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On July 10, 2009, about 1927 eastern daylight time, an Ayres Corporation S2R-T34, N357CA, registered to Craft Air Services LLC, operated by Craft Air Service, Inc., crashed in a cornfield near Craig Craft Airport (86NC), Hertford, North Carolina. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 91 other work use flight. The airplane sustained substantial damage and the certificated commercial pilot was killed. The flight originated from 86NC about 1907.
The founder and chief pilot of Craft Air Services LLC (chief pilot) flew the accident airplane earlier that day for approximately 14 minutes, and performed spray passes applying water. The only discrepancy he noted was related to the spray nozzles, which were adjusted after the flight.
This was the pilot's first flight in a turbine powered Ayres airplane. Before the accident flight departed, the pilot filled the left fuel tank with Jet A, and added 225 gallons of water to the hopper tank. A witness reported the departure appeared normal and the accident pilot proceeded to make a spray pass over a cornfield located adjacent to the runway. The pilot then proceeded across the street to a large open area without nearby obstructions, and was observed making practice spray runs.
The chief pilot, who was airborne in another airplane spraying chemical near the approach end of the runway at 86NC, noticed the accident pilot returning to 86NC, and asked the pilot if he was landing. The accident pilot responded that he wanted to go back and make a few more passes.
Another individual who heard the accident pilot state he wanted to make a few more passes to, "…get the [feel] of the plane some more" heard the pilot perform 2 or 3 more passes which during the propeller sound during the pull-up and turn maneuver was consistent. During the last pull-up and turn maneuver, the sound from the propeller was not the same at the end of the procedure. He reported typically during a pull-up and turn, the sound starts low then gets louder and at a higher pitch then ends the same way it started. During the last pull-up maneuver the sound "…started low got louder and at a high pitch, like always, but it seemed to stay that way just a moment too long and then I heard one solid lick!" The witness ran to the center of the runway and looked for the crashed airplane but did not see it. He ran to a radio and called for the accident pilot but there was no response. The witness called on the radio to the chief pilot asking him to fly in the area to check on the accident pilot and about 20 to 30 seconds later the chief pilot radioed him to call 911, which he did. The chief pilot landed and both drove in a vehicle near the crash site.
The chief pilot reported that he noted what appeared to be a whisp of rising smoke and simultaneously heard a ground crewmember calling on the radio to the accident pilot, but there was no response. The chief pilot flew his airplane towards the area of the smoke and noted the airplane was inverted in a cornfield.
The pilot, age 37, held airline transport pilot, commercial, and certified flight instructor certificates. The airline transport pilot certificate was endorsed with airplane multi-engine land rating, the commercial pilot certificate was endorsed with airplane single engine land, and the certified flight instructor certificate was endorsed with airplane single engine rating. He held a second class medical certificate issued January 27, 2009, with no medical restrictions or limitations. He listed having 10,800 hours total flight time on the application for his last medical certificate. The brother of the pilot estimated his total time was 14,000 hours, and reported he was familiar with flying an airplane equipped with a PT6 engine because he had flown a Cessna 208 (Caravan) airplane. The NTSB Pilot/Operator Aircraft Accident/Incident Report submitted by the operator indicated the pilot's total time in all aircraft for the last 90 days, 30 days, and 24 hours were 250, 75, and 4 hours, respectively.
The pilot began full-time employment with Craft Air Services LLC in late February or early March 2009. The operator reported the pilot had accumulated 250 hours in an Air Tractor AT-301 airplane, which is an agricultural spray airplane equipped with a radial engine. The accident flight was the pilot’s first flight in a turbine powered Ayres airplane.
The airplane was manufactured in 1978 by Ayres Corporation as model S2R-T34, and was designated serial number 6000. At the time of manufacture, it was equipped with a Pratt & Whitney PT6-34AG engine and a Hartzell HC-B3TN-3C propeller; however, at the time of the accident, a PT6A-27 engine and Hartzell HC-B3TN-3D propeller with Blade Model T10282N+4 propeller blades were installed. The Hartzell propeller is a three-bladed constant speed, feathering and reverse capable propeller.
Review of the engine maintenance records revealed an entry dated March 20, 1992, indicating installation of the PT6A-27 engine. More recently, an entry dated April 2007, indicated a hot section inspection was performed. The engine total time at that time was recorded to be approximately 17,873 hours. The engine maintenance records also reflect an entry dated June 25, 2009, indicating removal, inspection, reassembly, and reinstallation of the power section. The engine total time at that time was recorded to be approximately 18, 379 hours.
The mechanic who performed the last power section inspection reported it was required due to propeller blade damage that occurred on landing by another pilot in Illinois in August 2008. The mechanic reported the following month he removed the propeller and power section of the engine but did not log the removal in the maintenance records. He completed the inspection and repair of the power section on February 1, 2009, and installed it on June 25, 2009. At that same time a new propeller was installed and an annual inspection was signed off as being completed. The airplane total time at the last annual inspection was reported to 11,614 hours, and the hour meter at that time was 3314.1 hours. The airplane was then flown by the chief pilot from Illinois, to North Carolina.
On June 29, 2009, approximately 5.0 hours since the new propeller was installed while the airplane was in North Carolina, the propeller was removed. Records indicated the bulkhead was removed and replaced, the propeller blade angles and track were checked, and the propeller was statically balanced. The propeller was re-installed with new hardware on July 6, 2009, and test run with no leaks noted. The mechanic who performed the work stated the propeller was removed in order to replace the propeller spinner dome. The airplane had been operated on two flights including the accident flight lasting a total of approximately 34 minutes since the propeller was last installed.
A surface observation weather report taken at Elizabeth City Coast Guard Air Station/Regional Airport (ECG) at 1954, or approximately 27 minutes after the accident indicates the wind was from 070 degrees at 8 knots, the visibility was 10 statute miles, and clear skies existed. The temperature and dew point were 22 and 15 degrees Celsius, respectively, and the altimeter setting was 30.26 inches of Mercury. The ECG airport is located approximately 15 nautical miles and 094 degrees from the accident site location.
WRECKAGE AND IMPACT INFORMATION
Examination of the accident site by a FAA airworthiness inspector and also the operator revealed the airplane came to rest inverted in a corn field. Personnel of the operator and also the FAA reported damage to corn was only noted directly under the airplane. Damage to corn ahead of the right wing was attributed to fuel contact. The accident site was located at approximately 36.278732 degrees North latitude and 076.481743 degrees West longitude.
Examination of the airplane by several FAA airworthiness inspectors revealed no postcrash or in-flight fire. All components necessary to sustain flight remained attached. The left wing was more extensively damaged than the right wing. The leading edge of the left wing exhibited full-span chordwise crushing, and accordion wrinkles were noted on the left wingtip. Upward bulging of the lower skin of the left wing was noted while the airplane was inverted. The right wing exhibited compression wrinkles on the lower surface of the wing skin. The vertical stabilizer was crushed down. All primary and secondary flight controls remained attached; flight control continuity was confirmed for roll, pitch, and yaw. The flaps appeared retracted. The engine remained attached to the engine mount collar, but the engine was separated from the airframe. The propeller remained attached to the engine, but one propeller blade was separated from the propeller hub. The separated blade was located beneath the resting point of the engine.
Examination of the cockpit engine control quadrant revealed the propeller control was midrange, the fuel condition lever was in the "full forward" or flight idle position, and the power lever was in the "reverse" or full aft position. The FAA inspector reported the power lever gate tab was bent up approximately 90 degrees. Two global positioning system (GPS) receivers located in the wreckage were retained for further examination. The airplane was recovered and secured for further examination.
Examination of the engine following recovery by a representative of the engine manufacturer revealed impact damage to the lower section of the reduction gearbox and accessories attached to it including the propeller governor, propeller overspeed governor, and also Np tachometer generator. Examination of the exhaust duct revealed no evidence of blade contact marks on the interior surface. The gas generator case exhibited radial deformation forward of the engine mount collar to the upper and lower circumferences. Examination of the accessory gearbox revealed impact damage to the left hand circumference, and to the accessories attached to it. The fuel control input lever was continuous to the controls cambox, and the fuel control link arm was impact fractured. Inspection of the power control and reversing linkage revealed the forward linkage was separated forward of the "A" flange and was not located; however the linkage was continuous from the "A" flange to an impact fracture at the cambox clevis fitting. The cambox was disintegrated. The airframe input rod was continuous to the cambox input fitting. Examination of the compressor discharge air (P3) and the power turbine control (Py) lines revealed both were continuous from their respective fittings, but the P3 line exhibited severe impact damage. The fuel inlet and outlet, and the oil filters were clean. The reduction gearbox chip detector was free of ferrous particles.
Further examination of the engine revealed severe impact damage which precluded formal engine disassembly. The gas generator case was saw cut around the circumference immediately adjacent to the "C" flange in order to gain access to the turbine and compressor sections of the engine. Impact damage and deformation precluded examination of the compressor section of the engine. Inspection of the combustion chamber and small exit duct revealed impact damage but no evidence of operational distress. Examination of the compressor turbine guide vane ring revealed the vane airfoils did not exhibit any indication of operational distress. The downstream side inner drum displayed circumferential rubbing due to axial contact by the compressor turbine. The compressor turbine shroud displayed circumferential scoring due to contact by the compressor turbine blade tips.
Inspection of the compressor turbine revealed scoring of the upstream side of the outer rim due to contact by the compressor turbine guide vane ring. Metallic material was heat fused to the blade root leading edges. Heavy circumferential rubbing was noted on the downstream side due to contact by the power turbine guide vane ring and the power turbine disk. Severe radial deformation was noted to the power turbine housing. Inspection of the power turbine guide vane ring and interstage baffle revealed the interstage baffle was liberated from the inner drum due to impact deformation. The vane airfoil trailing edges displayed heavy circumferential machining and fractures due to contact with the power turbine. The upstream side of the vane ring inner drum and baffle face displayed heavy circumferential rubbing due to contact with the compressor turbine. The downstream side of the baffle face displayed heavy circumferential scoring due to contact with the power turbine.
Inspection of the power turbine revealed the majority of the blade platforms were displaced axially from the disk due to contact with the power turbine guide vane ring. The blade airfoils were impact fractured due to contact with the guide vane and shroud, and were located in the exhaust duct. The blade root upstream faces and the disk face displayed heavy circumferential rubbing due to contact with the power turbine guide vane ring. The disk hub displayed heavy circumferential rubbing machining due to contact with the compressor turbine through the interstage baffle. Inspection of the 1st and 2nd stage gearing of the reduction gearbox revealed no indications of operational distress.
Examination of the propeller by a representative of the propeller manufacturer revealed impact damage to the spinner dome caused by each propeller blade counterweight. The impact marks to the spinner dome indicate each propeller blade was in the normal operating position; the propeller blades were not in feather or reverse positions at the time of the counterweight contacts. Initial examination of the propeller blades revealed the No. 1 propeller blade was separated from its clamp, and the Nos. 2 and 3 propeller blade had rotated in their clamps. The No. 1 propeller blade was bent aft approximately 10 degrees and the leading edge was twisted towards low pitch. Paint on the cambered and non-cambered sides near the leading edge was abraded, and the outer 5 inches of the blade tip was torn off and missing. The fractured end of the blade was curled aft and bent aft at the leading edge. The retention shoulder was partially sheared. The No. 2 propeller blade was bent forward approximately 90 degrees at 1/3 the radius, and the outer half of the blade span was twisted towards low pitch and bent aft. The No. 3 propeller blade was bent slightly aft at mid-blade, and the outer 6 inches of the blade tip was bent aft and twisted towards low pitch. Impact damage precluded cycling of the pitch change mechanism. The engine/propeller attachment was intact and unremarkable, and the beta feedback collar was cocked from its normally installed position. The Beta rods were slightly bent but the mechanism remained intact. No evidence of preimpact failure or malfunction was noted.
MEDICAL AND PATHOLOGICAL INFORMATION
A postmortem examination of the pilot was performed by the Division of Forensic Pathology at the East Carolina University, Greenville, North Carolina. The cause of death was listed as “Multiple blunt trauma due to airplane crash.”
Forensic toxicology was performed on specimens of the pilot by the FAA Bioaeronautical Sciences Research Laboratory (CAMI), Oklahoma City, Oklahoma, and the Office of the Chief Medical Examiner, Chapel Hill, North Carolina. The toxicology report from CAMI indicated the results were negative for carbon monoxide, cyanide, volatiles, and tested drugs. The toxicology report from the Office of the Chief Medical Examiner indicated the result was negative in the submitted blood specimen for ethanol.
TESTS AND RESEARCH
The aircraft was equipped with a Garmin GPSMAP 496 receiver and a SATLOC SLXg-3 GPS receiver. These were submitted to the Safety Board's Vehicle Recorders Division, located in Washington, D.C., for readout. According to the GPS Factual Report, only the SATLOC SLXg-3 was determined to have recorded data associated with the accident flight. The individual log files associated with the SATLOC GPS unit were processed using the manufacturers supplied download and processing software, and were found to record data points every 2 seconds. The data points recorded by the SATLOC GPS consisted of time, date, altitude, heading, latitude, longitude, groundspeed, spray system on or off, and also cross track error. The altitude data point recorded directly by the GPS unit is calculated by knowing the aircraft's GPS altitude position and determining the "above ground" height relative for the actual ground reference. The altitude data was offset by adding 107 feet to all of the values to correct for an offset error.
The groundspeed data point is calculated by the downloaded software using the time-stamped and recorded position data, and was displayed as miles-per-hour (mph) in order to agree with the airspeed indicator markings. Review of plots associated with factual report revealed that the first and last recorded data points associated with the accident flight were at 1907:32, and 1927:36, respectively. With respect to groundspeed, it only on one occasion went below 100 mph, and nearly consistent changes in heading and airspeed associated with practice spray turns was noted.
A review of a plot between 1925:24,and 1926:24, revealed the airplane heading remained west-southwest, the groundspeed remained nearly constant at 150 mph, and the altitude increased from 200 to 300 feet. Between 1926:24, and 1927:36, the lowest recorded groundspeed value was approximately 110 mph, and from 1927:14 to the last recorded data point, the heading remained nearly constant on a north-northeasterly heading (030), the altitude decreased from approximately 292 feet to 48 feet above ground level, and the groundspeed increased from approximately 137 mph to 151.6 mph. The accident site was located approximately 1,220 feet and 223 degrees from the last recorded GPS data point location.
Review of the airplane type certificate data sheet revealed the approved engine model is Pratt & Whitney PT6A-34AG, with optional Pratt & Whitney engines consisting of PT6A-34, PT6A-36, PT6A-41, PT6A-41AG, and PT6A-42. The airplane type certificate data sheet also indicates that the approved propeller is Hartzell HC-B3TN-3C or HC-B3TN-3D with Blade Model T10282, or optional Blade Model T10282N+4 blades. As previously reported, the airplane was equipped with a PT6A-27 engine and Hartzell HC-B3TN-3D propeller with T10282N+4 propeller blades.
Safety Board review of FAA Aircraft Records revealed no supplemental type certificate (STC) indicating a change to the airplane type certificate by installation of the PT6A-27 engine.
According to the engineering manager for the airplane type certificate holder (Thrush Aircraft, Inc.), although technically the PT6A-27 engine is not an approved engine for the accident make and model airplane (S2R-T34), the engine is approved in a S2R-T15 airplane, which has nearly an identical airframe as the accident airplane. As such, the engineering manager did not feel there would be any adverse flight characteristics due to installation of the PT6A-27 engine.
Review of the engine type certificate data sheet comparing the originally installed engine (PT6A-34AG) with the engine installed at the time of the accident (PT6A-27) revealed both engines were similar for output rpm (2,200), gas generator rpm (38,100), reduction gear ratio (.0663:1), maximum reverse output rpm (2,100), oil tank capacity (2.3 gallons), usable oil tank capacity (1.5 gallons), principal dimension for length (61.89 inches), nominal diameter (18.29 inches), and maximum radius (11.50 inches). Engine differences related to dry weight, and horsepower (hp) were noted. The accident engine was: 3 pounds lighter than the original installed engine; produced 68 equivalent shaft hp less; produced 70 shaft hp less; produced 8 pounds more jet thrust; and produced 100 shaft hp less in maximum reverse.