CEN25FA033

On October 29, 2024, about 1426 central daylight time, a Beech 58 airplane, N811PB, was destroyed when it was involved in an accident near Arlberg, Arkansas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. Earlier on the morning of the accident, the pilot flew the airplane from Roscoe Turner Airport (CRX), Corinth, Mississippi, to Drake Field Airport (FYV), Fayetteville, Arkansas, to have the airplane inspected at an avionics shop to troubleshoot an intermittent autopilot issue where the airplane exhibited an occasional slow pitch oscillation with the autopilot engaged and a 100 ft out-of-trim condition when the autopilot was subsequently disengaged. The avionics technician’s initial recommendation was to examine the autopilot pitch servo and pitch trim servo. The avionics technician disassembled the rear baggage compartment to gain access to the aft fuselage where the autopilot pitch servo and pitch trim servo were installed. A visual inspection revealed that there were two loose bolts securing the autopilot pitch servo capstan assembly to the servo mount bracket. Additionally, the elevator pitch control bridle cable appeared to be overtightened. The autopilot pitch servo was removed for bench testing and was not reinstalled before the accident flight. Further examination revealed excessive grease on the pitch trim cable routed through the pitch trim servo idler pulley. The avionics technician stated that while he rubbed a shop towel along the pitch trim cable it snagged a frayed portion of the cable. The frayed pitch trim cable was, looking forward, the far-left-cable routed through the pitch trim servo capstan. According to the Beech 58 Airplane Maintenance Manual, the frayed cable was identified as the “nose up” pitch trim cable. The avionics technician told the pilot that the pitch trim cable was frayed and asked for the pilot’s mobile phone so he could take a couple photos of the frayed pitch cable for the pilot to review with his aviation mechanic, as shown in Figure 1. The avionics technician was concerned that the frayed pitch trim cable could fail during flight and told the pilot that the pitch trim cable required replacement. Figure 1. Photo of frayed pitch trim cable before accident flight. The pilot then called his aviation mechanic and texted him the photos of the frayed pitch trim cable. After discussing the frayed pitch trim cable, the pilot indicated that he wanted to his aviation mechanic to replace the frayed cable and that he would fly the airplane without any repairs being completed. According to the avionics technician, the pilot did not appear to be concerned about the frayed pitch trim cable. Specifically, the pilot reportedly told the avionics technician that the frayed cable was “not that bad” and that he had “seen worse cables”. The pilot also reportedly told the secretary that the avionics technician was “overreacting” to the frayed pitch trim cable situation. The pilot told the avionics technician multiple times that he needed to depart and return to his homebase in Mississippi that afternoon. Worried that the frayed pitch trim cable would fail during flight, the avionics technician decided to install a single length of 0.041-inch safety wire to “bridge” the frayed section of the pitch trim cable. According to the avionics technician, before the installation of the safety wire, the pitch trim system was moved to a “neutral” position because he believed it would be the “safest position” and that the takeoffs are made in the neutral pitch trim position. However, the frayed pitch trim cable was “catching” on the capstan while the pilot moved the cockpit pitch trim control wheel from a full-nose-down position toward the neutral pitch trim position. The avionics technician wound the frayed wires around pitch trim cable and applied “super glue” to affix/secure the frayed wires. The pitch trim was then positioned to neutral, as determined by the cockpit pitch trim indicator positioned at “zero” and both (left/right) pitch trim tabs were aligned with their respective elevator (the trailing edges of the trim tabs and elevators were aligned). The avionics technician stated that after he confirmed the pitch trim was in the neutral position he installed the single strand of 0.041-inch safety wire to the frayed pitch trim cable. He made the first connection at the “rear turnbuckle” and then routed the safety wire forward, under the metal pully guard at the pitch trim servo capstan, and then terminated the safety wire through two turnbuckles located forward of the pitch trim servo. The avionics technician noted that he was unable to get the safety wire significantly tight during its installation. When interviewed after the accident, the avionics technician explained that the installation of the safety wire was not meant to disable the pitch trim system, but rather to keep the frayed pitch trim cable tethered if it failed during flight. The avionics technician acknowledged that the installation of safety wire was “not standard protocol” but, because the pilot intended to fly the airplane without replacing the frayed pitch trim cable, it was the only way he knew to “make it safe” if the frayed pitch trim cable failed during flight. Additionally, the autopilot and pitch trim circuit breakers were pulled-and-collared, and the avionics technician told the pilot not to use the manual pitch trim if he intended to fly airplane with the frayed pitch trim cable. The avionics technician stated that he installed the safety wire by himself and did not receive any assistance from the pilot. When asked how he identified which pitch trim cable at the rear of the aft fuselage to make his first safety wire attachment, the avionics technician answered that the pitch trim cable was “easy to follow” from the frayed section rearward. After the safety wire was installed, with the avionics technician still in the aft fuselage, the pilot moved the elevator and rudder controls through their full range-of-travel to confirm that there were no anomalies or binding of the control cables. The avionics technician stated that he intentionally did not test the pitch trim because he was “afraid to move it and break the frayed cable”. The avionics technician then completed an additional preflight check, completed from outside the airplane, that did not identify any binding while the elevators and rudder were moved through their full travel by hand, and that the pitch trim tabs remained aligned with their respective elevator. The avionics technician stated that he was the only employee that performed work on the airplane and that he did not request another technician to check his work after the safety wire was installed. The avionics technician stated that he closed the workorder without the frayed pitch trim cable being replaced. The avionics technician noted that he had the authority to close the workorder without another employee checking his work. Additionally, he and the pilot did not discuss if a Federal Aviation Administration (FAA) issued ferry permit was required for the flight. The avionics technician stated that he was in the process of closing out the workorder and writing up the logbook entries when the pilot departed the facility on the accident flight. He stated that the pilot was eager to depart and did not remain at the facility until the workorder and logbook paperwork was completed. According to FAA Automatic Dependent Surveillance - Broadcast (ADS-B) data, at 1355, the airplane departed from runway 16 at FYV. After takeoff, the airplane made a climbing left turn toward east and then established a direct course toward CRX. As the flight continued, the airplane climbed to a cruise altitude of about 9,000 ft mean sea level (msl), as shown in Figure 2. Betwee