N41173Piper PA-31-350 · 1984

On June 2, 2018, about 1433 eastern daylight time, a Piper PA-31-350, N41173, was destroyed when it impacted the Atlantic Ocean near Amagansett, New York. The commercial pilot and three passengers were fatally injured. The airplane was privately owned by the pilot who was operating it as a Title 14 Code of Federal Regulations Part 91 personal flight. Marginal visual meteorological conditions prevailed, and no flight plan was filed for the flight, which originated from Newport State Airport (UUU), Newport, Rhode Island, and was destined for East Hampton Airport (HTO), East Hampton, New York.

The accident airplane was one of a flight of two airplanes that had flown to UUU from HTO. The pilot of the second airplane, a Beech Bonanza, stated that he and the accident pilot talked for about 1 hour about the weather along the route of flight before departing for the return flight to HTO. They both planned to fly south toward Block Island, Rhode Island, then turn west and follow the Long Island shoreline to HTO. They looked at the weather online. It was visual flight rules (VFR) to the destination. The Bonanza departed first, followed by the accident airplane. After takeoff, the pilot of the Bonanza contacted air traffic control (ATC) and was informed that there was a thunderstorm near HTO and that it was moving slowly. The Bonanza pilot stated that he did not hear the accident pilot on the air traffic control frequency en route, and that, upon contacting the tower controller at HTO, he could hear the controller attempting to contact the accident airplane. The Bonanza subsequently landed uneventfully at HTO.

Radar data provided by the Federal Aviation Administration (FAA) depicted that about 1430, the accident airplane was 5 miles ahead of the Bonanza and over the Atlantic Ocean south of HTO at an altitude of 432 ft mean sea level (msl) and about 6 miles from the airport. The target climbed to 512 ft and then descended to 152 ft. The last radar return at 1433, indicated 532 ft about 2 miles south of Indian Wells Beach. The pilot told air traffic control at HTO, that he was flying at 700 ft and was "coming in below" the thunderstorm. The airplane was about 5 miles from HTO at that point. There were no further communications from the pilot.

The pilot held a commercial pilot certificate with ratings for airplane single-engine land, multi-engine land and instrument airplane. He also held a flight instructor certificate. His most recent FAA second-class medical certificate was issued May 30, 2017. At the time of the medical examination, the pilot reported 3,000 total hours of flight experience. The pilot's logbooks were not recovered. His recent flight experience and instrument flight experience could not be determined,

The seven-seat, low-wing airplane was manufactured in 1984. It was powered by two Lycoming TIO-540-J2B, 350-horsepower engines equipped with four-bladed Hartzell propellers. The airplane was equipped with a Garmin MX20 MFD and a Garmin 530 GPS, both capable of displaying weather information. The most recent annual inspection was completed on November 3, 2017. At the time of the accident, the airframe total time was 5776.6 hours. The left engine had 359.5 hours since major overhaul and the right engine had 535.7 hours since major overhaul. The airplane had flown 39 hours since the annual inspection.

At 1435, the weather recorded at HTO included calm wind, 7 miles visibility in light thunderstorm rain showers, scattered clouds at 1,300 ft, scattered clouds at 2,100 ft, overcast ceiling at 2,600 ft, temperature 22°C, dew point 20°C, and an altimeter setting of 29.76 inches of mercury.

Two inflight weather advisories were issued for the route and area of the destination about 42 and 15 minutes before the accident flight departed, respectfully, and warned of heavy to extreme precipitation associated with thunderstorms. There was no record of a weather briefing provided to the pilot of the accident airplane.

Review of weather radar revealed a low-pressure system associated with a frontal wave over Long Island Sound with a cold front stretching westward over Long Island into central New Jersey and a warm front turning back to a cold front eastward. The models also indicated scattered thunderstorms over the area of HTO

Figure 1 depicts the accident airplane's flight track overlaid on the Boston WSR-88D base reflectivity image for 1438 (Echoes less than 10 dBZ have been removed from the image). The airplane's flight track entered the leading of the echoes with a maximum of 53 dBZ "extreme" intensity echoes with tops near 48,000 ft. Extreme intensity echoes over 50 dBZ extended between the accident site and HTO.

Figure 1: Boston WSR-88D Base Reflectivity Image at 1438 with flight track

A local resident about 1/2 mile from the accident site took several photos of the approaching thunderstorm, which documented a shelf cloud and cumulus mammatus clouds along the leading edge of the storm, indicative of potential severe turbulence.

(For more information, see the NTSB Meteorological Factual Report for this accident in the public docket).

The seven-seat, low-wing airplane was manufactured in 1984. It was powered by two Lycoming TIO-540-J2B, 350-horsepower engines equipped with four-bladed Hartzell propellers. The airplane was equipped with a Garmin MX20 MFD and a Garmin 530 GPS, both capable of displaying weather information. The most recent annual inspection was completed on November 3, 2017. At the time of the accident, the airframe total time was 5776.6 hours. The left engine had 359.5 hours since major overhaul and the right engine had 535.7 hours since major overhaul. The airplane had flown 39 hours since the annual inspection.

The wreckage was located about 1 mile south of Indian Wells Beach in 50 ft of water and was subsequently recovered for examination. The fuselage was impact damaged, fractured, and separated into multiple pieces. The left and right wings were both separated from the fuselage at the wing root and were fragmented. One left wing fuel cell was recovered.

The left and right engines remained partially attached to the airframe through the mounts. The oil sump was fractured and corroded on both engines. The No. 1 cylinders were impact damaged on both engines. The spark plugs were removed, and the engines were rotated by turning the propeller flange. Continuity to the rear gears and to the valve train was confirmed on each engine. Thumb compression and suction were confirmed for each cylinder. The pistons, valves, and cylinders were examined using a lighted borescope. No anomalies were noted except corrosion and sand consistent with saltwater immersion.

Both left and right propellers were fractured from their respective engine crankshaft mounting flanges and exhibited corrosion consistent with saltwater immersion. Both propeller spinner domes were torn from the propeller assemblies and were not recovered. All four blades of the left and right propellers were bent aft in varying degrees and twisted toward low pitch.

An autopsy was performed on the pilot by the Office of the Medical Examiner, Suffolk County, New York. The report listed the cause of death as blunt force trauma.

Forensic toxicology was not performed as the body was recovered from the ocean about 2 days after the accident.