ERA18LA031

The pilot performed a preflight inspection of the turboprop airplane and an engine run-up with no anomalies noted. The takeoff roll and lift off from the runway were normal; however, when the pilot initiated a landing gear retraction, the engine torque decreased, but the rpm did not change. The torque then surged back to full power and continued to surge as the pilot attempted to return to the runway. The left wing of the airplane struck the ground, and the airplane came to rest in the grass on the side of the runway. Examination of the engine, engine accessories, and propeller revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation before the accident. The reason for the partial loss of engine power could not be determined based on the available information.

On November 25, 2017, about 1315 eastern standard time, a Piper PA-46-500TP, N863RB, was substantially damaged when it experienced a loss of engine power during the initial climb from St. Pete/Clearwater International Airport (PIE), Clearwater, Florida. The airline transport pilot sustained minor injuries. The airplane was registered to and operated by a corporation as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident, and an instrument flight rules flight plan was filed for the flight that was destined for Pensacola International Airport (PNS), Pensacola, Florida.According to the pilot, he performed a preflight inspection of the airplane and engine runup with no anomalies noted. The takeoff roll and lift off from runway 36 were "normal;" however, when he initiated a landing gear retraction, the engine torque decreased to 300-400 [ft-lbs], and rpm remained at 2,000. The torque surged back toward full power; however, he could not recall how high. The pilot initiated a 20° right turn in anticipation to return to the runway, and throughout the engine continued to surge. The pilot attempted to return to the runway instead of landing in the water; however, the left wing of the airplane struck the ground and it came to rest near runway 18. Initial examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the left wing was impact separated. The right wing remained attached to the fuselage. The fuselage was partially separated at the cabin section of the airframe. The engine remained attached to the airframe and the propeller remained attached to the engine. According to the pilot, he held an airline transport pilot certificate with ratings for airplane multiengine land and instrument airplane. In addition, he held a flight instructor certificate with a rating for airplane single-engine. His most recent FAA first-class medical certificate was issued on October 11, 2017. He reported 15,000 hours of total flight time, of which, 25 hours were in the same make and model as the accident airplane. In addition, in the previous 90 days, he had accumulated 35 hours of flight time. According to FAA airworthiness records, the airplane was manufactured in 2005. It was powered by a Pratt & Whitney PT6A-42A, 850-shaft-horsepower engine equipped with a Hartzell constant-speed propeller. According to airplane maintenance logbooks, the most recent annual inspection was completed on April 1, 2017, at a total time of 1,341.0 hours and 912 cycles. Examination of the airframe revealed that the there were no blockages noted with the fuel system. The both electric fuel pumps were tested, and no anomalies were noted. In addition, fuel similar to Jet A was noted in the right-wing during recovery of the airplane. The left fuel tank was breached. The engine and propeller were removed from the airplane for further examination. Examination of the propellerrevealed that all four propeller blades were bent aft, opposite the direction of rotation, and twisted towards a low pitch blade angle. Two blades fractured approximately 8 inches outboard of the blade shank and separated from the propeller assembly during the impact sequence. In addition, chordwise scratching and leading-edge gouging was noted. When the propeller was disassembled, all of the blades were not in a feathered position and the pitch change components were impact damaged. The beta ring was removed, and no anomalies were noted. There were no anomalies noted with the propeller that would have precluded normal operation prior to the accident. The engine was sent to the manufacturer for further examination and teardown. The first stage power turbine exhibited rotational scoring. The compressor turbine rotated with no binding or scraping. The disk and blade fir tree faces of the compressor turbine exhibited rotational scoring. The axial compressors were rotated without anomaly. They were all removed and examined. The turbine blades exhibited a small amount of rotational scoring. The two bleed valves were removed and could be actuated by hand. The o-rings and gaskets were examined with no cracking noted. There were no anomalies noted with the engine that would have precluded normal operation prior to the accident. The fuel pump, fuel control, fuel filter, torque controller, and propeller governor were removed and sent to Pratt & Whitney Canada for further examination . Each component was tested an no anomalies were noted. The data acquisition unit (DAU) was removed from the airframe and sent to the NTSB Recorders Laboratory for data download. The DAU was an engine instrument display system that also included dual instrument panel mounted displays and various engine and fuel tank sensors. It recorded engine condition trim monitoring data, exceedances, and fault data on two channels; both channels of the DAU were downloaded. There were no engine condition trend monitoring data nor exceedances recorded on the day of the accident. Two faults were recorded on the day of the accident which noted "oil press AtoD reversion failure" and "Torque AtoD reversion failure.; however, the faults could not be correlated to the accident.