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N506SD accident description

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Tail numberN506SD
Accident dateMarch 21, 1998
Aircraft typeCessna U206G
LocationGrain Valley, MO
Additional details: None

NTSB description

HISTORY OF FLIGHT

On March 21, 1998, at 1752 central standard time, a Cessna U206G, N506SD, piloted by a commercial pilot was destroyed during a collision with the ground and post-impact fire. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 parachute jump flight was not operating on a flight plan. The pilot and five parachute jumpers were fatally injured. The flight departed Independence, Missouri, exact time unknown.

The pilot of N506SD contacted the Federal Aviation Administration's (FAA) Kansas City International Airport approach controller at 1740:22. The pilot referred to his flight as "...Skydive Six." The controller told the pilot that his airplane was 4-miles northeast of the Independence, Missouri, airport. He asked the pilot to "...say your request." N506SD's pilot did not respond. The controller made three more attempts to contact the pilot.

During the third radio transmission to N506SD the controller repeated his earlier position report and advised the pilot of air traffic. At 1741:23, N506SD's pilot responded, "...Skydive six going to one one thousand." At that time radar data showed N506SD was at 3,000 feet above mean sea level (msl). Times between the radio contacts were filled with wind and engine noise according to the FAA records.

At 1749:39, the FAA record reflects the controller heard engine and wind noise again from an unknown source. Fourteen seconds later, the record showed, an unknown source said, "What the .... was that?" At 1750:24, the report showed that the engine and wind noise ended. The controller called N506SD's pilot at 1750:54. The pilot responded, "...skydive six is, uh, cancelling, uh jumps operations." The controller responded, "...roger and I think you got a little...button sticking on your mike every now and then, I'm getting a hot mike from you." There was no further response from N506SD's pilot. At 1750:55, radar showed N506SD was flying at 3,700 feet msl. According to the radar data, the highest altitude N506SD had flown to was 5,200 feet msl.

A witness located about 8-miles northeast of the accident site said, he saw the airplane about 1-mile south of his position. He said the airplane "...was trailing a heavy stream of white smoke..." as it was heading west about 2,000-feet above the ground. He said his wife observed the white smoke and "...instances of black smoke mixed within the white steam." This witness said he observed the airplane fly out of sight trailing the smoke.

A witness about 2-miles north of the accident airport said he observed the airplane flying south-southwest over his property about 500-feet above the ground. As N506SD passed over the witness, he said its engine was making a banging sound and had black smoke coming from the engine cowl area.

Two witnesses at the Grain Valley Airport, Grain Valley, Missouri, said they observed N506SD approaching from the northeast about 100-feet above the ground. According to these witnesses, the airplane had flames exiting the engine cowl's top rear area. These flames were going up the windshield. One witness reported that he saw two bright lights that "...looked like flares falling from [the] plane as it went past us... ."

A third witness at the accident airport said he saw the airplane flying about 150-feet above the ground. As it passed his position he said "...it started to smoke heavy off the right side. The smoke was dark black at first, then turning a light yellow or brown color." He said the airplane rolled to the right, pitched down, and dropped from his line of sight. Several other witnesses reported that N506SD had approached the airport with white and black smoke coming from its cowling. As the airplane descended toward the airport, they reported seeing black smoke and orange flames coming from the cowl.

Other witnesses said the airplane flew low over a tree line paralleling the east-west oriented Gateway Western Rail Road tracks on the airport's south boundary. They said the airplane appeared to bank to the right at a low altitude. Witnesses reported that the right wing struck the ground, the airplane cartwheeled, and came to rest on fire.

PERSONNEL INFORMATION

The pilot possessed a commercial pilot certificate with single and multi-engine land airplane ratings. The certificate was issued on July 6, 1971, according to an FAA Form 8060.4, Temporary Airman Certificate, found in one of the three logbooks made available by the family for review. According to FAA records, the pilot did not possess an instrument rating. His commercial pilot certificate priviledges were limited to visual flight rules operations.

One logbook showed the pilot had flown 1,848.8 total hours between July 16, 1969 and December 31, 1979. A second logbook, dated between January 16, 1975, and September 14, 1985, showed he had a total time of 2,947.6 hours. The third logbook had one entry in it showing successful completion of a flight review on August 16, 1992, in a Cessna 172. This logbook showed a second flight review entry that was successfully completed in a Cessna 182. The entry did not show the date of the flight review. There were no other written or flight time entries found in this logbook. According to FAA records, the pilot obtained an airplane type rating in a Lockheed L-18 on May 6, 1994. Excerpts of the pilot's logbook are appended to this report.

AIRCRAFT INFORMATION

N506SD's airframe logbook showed its annual inspection had been completed on November 5, 1997. At that time, the airplane had 7,280 hours on its airframe. A copy of the logbook is appended to this report.

N506SD's engine had been overhauled on March 8, 1991, by Mid- States Aircraft Engines, Incorporated, located in Tulsa, Oklahoma. On May 29, 1994, Air Repair, Incorporated of Cleveland, Mississippi, reported that the N506SD's engine crankcase was unairworthy because it was "...cracked at forward left through bolt and leaking oil." On June 7, 1994, John Jewell Aircraft, Incorporated of Holly Springs, Mississippi, installed a "...certified crankcase..." on the engine. It was returned to service. Copies of the engine logbooks are appended to this report. The engine was installed on N506SD's airframe on July 15, 1995. At that time the logbook showed it had 774 hours since major overhaul.

WRECKAGE AND IMPACT INFORMATION

N506SD's main wreckage was located about 60 feet north of the east-west railroad tracks that border the airport's south boundary. About 60 feet east of N506SD's main wreckage was a depressionj in the ground measuring about eight feet in diameter and six to 10 inches deep. The depression had burnt earth and vegetation in and around its perimeter. This area contained small pieces of aluminum and plastic that had been damaged by fire. The Cessna party member identified components of the nose landing light assembly in this area. About 40 feet east-southeast of the ground depression a ground scar, about 30 feet long, varying in width between 18 and 10 inches, was observed. The scar varied between eight and three inches in depth. The Cessna party member identified components from the right wing tip at the ground scar's starting point. About 160 feet southeast of the ground scar's beginning, freshly broken trees limbs were observed at the tops of trees that were about 30 feet high. Pieces of the trees were found along the railroad track embankment and around the damaged trees.

Examination of N506SD's wreckage revealed the left horizontal stabilizer's top and bottom surfaces were oil covered. Fragments of 1/4 inch thick clear plexiglass were found with the convex curved side covered with a thin film of oil and soot. Oil streaks were observed on the top and bottom of the left wing's main strut. Oil streaks were observed on the left wing's lower surface from the wing strut junction point inboard to the wing root.

N506SD's engine mount and firewall were oil covered. The left exhaust system muffler was covered with an oil film. The engine's oil filler tube was not mounted on the engine. Examination of the three screw holes that attach the oil filler tube to the crankcase revealed no pulled threads in one hole and pulled threads near the top of the hole on the other two holes. The three filler tube mounting screws were not found during a search of the accident site. Five of the six valve cover screws were missing from number six cylinder valve cover. The remaining screw was lose. Number six cylinder bottom spark plug lead was not attached to the spark plug. The spark plug lead was hanging from its cowl baffle mount. The threads on the sparkplug attaching nut were not striped. The number two and four cylinder valve covers had one screw missing from each assembly.

Flight control continuity was established for all three axes. The landing flaps were retracted. The propeller governor control arm showed the propeller was in the high RPM setting. The fuel tank selector was found in the left fuel tank "ON" position. The selector valve rotated to all positions. Air flowed through the valve when selected in the "Right" or "Left" position. No air flowed through the valve when it was in the "Off" position. The fire damaged fuel boost pumps' impeller and armature rotated.

The engine had been involved in a post-impact fire. Examination of the engine was conducted at Teledyne Continental Motor's Factory in Mobile, Alabama, on May 19, 1998. Both front engine mount legs had fractured. The edges of the fracture had shear lips and the fracture surfaces were grainy in appearance. Both magnetos were fire damaged as were their respective spark plug leads. The oil sump was crushed inward toward the engine's case and punctured on its right side. The rubber induction hoses were fire damaged. The right exhaust pipe was crushed against the engine's cylinder barrels.

The engine oil sump had metallic debris in it. This debris was identified by the Continental party member as pieces of connecting rod, connecting rod cap, and piston.

The engine oil pump gears and respective cavities were scratched. Pieces of metallic debris were in the oil pump cavity. The oil pickup tube was partially obstructed by metallic debris. The oil pressure relief valve had a piece of melted aluminum in its cavity. About 70 percent of the oil screen's area was covered by silver and bronze colored metallic debris.

All cylinder bores exhibited fire damage. Cylinders number one, two, five, and six had cutting and denting damage to their lower skirt sections. Pistons number one and five had impact marks on their domes and sides. Pistons two and six had cuts and dents along their bottom edges. Pistons number three and four had deep skirt scoring.

The piston rings were all free in their respective ring grooves. Number four piston had its piston pin plug rolled over its edge and its surface was scored.

The crankcase's main bearing journals were scored and had varying intensities of black, blue, bronze, and silver coloring on them. The bearings were loose in the bearing bores and would no longer snap into place. The crankcase's parting surfaces were fretted at the number two and three upper bearing bosses. Crankshaft rod journals for number two and six cylinders were partially melted. Holes were observed on the engine's left crankcase section near cylinders number two and six.

Connecting rods number two and six were not attached to the crankshaft. Both connecting rods were colored black and blue in varying intensities. The connecting rod bearings for cylinders number one, three, four and five were scored and worn down to their base metal. The crankshaft counterweight's movements were free and unrestricted.

The valve lifters were found seized in their bores. The faces of the lifters were not spalled or fretted. The camshaft at the front governor gear support was fretted. Its lobes were smooth. The propeller governor screen was removed and had metallic debris in it. Oil sludge contaminated with metallic debris was found at the starter adapter needle bearing, the camshaft bore plate on the crankcase nose, and the propeller shaft inside bore.

MEDICAL AND PATHELOGICAL INFORMATION

The pilot's autopsy was conducted on March 23, 1998, by Dr. Sam P. Gulino, Deputy Medical Examiner of Jackson County Missouri. The FAA's Civil Aeromedical Institute conducted the toxicological examination on the samples provided by the medical examiner. The toxicological report stated "Pseudoephedrine and phenylpropanolamine [were] detected in the urine." No other drugs were reported. According to the 47th Edition of the Physicians' Desk Reference, both drugs are part of over-the- counter cold remedies.

FIRE

Witnesses observed and described an inflight fire in the engine compartment area. The on-scene and engine teardown examination at the manufacturer confirmed their statements. The wing fuel tanks ruptured, ignited, and burned.

SURVIVAL ASPECTS

According to the Jackson County Missouri Medical Examiner, three of the airplane's occupants cause of death was "Smoke Inhalation." The medical examiner's report says that the remaining three occupant's cause of death was "Smoke inhalation and blunt trauma."

TESTS AND RESEARCH

The NTSB's Office of Research and Engineering Materials Laboratory examined components from the engine. The Materials Laboratory factual report said, "Initial examination [of the parts] revealed [they] were darkly discolored and covered with soot, indicitive of exposure to elevated temperatures and fire."

The report said "The fracture face on the [number six] rod cap...[was] relatively smooth and contained crack arrest positions indicitive of fatigue propagation. The fatigue cracking originated on the bearing surface of the cap... ." The report continues, "...the fracture features were typical of an overstress separation stemming from the terminus of the fatigue fracture zone. Examinations revealed that portions of the fracture adjacent to both the exterior and interior surfaces of the connecting rod piece contained crack arrest positions and ratchet marks, features typical of fatigue cracking. Examination of the bearing surface revealed severe rotational scoring and galling."

According to the report, "The location of the [number two rod end] separation and fracture features in this piece were similar to the rod arm fracture in the number six connecting rod. The fracture surface outside the fatigue fracture zones had features typical of an overstress stemming from the termini of the fatigue fractures. The bearing surface contained evidence of rotational scoring and galling."

"The [number] 2 rod end [bottom]... appeared to be a severely deformed (flattened) piece of a separated connecting rod cap... ." The report said "The submitted piece of cap was subjected to severe post separation mechanical damage, as was evident from the amount of score and impact marking throughout its entire surface. This damage destroyed most of the fracture face; however, examination at higher magnifications showed features indicating that the cap had separated after very few stress cycles."

The section of the engine's left crankcase that had the oil filler tube opening in it was examined. The report said "...that two of the three holes that secure the oil filler neck to the crankcase were damaged." One hole "...exhibited stripping damage to approximately two threads adjacent to the [exterior] surface [of the crankcase]. It was noted that the edge of this hole was deformed as if by sliding motion of the bolt. The [second] hole... exhibited stripping damage to several threads towards the aft part of the engine. No apparent damage was noted in the third hole. All fractures in the submitted piece of the crankcase were typical of an overstress." A copy of the report is appended to this report.

ADDITIONAL INFORMATION

Parties to the investigation were the Federal Aviation Administration Flight Standards District Office, Kansas City, Missouri, Cessna Aircraft Company, Wichita, Kansas, and Continental Engines, Mobile, Alabama. The wreckage was released on March 24, 1998, to a representa

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