WEST PALM BEACH, FL, USA
N32TS
BEECH G35
The airplane was seen flying erratically, in a rapid descent, with smoke coming from the engine compartment and flames coming from the airplane's right side. Subsequently, the airplane crashed/landed and burned. An investigation revealed that the #1 cylinder had separated from the engine. Examination of the #1 cylinder revealed the upper crankcase thru-bolt at the 10 o'clock position had failed in fatigue below the cylinder deck surface. The lower thru-bolt at the cylinder pad's 8 o'clock position was intact; however, the nut was missing and the threads were battered and polished. The cylinder had 6 deck studs in addition to the thru-bolts. The studs at the 11 and 1 o'clock positions were missing; the studs at the 5 and 7 o'clock positions failed in fatigue; and the studs at the 2 and 4 o'clock positions were fractured with the fractured ends battered. Also, a silicon sealant (RTV) had been used on the thru-bolt threads, though not recommended by the manufacturer. The remaining thru-bolts were examined for tightness using a torque wrench; all were found undertorqued. During a top overhaul of the engine, about 85 flight hours before the accident, all of the cylinders had been removed and reinstalled.
HISTORY OF FLIGHT On January 9, 1995, about 1750 eastern standard time, a Beech G35, N32TS, collided with the terrain approximately 20 miles west of West Palm Beach, Florida. The pilot was fatally injured, and the airplane was destroyed. Visual meteorological conditions prevailed, and no flight plan had been filed. The personal flight was being conducted under 14 CFR Part 91. The airplane had departed the Palm Beach County Glades Airport, Pahokee, Florida, at an undetermined time en route to a private airstrip at Wellington, Florida, located approximately 15 miles east of the departure airport. A Florida State Highway Patrol (FHP) Pilot who was flying traffic alert, saw N32TS descending rapidly. The FHP Pilot stated that he had received an alert "...from the onboard TCAD [Traffic Collision Alert Device]." He said the TCAD indicated that there was an air traffic collision threat "less than one mile horizontally, and 500' ft. above my altitude (which was 600' ft. above ground level) over open sugar cane/sawgrass swamp land." As he proceeded in an easterly direction, the target kept closing on the FHP airplane, and although the pilot was searching for the target airplane, he was unable to visually locate the airplane. According to the FHP Pilot's statement: ...I then observed below and behind my left wing a trail of smoke (light blue/gray) in color...the smoke was coming from a dark in color, "V-Tail" Beechcraft Bonanza airplane. The Bonanza was rolling and pitching up and down erratically as it went by me in it's descent. I saw a bright orange glare coming from the airplane's midsection (right side, above the leading edge of the wing). I believe this glare to be flames...the airplane's speed appeared to be excessive, (200 mph) or more, and consistent with it's steep angle of decent. [The airplane] was heading in a northerly direction...and lined up with the L-8 canal. At this point the Bonanza seemed to "pull-out" of it's dive slightly. It then did an instantaneous pitch-up (nose high, 40 to 60 degrees)...to the right in a "wing over" fashion, very abruptly. It began to roll violently, inverted, and in a horizontal "cork screw" fashion. Its altitude appeared to be 100 to 200" feet above ground level. The Bonanza continued to roll past inverted to vertical, then again pitch-up (nose high) very sharply. The plane's direction changed slightly...to an angle slightly left, or northwest, and downward in the corkscrew fashion. The left wing appeared to contact the ground on the east side of the dirt road, (L-8 Canal Bank/Levee). It continued across the dirt road/levee, and came to rest on the west slope of the levee in rough vegetation.... Two men driving east on state road 80, first noticed N32TS flying parallel and to the right of there line of travel. The driver stated: The aircraft overtook us from behind and as it passed us...I noticed a couple of things...the aircraft was flying lower than normal...between 100 and 200 feet above the ground...[and] there was a thin trail of smoke coming from the aircraft...As I watched, the aircraft was blocked from my view...the aircraft came back into view as it banked to its left...a quarter of a mile in front of our vehicle...I could see what appeared to be flames coming from just behind the engine compartment...the aircraft continued in an attitude with the wings perpendicular to the ground and it started losing altitude rapidly as the nose of the aircraft followed an arc toward the ground. The aircraft was in a nose down attitude when it was lost from view.... The accident occurred during the hours of dusk approximately 26 degrees, 41 minutes north, and 80 degrees, 21 minutes west. PERSONNEL INFORMATION The pilot held a Private Pilot Certificate, with single engine land, airplane rating. An FAA Third Class Airman Medical Certificate was issued on July 28, 1993, with the limitation that he must wear corrective lenses. The pilot's log book, showing his total flight hours, was destroyed in the wreckage. According to FAA records, at his last flight physical he had a total of 250 flight hours. Approximately 78 of those hours were in this make and model airplane. AIRCRAFT INFORMATION An examination of the airplane's log books revealed that approximately 85 hours prior to the accident the engine had undergone a top overhaul. This involved; two invoices which referenced the top overhaul, invoice #2050, dated April 29, 1994, work order 1281, indicated that the overhaul was performed. As per repair order, #097128, dated May 5, 1994, the work on the cylinders was subcontracted. According to an engine log book entry dated May 5, 1994, at a total time of 4031.9 hours, the following work was performed on the engine: Removed cylinders...removed con rods [connecting rods] ... miked [sic] crankshaft...replaced rod bgr. [bearings]...all standard new rod bolts...rod nuts...checked hyd [hydraulic] lifters, new push rods housing and clips...cyl [cylinder] per job #1281 Dumont Aircraft Avon Park, [FL]. New +.015 piston...steel cyl. New Superior rings and gaskets...all work per Continental Service Manual E-225...this engine has a complete top ohc. [overhaul]...[signature unreadable] 2009566 A&P.... The Safety Board made several attempts to have the mechanic that performed the top overhaul submit a written statement explaining the procedures he used during the overhaul. All the attempts were unsuccessful. WRECKAGE AND IMPACT INFORMATION The wreckage was examined at the accident site on January 10-11, 1995. All the major components of the airplane were accounted for within the accident site. The airplane impacted in a grassy area west of a north-south dirt road/levee, that was located approximately 100 feet west of a canal that paralleled the dirt road. The dirt road was elevated on a levee approximately 10 feet above the canal. The first ground scar observed along the wreckage path, was located about 10 feet west of the canal and approximately 40 feet east of the dirt road/levee. The ground scar was shallow, and several pieces of the airplane were found in the ground scar. The length of the ground scar was 45 feet and was oriented on a heading of 233 degrees. Additional ground scars were located to the west of the first scar, up the 10 foot embankment, and on the dirt road. The airplane came to rest approximately 390 feet from the first ground scar, and about 10 feet west of the dirt road. The nose of the airplane came to rest in a northerly direction. The cabin area was destroyed by fire damage, rendering all the instruments and switches unreadable. Control continuity was established to all the flight controls through the control cables. The landing gear and flaps were found in the up position. Examination of the engine revealed that it had sustained impact damage. There was no fire damage observed. Oil was observed on the rear of the engine case. The engine and propeller had separated from the airframe and were located approximately 200 feet east of the main wreckage, and approximately 5 feet west of the canal. The number 1 cylinder, piston and piston pin had separated from the engine. The cylinder was found lying on the ground approximately 30 feet southeast of the engine and propeller. There was a hole in the crankcase between cylinders number 1 and 2. The number 2 connecting rod was attached to the crankshaft, and the bushing was missing. The propeller was attached to the crankshaft flange. The blades were bent rearward and did not display any chordwise marks. Both magnetos were still attached, as was the alternator, starter and vacuum pump. The engine was removed from the accident site and shipped to the manufacturer for further examination. TEST AND RESEARCH The engine from N32TS, serial number (S/N) 35913-D-2-8-R, was examined on February 4, 1995, at Teledyne Continental Motor's (TCM) facilities, Mobile, Alabama, under the supervision of an NTSB Investigator. The engine was disassembled and all components except cylinder number 1, displayed no discrepancies. Examination of cylinder number 1 revealed that the thru bolt was broken below the cylinder deck surface. The lower thru bolt was intact, however the nut was missing and the threads on the bolt were battered and polished. There were six studs. Two were broken at the cylinder deck, two were broken outboard (their ends were battered), and the remaining two were missing. The two that were missing were attached to the missing top section of the crankcase. The cylinder deck displayed gouges on one side and the bottom. The cylinder deck surface exhibited fretting. The remaining cylinder thru bolts were examined for tightness using a torque wrench. The manufacture's, "E" Series Overhaul Manual, specifies that the thru bolt torque should be 40.8 to 42.5 foot/pounds (ft/lbs), and cylinder deck studs from 34.2 to 35.8 ft/lbs (torque). The break-away torque on the thru bolts on engine S/N 35913-D-2-8-R, measured from 0 to 25 ft/lbs. The break-away torque on the cylinder deck nuts measured from 0 to 5 ft/lbs. Continental Motor's Metallurgist, Jeff Paust, inspected the broken cylinder deck studs and thru bolts. Mr. Paust determined that the thru bolt at the cylinder pad 10 o'clock position had failed in "fatigue." The thru bolt located at the 8 o'clock position was not broken. The threads on thru bolt located at 8 o'clock were damaged and rubbed. The studs at the 11 and 1 o'clock positions were missing with the missing piece of crankcase. The deck studs at the 5 and 7 o'clock positions also "exhibited fatigue fractures." Examination of the number 1 connecting rod revealed it was bent at the beam section, and the small piston pin end was stretched. The remainder of the piston pin bushing was missing. The connecting rod bolts were elongated. A silicon sealant (RTV) was found around all of the crankcase thru bolt threads. According to TCM, "...the use of RTV sealant on the through-bolts[sic] may have contributed to a relaxation of torque at the cylinder decks...RTV silicon is not a TCM recommended sealant." Magnetos Both magnetos were rotated by hand and spark was observed at all terminals. Vacuum Pump The vacuum pump was disassembled. The driveshaft was intact and no discrepancies were reported. On November 22, 1995, the No. 1 cylinder, pieces of two broken cylinder hold studs, portion of the No. 1 piston head, an a piece of a broken piston ring, were retrieved from Loss Management Services, Orlando, Florida. The parts were received by the NTSB investigator-in-charge, and sent to the NTSB Materials Laboratory, Washington, DC, for further examination. The NTSB Metallurgist's Factual Report stated, that one of the studs contained a "flat transverse fracture with ratchet marks on one side." Ratchet marks are small steps in the fracture that usually separate crack origin areas on slightly offset planes. The fracture on the other stud contained "multiple flat facets" and "had ratchet marks around much of the circumference of the stud." The Metallurgist's Factual Report stated: Fracture features on both of the studs were typical of fatigue cracking that initiated in the thread roots and propagated most or all of the way through the stud cross section before final separation...examination of the piston ring piece and the piston piece reveled no evidence of preexisting fracture areas. The NTSB Metallurgist reviewed the TCM, Engine Teardown Report and concurred with it's findings. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot, January 9, 1995, at the Medical Examiner's Office, in West Palm Beach, Florida, by Dr. Steven Nelson. According to the Medical Examiner's Autopsy Report, the cause of death was, "inhalation of products of combustion." Toxicological tests were conducted at the Federal Aviation Administration's (FAA), Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma and revealed, "no drugs or alcohol." The toxicological tests revealed that "26.000 (%) [Carbon Monoxide] Carboxyhemoglobin [was] detected in Blood." In addition "2.020 (ug/ml) Cyanide [was] detected in Blood." A telephone conversation on September 5, 1995, with Dr. Dennis Canfield, Manager, FAA Toxicology and Accident Research Laboratory, reference the Carbon Monoxide and Cyanide found in the blood, Dr. Canfield said, "the pilot was inhaling carbon monoxide from fire coming into the interior of the airplane." He calculated that both doses indicated on the toxicological report were "sufficient to cause death and were lethal." ADDITIONAL INFORMATION The airplane wreckage was released to Steve Smalley, representing the owner's insurance company, on January 11, 1995.
Improper top overhaul by maintenance personnel, and improperly torqued crackcase thru-bolts and cylinder deck studs at the number one cylinder, which led to fatigue failure of four of the bolts, failure and/or separation of the number one cylinder, and a subsequent fire.
Source: NTSB Aviation Accident Database
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