HISTORY OF FLIGHT

On February 15, 2000, at 2024 hours mountain standard time, a Cessna T210M, N761KC, collided with ground obstructions and nosed over during a forced landing near Elfrida, Arizona. The forced landing was precipitated by a catastrophic engine failure during cruise. The airplane was operated by the Department of the Treasury, U.S. Customs Service, as a public-use airplane under 14 CFR Part 91 of the Federal Aviation Regulations. The airplane sustained substantial damage. The two pilots, the sole occupants, were not injured. Visual meteorological conditions prevailed and a company visual flight rules flight plan was filed. The flight originated from Davis-Monthan Air Force Base, Tucson, Arizona, at 1940 as a training flight.

According to information provided by the U.S. Customs Service and the pilots, the flight left the US Customs Tucson Air Operations base at Davis-Monthan AFB for a training flight in the Douglas, Arizona, area. No discrepancies were noted with the run-up at Davis-Monthan AFB or until the engine problem happened. The pilot said he was at 5,100 feet msl and using a power setting of 30 inches of manifold pressure and 2,600 rpm. Both pilots heard a loud bang, like a hammer hitting the inside of the engine, which was followed by severe vibrations and sparks emanating from the front of the airplane. According to both crewmembers, the vibrations were constant; however, when the pilot powered back the vibrations seemed to intensify. The pilot reported that from the sparks he thought they might have lost a portion of a propeller blade and began looking for a place to land. They were over a highway running through a built up area, but the pilot considered that there was a likelihood of power lines over and around the highway. They saw a dirt road reflecting in the moon light and set up for a landing there.

On short final to the road, the pilot had to maneuver to the left in order to miss a large tree on the right-hand side of the road. As the pilot maneuvered back to the center of the road, the right wing began to contact trees on the roads right shoulder, which slued the airplane into a drainage ditch. It contacted a barbed wire fence and several other trees, and then nosed over.

Ground witnesses reported observing sparks emanating from the cowl area as the airplane descended toward the road.

Gross external visual assessment of the engine disclosed a large hole in the engine case on each side of the upper spine between the numbers 1 and 2 cylinders and a quantity of oil on the fuselage from the firewall aft to the tail.

PERSONNEL INFORMATION

The pilot holds a commercial pilot certificate with airplane ratings for single engine land, multiengine land, and instruments, and also ratings for rotorcraft helicopters and instrument helicopter. In addition, his certificate is endorsed for private privileges in gliders limited to aero tow only. The most recent issuance of the certificate was August 8, 1998. The most recent second-class medical certificate was issued on October 11, 1999, without limitations. He is employed by US Customs as a pilot and flies both fixed wing and helicopters for the service. The pilot's total time was 4,151 hours, of which 3,395 were accrued in helicopters, with 22 hours in the Cessna T210. His total night experience was 722 hours. According to US Customs records, he completed a standardization check ride on October 23, 1999, which also covered the requirements of a biennial flight review. In addition, he completed an instrument competency check and a check out in the Cessna T210 on February 3, 2000.

The second pilot is also employed by US Customs as a fixed wing and rotorcraft pilot, and holds an Airline Transport Pilot certificate with an airplane multiengine land rating and type ratings for the Beech 200 and Cessna 500. In addition, his certificate is endorsed for commercial privileges in single engine land airplanes, rotorcraft helicopters and instrument helicopters. His most recent first-class medical certificate was issued without limitations on May 13, 1999. According to Customs records, he has accrued a total time of 1,950 hours, of which 550 were in helicopters, with 18 in the Cessna T210. His most recent US Customs standardization check ride was accomplished on August 30, 1999, in a Cessna 550.

Both pilots were wearing shoulder harnesses; however, they did not have helmets.

AIRCRAFT INFORMATION

The Cessna T210M aircraft, serial number 21062308, was operated by US Customs and maintained on an annual/100-hour inspection program. A contractor, Raytheon Aerospace Company, a Federal Aviation Administration (FAA) certificated Repair Station, performed the maintenance on the aircraft and engine at the Tucson Air Branch base, and at a facility in Phoenix, Arizona.

The maintenance records were reviewed. At the time of the accident, the airframe had accumulated a total time in service of 5,579 hours. The airplane flew approximately 30 hours per month on a historical average. A 100-hour inspection was completed on the morning of the accident at the Phoenix maintenance facility. The aircraft was then ferried down to the Tucson base and was dispatched on the accident flight. The records disclosed that there were no unresolved maintenance discrepancies or open items at the time of departure.

The airplane was refueled prior to departure on the accident flight from a USAF truck with 100LL aviation gasoline. Fuel samples were taken from the refueling truck and from the aircraft, and sent to the USAF laboratories at Wright Patterson AFB for analysis. The sample from the truck met specification ATSM D-910 for 100LL aviation gasoline. The sample from the aircraft wing tank met all specifications except for sulfur content, which exceeded the maximum allowable percent/mass by 0.14.

The historical maintenance and rebuild records for the engine were examined. The Teledyne Continental TSIO-520-R engine, serial number 293964-R, was rebuilt by the Continental factory to zero time tolerances on March 20, 1998. The engine was then shipped to Raytheon Aerospace Services and installed in N761KC on May 15, 1998, at an airframe total time of 5,106 hours. A 100-hour inspection was completed on the engine on the morning of the accident.

FAA Priority Letter Airworthiness Directive (AD) 99-09-17 was issued on April 22, 1999, and mandated compliance with Teledyne Continental Motors Mandatory Service Bulletin (MSB) 99-3 for specific engines identified by serial number. The accident engine was subject to both the AD and the MSB. AD 99-09-17 was subsequently superceded by AD 99-19-01 on September 30, 1999; however, the applicability provisions remained the same.

The AD and the MSB were issued due to a history of 8 crankshaft failures (the 8 fractured crankshafts were as of July 27, 1999), which were traced to a Teledyne Continental factory manufacturing process involving the installation of crankshaft counterweight bushings on the crankshaft counterweight hangar blade. According to the MSB, the manufacturing process discrepancy produced a condition, which induced a crack and catastrophic fracture of one or more crankshaft cheeks. The AD and MSB required visual and ultrasonic inspections of the identified crankshafts for cracks. The AD and MSB mandated that these inspections be accomplished by Teledyne Continental factory service representatives.

Three versions of MSB 99-3 were eventually issued: 99-3A was issued on April 22, 1999; 99-3B superceded 99-3A and was issued on July 6, 1999; 99-3C was issued on July 27, 1999, and superceded 99-3B. All three versions of MSB 99-3, and AD's 99-09-17 and 99-19-01, are appended to this report for reference. An additional Teledyne Continental Service Bulletin, SB 00-3, and pertinent pages from the TSIO-520 overhaul manual are also appended to provide the reader with illustrations of the parts and components referenced herein for clarity. Continental SB 00-3, which was issued on February 2, 2000, provided detailed and specific procedures for the reinstallation of crankshaft counterweights, including the correct orientation and installation of the counterweight pins, retainer plates, and snap rings.

In pertinent part, the TSIO-520 crankshaft is designed to incorporate four counterweights, which are installed on hangar blades extending out on each side of the numbers 2 and 5 crank cheeks (CC). The number 2 crank cheek is between the number 1 and 2 rod journals (RJ) at the rear of the crankshaft. The number 5 crank cheek is located between the number 3 and 4 rod journals. The hangar blades are on each side of the designated crank cheeks. With the number 1 rod journal at the 12 o'clock position and looking forward from the rear of the crankshaft, the hangar blade nomenclature is as follows: 1) the blade on the right side of CC2 is the number 2 leading blade and the counterweight is the number 2 leading weight; 2) The blade on the left side of CC2 is the number 1 trailing blade and weight; 3) The blade on the upper side of CC5 (CC5 is nearly horizontal with the No. 1 RJ at 12 o'clock) is the number 4 leading blade and weight; and 4) the blade on the lower side of CC5 is the number 3 trailing blade and weight.

The crankshaft counterweight hangar blades have two holes bored, and bushings are pressed into these bores. The weights have corresponding holes bored with bushings pressed into them and are retained on the blades by pins, which extend through the blade bushing and into the weight bore bushings. The pins are held in the bores by counterweight pin retaining plates placed in the bores on each side of the weight. These plates are slightly elliptical on one edge of the circumference, which forms an ear that results in an interference fit within the bores of each weight. The plates are held in place by snap rings that fit into separate grooves machined into the weight bores. The weights attached at each blade are specific part numbers for that position, and each weight requires specific part numbered pins for that particular weight. The weights must be installed on opposing blades as a matched set of equal weight and with the same part number.

Continental SB 00-3 specifies that the pin retainer plates and snap rings must be installed in specific orientations within the bores; the plate ears must point outward away from the crankshaft centerline and the snap ring ears must face inward toward the crankshaft. One side of the snap ring has a sharp beveled edge, which must point away from the weight. For the snap ring to be fully seated in the groove, a minimum dimension of 0.179 inches must separate the snap ring ears. Review of the precursor service bulletins to SB 00-3 disclosed that it was the first one to detail and emphasize the criticality of the retainer plate and snap ring orientations within the bores, and provide a measurement between the snap ring ears when the ring is fully seated within the weight bore. The engine overhaul manual does not go into specific detail regarding the orientation of the pin retainer plates and snap rings within the counterweight bores, nor does it provide a measurement of the snap ring ears to verify full seating of the ring.

All three versions of MSB 99-3 require that cylinders 1 and 3, and their associated connecting rods, be removed to facilitate the visual and ultrasonic inspection of the crankshaft cheeks Nos. 5 and 2 associated with the counterweight hangar blades on those cheeks. Following the cylinder and connecting rod removal, all four crankshaft counterweights must be removed to fully expose the area to be inspected. The principal difference between MSB 99-3A, and versions 99-3B and 99-3C, is that versions B and C incorporate the guidance on counterweight pin retainer plate and snap ring installation found in SB 00-3. Versions 99-3B and 99-3C specifically emphasize the 0.179-inch dimension between snap ring ears when the rings are fully seated in their grooves.

Review of the maintenance records and Raytheon work orders disclosed that AD 99-09-17 and MSB 99-3A were complied with on this engine on May 4, 1999, 220 hours prior to the accident, at the Raytheon maintenance facility in Phoenix. Recall that revision "B" of MSB 99-3 was not issued until July 6, 1999. A Raytheon mechanic prepared the engine by removing cylinders 1 and 3 and the associated connecting rods. When the Teledyne Continental representative arrived to perform the visual and ultrasonic inspections of CC2 and CC5, the mechanic removed the counterweights. Following the inspection, the mechanic reinstalled the weights, connecting rods, and cylinders. According to the mechanic who performed the job, the work was inspected by a Raytheon inspector at each stage and signed off on the work order.

Investigators noted during teardown of the engine that all the work related to the removal and reinstallation of the weights on the crankshaft blades would have to have been accomplished through the 5.5-inch diameter cylinder base openings for the Nos. 1 and 3 cylinders in the crankcase. The weight bores and the retaining plate snap rings would be perpendicular to the openings and only clearly visible with the aid of inspection mirrors. The crankshaft counterweights are not typically removed or reinstalled in the field, and this work is usually performed in overhaul facilities with the crankshaft out of the engine.

The mechanic, the inspector, and the Teledyne Continental service representative were interviewed, and they also submitted written statements. In addition, the Raytheon Chief Quality Control Inspector at the Tucson maintenance base was interviewed.

The chief quality control inspector said that as part of his duties he maintains the various maintenance documents for the aircraft maintained at the facility. When Airworthiness Directives or Manufacturers Service Bulletins are received, he determines applicability and schedules the work to be done. When AD 99-9-17 and Continental Mandatory Service Bulletin 99-3 came, he determined that it was applicable to N761KC by engine serial number. Coordination was done to schedule the crankshaft inspection with Continental. He prepared the work order package for the Phoenix facility. The package would have consisted of a work order (subsequently identified as Work Order 990768, which is appended to this report) specifying the work to be performed, copies of the AD, MSB, and all other relevant references, plus a kit of parts anticipated for the work. By checking the maintenance document revision log, he determined that version 99-3A of the Continental Mandatory Service Bulletin would have been sent in the package.

The mechanic who performed the work in Phoenix holds a FAA Airframe and Powerplant Technician certificate and a FAA Inspection Authorization. He is also a designated inspector for Raytheon Aerospace. The mechanic recalled doing the work specified in the work order concerning the crankshaft inspection. He stated that prior to the Continental representative arriving, he prepped the engine by removing cylinders one and three, including the pistons and connecting rods, in order to gain access to the affected counterweights. When the Continental representative arrived, the snap rings and retainer plates holding the counterweight pins were removed with the aid of snap ring pliers and a small hook end scribe. The counterweight pins and the weights were then removed. The Continental representative performed the ultrasonic inspection of the crankshaft. As each throw of the crankshaft was inspected, he put the weights and pins back on the weight blades. He stated that the snap rings and pin end retainer plates were new parts supplied in the inspection kit and he installed them with the Continental representative watching his actions. He said that at each step of the counterweight reinstallation, he had the Continental technical representative verify that the installation was complete and correct. He specifically asserted that he installed the snap rings with the sharp edge out and had the Continental representative verify that the snap rings were correctly installed. When the inspection was completed and the counterweights reinstalled, the Continental representative left the facility and he (the mechanic) went home. The next day, he reinstalled the connecting rods, cylinders, and other components to complete the restoration of the engine, and torqued each nut and bolt to the specifications in the maintenance manual. The company inspector at the Phoenix facility performed the inspection on the work at each stage per company policy, and the aircraft was returned to service.

The Raytheon inspector at the Phoenix facility holds a FAA Airframe and Powerplant Technician certificate and a FAA Inspection Authorization. He stated that he was present when the mechanic was doing the work for the crankshaft inspection and he watched the entire process. He reported that the Continental representative did verify that the snap rings and pin retainer plates were installed correctly as the counterweights were put back on the crankshaft blades. He then inspected that work and each stage of the engine restoration the next day. He then placed his inspection stamps in the appropriate places on the work order and signed off on the document for the return to service of the aircraft.

The Teledyne Continental Motors technical representative who performed the inspection on the crankshaft said he does not specifically recall this particular engine. His records show that he inspected six crankshafts that day at different airports in the Phoenix area. He said he does remember that the mechanic had a lot of trouble pulling the pin retainer plates out of the counterweight bores and he helped him make a special tool. He emphatically denied that he inspected, verified, or approved the counterweight reinstallation performed by the mechanic. He stated that it was a normal course for him to emphasize to the mechanics performing the reinstallation the importance of getting the snap rings fully seated and in the correct orientation.

METEOROLOGICAL INFORMATION

The closest aviation weather observation station is at the Douglass-Bisbee International Airport, about 17 miles south east of the accident site. At 2051, the station was reporting clear skies; visibility 30 miles; temperature 55 degrees Fahrenheit; and dew point 16 degrees Fahrenheit.

A Safety Board computer program was used to calculate the position of the sun and moon at the time of the accident. According to the program calculations, nautical twilight ended at 1904, and astronomical twilight ended at 1932. The moon was on a magnetic bearing of 118 degrees and was 75 degrees above the horizon. Eighty-four percent of the moon's disk was illuminated.

WRECKAGE AND IMPACT

The accident site is on the eastern outskirts of the town of Elfrida, on Gleason Road, an east/west-oriented dirt road. The aircraft was found inverted with the tail pointing east. It was located about 16 feet south of the south edge of Gleason Road, and 60 feet from the intersection of Gleason and Mormon Roads. Gleason Road was measured at 25 feet wide. The south edge of Gleason Road consists of a drainage depression running parallel with road, about 16 feet wide, which terminates on the ditch's south edge with a barbed wire fence. The fence is about 4 feet tall and is supported by metal stanchions. Looking west from the aircraft along the road, a series of Mesquite trees/brush of varying heights were located in the ditch and along the south border of the ditch.

Within a distance of about 150 feet west of the aircraft, nose wheel components, disturbed brush and mesquite trees, and disrupted barbed wire fencing was found. About 305 feet west of the aircraft, a mesquite tree was found with a disturbance to the upper branches; the disturbance was noted at a height of 8 to 9 feet above ground. A large 25-foot-tall mesquite tree was noted 150 feet further west of the disturbed tree and 10 feet south of the road's south edge; no upper branch disturbance was observed. A larger 30-foot-tall mesquite tree was observed 72 feet west of the last tree and 25 feet south of the roads south edge.

The nose landing gear was sheared off and located about 110 feet west of the fuselage. Both main landing gear remained attached to the fuselage. The right gear door was detached from the airplane, and the left was still attached.

The bottom of the airplane from the nose section to the under side of the tail section showed a flow line of oil. There was no oil present on the upper side of the fuselage, empennage, or tail section.

Skin wrinkles were noted on the fuselage's right side just behind the rear window. The right elevator's leading edge was crushed over the outboard 2 feet, with the mass balance weight housing accordioned. The top of the rudder was crushed downward; however, the beacon light remained intact. The outboard 3 feet of the left elevator leading edge exhibited a crushed area about 1 inch wide and 3 inches long. Both wings exhibited leading edge damage and chordwise crushing.

A barbed wire fence stanchion penetrated the bottom right side of the fuselage near the forward edge of the right-hand door. The stanchion penetrated vertically into the cockpit and lodged in the right-hand edge of the second pilot's seat. A second barbed wire fence stanchion penetrated the left wing from top to bottom between the left main fuel cell and the rear spar.

The McCauley D3A34C 402-C propeller, hub serial number 922417, remained attached to the crankshaft. All three blades were loose in their clamps. One blade exhibited a smooth 30-degree forward bend, with leading edge nicks and a mixed pattern of chordwise, spanwise and diagonal scratches. The second blade was straight, with a similar pattern of faint mixed directional scratches. The third blade was curved smoothly aft and exhibited leading edge nicks, paint removal, and a pattern of mixed directional scratches. No appreciable leading edge damage was noted on any blade. The spinner nose was crushed rearward without torsional deformation. The propeller governor was found in the full aft position; however, one control cable clamp was found broken and the cable was bent and distorted into a 'U' shape.

TESTS AND RESEARCH

The wreckage was recovered from the accident site and transported by truck to the Tucson Air Branch maintenance facility for detailed examination of the engine.

The upper engine cowling was removed. Oil was deposited over the inside surface of the upper cowling and engine, with no oil evident aft of the baffling on the accessory section or firewall. The bottom inside of nose section cowling was covered in oil. There was no oil observed on the outside or inside of the exhaust risers.

A piece of rod end cap, subsequently identified as the No. 2, was found loose in the nose cowling area. A nut, cotter key, and a section of one bolt remained in place. The bolt was not stretched or necked. The bolthole was elongated to the side, with the corresponding bolt fracture face exhibiting shear characteristics. No evidence of heat discoloration was noted.

All of the spark plugs were Champion RHB32E; the No. 2 cylinder plugs were oil fouled and the rest exhibited oil deposits. Oil was present inside the rocker box covers. The engine could not be rotated. Both magnetos, which are mounted on drive pads directly above the previously noted upper case breach, were broken from their mounts. Main fuel line to the engine driven pump was sheared off and the fitting was broken. The scavenge oil pump fitting was broken at the pump. Fresh oil was found in the end of the breather tube.

The oil pan was removed from the engine. Prior to removal it was observed that the pan had two gashes in the bottom and several inside to outside impact dents. A damaged and battered connecting rod, pieces of rod end cap, rod bolts with nuts and cotter keys were found in the oil pan along with other parts and components. With the assistance of a technical representative from Teledyne Continental Motors, the oil sump contents were subsequently identified and inventoried as follows:

1. A crankshaft counterweight (in pieces) bearing part number 639195, which is a 6th order weight mounted on crank cheek 2 as the leading weight (refer to the AIRCRAFT INFORMATION section for a description of counterweight nomenclature). 2. 2 Crankshaft counterweight pins, part Nos. A101 and A103. The A101 pin is for the 6th order weight in the aft or trailing pin bore. The A103 pin is for the 4th order weight forward or leading pin bore. 3. 4 Counterweight pin retaining plates 4. 5 counterweight retaining plate snap rings 5. Broken pieces of bushings identified as from both the counterweight bores and the crankshaft counterweight hanger blade bores. 6. Broken piston pieces 7. Sections of broken piston rings 8. One wrist pin 9. Pieces of rod bearing journal shells. 10. Pieces of material similar to cylinder skirt. 11. 2 lifters and bits of case material

Of the four recovered counterweight pin retaining plates from the oil sump pan, two were bent and distorted and two were not damaged or distorted. For the recovered pin retaining plat snap rings, three were distorted and two were not; the undistorted snap rings measured 1.79 inches in diameter, which is the nominal measurement for serviceable rings.

During disassembly of the engine, the condition of the three remaining counterweight assemblies were documented as follows:

The No. 1 trailing weight on crank cheek 2 remained attached to the blade and had semi-free movement on the pins. The forward or leading pin bore in the weight was peened and distorted, and had jammed the snap ring (which was visibly distorted) and pin retaining plate in the bore. The weight was stamped with part number 639195, which is a 6th order weight and matches the weight from the opposite side recovered in the oil pan. All snap rings are mounted in the bores with the ears or points pointing in toward the crankshaft in accordance with SB 00-3. During removal of the weight from the crankshaft, the pins were found to be A101's.

The No. 2 leading counterweight was recovered in pieces in the oil pan and documented above. The trailing corner of the counterweight hanger blade on the crankshaft was torn off through the bore; the fracture zones were peened over with mechanical damage. Leading pin bushing remained in place in the blade bore.

The No. 3 trailing weight on crank cheek 5 was stamped with part number 639196, and was partially retained on the hangar blade by the forward pin. The aft pin was missing. One side of the aft or trailing bore snap ring and retaining plate were also missing. The missing snap ring was recovered in the oil pan. The missing retaining plate was found during a subsequent search of the engine compartment; the plate had mechanical damage on a portion of the outer circumference. The bushings remained in both the weight and hangar blade bores. The exterior outer circumference exhibited mechanical peening and smearing damage. The forward or leading pin was in place and retained by its associated retainer plates and snap rings. One snap ring is installed with the ears pointing in toward the crankshaft and one ring is installed with the ears pointing out. During removal of the weight from the crankshaft hangar blade, the forward pin was noted to be part number A103. The counterweight was a part number 639196.

The No. 4 leading weight on crank cheek 5 remained on its hangar blade. All snap rings and retainer plates were intact and installed in accordance with SB 00-3. The exterior circumference of the counterweight exhibited mechanical peening damage. The counterweight moved freely on the pins. During removal of the weight from the hangar blade, the pins were noted to be part number A104's. The counterweight is a part number 639196.

Scoring was noted on the inside of the oil pump housing. Small pieces of metal were found on the driven and driver gears. The oil cooler was clean and contained no debris on the outside or on the inside. The scavenge pump fitting was broken. Metal debris was found inside the oil filter.

All accessory drive gears were undamaged. A gear from the vacuum pump was found free and in the front of the nose section.

The turbocharger was disassembled for examination. The compressor impellor and housing were unremarkable. The turbine was found to turn freely in its housing and no debris was observed in the exhaust gas path.

All of the cylinders were removed. On cylinder Nos. 1 and 2, the through bolts were not tight; however, a large portion of the upper case on each side of the spine was missing in-between those cylinders on the crankcase. Torque paste was in place on cylinder Nos. 3, 4, 5, and 6. Cylinder No. 6 was intact and without skirt deformation. Skirt pieces were missing from cylinder No. 4. Deformation and peening was observed to the skirts of cylinders Nos. 1, 2, 3, and 4. All cylinder barrels exhibited combustion deposits on the cylinder domes. No evidence of detonation or pre-ignition was noted.

The No. 1 piston skirt was broken and oil residue was present in the piston bottom. The No. 3 piston skirt was broken. The No. 2 piston and connecting rod could not be removed from the cylinder barrel due to the cylinder skirts deformation. Pieces of the No. 2 piston were missing and the piston connecting rod was broken at the crankshaft journal end. The No. 4 piston skirt was broken. The Nos. 5 and 6 piston skirts were undamaged.

The serial numbers for the crankshaft and camshaft were noted to be C069810N and 653052G, respectively.

The camshaft was bent in the area of the Nos. 2 and 4 cylinders, with peening damage noted. All camshaft bearing journals were shinny. The cam lobes appeared to be of equal profile and were shinny.

Mechanical peening damage was noted on the crankshaft at rod journal No. 3. Scoring and metal transfer were noted on rod journal No. 2. All other rod journals were shinny. All crankshaft main journals were shinny and unremarkable, and without heat discoloration.

The crankcase was opened and laid out in open book fashion for examination.

For the left half of the case, mechanical damage was noted to the interior in the area of the Nos. 1 and 2 cylinders, with damage to the lifters for those cylinders apparent. The No. 2 cam bearing was scored, while minor pitting and scoring were found on the Nos. 3 and 4 cam bearings.

The main bearings were sitting in their respective tab slots and were without elongation. Scoring was noted to the Nos. 2 and 4 main bearings, while the No. 3 main bearing was unremarkable. No heat discoloration was observed.

The lifters on the No. 2 cylinder mounting plate were damaged. The housing was crushed in and the surfaces exhibited chipping. No pitting was noted on the lifters rubbing surfaces.

For the right half of the crankcase, pitting was observed on the mating areas of the main bosses. Main bearing tab slots were unremarkable and without elongation. Scoring was noted on the No. 4 main bearing. Mechanical damage was noted to the case in area of Nos. 1 and 3 cylinder mating surfaces.

ADDITIONAL INFORMATION

The airframe was released to US Customs at the conclusion of the examination on February 24, 2000. The crankshaft and counterweight components were released and returned to the Tucson Air Branch maintenance facility at the conclusion of those examinations.