FTW97FA103
FTW97FA103

HISTORY OF FLIGHT

On February 14, 1997, approximately 2315 mountain standard time, a Piper PA-24-250, N6433P, registered to and operated by Flying Z Aviation, Inc., of Albuquerque, New Mexico, was destroyed when it impacted terrain in an uncontrolled descent after takeoff from the Four Corners Regional Airport in Farmington, New Mexico. The commercial, instrument rated pilot and his four passengers were fatally injured. Night visual meteorological conditions prevailed, and no flight plan was filed for the Title 14 CFR Part 91 personal cross-country flight which was en route to Belen, New Mexico.

According to witnesses, the airplane landed at the Four Corners Regional Airport about 2030. After eating dinner at the airport restaurant, the pilot and passengers reboarded the airplane for the flight to Belen. A line service technician, employed by the fixed base operator, observed the airplane takeoff on runway 25, "breaking ground parallel to taxiway Delta." (Taxiway Delta is approximately 4,000 feet from the beginning of runway 25.) He reported that the airplane made "a normal climb to about 200 feet, and then descended to approximately 15-20 feet above the runway, gear up." The line service technician further reported that the airplane "accelerated in ground effect and established a high rate of climb toward the end of the runway." The line service technician observed the airplane begin "a shallow left hand turn " before he lost sight of it as it "passed behind the control tower."

Although the control tower had closed at 2200 and was not providing ATC service to the airplane, there was a witness in the control tower at the time of the accident. The witness did not observe the airplane takeoff, but did observe "an aircraft approximately 1/2 to 3/4 of a mile southwest of the airport at approximately 400 feet agl in altitude that appeared to be spinning." The witness "observed flames as the aircraft impacted the ground and notified Farmington fire/dispatch."

Another witness, who was in the front passenger seat of a car driving eastbound on Highway 64, observed the airplane "taking off, [and] heading west parallel to the highway." The witness "watched the craft until it passed" and subsequently noticed it "come up parallel on [her] right side heading east." She estimated the airplane was "between 100 and 200 feet above the ground." As she continued to observe the airplane, "it appeared to suddenly slow down as if going into a stall." The witness stated that "the wing of the plane tipped and in an apparent stall the plane started into a clockwise spiral and nose dived into the ground. Upon impact the plane burst into a ball of flames."

PERSONNEL INFORMATION

On December 29, 1996, the pilot passed the practical test for the instrument airplane rating. On February 2, 1997, he passed the commercial airplane single engine land practical test. The flight check portions of both tests were completed in the accident airplane. On the enclosed NTSB Pilot/Operator Aircraft Accident Report completed by the father of the pilot, the pilot's total time in the Piper PA-24-250 was listed as 201 hours with 162.8 of those hours as pilot in command. Total night flight time listed was 101.1 hours with 94 of those hours as pilot in command, and total instrument time listed was 76.8 hours. The report indicated that the source of this flight time information was the pilot's logbook.

AIRPLANE INFORMATION

According to the maintenance records, the 4-seat, single engine, retractable gear airplane received its last annual inspection on July 5, 1996. At the time of that inspection, the airframe had accumulated 3,914.1 hours since its date of manufacture on November 16, 1959, and the engine had accumulated 292.9 hours since major overhaul on October 15, 1994. Review of the maintenance records by the NTSB investigator-in-charge did not reveal evidence of any uncorrected maintenance discrepancies.

The airplane's gross weight at the time of the accident was calculated by the NTSB investigator-in-charge at 2,693 pounds with a center of gravity of 89.8 inches. The airplane's maximum gross weight limit was 2,800 pounds with an allowable center of gravity range at gross weight of 87.8 to 93.0 inches.

METEOROLOGICAL INFORMATION

The weather observation taken at 2315 by the Four Corners Regional Airport weather observer was wind 260 degrees at 10 knots; visibility 15 miles; sky clear; temperature 0 degrees C; dewpoint -7 degrees C; altimeter setting 30.31 inches of Hg. According to the U.S. Naval Observatory, at 2315, the moon was at an altitude of 29.2 degrees above the horizon, an azimuth of 269.1 degrees, and 59% illuminated.

WRECKAGE AND IMPACT INFORMATION

The accident site was located approximately 1 mile south of the Four Corners Regional Airport in a residential area of Farmington. The airplane impacted in a horse corral located east of the residence at 2400 Ridgeview Drive and came to rest in the upright position at the point of impact on a measured magnetic heading of 190 degrees. Both wings remained attached to the fuselage and were crushed aft along their entire span. A ground scar, located about 2 feet in front of and running parallel to the wing span of the right wing, measured approximately 4 feet in length and 6 inches in width. Pieces of the right fiberglass wingtip and the right navigation light were embedded in the ground scar. The metal housing for the right navigation light was buried in the ground at a measured angle of 80 degrees to the horizontal.

The right stabilator was crushed aft and inward, and the left stabilator displayed light impact damage. The leading edge of the vertical stabilizer displayed impact damage which increased in severity towards the upper cap. Control continuity was confirmed from the flight control surfaces to the cockpit controls. The cabin section of the airplane, including all cockpit instrumentation, was destroyed by the post-crash fire. The landing gear were found in the up position, and the position of the flaps could not be determined due to the extent of impact and fire damage. The elevator trim drum shaft upper extension measured 5/16 inches. According to the airframe manufacturer party representative, this corresponded to a "near neutral" elevator trim setting.

The engine remained attached to the airframe and was partially buried in the ground, inclined down at a measured angle of approximately 40 degrees. The propeller was not initially visible. When the engine was raised from the ground, the propeller was found attached to the engine, but was broken away at the starter ring gear support assembly. One propeller blade was bent aft approximately 80 degrees at mid-span folding it back along the side of the engine. The opposite propeller blade was bent slightly aft at mid span, and the tip was curled.

Only slight rotation of the engine crankshaft was possible; however, it was sufficient to confirm continuity to the magneto drive gears. Both magnetos, the carburetor, the generator, the vacuum pump, the oil filter, and the oil filter housing were broken away from the engine and displayed heavy impact damage. The exhaust system and the oil sump were crushed.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy and toxicological tests of the pilot were performed. Toxicological tests for carbon monoxide, cyanide, volatiles (alcohol), and drugs were negative. The autopsy was performed by Marcus Nashelsky, MD, at the Office of the Medical Investigator in Albuquerque, New Mexico, on February 16, 1997. The autopsy report included the following statement:

Microscopy of the heart revealed a single focus of myocarditis (chronic inflammation with myocyte necrosis), contraction bands, and stenosis [narrowing] of the atrioventricular artery. The myocarditis may initiate a cardiac arrhythmia. The significance of the latter findings is unknown.

At the request of the NTSB investigator-in-charge, the Armed Forces Institute of Pathology (AFIP) in Washington, DC, examined all heart tissue samples and slides available from the autopsy and provided a report of their findings. The AFIP pathologists found a single focus of myocarditis and "approximately 70% luminal narrowing" of the artery to the atrioventricular (AV) node. They made the following comment:

The significance of the findings is unclear. We have demonstrated dysplastic narrowing of the AV nodal artery in 44% of unexplained cardiac death, compared to 6% of controls(1), suggesting that [in] some cases this finding precipitates sudden death. A single focus of inflammation with myocyte necrosis does not, in our opinion, warrant a diagnosis of myocarditis as a cause of sudden death, as this finding may also be seen in in non-cardiac deaths. We were unable to appreciate ischemic changes in the myocardium.

1. Burke A, Subramanian R, Virmani R, Smialek J. Non-atherosclerotic narrowing of atrioventricular nodal artery and sudden death. J Am Coll Cardiol. 1993;21:117-22.

The FAA Southwest Regional Flight Surgeon reviewed the autopsy report and the AFIP report and stated that "an acute physical incapacitation could have been very likely in this case given the pathology found." The flight surgeon further stated that "another possiblity, given the fact that the flight took place at night, could be a spatial disorientation event leading to loss of control of the aircraft."

During telephone interviews conducted by NTSB investigators, the pilot's parents reported that the pilot had no known history of heart disease. They further reported that the pilot had made no mention to them of feeling ill in the weeks prior to the accident. TESTS AND RESEARCH

A teardown of the airplane's engine, a Lycoming O-540-B2B5, S/N L-5842-40, was conducted under the supervision of an FAA inspector on April 22, 1997, at Four Corners Aviation in Farmington, New Mexico. According to the inspector, "no anomalies [were] noted" during disassembly of the engine.

ADDITIONAL INFORMATION

The wreckage was released to a representative of the owner on May 7, 1997.

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