Hamilton, TX, USA
N725HP
GARRATT MANSFIELD W IV-P
The pilot reported that, while flying the airplane at flight level 200 in instrument meteorological conditions, including rain showers, he heard a "loud bang," which he believed was due to an engine compressor stall. About 1 minute later, the pilot heard another "loud bang," and the airplane encountered heavier rain and moderate turbulence. The pilot subsequently asked an air traffic controller to clear the flight to descend to 13,000 ft mean sea level (msl) due to approaching severe weather and the controller cleared the descent. When the airplane approached 13,000 ft msl, the pilot applied engine power to arrest the descent. During the power application, the pilot realized that the engine had lost power. The pilot declared an emergency and subsequently executed a forced landing to a field. Postaccident examination and functional testing of the engine did not reveal any anomalies that would have caused the engine power loss. A review of weather information showed that the airplane encountered severe thunderstorm activity and icing conditions along the route of flight and that severe weather warnings were issued within the hour before the flight. The pilot reported that, before the flight, he obtained a weather briefing through an online weather service and that, during the flight, he was using onboard weather equipment. Therefore, he should have been aware of the severe weather conditions along the flight route. The loss of engine power was consistent with the engine ingesting water and ice during the descent, which resulted in an engine flameout.
On May 25, 2015, about 1335 central daylight time, a Mansfield Lancair 4PT experimental amateur-built airplane, N725HP, was substantially damaged when it impacted terrain following a loss of engine power near Hamilton, Texas. The airline transport pilot and passenger were not injured. The airplane was registered to Tailwinds Ltd, Aspen, Colorado, and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions (IMC) prevailed for the flight, which operated on an instrument flight rules flight plan. The flight departed the Lakefront Airport (NEW), New Orleans, Louisiana, at 1140, and was en route to San Angelo, Texas. While flying at flight level (FL) 200 in IMC and rain showers, the pilot heard a loud bang which he believed was a compressor stall in the engine. About one minute later, the pilot heard another loud bang and encountered heavier rain and moderate turbulence. The pilot requested to air traffic control to descend from FL 200 due to "pretty bad conditions", and the air traffic controller cleared him to descend to 13,000 feet mean sea level. When the airplane approached 13,000 feet, the pilot applied engine power to arrest the descent. During the power application, the pilot realized the engine had lost power. The pilot declared an emergency and executed a forced landing to a field. During the forced landing, the nose and right main landing gear collapsed. The right wing partially separated from the fuselage at the wing root. An Advance Flight Systems electronic flight display was installed in the airplane and contained non-volatile memory (NVM) related to engine monitoring. According to the downloaded data, at 1329:30, the engine's oil pressure, which was about 32-33 psi for most of the flight, dropped to 16 psi and then 0 psi, at 16,650 feet msl. Prior to the flight, the pilot obtained a weather briefing through an online weather service. He also reported that, during the flight, he was extensively using onboard ADS-B weather equipment and that he had a portable ADS-B receiver transmitting weather to his iPad. At 1335, the Hamilton Municipal Airport (MNZ), Hamilton, Texas, located about 6 miles south of the accident site, automated weather observation system (AWOS) reported wind from 170 degrees at 20 knots, gusting to 24 knots, visibility 10 miles in thunderstorm and light rain, ceiling broken at 1,100 feet above ground level (agl), broken at 1,600 feet, broken at 2,300 feet, temperature and dew point 23 degrees Celsius, and altimeter setting of 29.84 inches of mercury (Hg). The closest Weather Surveillance Radar-1988, Doppler (WSR-88D) to the accident site was from the National Weather Service (NWS) Dallas/Fort Worth Weather Forecast Office, located about 57 miles north of the accident site. The WSR-88D data was analyzed along the approximate flight track at 1330. The analysis depicted echo tops near 40,000 feet with a reflectivity core of greater than 50 decibels (dBZ), reaching 20,000 feet, and echoes between 40 to 50 dBZ to 28,000 feet, which extended over the flight track and altitude of the airplane as it descended. The temperatures at these levels were below freezing when the flight encountered the echoes, and indicated a high likelihood of the flight encountering supercooled precipitation and severe icing conditions. The NWS Area Forecast, issued at 0445, for the south central United States, expected a ceiling broken at 2,500 feet, with a second broken layer at 5,000 feet, and general cloud tops near 16,000 feet, with widely scattered rain showers and thunderstorms, possibly severe. The accident site was located within the border of Weather Watch 211, which was issued at 1050 and valid until 1800. The watch warned of the potential for severe tornadic thunderstorms, large hail, and damaging winds up to 70 knots. The maximum storms were expected to 60,000 feet and were moving from 240 degrees at 35 knots. The Turbine Power Technologies M601D turbine engine was removed from the airframe and functionally tested under the supervision of a NTSB investigator. The engine functional test was completed with no anomalies noted.
The pilot’s decision to continue flight into known severe thunderstorm conditions, which resulted in the loss of engine power during the descent due to the engine’s ingestion of water and ice and a subsequent forced landing.
Source: NTSB Aviation Accident Database
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