NTSB Factual Report

HISTORY OF FLIGHT

On June 18, 2011, about 1306 eastern daylight time, a Cessna T210N, N210KW, was substantially damaged following a collision with trees and terrain at Armonk, New York. The certificated commercial pilot and three passengers were fatally injured. The airplane was registered to Wein-Air Aviation LTD and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed and active. The flight originated from Westchester County Airport (HPN), White Plains, New York, about 1303 and was destined for Montauk Airport (MTP), New York.

After takeoff from runway 34 at HPN, the pilot reported to air traffic control (ATC) that he needed to return to the airport and requested runway 16. The controller asked the pilot if he was declaring an emergency, and the pilot reported that he was. The pilot did not state the nature of the emergency. The controller then asked the pilot to switch to tower frequency, and the pilot responded that he could not switch to tower. This was the last recognizable communication from the pilot. A review of the recorded radar data indicated that the airplane reached a maximum altitude of about 1,400 feet mean sea level, or about 1,000 feet above ground level, after takeoff. Radar contact was lost at 87 knots ground speed and on a heading of 169 degrees, at the same approximate location as the accident site.

A locally-based pilot reported that he observed the accident pilot perform about eight engine run-ups at the end of runway prior to departure. He stated that it sounded like the pilot was trying to clean the spark plugs or he was having trouble with the magnetos firing properly. During the first few run-ups, the engine made a "chugga-chugga" sound, and then smoothed out during the final two or three run-ups prior to departure. He added that the takeoff roll was unusually long, and the airplane did not climb as well as he expected after takeoff. He did not observe the accident.

A summer intern at Panorama Flight Service, who was also a private pilot, observed the pilot start the engine of the accident airplane on the ramp at HPN prior to the flight. He stated that the engine started normally, but had a "clunky" idle. There was some exhaust smoke during the start, but nothing that seemed abnormal. He stated that the pilot proceeded to perform an engine run-up in the tie down area, which he considered unusual and was generally considered "bad form" due to the noise and propeller blast generated. He added that, during the run-up, the nose gear strut appeared compressed from the force generated by the propeller. He heard two short lulls which he believed were magneto checks. These lulls sounded normal. After a brief period at idle, the pilot advanced the throttle again and cycled the propeller at least three times. The pilot then advanced the throttle to a high power setting and ran the engine for about one minute before reducing the throttle. The entire sequence lasted about three to four minutes.

PERSONNEL INFORMATION

According to FAA records, the certificated commercial pilot held airplane single engine land, airplane multi-engine land, and instrument airplane ratings. He was also a certified flight and ground instructor. His pilot logbooks were not located after the accident; however, he reported 4,150 hours on his latest FAA medical certificate, dated May 6, 2011.

AIRCRAFT INFORMATION

The airplane was a single-engine, high-wing, retractable gear airplane, serial number 21064181. It was powered by a Continental TSIO-520R9B engine rated at 310 horsepower.

A review of the aircraft maintenance records indicated that an annual inspection of the airframe and engine was performed on June 4, 2010. The aircraft total time at the time of the annual inspection was 2,790.9 hours.

A review of the engine logbook revealed that the factory-rebuilt engine was originally installed on the airframe on February 12, 2007. During an annual inspection on March 10, 2009, at 30.2 hours since major overhaul (SMOH), the magnetos were retimed. The last recorded engine maintenance was on February 11, 2011, at 74.2 hours SMOH, and included an oil and filter change and the replacement of the oil cooler vernatherm. Fueling records indicate that the pilot purchased a total of 89 gallons of fuel between February 11, 2011 and May 28, 2011. There were no records located to indicate that the accident airplane was flown between May 29, 2011 and June 17, 2011.

METEOROLOGICAL INFORMATION

The 1256 recorded weather observation at HPN included winds from 300 degrees at 10 knots, scattered clouds at 4,600 feet, a broken ceiling at 6,000 feet, 10 miles visibility, temperature 27 degrees C, dew point 17 degrees C, and an altimeter setting of 29.84 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

The wreckage was located in a wooded area, about one mile north-northeast of the approach end of runway 16. The wreckage path was oriented on a heading of about 153 degrees and was about 350 feet in length. The first identifiable point of impact along the wreckage path was the top of a mature maple tree, about 60 feet tall. The main wreckage came to rest near the base of a tree that exhibited impact damage at a height of about 40 feet.

The cockpit and cabin sections were inverted and mostly consumed by the post-crash fire. The cockpit instruments were unreadable. No components were located with non-volatile memory that survived the fire.

Both wings and the empennage were found within the area of the main wreckage. Flight control continuity was established from the control surfaces to the cockpit controls. The landing gear and flaps were found in the retracted positions.

The propeller remained attached to the engine, and the engine sustained minor damage from impact and heat. The turbocharger rotated freely by hand. The fuel gascolator was opened and inspected. The bowl and screen were clean and were free of fuel.

The airplane was equipped with a McCauley three-bladed constant-speed metal propeller. With the exception of impact-related bends and dents, the blades did not exhibit torsional twisting, deformation, leading edge gouges, or chordwise scratches. A smooth cut was observed on a tree trunk that was located adjacent to one of the propeller blades.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot was performed at the office of the Westchester County, New York Medical Examiner on June 19, 2011. The autopsy report included findings of chest blunt force trauma and heart lacerations as the result of the airplane accident. The report noted the cause of death as "PLANE CRASH."

Forensic toxicology testing was performed on specimens of the pilot and his wife by the Federal Aviation Administration (FAA) Bioaeronautical Sciences Research Laboratory (CAMI), Oklahoma City, Oklahoma. The CAMI toxicology report for the pilot indicated negative for cyanide, ethanol, and carbon monoxide. Cetirizine was detected in the urine but not in the blood. Pseudoephedrine was detected in the urine.

The CAMI toxicology report for the pilot's wife indicated negative for cyanide and carbon monoxide. Testing for volatiles and drugs was not performed.

The pilot was issued a third class medical certificate, dated May 6, 2011. The following limitation was listed on the certificate, "Must wear corrective lenses."

TESTS AND RESEARCH

Engine Examination

The engine was sent to the Continental Motors, Inc. facilities in Mobile, Alabama for a more detailed examination. The inspection occurred on July 18, 2011.

The oil system was examined and was found to contain fine aluminum particles. The magnetic chip detector was removed and some larger metallic particles were present.

The left magneto timing was checked and found to be set at 30 degrees before top dead center (BTDC). The manufacturer's specifications required magneto timing to be at 22 degrees BTDC. The right magneto was broken free at the engine mount due to impact damage and its timing could not be determined. The left and right magnetos were installed on a test bench and operated normally.

The spark plugs were removed and examined. All spark plugs, with the exception of the number 2 cylinder plugs, were normal in wear and color when compared to a Champion Aviation Check-A-Plug chart. The electrodes of the number 2 cylinder plugs were fully imbedded with aluminum and appeared incapable of producing a spark.

Further disassembly of the engine revealed that the number two cylinder combustion chamber contained molten aluminum debris. The intake and exhaust valve heads also exhibited molten aluminum debris. The rocker box area had an oil residue indicating lubrication of the overhead. The cylinder overhead components (valves, rockers, guides, springs, retainers, and shafts) were lubricated and undamaged. The number 2 piston head exhibited thermal deterioration consistent with a pre-ignition or detonation event. The piston rings exhibited mechanical damage. The piston pin and plug assembly were intact and exhibited damage consistent with a pre-ignition or detonation event.

The numbers 1, 3, 4, 5, and 6 cylinder combustion chambers exhibited normal combustion deposits and operating signatures. The cylinder overhead components were normal in appearance showed no evidence of a lack of lubrication.

The numbers 1, 3, 4, and 5 pistons exhibited normal combustion deposits, wear, and operating signatures. The number 6 piston exhibited less than a normal amount of combustion deposits and there was pitting of the face of the piston.

The throttle body and mixture metering unit in addition to the fuel pump, fuel manifold, fuel manifold lines and six fuel nozzle assemblies were all tested on the manufacturer's calibrated test benches and found to function properly through their full range of operation.

Sound Spectrum Study

Noise abatement monitoring microphones were positioned at various locations near HPN. The airport's Noise Abatement Officer provided an audio recording to investigators of an airplane identified at N210KW. The recording, associated radar data, and locations of the noise abatement monitoring microphones were forwarded to the NTSB Vehicle Recorder Division, Washington, DC for a sound spectrum study. The recording contained three distinct regions of noise. The first region, about 3 minutes and 18 seconds into the recording, is consistent with engine noise from an aircraft during takeoff climb. The second region, about 4 minutes and 40 seconds into the recording, was also consistent with engine noise from an aircraft. This region was identified with the accident airplane returning to HPN. The third region, about 4 minutes and 59 seconds into the recording, was consistent with the aircraft impacting the trees and terrain.

The sound spectrum study revealed that the engine was producing significantly less sound pressure on the inbound (return) leg as compared to the outbound (takeoff) leg. For additional information and calculations regarding the sound spectrum study, refer to the Specialist's Report located in the public docket for this investigation.

NTSB Probable Cause

The pilot's decision to depart on the flight with a suspected mechanical deficiency and his subsequent decision to fly the final approach at a reduced power setting. Contributing to the accident was the improper timing of the magneto(s) that resulted in a severe detonation event.