DEN01FA152
DEN01FA152

HISTORY OF FLIGHT

On August 24, 2001, approximately 1930 mountain daylight time, a North American SNJ-5, N2686D, registered to and operated by SNJ Aviation Adventures LLC, was destroyed when it impacted terrain while in an uncontrolled descent 1/2-mile north of the Raton Municipal Airport, Raton, New Mexico. The airline transport certificated pilot and one passenger were fatally injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the personal flight being conducted under Title 14 CFR (Code of Federal Regulations) Part 91. The flight originated at Raton approximately 1925.

On the morning of the accident, the airplane's mechanic flew with the pilot to Raton. He said that as the airplane was taking off from Coronado Airport in Albuquerque, New Mexico, he could hear the engine detonating.

There were no less than 12 witnesses to the accident, 7 of whom submitted written statements, including the accident pilot's wife (who flew a similar airplane in aerobatic routines with her husband), another T-6 pilot, a retired United Air Lines captain, and a YAK-52 pilot.

According to the T-6 pilot, he was in his airplane on the ramp. As he watched the SNJ-5 "descending to gain airspeed for [an] entry into a loop," he saw "blackish dark colored smoke coming from the exhaust area of the cowling." The airplane was then "climbing vertically. As [the airplane] approached the top of the loop, [the pilot] said, 'My engine just quit.'" The witness said the pilot turned the airplane "left and down toward the ground and gained enough airspeed to pull out at the bottom." He saw "only light residual smoke" coming from the airplane and he asked the pilot, "Are you okay," and the pilot replied, "I think so." He then looked away and did not see the impact.

According to the pilot's wife, she watched her husband make a pass over the runway and said the engine sounded "good." When she saw the airplane again, it was dropping behind a hill, "left wing down."

A retired United Air Lines captain and his wife were standing in front of the terminal building about a mile from the accident site. He said he had seen the pilot and his wife perform at another air show and was impressed with their conservative routine. At the time of the accident, it was dusk and depth perception was "in question for maneuvers close to the ground." The pilot performed "a loop with a very slow recovery...one with a mushing pull-up at the backside and bottom." Next, he did a "hammerhead" turn that alarmed him because the recovery, with a "mushing pull-up at the bottom," was initiated "far too low." As the pilot pulled up from this maneuver, the witness's attention was diverted but he heard the pilot's wife say, "What is he doing? He knows better than that." He looked back and saw the airplane flying north "with a very jerky rocking motion of the wings of maybe 10 to 30 degrees." The airplane made a left turn, "nosed over [and] went straight down, wings level." He said the nose started to come up again but then went straight down again. He surmised it was an attempt to recover from a stall that resulted in a secondary stall.

When the YAK-52 pilot saw the SNJ-5, it was "at the top of a maneuver... The pilot started what appeared to be a 45-degree down line to a loop or Cuban 8. At the bottom of the maneuver, I thought I saw a trail of smoke (fuel or oil). The engine did not sound like it was producing full power (SNJ props make a crackle at that speed). As the aircraft climbed to vertical, it was too slow to continue. It appeared to tail slide until the pilot could get enough airspeed to recover. At that point the aircraft was very close to the ground and I think it stalled and snapped into the ground."

One witness, a Skybolt pilot, saw the airplane "in a steep (near vertical) dive. It rolled about 1/4-turn while descending (similar to a cloverleaf maneuver with the 1/4-roll on the downturn. As it continued down, I noticed it 'twitch' in the roll axis 2 (or maybe 3) times, as if he was attempting to pull but didn't have sufficient speed. It continued in a steep dive and appeared to be recovering slightly" before disappearing behind a slight rise.

Another witness, also a Skybolt pilot, said the airplane made a "low pass down the runway" and rolled once. When it was west of the airport and parallel to the runway, it dove "to enter what appeared to be a loop." The airplane "stopped short at the top and did an apparent hammerhead and slid backwards (straight down, tail slide) before rotating towards the left wing and going nose down. The airplane recovered and started climbing out, then "entered what I thought was going to be a barrel roll or aileron roll." The maneuver was "entered from wings level, climbing flight...The aircraft entered a nose down attitude and did erratic turns, not complete spins" before disappearing below a small hill.

PERSONNEL INFORMATION

The 61-year-old former Delta Air Lines captain held an airline transport pilot certificate with an airplane multiengine land rating, type ratings in the Boeing 727, 757, 767, Douglas DC-9, and McDonnell Douglas MD-11, and commercial privileges in airplanes single-engine land, dated December 8, 1994; a flight engineer certificate with a reciprocating engine rating, dated August 17, 1967; an expired flight instructor certificate with an airplane single-engine rating, dated November 30, 1981; and a mechanic's certificate with airframe and powerplant ratings, dated January 25, 2000. His second class airman medical certificate, dated March 8, 2001, contained the restriction, "Must have available glasses for near vision."

According to documents submitted by Delta Air Lines, the pilot joined the company in October 1965, and took an early retirement in May 1997. His last proficiency check was dated November 30, 1999, and taken in the MD-11. At the time of his retirement, he had logged the following flight times as a captain:

MD-11--- 1,748:23
B-757/767 --- 3,432:02
B-727 --- 354:08
Total --- 5,534:33

According to the accident report submitted by his wife, she estimated his total flight time to be 22,000 hours, of which 1,141 hours were in single-engine airplanes and 653 of those hours were in the SNJ-5/T-6 type airplane. She estimated her husband had flown 73, 20, and 2 hours in the previous 90 days, 30 days, and 24 hours, respectively, all in the SNJ-5. His last biennial flight review was taken in the SNJ-5 on November 8, 2000.

AIRCRAFT INFORMATION

N2686D (s/n 91051), a model SNJ-5 (Navy, AT-6D Air Force), was built by North American Aviation Corporation on June 18, 1944. It was equipped with a Pratt & Whitney R-1340-AN-1 engine (s/n ZP 101498), rated at 600 horsepower, and a Hamilton-Standard 2-blade, all-metal, constant speed propeller (m/n 12D40-31015).

According to the aircraft's maintenance records, the following inspections were performed:

ANNUAL 100-HOUR

Date March 12, 2001 August 20, 2001
Hobbs Meter 969.0 hours 1,095.0 hours
Total Time, Airframe 8,170 hours 8,295.2 hours
Total Time, Engine 5,809.0 hours
Since Major Overhaul 588.8 hours

METEOROLOGICAL INFORMATION

The following METAR (Aviation Routine Weather Report) observation was recorded the Raton Municipal Airport 15 minutes before the approximate time of the accident: Wind, 150 degrees at 4 knots; visibility, 10 statute miles or greater; sky condition, clear; temperature, 25 degrees C. (77 degrees F.); dew point, 4 degrees C. (39 degrees F.); altimeter setting, 30.13. According to the U.S. Naval Observatory, official sunset was at 1937.

WRECKAGE AND IMPACT INFORMATION

The debris path varied between magnetic headings of 224 and 206 degrees. The initial ground scar was 42 feet long, terminating at a large ground depression. Embedded in this depression was one of the propeller blades broken at the shank. The remainder of the wreckage was contained in an area that had been exposed to a postimpact ground fire. Three large portions of the left wing, along with a section of the left aft fuselage, were located along the outer (south) fringes of the fire area. The aft portion of the fuselage, including the vertical and right horizontal stabilizers, rested on its left side and was at the western edge of the burn area. The engine and the second propeller blade were outside the burn area southwest of the impact point. In addition to the accessory gear box, carburetor, and magneto mounting pads, four cylinders --- the cooling fins crushed --- had been knocked off the engine case. The altimeter was set to 30.10, and the tachometer, indicated 1,750 rpm. Throttle, mixture and propeller controls were full forward.

MEDICAL AND PATHOLOGICAL INFORMATION

The New Mexico State Medical Examiner's Office (MEO) performed an autopsy (#4124-80-8C) on the pilot. In addition, the MEO and FAA's Civil Aeromedical Institute (CAMI) performed toxicological protocols. According to the MEO's report, 0.052% ethanol and less than .01% methanol was detected in blood taken from the heart. CAMI's report (#200100257001) indicated 83 and 122 (mg/dL, mg/hg) ethanol, 21 and 5 (mg/dL, mg/hg) acetaldehyde, and 5 and 7 (mg/dL, mg/hg) N-propanol were detected in kidney and muscle tissue, respectively. "The ethanol found in this case may potentially be from postmortem formation and not from the ingestion of ethanol," the report stated. It was noted that the samples, when received, were putrefied. MEO's report indicated less than 5 percent carbon monoxide saturation in heart blood. CAMI's report indicated diphenhydramine, found in common over-the-counter cold medications and sleep aids, was detected in the kidney and liver.

TESTS AND RESEARCH

On February 12, 2002, the engine was disassembled and examined at the facilities of Covington Aircraft Engines, Tulsa, Oklahoma, under the direction of NTSB. According to Covington's report, "No cause for the reported loss of power...was discovered at this investigation."

ADDITIONAL INFORMATION

Five months after the accident, the pilot's wife submitted a letter relative to her husband's flying habits. In it, she said he had never done hammerhead maneuvers in the T-6. When she had previously experimented with the maneuver, she found it to be "unpredictable." She also said her husband did not perform "looping maneuvers" during the accident flight with a "neophyte" passenger on board (as some witnesses had said they had seen); instead, she believed he was making a "yo-yo turn," involving pulling the nose "up to about 70 degrees pitch, releas[ing] back pressure and execut[ing] a coordinated turn...essentially a steep wingover." Both she and her husband had agreed that "the most critical time for an engine failure...was near vertical...[and the] recovery [would be] via a yo-yo turn."

After receiving the preliminary findings of the engine disassembly and examination, the pilot's wife submitted a second letter, documenting her "attempts at duplicating the engine failure." She found that she "could easily cause the engine to quit by pulling up straight ahead to 70 degrees (on another occasion 90 degrees), and pushing over to a dive. On each try, it took at least 20 to 30 degrees of pitch change over the top before the engine quit." The engine would not regain power until the airplane had been kept in a dive for several seconds, then power would surge to 2,500 rpm before settling down. She tried several "yo-yo" turns, with pitch up varying between 70 and 90 degrees and entry speeds varying up to 190 knots. The result was a momentary engine "stutter" with normal power returning "virtually immediately." She concluded her letter by surmising that "for unknown but fuel-related reasons, ...the engine failed when [the pilot] was in a steep pull-up for a wingover or loop. [As he] performed a wingover and pulled out close to cornering speed and maximal tolerated G-force, and while he was still slow with the wings still G-loaded, the engine caught and surged, with resultant torque causing a roll into the ground..."

Other than the Federal Aviation Administration, there were no other parties to the investigation.

After the engine disassembly and examination, the wreckage was released to the owner's insurance company on April 23, 2002.

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