BEECH C99
Norfolk, NE, October 8, 2024
Event Information
| Date | October 8, 2024 |
| Event Type | ACC |
| Location | Norfolk, NE |
| Country | USA |
| Coordinates | 41.97386, -97.43256 |
| Airport | NORFOLK RGNL/KARL STEFAN MEML |
| Highest Injury | FATL |
| NTSB Number | CEN25FA006 |
| Event ID | 20241008195272 |
Aircraft
| Make | BEECH |
| Model | C99 |
| Registration # | N130GP |
| Operator | Ameriflight, LLC |
| Owner | UAS Transervices Inc. |
| Category | AIR |
| FAR Part | 135 |
| Aircraft Damage | DEST |
Conditions
| Light Condition | DUSK |
| Weather | VMC |
Injuries
| Fatal | 1 |
| Serious | 0 |
| Minor | 0 |
| None | 0 |
| Total Injured | 1 |
Event Location
Probable Cause
The pilot’s failure to maintain adequate airspeed following a partial loss of engine power during takeoff, which resulted in a loss of airplane control. Contributing to the accident was the fatigue failure of the compressor turbine fan disk blade.
Full Narrative
HISTORY OF FLIGHTOn 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 Stefan Memorial 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. PERSONNEL INFORMATIONThe 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. AIRCRAFT INFORMATIONThe 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. AIRPORT INFORMATIONThe 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. WRECKAGE AND IMPACT INFORMATIONThe 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 varying heights 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. ADDITIONAL INFORMATIONEmergency 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). MEDICAL AND PATHOLOGICAL INFORMATIONAn 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. TESTS AND RESEARCHCT 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 smooth and 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.
About This NTSB Record
This aviation event was investigated by the National Transportation Safety Board (NTSB). NTSB investigates all U.S. civil aviation accidents to determine probable cause and issue safety recommendations to prevent future accidents.