Crash of a Beechcraft 200 Super King Air in Rockford: 1 killed

Date & Time: Aug 20, 2020 at 1542 LT
Operator:
Registration:
N198DM
Flight Phase:
Flight Type:
Survivors:
No
Schedule:
Rockford - DuPage
MSN:
BB-1198
YOM:
1984
Crew on board:
1
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total flying hours:
3650
Aircraft flight hours:
8018
Circumstances:
On August 20, 2020, about 1542 central daylight time, a Beech B200 airplane (marketed as a King Air 200), N198DM, was destroyed when it was involved in an accident near Rockford, Illinois. The private pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 positioning flight. The purpose of the flight was to relocate the airplane to the pilot's home base at the DuPage Airport (DPA), West Chicago, Illinois. The airplane had been at Chronos Aviation, LLC (a 14 CFR Part 145 repair station), at the Rockford International Airport (RFD), Rockford, Illinois, for maintenance work. Multiple airport-based cameras recorded the accident sequence. The videos showed the airplane taking off from runway 19. Shortly after liftoff, the airplane started turning left, and the airplane developed a large left bank angle as it was turning. The airplane departed the runway to the left and impacted the ground. During the impact sequence, an explosion occurred, and there was a postimpact fire. A video study estimated the airplane’s maximum groundspeed during the takeoff as 105.5 knots (kts). Data recovered from an Appareo Stratus device onboard the airplane showed that about 1538, the airplane began taxing to runway 19. At 1540:34, the airplane crossed the hold short line for runway 19. At 1541:19, the airplane began a takeoff roll on runway 19. At 1541:42, the airplane began to depart the runway centerline to the left of the runway. Subsequent tracklog points showed the airplane gaining some altitude, and the tracklog terminated adjacent to a taxiway in a grassy area. The Appareo Stratus data showed the airplane began to increase groundspeed on a true heading of roughly 185° about 1541. Airplane pitch began to increase at 1541:41 as the groundspeed reached about 104 kts. The groundspeed increased to 107 kts within the next 2 seconds, and the pitch angle reached around 4° nose-up at this time. In the next few seconds, pitch lowered to around 0° as the groundspeed decayed to around 98 kts. The pitch then became 15° nose-up as the groundspeed continued to decay to about 95 kts. A right roll occurred of about 13° and changed to a rapidly increasing left roll over the next 5 seconds. The left roll reached a maximum of about 86° left as the pitch angle increasingly became negative (the airplane nosed down). The pitch angle reached a maximum nose down condition of -73°. The data became invalid after 1541:53.4. An airplane performance study based on the Appareo Stratus data showed that during the takeoff from runway 19, the airplane accelerated to a groundspeed of 98 kts and an airspeed of 105 kts before rotating and lifting off. The airplane pitched up, climbed, and gained height above the ground. Then, 4 seconds after rotation, the airplane began descending and slowing, consistent with a loss of power. A nose-left sideslip, a left side force, and a left roll were recorded, consistent with the loss or reduction in thrust of the left engine. The sideslip was reduced, likely due to opposite rudder input, and the airplane briefly rolled right. The airplane pitched up and was able to begin climbing again; however, it continued to lose speed. The sideslip then reversed, and the airplane rolled left again and impacted the ground. One witness reported that he observed the accident sequence. He did not hear any abnormal engine noises, nor did he see any smoke or flames emit from the airplane before impact. The airplane came to rest on a flat grass field to the east of runway 19 on airport property. The airplane sustained fire damage and was fragmented from impacting terrain.
Probable cause:
The pilot’s failure to maintain airplane control following a reduction of thrust in the left engine during takeoff. The reason for the reduction in thrust could not be determined based on the available evidence.
Final Report:

Crash of a Piper PA-31-325 Navajo C/R in Sumter

Date & Time: Aug 1, 2020 at 1000 LT
Type of aircraft:
Operator:
Registration:
C-GXKS
Flight Phase:
Flight Type:
Survivors:
Yes
Schedule:
Manning - Manning
MSN:
31-7512038
YOM:
1975
Crew on board:
2
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
1625
Captain / Total hours on type:
550.00
Aircraft flight hours:
12038
Circumstances:
According to the pilot, he and the copilot were flying low-level mapping flights in the twin-engine airplane. Although the copilot was not multi-engine rated, he and the pilot regularly switched control of the airplane during the mapping flights. On the accident flight, the pilot was seated in the right seat; the copilot was seated in the left seat; and they were flying the airplane at an altitude of about 300 ft above ground level. According to the pilot, they flew for about 2 hours before he, who was the pilot flying at the time, switched fuel tanks from the inboard tanks to the outboard tanks. The pilot did not tell the copilot he had switched fuel tanks. About 1.5 hours later, while the copilot was the pilot flying, the left engine started to surge and lose power. The pilot began the steps of the emergency procedure for an engine failure in cruise flight starting with moving the fuel selectors to the inboard tanks. Power was not restored; the airplane immediately began losing altitude; and the pilot took over control of the airplane. The copilot stated that at the time the pilot took over control, he looked at the fuel tank quantity gauges, and they both displayed zero. The pilot reported that the airplane stalled just above the ground during the emergency landing in a field. The right wing struck first, and within a couple of seconds, the right outboard fuel tank exploded. The pilot and copilot egressed out the rear door. Examination of the wreckage revealed that neither engine exhibited evidence of power at impact. The left outboard fuel tank was found completely full of fuel, and the left inboard fuel tank was empty. Both right wing tanks were fire damaged, and the fuel quantity in the tanks at impact could not be determined. Further examination revealed that the fuel crossfeed valve was in the “crossfeed/open” position. No fuel was observed in the valve or attached fuel lines during disassembly. The left fuel selector valve was found in the “OFF” position, and no fuel was observed within the fuel line between the valve and gascolator. The right fuel selector valve was damaged by fire, and its position at impact could not be determined. No other anomalies were noted in the engines or airframe. According to the pilot, all fuel tanks were full before the flight. According to the pilot’s operating manual, the airplane likely consumed about 33.1 gallons of fuel per hour or a total of about 115 gallons of fuel during the 3.5-hour flight. Given that the inboard fuel cells held 56 gallons each (112 gallons total), that the left inboard tank was found empty, and that the copilot noticed that the fuel gauges were reading zero just before impact, it is likely that each engine was drawing fuel from its respective inboard tank throughout the flight until those tanks were empty. The left engine lost power first, and the right engine likely lost power just before impact. The postaccident positions of the crossfeed valve (on) and the left fuel selector (off) did not correspond to the pilot’s statements regarding his positioning of the fuel selector valves during the flight. The fuel panel was located between and behind the pilots’ seats and required the pilots to look down and back in order to see the panel when making changes to the panel; therefore, it is likely the pilot misconfigured the valves when he switched tanks 2 hours into the flight, when he switched tanks after the left engine lost power, or on both occasions. It is unlikely the copilot would have been able to see an incorrect switch selection on the fuel panel due to the location of the panel, and he would have been unlikely to look at the 2-hour point as the pilot did not verbalize that a change to the panel had been made.
Probable cause:
The pilot’s fuel mismanagement during flight, which resulted in a total loss of engine power from both engines due to fuel starvation.
Final Report:

Crash of a De Havilland DHC-2 Beaver in Soldotna: 6 killed

Date & Time: Jul 31, 2020 at 0827 LT
Type of aircraft:
Operator:
Registration:
N4982U
Flight Phase:
Survivors:
No
MSN:
904
YOM:
1956
Location:
Crew on board:
1
Crew fatalities:
Pax on board:
5
Pax fatalities:
Other fatalities:
Total fatalities:
6
Captain / Total flying hours:
19530
Captain / Total hours on type:
13480.00
Aircraft flight hours:
23595
Circumstances:
On July 31, 2020, about 0827 Alaska daylight time, a de Havilland DHC-2 (Beaver) airplane, N4982U, and a Piper PA-12 airplane, N2587M, sustained substantial damage when they were involved in an accident near Soldotna, Alaska. The pilot of the PA-12 and the pilot and the five passengers on the DHC-2 were fatally injured. The DHC-2 was operated as a Title 14 Code of Federal Regulations (CFR) Part 135 on-demand charter flight. The PA-12 was operated as a Title 14 CFR Part 91 personal flight. The float-equipped DHC-2, operated by High Adventure Charter, departed Longmere Lake, near Soldotna, about 0824 bound for a remote lake on the west side of Cook Inlet. The purpose of the flight was to transport the passengers to a remote fishing location. The PA-12, operated by a private individual, departed Soldotna Airport, Soldotna, Alaska, (PASX) about 0824 bound for Fairbanks, Alaska. Flight track data revealed that the DHC-2 was traveling northwest about 78 knots (kts) groundspeed and gradually climbing through about 1,175 ft mean sea level (msl) when it crossed the Sterling Highway. The PA-12 was traveling northeast about 1,175 ft msl and about 71 kts north of, and parallel to, the Sterling Highway. The airplanes collided about 2.5 miles northeast of the Soldotna airport at an altitude of about 1,175 ft msl. A witness located near the accident site observed the DHC-2 traveling in a westerly direction and the PA-12 traveling in a northerly direction. He stated that the PA-12 impacted the DHC-2 on the left side of the fuselage toward the back of the airplane. After the collision, he observed what he believed to be the DHC-2's left wing separate, and the airplane entered an uncontrolled, descending counterclockwise spiral before it disappeared from view. He did not observe the PA-12 following the collision.
Probable cause:
The failure of both pilots to see and avoid the other airplane.
Contributing to the accident were:
1) the PA-12 pilot’s decision to fly with a known severe vision deficiency that had resulted in denial of his most recent application for medical certification and
2) the Federal Aviation Administration’s absence of a requirement for airborne traffic advisory systems with aural alerting among operators who carry passengers for hire.
Final Report:

Crash of a De Havilland DHC-2 Beaver in Lake Coeur d'Alene: 6 killed

Date & Time: Jul 5, 2020 at 1422 LT
Type of aircraft:
Operator:
Registration:
N2106K
Flight Phase:
Survivors:
No
Schedule:
Coeur d'Alene - Coeur d'Alene
MSN:
1131
YOM:
1957
Crew on board:
1
Crew fatalities:
Pax on board:
5
Pax fatalities:
Other fatalities:
Total fatalities:
6
Captain / Total flying hours:
21173
Captain / Total hours on type:
217.00
Aircraft flight hours:
6171
Circumstances:
The float-equipped De Havilland DHC-2 was on a tour flight, and the Cessna 206 was on a personal flight. The airplanes collided in midair over a lake during day visual meteorological conditions. No radar or automatic dependent surveillance-broadcast data were available for either airplane. Witnesses reported that the airplanes were flying directly toward each other before they collided about 700 to 800 ft above the water. Other witnesses reported that the Cessna was at a lower altitude and had initiated a climb before the collision. Review of 2 seconds of video captured as part of a witness’ “live” photo showed that both airplanes appeared to be in level flight before the collision. No evidence of any preexisting mechanical malfunction was observed with either airplane. Recovered wreckage and impact signatures were consistent with the upper fuselage of the Cessna colliding with the floats and the lower fuselage of the De Havilland. The impact angle could not be determined due to the lack of available evidence, including unrecovered wreckage. The available evidence was consistent with both pilots’ failure to see and avoid the other airplane.
Probable cause:
The failure of the pilots of both airplanes to see and avoid the other airplane.
Final Report:

Crash of a Mitsubishi MU-2B-60 Marquise in Sioux Falls: 1 killed

Date & Time: Jun 7, 2020 at 0415 LT
Type of aircraft:
Operator:
Registration:
N44MX
Flight Phase:
Flight Type:
Survivors:
No
Schedule:
Everett – Huron - Kokomo
MSN:
1526
YOM:
1981
Flight number:
MDS44
Crew on board:
1
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total flying hours:
22000
Captain / Total hours on type:
10900.00
Aircraft flight hours:
12104
Circumstances:
The pilot departed on a cross country flight in a turbine-powered, multiengine airplane at night and in visual meteorological conditions. Recovered GPS data revealed that as the airplane accelerated down the runway, it drifted to the right of the runway centerline. A video recording showed that shortly after takeoff, the airplane rolled right, the nose dropped, and the airplane impacted the ground. It came to rest on its left side with both wings separated and the fuselage was highly fragmented forward of the main landing gear. A post-accident examination of the airframe and engines found no mechanical malfunctions or anomalies that would have precluded normal operation. A witness that spoke to the pilot shortly before the accident flight stated that the pilot exhibited difficulty in completing some paperwork; however, no medical reasoning for this difficulty could be determined based upon the available evidence. The investigation determined that at the time of the accident the pilot had been on duty for about 19 hours and 20 minutes, which was contrary to duty and rest regulations. At his estimated arrival time into the destination, the pilot would have accumulated about 20 hours and 54 minutes of duty time. The investigation was unable to determine if the pilot took advantage of the opportunity for rest that existed during the day, and therefore could not determine if fatigue contributed to the accident. Investigators were unable to determine the reason for the loss of control on takeoff with the available information.
Probable cause:
The pilot’s failure to maintain control of the airplane during takeoff for reasons that could not be determined.
Final Report:

Crash of a Piper PA-31T Cheyenne near Eatonton: 5 killed

Date & Time: Jun 5, 2020 at 1520 LT
Type of aircraft:
Registration:
N135VE
Flight Phase:
Flight Type:
Survivors:
No
Schedule:
Williston – New Castle
MSN:
31-7520024
YOM:
1975
Crew on board:
2
Crew fatalities:
Pax on board:
3
Pax fatalities:
Other fatalities:
Total fatalities:
5
Captain / Total flying hours:
2000
Copilot / Total flying hours:
15
Aircraft flight hours:
7749
Circumstances:
Before the personal instrument flight rules flight began, the pilot obtained a preflight weather briefing that indicated that instrument meteorological conditions, convective activity, and moderate-to-severe icing conditions would be occurring along the route of flight. According to track data, while the pilot was navigating to avoid weather, the pilot was using the autopilot for maneuvering. After the pilot reported to air traffic control that the airplane would be turning direct to its destination, the performance analysis of track data showed that the airplane began a slight left turn with a bank angle of about 10°, which was consistent with the intended route of flight. However, the turn then reversed, and the airplane began banking to the right, reaching about 120° right wing down during the next 70 seconds and showing a slow oscillation in pitch attitude. Satellite imagery showed that the airplane was likely in instrument meteorological conditions when it began a rapid descent, and the airplane’s descent rate was about 7,000 feet per minute. Postaccident examination of the airplane and right engine (the left engine was not recovered) revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The dynamics of the airplane’s movements after the right turn began indicated that the airplane likely was not being actively controlled when it diverted from the intended flightpath. The circumstances of this accident were thus consistent with the pilot’s lack of timely recognition that the autopilot was disengaged. The available evidence for this accident precluded a determination of where the pilot’s attention was directed while navigating direct to the destination. However, the turbulence would have increased the pilot’s workload, and the restricted visibility conditions would have prevented the pilot’s use of outside cues to detect deviations in the airplane’s attitude. Also, the initial roll rates might not have been sufficient to provide reliable cues to the pilot of the developing bank, and the convective conditions would likely have made it difficult for the pilot to detect and recover from the fully developed unusual attitude.
Probable cause:
The pilot’s failure to maintain control of the airplane while maneuvering in instrument meteorological conditions, which placed the airplane in an unusual attitude from which the pilot could not recover. Contributing to the accident was the convective and turbulent weather.
Final Report:

Crash of a Rockwell Shrike Commander 500S off Aniak

Date & Time: May 28, 2020 at 1600 LT
Operator:
Registration:
N909AK
Flight Phase:
Survivors:
Yes
Schedule:
Aniak - Aniak
MSN:
500-3232
YOM:
1975
Location:
Crew on board:
1
Crew fatalities:
Pax on board:
3
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
4869
Captain / Total hours on type:
30.00
Aircraft flight hours:
6966
Circumstances:
On May 28, 2020, about 1600 Alaska daylight time, an Aero Commander 500S airplane, N909AK sustained substantial damage when it was involved in an accident near Aniak, Alaska. The pilot and three passengers sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 public aircraft flight. The airplane was owned by the State of Alaska and operated by the Division of Forestry. According to the pilot, after arriving in Aniak, he had the local fuel vendor's ground service personnel refuel the airplane. He then signed the fuel receipt, and he returned to the airplane's cockpit to complete some paperwork before departure. Once the paperwork was complete, he then loaded his passengers, started the airplane's engines, and taxied to Runway 29 for departure. The pilot said that shortly after takeoff, and during initial climb, he initially noticed what he thought was mechanical turbulence followed by a reduction in climb performance, and the airplane's engines began to lose power. Unable to maintain altitude and while descending about 400 ft per minute, he selected an area of shallow water covered terrain as an off-airport landing site. The airplane sustained substantial damage during the landing. The fueler reported that he was unfamiliar with the airplane, so he queried the pilot as to where he should attach the grounding strap and the location of the fuel filler port. Before starting to refuel the airplane, he asked the pilot "do you want Prist with your Jet" to which the pilot responded that he did not. After completing the refueling process, he returned to his truck, wrote "Jet A" in the meter readings section of the prepared receipt, and presented it to the pilot for his signature. The pilot signed the receipt and was provided a copy. The fueler stated that he later added "no Prist" to his copy of the receipt, and that he did not see a fuel placard near the fueling port. A postaccident examination revealed that the reciprocating engine airplane had been inadvertently serviced with Jet A fuel. A slightly degraded placard near the fuel port on the top of the wing stated, in part: "FUEL 100/100LL MINIMUM GRADE AVIATION GASOLINE ONLY CAPACITY 159.6 US GALLONS."
Probable cause:
Loss of engine power after the aircraft has been refueled with an inappropriate fuel.
Final Report:

Crash of a Cessna 402C in Hampton

Date & Time: May 9, 2020 at 1513 LT
Type of aircraft:
Operator:
Registration:
N4661N
Survivors:
Yes
Schedule:
Peachtree City - Peachtree City
MSN:
402C-0019
YOM:
1979
Crew on board:
2
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
7330
Captain / Total hours on type:
11.00
Copilot / Total flying hours:
1096
Copilot / Total hours on type:
5
Aircraft flight hours:
17081
Circumstances:
According the commercial pilot and a flight instructor rated check pilot, they were conducting their first long-duration, aerial observation flight in the multiengine airplane, which was recently acquired by the operator. They departed with full fuel tanks, competed the 5-hour aerial observation portion of the flight, and began to return to the destination airport. About 15 miles from the airport, the left engine fuel warning light illuminated. Within a few seconds, the right engine stopped producing power. They attempted to restart the engine and turned the airplane toward an alternate airport that was closer. The pilots then turned on the electric fuel pump, the right engine began surging, and soon after the left engine stopped producing power. They turned both electric fuel pumps to the low setting, both engines continued to surge, and the pilots continued toward the alternate airport. When they were about 3 miles from the airport, both engines lost total power, and they elected to land on a highway. When they were a few feet above the ground, power returned briefly to the left engine, which resulted in the airplane climbing and beginning to roll. The commercial pilot pulled the yoke aft to avoid a highway sign, which resulted in an aerodynamic stall, and subsequent impact with trees and terrain. The airplane sustained substantial damage to the wings and fuselage. Although both pilots reported the fuel gauges indicated 20 gallons of fuel remaining on each side when the engines stopped producing power, the flight instructor noted that there was no fuel in the airplane at the time of the accident. In addition, according to a Federal Aviation Administration inspector who responded to the accident site, both fuel tanks were breached and there was no evidence of fuel spillage.
Probable cause:
A dual total loss of engine power as a result of fuel exhaustion.
Final Report:

Crash of a Piper PA-61 Aerostar (Ted Smith 601) near Craig: 1 killed

Date & Time: Apr 23, 2020 at 2130 LT
Registration:
N601X
Flight Phase:
Flight Type:
Survivors:
No
Site:
MSN:
61-0393-117
YOM:
1977
Location:
Crew on board:
1
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total flying hours:
30
Circumstances:
The student pilot, who was not qualified to operate the airplane, reportedly flew from California to Pennsylvania on a commercial flight the morning of the accident to pick up and fly the accident airplane, which he purchased, to California. The student pilot departed Pennsylvania at 0719 and made several en route stops before arriving at the departure airport at 1949. A witness stated that the airplane’s right engine quit during taxi at the last en route stop and the pilot said he "cut it a little close on fuel." Another witness said that the pilot was “really tired” and planned to fly over the mountains for his return flight. The student pilot was not in communications with air traffic control while en route from the departure airport and did not receive an instrument flight rules clearance to operate the flight in class A airspace as required by Federal Aviation Regulations. The airplane was not equipped with automatic dependent surveillance-broadcast as required for flight in class A airspace. Radar track data indicate the airplane last departed from Fort Collins, Colorado, and maneuvered while climbing to 16,000 ft. The airplane proceeded west/southwest for a little over 40 miles before climbing to about 22,000 ft. The airplane then made several large heading changes and altitude changes between 20,000 ft and 23,000 ft before entering a tight looping turn to the left and losing altitude rapidly before track data was lost. All components of the airplane were distributed along the wreckage path in a manner consistent with a low-angle, high-speed impact with terrain. The airplane was destroyed. A green cylindrical tank consistent in color with an oxygen tank was separated from the airframe and was found along the wreckage path. Portions of pneumatic lines were attached to the tank and exhibited impact damage and separations from impact. Due to accident-related damage, the amount of the tank’s contents prior to the accident are unknown, and the functionality, if any, of the oxygen system is unknown. The reason for the airplane’s impact with terrain could not be determined based on available evidence.
Probable cause:
The student pilot’s flight into terrain for undetermined reasons.
Final Report:

Crash of a Pilatus PC-12/47 in Mesquite

Date & Time: Apr 23, 2020 at 1600 LT
Type of aircraft:
Operator:
Registration:
N477SS
Flight Type:
Survivors:
Yes
Schedule:
Dallas – Muscle Shoals
MSN:
813
YOM:
2007
Crew on board:
1
Crew fatalities:
Pax on board:
0
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total flying hours:
2283
Captain / Total hours on type:
1137.00
Aircraft flight hours:
7018
Circumstances:
Shortly after takeoff the pilot reported to the air traffic controller that he was losing engine power. The pilot then said he was going to divert to a nearby airport and accepted headings to the airport. The pilot then reported the loss of engine power had stabilized, so he wanted to return to his departure airfield. A few moments later the pilot reported that he was losing engine power again and he needed to go back to his diversion airport. The controller reported that another airport was at the pilot’s 11 o’clock position and about 3 miles. The pilot elected to divert to that airport. The airplane was at 4,500 ft and too close to the airport, so the pilot flew a 360° turn to set up for a left base. During the turn outbound, the engine lost all power, and the pilot was not able to reach the runway. The airplane impacted a field, short of the airport. The airplane’s wings separated in the accident and a small postcrash fire developed. A review of the airplane’s maintenance records revealed maintenance was performed on the day of the accident flight to correct reported difficulty moving the Power Control Lever (PCL) into reverse position. The control cables were inspected from the pilot’s control quadrant to the engine, engine controls, and propeller governor. A static rigging check of the PCL was performed with no anomalies noted. Severe binding was observed on the beta control cable (propeller reversing cable). The cable assembly was removed from the engine, cleaned, reinstalled, and rigged in accordance with manufacturer guidance. During a post-accident examination of the engine and propeller assembly, the beta control cable was found mis-rigged and the propeller blades were found in the feathered position. The beta valve plunger was extended beyond the chamfer face of the propeller governor, consistent with a position that would shut off oil flow from the governor oil pump to the constant speed unit (CSU). A wire could be inserted through both the forward and aft beta control cable clevis inspection holes that function as check points for proper thread engagement. The forward beta control cable clevis adjustment nut was rotated full aft. The swaging ball end on the forward end of the beta control cable was not properly secured between the clevis rod end and the push-pull control terminal and was free to rotate within the assembly. Before takeoff, the beta valve was in an operational position that allowed oil flow to the CSU, resulting in normal propeller control. Vibration due to engine operation and beta valve return spring force most likely caused the improperly secured swaging ball to rotate (i.e. “unthread”) forward on the beta control cable. The resulting lengthening of the reversing cable assembly allowed the beta valve to stroke forward and shut off oil flow to the propeller CSU. Without propeller servo oil flow to maintain propeller control, the propeller faded to the high pitch/feather position due to normal leakage in the transfer bearing. The reported loss of power is consistent with a loss of thrust due to the beta control cable being mis-rigged during the most recent maintenance work.
Probable cause:
The loss of engine power due to a mis-rigged beta control cable (propeller reversing cable), which resulted in a loss of thrust inflight.
Final Report: