Friday, March 17, 2017

Snider v. Sterling Airways $2.7M Verdict: Family Contended Defective Engine Caused Plane Crash; Cessna T210L Turbo Centurion, N30266, fatal accident occurred June 21, 2010 near William T. Piper Memorial Airport (KLHV), Lock Haven, Pennsylvania

The Legal Intelligencer
March 16, 2017

Date of Verdict:
Feb. 21.

Court and Case No.:
U.S. District Court, Eastern District of Pennsylvania, Philadelphia No. 2:13-cv-02949-JCJ.

J. Curtis Joyner.

Type of Action:
Wrongful death, products liability.

Burns, death.

Plaintiffs Counsel:
John R. Merinar Jr. and Allison B. Williams, Steptoe & Johnson, Bridgeport, West Virginia.

Plaintiffs Experts:
Marc Fruchter, pilot performance/error, Greenville, South Carolina; Mark Seader, aircraft, Loveland, Colorado; Allen Fiedler, accident reconstruction, Imperial; Colin Sommer, engineering, Broomfield, Colorado; Roger Griffith, economics, Charleston, West Virginia; Bennet Omalu, forensic pathology; Sacramento, California; Rodney Doss, FAA, Dallas; William Carden, materials science, Pensacola, Florida.

Defense Counsel:
Will S. Skinner and Leigh Woodruff, Skinner Law Group, Woodland Hills, California; Jeffrey W. Moryan and Susan Kwiatkowski, Connell Foley, Roseland, New Jersey; Patrick J. Hughes, Connell Foley, Cherry Hill, New Jersey; Laurie A. Salita and Mary Ann Mullaney, Jacobs Law Group, Philadelphia.

Defense Experts:
J.W. Morris Jr., metallurgy, Berkeley, California; John Goglia, aircraft maintenance; Bethesda, Maryland; Cyril Wecht, pathology, Pittsburgh; Terry Horton, aircraft maintenance, Silverhill, Alabama; William Brogdon, engineering, Mobile, Alabama.

On June 21, 2010, plaintiff Daniel Snider, 30, an employee of the U.S. Forest Service, died in an airplane crash, in Lock Haven.

Snider had been on board a Cessna T210L single-engine aircraft with another U.S. Forest Service employee. The plane was flying form Clarion to Lock Haven, where it was to make a planned stop for fuel.

The purpose of the flight was to conduct an aerial deforestation survey. As the plane neared the runway of a Lock Haven airport to land, an engine failure occurred when the plane was around 1,500 feet northwest of the runway. The plane crashed into a residential street and slid about 270 feet, where it caught fire. Snider, the pilot, and the other governmental worker all died.

The plane, owned and maintained by Sterling Airways Inc., had been manufactured in 1973 and was equipped with a Continental Motors TSIO-520-H engine, which Sterling Airways had overhauled in 2004.

Snider's estate sued Continental Motors and Sterling Airways, alleging claims under a theory of products liability, including manufacturing defect, failure to warn and strict liability.

Snider's estate also sued Technify Motors (USA) Inc., which owned Continental, TDY Industries Inc., Allegheny Technologies Inc. and Teldyne Technologies Inc.—all companies that the estate believed had been affiliated with Continental at some time. All of the parties, except Continental Motors and Sterling Airways, were voluntarily dismissed, prior to or during trial.

Continental brought in the federal government as a third-party defendant (the plane was being operated pursuant to a charter plane and pilot contract between Sterling Airways and the U.S. Forest Service), and the federal government was dismissed via summary judgment.

The estate's counsel faulted Continental Motors for failing to provide proper instructions/warnings to Sterling Airways regarding the engine's cylinder assembly and overall maintenance.

The estate's expert in engineering testified that the exhaust valve guides in cylinders, which were put into the engine during a 2004 overhaul, were too soft and failed, which in turn initiated a series of events that caused the failure of the engine. According to the expert, the accident occurred from wear of the exhaust valve guide in the number-two cylinder assembly, which permitted the exhaust valve to wobble in the exhaust valve guide, and that wobble over time caused the valve guide to fracture. This fracture in turn led to fracture of the valve, the disintegration of the piston, the failure of the cylinder, and ultimately the failure of the engine. The expert concluded that the crash resulted not from a maintenance issue or pilot error, but from the fact that the exhaust valve guide did not meet the hardness specification of the manufacturer.

The estate's expert in aircraft maintenance tested the TSIO-520-H engine to determine whether the configuration of parts, installed in the 2004 overhaul, would have caused elevated temperatures to soften the exhaust valve guides, which Continental had claimed. From this test, the estate's expert in materials science opined that the testing demonstrated that the valve guides were unaffected by higher temperatures, and the exhaust valve guides did not meet the manufacturer's hardness specification.

According to the estate's experts in Federal Aviation Administration regulations and accident reconstruction, in 2007, two of the six cylinders which had been installed in 2004 were removed and the exhaust valve guides and valves were replaced due to excessive wear. Sterling Airways, knowing this, and knowing that the six cylinders came from the same manufacturer, was negligent in its decision to fly the plane without further addressing the engine issue.

Continental Motors' expert in metallurgy maintained that it was highly improbable that the exhaust valve guide would have been as soft as the estate's experts' measurements showed. Even if the valve guide was as soft as alleged, it would only have had a small impact on the wear of the guide.

The company's expert in engineering opined that the wear on the valve guide was due to elevated temperatures created by Sterling Airways' installing improper parts during the overhaul in 2004.

Continental Motors' expert in aircraft maintenance faulted Sterling Airways for performing insufficient maintenance of the engine, which did not include an oil-trend analysis and an investigation involving a borescope. Had the maintenance been properly performed, Sterling Airways would have detected the engine-related problems and prevented the accident.

Continental Motors' expert in FAA regulations maintained that Sterling Airways' maintenance of the plane did not accord to FAA regulatory requirements. (The estate's experts in FAA regulations and accident reconstruction testified that Sterling Airways had maintained the plane in accordance with applicable FAA regulatory requirements.)

Sterling Airways' counsel echoed the estate's theories of liability as to how the Continental Motors TSIO-520-H engine was defectively manufactured. Sterling's expert in aircraft maintenance testified that the plane was appropriately maintained and therefore the crash was the result of an engine manufacturing defect.

Snider is survived by a wife and a child.

According to the estate's expert in pathology, Snider experienced conscious pain and suffering from smoke inhalation and the fire.

Snider's wife testified about his character and what life has been like for his family following his death. His estate sought damages under the Wrongful Death and Survival Acts.

Snider's estate sought to recover $1.3 million to $1.55 million in past and future lost earnings.

Continental's expert in pathology maintained that there was not enough evidence to demonstrate whether Snider suffered conscious pain and suffering.

Both Sterling and Continental had cross-claims against each other for indemnification and contribution.

The jury found that there was a manufacturing defect in the cylinder assembly of the Continental Motors' engine and that the cylinder assembly did not contain proper instructions/warnings.

Sterling Airways was found negligent, but its negligence was not a factual cause of Snider's injury.

Jurors found that Snider did not sustain conscious pain and suffering.

The estate was determined to receive $2,753,048.49.

This report is based on information that was provided by counsel for plaintiffs and Continental Motors Inc. Counsel for Sterling Airways Inc. did not respond to phone calls. TDY Industries Inc., Allegheny Technologies Inc., Teledyne Technologies Inc., Technify Motors (USA) Inc., and United States of America were not asked to contribute.

• Original article can be found here:

Additional Participating Entities: 
Federal Aviation Administration / Flight Standards District Office;  New Cumberland, Pennsylvania
Cessna Aircraft Company; Wichita, Kansas 
Teledyne Continental Motors; Mobile, Alabama
USDA Forest Service; Ogden, Utah
USDA Forest Service; Bly, Minnesota 

Aviation Accident Final Report - National Transportation Safety Board:

Docket And Docket Items - National Transportation Safety Board:

Aviation Accident Data Summary - National Transportation Safety Board:

NTSB Identification: ERA10GA320
14 CFR Public Use
Accident occurred Monday, June 21, 2010 in Lock Haven, PA
Probable Cause Approval Date: 03/08/2012
Aircraft: CESSNA T210L, registration: N30266
Injuries: 3 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.

The aerial observation flight was conducted by a 14 CFR Part 135 certificated on-demand air carrier under contract to the U.S. Forest Service. As the flight neared its destination airport, the pilot reported via the airport's common traffic advisory frequency his intent to land. Witnesses reported that, as the airplane overflew them on approach to the airport, it appeared to be in distress, trailing black smoke with the engine "sputtering." The airplane subsequently impacted a light stanchion about 1,300 feet short of the intended landing runway. Before coming to rest, the airplane struck a house and several parked cars, and it was nearly consumed during a post-impact fire. Postaccident examination revealed a catastrophic failure of the airplane's engine, which originated with a fatigue failure of the number 2 cylinder exhaust valve. The fatigue failure was likely due to abnormal loading associated with excessive valve-to-valve guide clearance resulting from valve guide wear. Typically, valve guide wear results from either overall elevated engine operating temperatures or individually elevated valve temperatures due to improper valve seating. The normal wear pattern observed on the number 2 exhaust valve seat suggested that improper valve seating was not an issue in this case. 

Significant exhaust valve guide wear was observed on all cylinders, with the valve guides of the generally cooler cylinders near the front of the engine showing less wear than those of the generally hotter cylinders near the rear of the engine. This overall pattern suggested a persistent elevated temperature problem, which could have resulted from either improper engine operation or an undiagnosed maintenance issue. 

The investigation revealed that, when performing engine cylinder differential pressure tests during required routine inspections of the airplane’s engine, the contract operator utilized gauges that had not been calibrated since their purchase and did not perform the tests in accordance with the engine manufacturer's recommendations. Also, the engine manufacturer recommended that cylinder borescope inspections be accomplished in conjunction with the differential pressure tests, and there were no notations in the engine maintenance records of any visual borescope inspections of the interior of the cylinders. Further, there was no notation in the records that the fuel injection system had been inspected and adjusted per the engine manufacturer’s recommendations. If properly performed, differential pressure tests and borescope inspections may have detected valve guide wear and prevented the exhaust valve failure, and fuel injection system inspections may have detected and corrected incorrect adjustment of the engine fuel system, which can result in elevated engine cylinder temperatures and lead to valve guide wear. These and other instances of non-compliance with manufacturer service recommendations discovered during the investigation indicated that the contract operator was not maintaining the airplane in a manner consistent with its "Operator's Manual," which dictated that inspections of time-limited components were to be conducted in accordance with the applicable manufacturers' recommendations.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The total loss of engine power resulting from the fatigue failure of the engine's number 2 cylinder exhaust valve. The fatigue failure was due to valve guide wear that led to excessive clearance between the valve and valve guide. Contributing to the accident was the contract operator’s lack of compliance with its own maintenance procedures, which, if followed, would have prevented the accident.


On June 21, 2010, at 1257 eastern daylight time, a Cessna T210L, N30266, registered to Sterling Airways, Inc., and operated under contract by the United States Department of Agriculture (USDA) Forest Service, was substantially damaged when it struck a light stanchion and collided with terrain while maneuvering for a forced landing following a total loss of engine power near William T. Piper Memorial Airport (LHV), Lock Haven, Pennsylvania. The certificated airline transport pilot and two USDA Forest Service mission specialists were fatally injured. Visual meteorological conditions prevailed, and a company visual flight rules (VFR) flight plan was filed for the public use aerial observation flight, which departed Clarion Country Airport (AXQ), Clarion, Pennsylvania, about 1035.

According to a representative of USDA Forest Service, the purpose of the flight was to conduct an aerial survey of tree defoliation in southwestern Pennsylvania. A review of fueling records revealed that the pilot serviced the airplane with 49 gallons of fuel on the evening of June 20, 2010. Automated Flight Following (AFF) data provided by the USDA Forest Service indicated that, on the morning of the accident, the pilot repositioned the airplane from its base at Hornell Municipal Airport (4G6), Hornell, New York, to AQX where the two USDA Forest Service mission specialists boarded it about 1030. 

The flight from AQX was scheduled to arrive at LHV about 1300 to refuel the airplane, before continuing with the survey. About 1250, AFF data indicated that the airplane was about 14 miles west of LHV, at an altitude of 2,500 feet msl (about 1,000 feet agl). Subsequent data indicated that the airplane tracked generally northeast over the next 6 minutes, toward the town of Lock Haven. The airplane's final indicated position was about 3 miles west of the LHV runway 9 threshold, at an altitude of 1,519 feet msl (about 1,000 feet agl).

According to a certificated flight instructor (CFI) who was flying in the traffic pattern at LHV for runway 27, he heard the accident pilot announce over the LHV Common Traffic Advisory Frequency (CTAF) that he was 8 miles southwest of the airport. The CFI also heard the accident pilot ask if fuel was available at the airport. About 2 minutes later, the CFI heard the accident pilot report that he was 5 miles southwest of the airport. The CFI heard no further transmissions by the accident pilot. The CFI also stated there was no tone of urgency in the accident pilot's voice nor did he declare an emergency at any point. 

A Piper PA-24 subsequently taxied onto runway 27, and the pilot announced his position via the CTAF before departing to the west. Shortly after that airplane departed, when the CFI had turned his airplane onto the base leg of the traffic pattern, an unknown person announced on the CTAF that there had been an explosion off the departure end of the runway, which the CFI later learned was the accident airplane.

Two witnesses, who worked at Lock Haven University, about 1.5 nautical miles northwest of the accident site, observed the accident airplane as it overflew university property. Both of the witnesses stated that the airplane was flying lower when compared to the other airplanes that they would normally see landing at the airport. Shortly after first observing the airplane, it began trailing smoke. The smoke trail then stopped, and they both heard a loud noise, similar to a "gun blast." Both witnesses stated that after the initial loud noise, the engine ceased operating for several seconds, and then it started to "cough and sputter." Both of the witnesses reported hearing a second loud noise while the engine continued to sputter. 

Numerous other individuals witnessed the accident airplane as it approached LHV over the town of Lock Haven, and their statements were generally consistent. Six of the witnesses described that the airplane’s engine was "sputtering" as it flew over them, and several remarked about how loud the engine was. One witness commented that "it sounded like a connecting rod problem with the engine due to the noise it was making." Six of the witnesses also commented that the airplane appeared to be "struggling" to maintain altitude, or that it was lower than normal as it overflew them. Several witnesses commented that they thought it unusual that the airplane's landing gear was retracted as it overflew them. 


The pilot, who was an employee of Sterling Airways Inc., held an airline transport pilot certificate with ratings for airplane single and multiengine land. He also held a flight instructor certificate with ratings for airplane single engine and instrument airplane. His most recent Federal Aviation Administration (FAA) second-class medical certificate was issued on December 29, 2009. The pilot’s logbooks were not recovered, but according to USDA Forest Service records, the pilot had logged 8,280 total hours of flight experience as of March 16, 2010, with 1,775 hours in the accident airplane make and model. 


According to FAA records, the airplane was manufactured in 1973. The airplane was equipped with a Teledyne Continental Motors TSIO-520-H engine. 

The most recent engine overhaul was completed by Sterling Airways Inc. on May 7, 2004, and on that date the airplane had accumulated 4,276 total hours of operation. According to maintenance records, the engine was "…overhauled [in accordance with] TSIO-520 sandcast series [overhaul manual]," and all hardware was replaced in accordance with Teledyne Continental Motors Service Bulletin (SB) SB97-6. All six cylinders and their respective exhaust and intake valves were replaced with new Teledyne Continental Motors parts. The following logbook entry documented a post-maintenance flight check conducted by the accident pilot. The pilot entered a remark of "fuel flow low," which was addressed in the following log entry, "Adjusted fuel flow pressure per overhaul manual. (Cessna) Ground run check good."

An engine logbook entry dated June 7, 2007, at 4,710 total aircraft hours, documented an annual inspection. The entry also noted, "Removed #3 & 6 cyl for valve (exh) & valve guides both cyl. Cylinders re-installed with new gaskets." No additional details regarding the cylinder work performed during this inspection were documented in the engine maintenance log. 

An airframe maintenance logbook entry dated January 18, 2008, documented the completion of an annual inspection and the flight of the airplane for a period of about 6 hours under 14 CFR Part 91. The entry noted that airworthiness directives (ADs) were complied with prior to departure and that an airworthiness conforming validation check was performed during the annual inspection. All time limited components were checked, and the airplane was cleared to return to 14 CFR Part 135 service. No further entries removing or reinstating the airplane to 14 CFR Part 135 service were noted.

The airplane's most recent annual inspection was completed on March 9, 2010, at 5,000 total aircraft hours. The engine logbook entry for the inspection noted a replacement of the engine oil and filter with an accompanying check of the oil and oil filter contents. The magnetos, timing, and compression checks were satisfactory, with a note describing the cylinder differential pressure test values as 75, 68, 72, 74, 77, and 70 psi for cylinders 1 through 6, respectively. The spark plugs were cleaned, gapped, tested, and reinstalled. The oil filter adapter was repositioned and the engine was washed. The entry noted that no applicable ADs were required to be complied with at the time, and a ground run of the engine was satisfactory. The airplane had accumulated about 45 additional hours of operation between the time of the annual inspection and the date of the accident flight.

Detailed inspection of the airplane's maintenance records from the time that the engine was overhauled in 2004 until the time of the accident showed that guidance used for conducting annual inspections varied. For the annual inspections completed in 2004 and 2005, the entries specified using the guidance provided by "Cessna 210 maint. man. insp. form." For annual inspections in 2006 and 2007, the entries specified using the guidance provided by, "FAR 43 Appendix D." An annual inspection completed in 2008 cited using "FAR 43 Appendix D & Cessna insp. sheet" as guidance, while entries for inspections in 2009 and 2010 again cited "FAR 43 Appendix D." A detailed comparison of the scope of guidance provided by each of the above listed inspections can be found in the public docket for this case.

Neither the engine nor the airframe maintenance logbooks explicitly detailed compliance with any manufacturer's service bulletins, service information directives, or service information letters following the entries detailing the engine overhaul in May 2004.


Weather, recorded at LHV at 1300, included no ceiling information, visibility 10 statute miles, temperature 21 degrees C, dewpoint 16 degrees C, and an altimeter setting of 30.10 inches of mercury. The winds were from 250 degrees true at 6 knots.


The airplane was examined at the accident site on June 21, 2010. The accident site was located on a residential street, about 1,300 feet west of the runway 9 threshold at LHV, at an elevation of 556 feet. The initial impact point was located about 7.5 feet below the top of a wooden street light stanchion, where the outboard section of the left horizontal stabilizer impacted the pole. The wreckage path was oriented about 120 degrees magnetic. The airplane struck the front porch of a residence and three parked cars before coming to rest about 260 feet from the initial impact point, headed about 250 degrees magnetic. Small parts of the airplane were strewn along the wreckage path, and all flight control surfaces were accounted for at the accident scene. 

The cockpit and cabin were substantially impact-damaged and partially consumed by a post-impact fire. The instrument panel was severely burned, and none of the flight instruments contained any legible information. The throttle was found in the full aft position, the mixture control was found in the full rich position, and the propeller control was found in the full forward position. The fuel selector valve was selected to the right fuel tank. 

Flight control continuity to the ailerons was traced through a single separation, consistent with overload, to the control column. Flight control continuity was confirmed from the rudder, elevator, and elevator trim tab to the cockpit area. Measurement of the elevator trim tab actuator correlated to between a 10- and 15-degree tab trailing-edge-up position. Measurement of the flap actuator jackscrew correlated to the flaps up position. The main landing gear was in the up position, although both were dislodged out of the up-locking mechanism. The nose gear was in the up and locked position.

All three propeller blades remained attached to the hub, which remained attached to the engine. One of the three propeller blades was bent aft at a point about 1/3 of its span, and had rotated 180 degrees in the propeller hub. The remaining two propeller blades exhibited minor scratching, and were relatively undamaged.

The engine exhibited impact and thermal-related damage, and a large portion of the engine was covered by dark black soot. The crankcase exhibited a protruding hole extending from the number 1 cylinder deck area over to the number 2 cylinder deck area extending forward to the number 4 cylinder deck area. The oil sump exhibited a puncture hole on the aft side of the sump. The oil sump drain was intact and secure with no safety wire present. The safety wire installed on the oil filter was oriented in a direction as to apply a loosening force to the filter; however, the oil filter was securely in place.

The left and right magnetos turned freely with impulse coupling engagement. Their outer cases exhibited impact related damage. The magnetos were installed and tested on the test bench and produced a blue spark across a 7 mm gap through the full range of test bench rpm. The number 2 top and number 2 bottom spark plugs exhibited mechanical damage. The numbers 1, 3, and 5 top and bottom sparkplugs exhibited worn signatures in accordance with the Champion Aviation check-a-plug comparison chart, while the numbers 4 and 6 top and bottom spark plugs exhibited normal wear signatures in accordance with the chart.

The oil sump was drained of oil, and the amount was measured to be approximately a half a quart. The oil was dark in color and contained metallic particles. Once the oil sump was removed there were numerous internal engine components located in the bottom of the oil sump. The oil pick-up tube was undamaged, and the oil suction screen was unrestricted. The oil filter housing was cut open and the filter element was cut from the canister to allow examination. The oil filter element was examined and contained an abundance of metallic flakes and slivers.

The fuel control exhibited a dark colored soot and thermal related damage. The throttle body valve was found in the full open position. The link rod and levers did not move freely by hand. The fuel pump turned freely and the fuel pump drive was intact and undamaged. The fuel nozzles were unrestricted and exhibited normal operating signatures, with the exception of the number 6, which exhibited a light amount of impact related damage on the upper portion of the nozzle. A fine, particle-type contamination was found within the fuel control finger screen, fuel pump, and fuel manifold valve. Samples of the contaminate were forwarded to the NTSB Materials Laboratory for further examination.

The turbocharger turbine wheel rotated freely by hand, and exhibited a normal amount of shaft end play.

The camshaft exhibited mechanical damage from the number one to number four cylinder locations. With the exception of the mechanical damage to the camshaft the camshaft lobes exhibited normal operating signatures.

The crankshaft and counterweight assembly exhibited mechanical damage concentrated at the number two, three and four connecting rod journals. The crankshaft main bearing journals were intact, undamaged and exhibited normal operating signatures. The number 1, 5, and 6 connecting rod journals were intact, undamaged and did not exhibit any signs of lubrication distress. The number 2, 3, and 4 connecting rod journals exhibited mechanical damage. The oil transfer passages were open and unrestricted, and the oil transfer collar was intact and undamaged. The crankshaft main bearings remained intact, and exhibited normal operating and lubrication signatures, with no signs of lubrication distress.

The number 1, 5, and 6 connecting rods were intact and undamaged. Their respective bushing and bearings exhibited normal operating and lubrication signatures. The number 2, 3, and 4 connecting rods exhibited extreme mechanical damage and had separated from their respective connecting rod caps. Fragments of the connecting rod caps exhibited mechanical damage. Fragments of the connecting rod bolts and nuts were fractured through and exhibited mechanical damage and signatures consistent with overload. The number 2, 3, and 4 connecting rod bearings could not be distinguished from the bearings found in the oil sump, though each of the six connecting rod bearings recovered from the oil sump exhibited extensive mechanical damage. 

All of the pistons displayed normal combustion deposits and varying levels of damage, with the exception of the number 2 piston, which was absent from its respective bore. Numerous piston fragments were recovered from the oil sump.

Each of the cylinders was removed from the crankcase and examined in detail. Cylinder numbers 1, 3, 4, 5, and 6 generally displayed similar signatures. The cylinder combustion chambers exhibited normal combustion deposits with bore conditions that were free of scoring and undamaged. Hone marks were visible in the cylinder bore ring travel areas, and the intake and exhaust valve heads exhibited normal deposits. An oil residue was present in the rocker box areas, and the cylinder overhead components (valves, rocker arms, guides, springs, retainers and shafts) were lubricated and undamaged. The number 3 and 5 exhaust valves and guides displayed part numbers consistent with FAA PMA components, and matched the part numbers of the replaced components detailed in the maintenance work orders dated May 25, 2007.

Examination of the number 2 cylinder revealed an extensive amount of mechanical damage. The cylinder skirt exhibited mechanical damage. There were hone marks visible in the cylinder bore ring travel area. The rocker box area had an oil residue. The exhaust valve face, a portion of the valve stem, and a portion of the exhaust valve guide had separated and were found with the loose components in the engine oil sump.

Dimensional examination of the exhaust valve and valve guides revealed average valve clearances of 0.0272, 0.0357, 0.0125, 0.0176, 0.0115, and 0.0169 inches for cylinders numbers 1 through 6, respectively.


An autopsy was performed on the pilot and the front seat passenger by the J.C. Blair Memorial Hospital Laboratory, Huntington, Pennsylvania. The basic published cause of death for both individuals was "inhalation of smoke with thermal injury."

The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing on the pilot and front seat passenger. Toxicological testing of both individuals was negative for cyanide, ethanol, and drugs. The pilot tested positive for a carboxyhemoglobin (carbon monoxide) saturation of 10 percent.


The number 2 cylinder assembly with number 2 exhaust valve pieces and exhaust valve guide piece; number 2 and number 4 connecting rod cap, nut, and bolt pieces; piston pieces; fuel metering valve; and fuel manifold valve were submitted to the NTSB Materials laboratory for detailed examination. According to the Materials Laboratory Factual Report, the interior of the number 2 cylinder was marked from foreign object damage, and the barrel skirt was deformed and fractured. The piston was fractured into numerous pieces. Several connecting rod bolts were fractured, and one connecting rod bolt was bent. The number 4 connecting rod cap was flattened and fractured. With the exception of the number 2 exhaust valve and guide, all of the submitted components generally exhibited fracture features consistent with overstress. 

Number 2 Cylinder Exhaust Valve

The exhaust valve for the number 2 cylinder fractured in the stem at the transition between the stem and head of the valve. The fracture face on the head side of the fracture was mostly obliterated by post-fracture contact damage. On the stem side of the fracture, ratchet marks were observed at the edges of the fracture consistent with fatigue cracking that emanated from multiple origins. The fracture face was cleaned and post-cleaning examination revealed crack arrest marks and thumbnail features that extended from three origin areas, consistent with fatigue cracking. Fatigue features emanated from multiple origin areas around the circumference of the valve stem.

The exhaust valve tip at the rocker contact face had a circular pattern near the middle of the face. Overall, the surface appeared uniformly shiny, consistent with repeated impact. Small lips of deformed material were observed at the edges of the tip contact face. The exhaust valve head piece showed foreign object contact deformation around the edges of the piece. The chamber face of the valve head was roughened, consistent with foreign object contact. In undamaged areas, the valve seat showed a normal contact pattern with some recession. The opposing face of the valve head displayed similar damage, in addition to a distinct area of discoloration over about 25-percent of the surface area. Three radially oriented cracks were observed around the outside circumference of the valve head, within the discolored area.

The diameter of the exhaust valve stem was measured near the head and tip ends, and was calculated to be an average diameter of 0.4313 inches. A new exhaust valve stem was specified to measure 0.4334 to 0.4341 inches. 

Number 2 Cylinder Exhaust Valve Guide

The exhaust valve guide for the number 2 cylinder was fractured where it intersected the rocker arm cavity of the cylinder head. The mating faces were smooth and appeared worn, consistent with post-fracture contact. The fracture features were obliterated from mechanical damage that resulted from the post fracture contact. 

The inside diameters of the intake and exhaust valve guides were measured using telescoping gages at 0 degrees and 90 degrees about the axis of exhaust valve guide, where 0 degrees was the orientation parallel to the length of the rocker arm, and 90 degrees was perpendicular to the length of the rocker arm. The diameters were measured at each orientation at positions near the top (rocker arm end), middle, and bottom (combustion chamber end) of the valve guides. The average valve guide diameter was calculated to be about 0.4628 inches. A new exhaust valve guide was specified to measure 0.4350 to 0.4362 inches after installation into a cylinder.

According to the Teledyne Continental Motors TSIO-520 Sandcast Series Overhaul Manual, the service limit for the clearance between the exhaust valve stem and guide was 0.0070 inches (valve stem outside diameter subtracted from the valve guide inside diameter). However, the average clearance between the number 2 cylinder exhaust valve stem and guide was calculated to be in excess of 0.0300 inches.

Fuel Metering and Fuel Manifold Valve Screens

The fuel metering valve was tinted dark and sooted, consistent with heat exposure. 
The brass screen was removed from the fuel metering valve, and light-brown particles fell out onto catch paper as the screen was pulled from the housing. The fuel manifold valve cover was unscrewed from the body, and the diaphragm was pulled out to expose the screen. Some similar light-brown particles were observed on the screen. A powdery white material was observed at the middle of the body adjacent to the screen. 

Samples of the light-brown particles from the fuel metering valve and the white powdery material from adjacent to the screen area on the fuel manifold valve were placed on carbon tape stuck to an aluminum stub for analysis using semi-quantitative standardless energy dispersive x-ray spectroscopy. Both samples showed peaks of carbon, oxygen, chlorine, and sulfur. The sample from the metering valve screen also showed a possible peak of zinc. The sample from the manifold valve screen area showed a high peak of aluminum with a small peak of magnesium. The exact chemical compositions for the samples could not be determined.


Operator Interviews

Sterling Airways' director of maintenance (DOM) was interviewed on August 25, 2010 at the facility in Hornell, New York. The DOM served as the company's primary mechanic, and held a mechanic certificate with ratings for airframe and power plant, and held an inspection authorization. During the interview, the DOM was asked to describe the in-house engine overhaul that was completed in May 2004, a process that lasted between 4 and 6 months. According to the DOM, he had ordered new engine manuals in preparation for the overhaul and after removing and disassembling the engine, sent out all of the components that required inspection or overhaul and replaced others. 

The company elected to replace all of the engine's cylinders (and their respective sub-components) with new cylinders manufactured by Teledyne Continental Motors. After the engine was reassembled, the DOM reinstalled the engine and performed a test run with the assistance of another airframe and powerplant mechanic not employed by the company. The only tool not immediately available to the mechanics during the reinstallation was a fuel pressure gauge, which they borrowed from an off-airport third-party vendor. The DOM also stated that he added a reference regarding compliance with Teledyne Continental Motors SB97-6 after a discussion with Sterling Airways' FAA Principal Maintenance Inspector.

The DOM was asked to discuss his procedures for performing engine cylinder differential pressure tests during routine inspections. When performing the tests, the DOM generally referred to 50 psi (out of 80 psi) as a minimum value for the retention of air pressure within the cylinder during the test. During the interview, the DOM was asked to provide calibration records for the pressure gauges he normally utilized. The DOM stated that he had records for torque wrench calibration, but no records documenting the calibration of the pressure gauges, and that he wasn't aware the gauges required calibration.

The DOM was also asked to describe in detail the engine maintenance log entry dated June 2007 detailing removal and reinstallation of engine cylinders number 3 and 5. The DOM stated that during the annual inspection he had found poor compression on two of the cylinders. When further questioned he was initially unable to recall the specific work he had performed, but after talking to the airframe and powerplant mechanic who assisted with the engine reinstallation, he recalled that he had removed the cylinders to clean carbon from the valves and guides with an emery cloth. When asked to provide documentation in the form of a company invoice or work order detailing the work performed, the DOM stated that none was required as the work had been performed "in-house."

In response to a follow-up written request, dated September 20, 2011, to Sterling Airways regarding the June 2007 cylinder work, the company provided two third-party maintenance work orders which detailed maintenance performed on two engine cylinders. According to the work orders, dated May 25, 2007, the exhaust valves and guides were replaced with FAA Parts Manufacturing Authority (PMA) components, the valve seats and intake valves were ground, and several gaskets, keys, and seals associated with the cylinders were replaced. The work orders did not detail the installation positions of the cylinders on the engine.

FAR 135 Operations Specifications and Operator's Manual

According to Sterling Airways Operations Specifications, the accident airplane was authorized to conduct 14 CFR Part 135 on-demand charter flights, carrying passengers under VFR during day and night conditions. The operations specifications also stated that the airplane's engine shall be maintained in accordance with the Continental Motors Service Manual and had a Time-in-Service (overhaul) Interval of 1,400 hours.

According to the Sterling Airways, Inc. Operator's Manual, the accident airplane was to routinely receive an inspection each 100 hours and/or annually. The DOM was charged with reviewing the current airworthiness directive listing and for scheduling of the new or the recurring airworthiness directives to be performed prior to the completion of the airplane's inspection. The manual further specified that, "Time-limited engines, propellers, components, accessories, and appliances will be inspected, serviced and overhauled in accordance with manufacturer's recommendations." The DOM was also to maintain a current Component Inspection, Replacement, and AD List (SAI Form M-1[A]) for each aircraft. When a time-limited component was inspected, replaced, or overhauled, the DOM was required to revise the list by making a new entry stating the next required compliance date or interval of aircraft time in service. A copy of the form was to be carried on each flight for reference by the pilot.

Sterling Airways Inc. surrendered its air carrier certificate to the FAA on April 15, 2011.

USDA Forest Service Contract

In March 2008, the USDA Forest Service contracted with Sterling Airways Inc. to provide an aircraft and pilot for the purpose of conducting aerial surveys. The contract listed numerous requirements and specified the configuration of the aircraft, the installation of required equipment, and the qualifications and duties of the pilot. Specifically, the contract listed that the aircraft be equipped for single pilot day and night VFR passenger operations per the requirements of 14 CFR Part 135, and that the airplane shall comply with all 14 CFR Part 135 requirements.

Engine Manufacturer's Service Information

Teledyne Continental Motors Service Bulletin (SB) SB03-3, titled "Differential Pressure Test and Borescope Inspection Procedures for Cylinders" dictated the procedures to be used as the standard for performing a cylinder differential pressure test on all Teledyne Continental Motors aircraft engines. The purpose of the cylinder differential pressure test was to identify leaks within the engine cylinders, and if present, identify the source of the leaks, with the engine under static conditions (not running), using a regulated pressure source. When performing a cylinder differential pressure test, a regulated test pressure of 80 psi was directed into the cylinder with the piston at top dead center at the end of the compression stroke and the beginning of the power stroke. After completing the procedure detailed in the SB, the mechanic was directed to record the resultant pressure displayed on a pressure gauge connected to the tested cylinder. The difference between the resultant pressure and the regulated pressure was the amount of leakage through the cylinder and was to be recorded in the engine maintenance log. The SB also outlined a procedure for establishing the acceptable pressure leakage limit utilizing a master orifice. The limit was required to be established by the mechanic prior to initiating the first test, and was to be logged in the engine log book, along with the pressure values observed at each cylinder.

In addition to inspecting the compression of the cylinders using the above described method, the SB also described how to perform a cylinder inspection utilizing a borescope. By inserting a borescope probe through the upper spark plug hole, the internal surfaces of each cylinder, exhaust valve, and exhaust valve seat could be examined for, in part, evidence of exhaust valve discoloration, cracking, or erosion. Detection of such anomalies was remedied with removal, repair, or replacement of the pertinent cylinder.

Each of the annual inspection entries were examined within the engine maintenance log book following the engine's overhaul in 2004. While each of the entries noted pressure values observed on each of the engine's 6 cylinders, no pressure leakage limit value was recorded. Additionally, there were no references to any borescope inspections having been performed.

The Service Bulletin prescribed the equipment and tools required to adequately perform the test and carried the following statement, "NOTE: Differential pressure test equipment must be certified and calibrated. Failure to properly maintain and calibrate test equipment may result in false cylinder differential compression readings."

Teledyne Continental Motors Service Information Directive (SID) SID97-3E (issued March 24, 2007, revised June 17, 2008), "Procedures and Specifications for Adjustment of Teledyne Continental Motors Continuous Flow Fuel Injection Systems", provided guidance for the adjustment of the TSIO-520 fuel injection system. The SID was applicable at engine installation, during 100 hour or annual inspections, following fuel system component replacement, or as required if engine operation was not within specification. The directive cautioned, "Engine performance, service life and reliability will be compromised if the engine's fuel system is neglected." The SID specified the equipment and procedures necessary for ensuring the proper fuel volume was passed into the engine cylinders through adjustments to the engine driven fuel pump and the observation of calibrated fuel pressure gauges installed specifically for the purposes of the test. The gauges were used to measure the unmetered fuel pressure as it discharged from the engine driven fuel pump, and the metered fuel pressure from the fuel metering unit. The bulletin further warned that, "Use of inaccurate gauges will result in incorrect adjustment of the engine fuel system, possible cylinder wear due to lean operation, pre-ignition, detonation, loss of power and severe engine damage."

Each of the maintenance log entries were examined within the engine maintenance log book following the engine's overhaul in 2004. No maintenance log entries citing compliance with the SID or explicitly noting inspection/adjustment of the fuel system were found.

Other Maintenance History

The Cessna Centurion Series Service Manual provided a detailed inspection program outlining tasks to be accomplished during 50, 100, and 200 hour inspections, or during other intervals dictated for particular components. Some specific requirements included: Inspection of the fuel injector screen for cleanliness or contamination every 50 hours; Replacement of engine hoses at engine overhaul or every 5 years; Overhaul of all landing gear retraction and brake system components every 5 years or 1,000 hours; Lubrication of the elevator trim tab actuator every 3 years or 1,000 hours. Review of the airplane's maintenance logs revealed no explicit reverences to compliance with any of the above required inspections, nor did SAI Form M-1A track or schedule their recurrence. When asked, the DOM was unable to provide any copies of the inspection program checklists used during previous annual/100 hour inspections.

McCauley Propeller Systems Service Bulletin SB137AE limited the overhaul interval for all propeller governors to 2,000 hours of operation or 60 calendar months in service. Review of the SAI Form M-1A showed that the next scheduled propeller governor overhaul was scheduled for September 2012 or 6,578 aircraft hours. Review of airframe, engine, and propeller logs showed that the most recent propeller governor overhaul was completed on August 14, 2002 at 4,116 aircraft hours. The propeller log detailed that the propeller was overhauled on August 6, 2008, but the propeller, airframe, engine logs did not note any action associated with the propeller governor. 

According to Slick Aircraft Products Service Bulletin SB2-80C, the Slick 6310 magnetos installed on the accident engine were required to be inspected externally every 100 hours and internally every 500 hours. Compliance with the service bulletin was to be documented with the appropriate log book entries. Review of the accident airplane's airframe and engine logs revealed no evidence of compliance with either of the above listed inspection requirements. Additionally, SAI Form M-1A, listed the time in service for the next scheduled magneto overhauls, but did not list a schedule for either of the above required inspections.

1 comment:

  1. O boy, Marc fruchter, now there's a self appointed expert