at the hub. One propeller blade exhibited leading edge gouging, chordwise scratching on the chambered side, slight "S" bending and torsional twisting. The second blade was bent aft about midspan about 90 degrees. It exhibited extensive chordwise scratching on both sides of the blade, extensive torsional twisting, "S" bending, and leading edge gouging.
The engine sustained impact damage to the underside portion of the engine. The oil sump was crushed and broken from the bottom of the engine case. The intake tubes, exhaust tubes, and the muffler were crushed in an upward direction. The bent and folded areas of the exhaust tubes exhibited smooth contours of the fold creases without breaking. The crankshaft could be rotated 360 degrees by hand. Gear and valve train continuity was established when the crankshaft was rotated. The propeller spinner remained attached to its backing flange; however, the front portion of the spinner was torn open and exhibited rotational bending.
The magnetos remained attached to the accessory gear case. They produced spark at all terminals upon hand rotation. The fine wire sparks plugs exhibited no unusual combustion signatures.
About 100 milliliters of blue-colored fuel was recovered from the left wing. The carburetor sustained impact damage. The engine driven fuel pump produced pumping action when hand activated and fuel was noted in the pump. The electric fuel pump internal screen was free of contaminants and contained fuel.
Medical and Pathological Information
A post mortem examination of all occupants was conducted under the authority of the Santa Cruz County Medical Examiner by the Forensic Science Center, 2825 E. District, Tucson, Arizona, on April 19, 1994. The examination revealed that the cause of death for all occupants was attributed to blunt force trauma.
A toxicological examination of the front seat occupants (first pilot and second pilot) was conducted by the Department of Defense, Armed Forces Institute of Pathology, on May 6, 1994. The examination was negative for alcohol and all screened drugs for both pilots.
The Safety Board released the wreckage, located at Air Transport, Phoenix, Arizona, to the owner's representatives on May 3, 1994. No parts or components were retained by the Safety Board.