CEN25FA006

The pilot was departing on the final leg of a four-leg cargo flight. Airport surveillance video captured the airplane as it climbed away from the runway, entered a left bank, and began to descend. The airplane was in a nose-down, steep left bank as it descended out of view. Publicly available ADS-B flight track data indicated that the airplane’s ground speed decayed from 105 knots (kts) to about 84 kts as the airplane turned left of the runway’s extended centerline and climbed to a peak altitude around 160 ft above ground level (agl). The last recorded position showed the airplane about 88 ft agl at 85 kts ground speed. The airplane’s wings level, no-flap aerodynamic stall speed was 87 kts calibrated airspeed (KCAS), and its single-engine minimum controllable airspeed was 89 KCAS. Recorded weather information for the airport about the time of the accident included a 6-knot left quartering headwind for the takeoff runway. The airplane impacted terrain about 640 yards from the departure end of the runway. The distribution of the wreckage indicated that the airplane impacted in a near-wings-level attitude with relatively little forward motion, consistent with an aerodynamic stall or near-recovery from an aerodynamic stall. The observed damage to the propellers was consistent with the left engine producing low power, and the right engine operating at a high power setting. Examination of the engines revealed damage to multiple fan blades of the left engine compressor turbine (CT) disk. Most blades displayed damage signatures consistent with overstress; however, one blade displayed signatures consistent with fatigue. Metallurgic and microhardness examinations of the blade did not reveal any defects. The fracture surface bisected multiple grains and no plastic deformation was observed, all features consistent with intragranular fatigue; however, the root cause of the fatigue cracking could not be determined. It is likely that the first blade failed as a result of fatigue, and subsequently resulted in secondary overstress damage to other CT disk blades and further internal damage as the separated blades continued through the engine’s gas path. The observed engine damage would have resulted in a disruption of engine power, and likely noticeable unusual engine vibrations and possibly sparks from the engine’s exhaust. The airplane was equipped with an autofeather system. Since the left propeller was not found in the feathered position, it is unlikely that the left engine stopped producing power but, rather, continued to operate at a low power setting following the CT disk blade failure. Performance information contained in the airplane’s flight manual indicated that the airplane was capable of climbing with one engine inoperative if the inoperative engine’s propeller was feathered and the landing gear was retracted. The pilot completed training for the accident operator on the accident airplane about 1 month before the accident. Notes from his trainingflights indicated that he exhibited deficiencies during practice engine failure after takeoff scenarios on several occasions, including comments that his response to the simulated failure was “slow.” Available flight track data showed that the airplane’s ground speed decayed from takeoff speed to about its aerodynamic stall speed during the initial climb. It is likely that the pilot became distracted while attempting to manage and diagnose a partial loss of left engine power during the initial climb and did not maintain adequate airspeed, which resulted in a loss of control at an altitude too low for recovery. The CT disk blades were subject to recurring inspections every 2,000 hours of operation and replacement every 5,000 hours of operation. At the time of the accident, the blades had accumulated about 3,382 hours of operation and were most recently inspected about 20 months before the accident. Whether the fatigue cracking was present or would have been detectable during the most recent inspection could not be determined.

Emergency Procedures The operator’s standard operating procedures stated that: If an engine failure occurs after rotation (below 1500 feet [above ground level]) and there is NOT sufficient runway left to land, the [pilot in command] must maintain directional control and promptly complete the applicable immediate action items…If the Autofeather system fails, the Captain must positively identify the failed engine immediately and feather the appropriate propeller. It should be noted that [minimum control speed] increases significantly if the propeller does not feather and the aircraft will not have sufficient power to maintain positive climb under these circumstances. The immediate action items for an engine failure after takeoff were: Power – Set maximum. Landing gear – (Verifying positive rate) UP. Flaps – UP. Autofeather – Verify (if the failed engine does not autofeather it is essential that the proper engine is manually feathered immediately). Previous CT Blade Failure Events Review of the NTSB database for pilot descriptions of CT blade failures returned descriptions such as “vibration and loss of power” (NTSB ID MIA97LA012), and “heard a loud bang, observed sparks and flames exiting the engine exhaust ports” (NTSB ID SEA02LA161). The airplane was configured with a cargo pod. Per company policy, the pilot left a cargo load manifest record at the departure airport, which showed that the loading of cargo was within weight and center of gravity limits. The airplane’s estimated takeoff weight for the accident flight was 9,034 lbs. According to performance charts in the airplane’s flight manual, the airplane was capable of a positive rate of climb at maximum takeoff weight and one-engine-inoperative at liftoff with the flaps fully retracted and the inoperative engine’s propeller feathered (using maximum takeoff power, or 90% minimum takeoff power on the remaining operating engine). Takeoff speed was 99 kts and climb speed was 109 kts. According to the airplane flight manual, the wings-level aerodynamic stall speed was 87 KCAS with engine power at idle, flaps fully retracted, and an operating weight of 9,000 lbs. The airplane’s minimum controllable airspeed (Vmca) was 94 KCAS. The airplane was equipped with an autofeather system, which automated the feathering of the propeller blades when the system sensed that engine torquemeter oil pressure dropped below 6.5 psi and the power setting for that engine was 85-90% N1 or greater. On October 7, 2024, about 1938 central daylight time, a Beech C99 airplane, N130GP, was destroyed when it was involved in an accident near Norfolk, Nebraska. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 cargo flight. The flight originated from Eppley Airfield (OMA), Omaha, Nebraska. The pilot flew to The O’Neill Municipal Airport-John L Baker Field (ONL), where he received cargo and additional fuel. The pilot continued to Norfolk Regional Airport/Karl StefanMemorial Field (OFK), Norfolk, Nebraska, where he received additional cargo. The accident occurred during departure on the return flight to OMA. Airport surveillance video captured the airplane departing from runway 20 around dusk. Shortly after takeoff, the airplane entered a left bank and began to descend. The airplane descended out of view behind a building in a steep left bank and nose-down pitch attitude. An internet-based flight tracking service captured ADS-B track data for the flight, which consisted of 8 points over 24 seconds. The first recorded point was at 1937:52 at an altitude of 1,525 ft and 105 knots (kts) ground speed. As the airplane continued to climb, the recorded ground speed decreased. The airplane reached its highest recorded altitude of 1,725 ft at 1938:07. At that time, the airplane’s ground speed had decreased to 84 kts. The final recorded point, at 1938:16, showed an altitude of 1,650 ft and 85 kts ground speed. Figure 1 depicts the ADS-B flight track information overlaid on satellite imagery of the departure runway. Figure 1. Plot of ADS-B flight track data. An autopsy of the pilot was authorized by the Madison County Attorney. According to the autopsy report, the cause of death was blunt force injuries. The FAA Forensic Sciences Laboratory performed toxicological testing on specimens from the pilot, which was positive for naproxen, a non-prescription nonsteroidal anti-inflammatory drug that is considered non-impairing (NSAID) and often used to treat pain and inflammation. The pilot held a commercial pilot certificate with ratings for airplane single- and multi-engine land, as well as a flight instructor certificate with ratings for airplane single- and multi-engine and instrument airplane. Review of FAA airman information indicated that on June 2, 2023, prior to his employment with Ameriflight, the pilot failed the practical test for his airline transport pilot (ATP) certificate. There was no record that the pilot attempted another practical test and attempts to obtain the pilot’s training records for ATP certification were not successful. According to company training records from the operator, the pilot was hired in July 2024 and started ground school for the Beech C99 on July 15, 2024. He progressed through the company’s training program with comments on several flights indicating deficiencies during practice engine failures on takeoff. Comments regarding a mock check ride the pilot performed on August 21, 2024, indicated that the pilot was “slow and a bit clunky but [satisfactory]” with the practice engine failure after takeoff. On September 3, 2024, the pilot completed the training program and was approved for line operations. CT Disk Laboratory Examination Examination of the CT disk found that most of the blade fracture surfaces were either rough and dimpled, consistent with ductile overstress fracture, or had post-fracture secondary smearing damage. One CT blade displayed a distinct area was relatively smoothand flat, consistent with fatigue. This flat region extended through the thickness of the blade starting at the trailing edge and extending forward approximately 0.25 inches. River marks near the trailing edge extended from the pressure side towards the suction side, consistent with a crack that propagated through the thickness of the blade. The blade was removed, cleaned and examined. Metallurgic and microhardness examinations did not note any defects. The blade was cross-sectioned, and the microstructure was found to be consistent throughout the blade. The fracture surface bisected multiple grains and no plastic deformation was observed, consistent with intragranular fatigue. The operator received the turbine disk blades from Pratt & Whitney Canada in January 2016. The blades and a turbine disk were installed on the engine of another company airplane as part of a “compressor turbine disk assembly replacement” for the hot section designated “PCE-38137.” In August 2016, gas generator PCE-38137 was removed from that airplane and installed in the left engine of the accident airplane. The turbine disk and blades were visually inspected every 2,000 hours. Since installation on the accident airplane, they were inspected on May 7, 2018, and February 11, 2023. At the time of the accident, the blades had accrued 3,382.3 hours, about 1,600 hours short of the 5,000-hour removal time established by Pratt & Whitney Canada. Warning and Advisory Panel The cockpit warning and advisory panel was removed and sent to the NTSB Materials Laboratory to determine the presence of filament stretching in the panel’s bulbs. Examination did not find any bulbs with filament stretching. The accident site was located about 640 yards southeast of the departure end of runway 20. The initial impact point consisted of multiple ground scars and divots consistent with the main landing gear, empennage, and wings. The airplane appeared to impact terrain in a flat pitch, near wings-level attitude. The tail section of the airplane and right main landing gear fractured and remained at the initial impact point. The main wreckage was located 24 yards east of the initial impact point facing northeast. A postimpact fire ensued that consumed a majority of the wreckage. All major components of the airplane were located at the accident site. The flight controls appeared to be continuous before impact. The rudder and one of the elevator cables were torn from the empennage. One elevator cable exhibited a portion of the elevator control horn still attached. The flaps were found in the fully retracted position, and the landing gear was found extended. Cockpit instrumentation was fire-damaged. No devices containing non-volatile memory were located or retained for download. Both engine firewall shutoff valves were found in the open position. Examination of the left engine revealed evidence that the engine was operating at impact. Compressor turbine (CT) blades were found fractured at varyingheights with impact damage to the leading and trailing edges of the remaining blades. Additional damage was observed throughout the engine that was consistent with the engine rotating at impact with downstream damage to components likely from the liberated CT blade fragments. The CT disk was sent to the NTSB Materials Laboratory for further examination. Examination of the right engine also found evidence consistent with the engine operating at impact. Damage to right engine components and rotational scoring was consistent with the engine rotation. Examination of both propellers revealed no discrepancies that would have precluded normal operation. All observed damage was consistent with high impact forces, and both propellers exhibited damage indicating rotation, with blade angles in the normal operating range of operation. Neither propeller exhibited damage indicating it was at or near a feathered position. Damage to the left propeller was consistent with it rotating at low power at impact. Piston marks and blade damage were consistent with the right propeller being operated at a high power setting, possibly near takeoff power.