LAX94FA193

The airplane departed an airport located at 3,932 feet mean sea level with four occupants. The density altitude was estimated at 6,500 feet. The airplane's gross weight was calculated to be within limits. Witnesses observed the airplane flying low and slow about 3/4 miles northeast of the airport and the wings appeared to be wobbling. The airplane began a left turn about 100 feet above ground and suddenly descended in a steep nose-down attitude to the ground. No mechanical malfunction was found.

History of the Flight

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.

Crew Information

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.

Aircraft Information

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.

Meteorological Information

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 o