Accident Overview
On June 1, 2023, at about 1455 eastern daylight time, a Beech V35A, registration N8074R, sustained substantial damage in an accident near Statesboro County Airport (TBR), Statesboro, Georgia. The pilot, the sole occupant, received minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight Details
The pilot reported that he was testing newly installed servos for the Garmin GFC-500 autopilot and calibrating the fuel flow sensor. During preflight, he moved the yoke and checked control surface movements. He programmed the flight director for a cruising altitude of 3,000 ft with a pitch climb between 5° and 7°.
During the takeoff roll, the pilot noted the controls felt "slightly heavy" and adjusted the ruddervator trim nose-up using the electric trim switch. After liftoff, he engaged the autopilot, and the airplane climbed to and maintained 3,000 ft. The pilot issued heading change commands via the GFC-500 display.
After about an hour, the pilot programmed the autopilot to descend to 2,000 ft in preparation for landing at TBR. However, the autopilot failed to intercept the set waypoint. He disconnected the autopilot and assumed manual control. On approach, he noticed the airplane descending lower than intended. He applied power, but the nose suddenly pitched down. Despite verifying the autopilot was disconnected, he could not move the yoke aft. The airplane continued descending, and he struggled to regain control.
On final approach, the airplane impacted a light pole about 1,000 ft short of the runway threshold, then struck the ground and came to a stop.
Postaccident Examination
Examination revealed an anomaly with the pitch servo bridle cable installation. The bridle cable clamp’s swaged ball fitting was positioned at the 1 o’clock position with the yoke in a full-forward position. However, the GFC 500 Installation Manual Addendum specified that the swaged ball should be at 1 o’clock with the yoke in the neutral position—defined as 4.5 inches aft of the instrument panel, per the Bonanza 35 Series Shop Manual.
This installation caused the bridle cable clamp to be positioned on the upper elevator cable such that it would bind against the former rib at flight station (F.S.) 179 when the yoke was pulled aft. Further examination determined that the installer did not verify the required 0.5- to 1-inch clearance between the bridle cable clamp and F.S. 179 when the elevator was in the full-up position, as specified in the installation manual addendum.
Additionally, the installer did not follow required procedures in the GFC 500 Autopilot with ESP Part 23 AML Installation Manual, paragraph 4.2.1, which required: moving flight controls through full range after servo installation and cable tensioning; ensuring control surfaces move freely from stop to stop; verifying no binding or restriction from servo installation; and confirming that servo cables, cable clamps, and main flight control cables maintain adequate clearance throughout the full range of motion.
During an interview, personnel from the maintenance facility that performed the installation acknowledged that the GFC-500 installation had been performed incorrectly.