A loose screw on a customized elevator counterweight receptacle may have led to the crash that killed air show legend Rob Holland a week ago. The NTSB issued a preliminary report on the crash that occurred at Langley Air Force Base on April 24 and said the screw, which Holland used to adjust the amount of weight to alter control feel of the MXS depending on the kind of routine he intended to fly. The screw was found about 10 feet from the wreckage and had red paint on it, suggesting it became jammed between the elevator and the fixed portion of the tail, which was also scratched and gouged. "The counterweight plug threads were intact and also contained similar dirt contamination consistent with that found on the elevator," the report said. "Additionally, about half of the circumference of the left elevator counterweight plug displayed gouging and there was evidence of paint transfer.
I watches a few of his in-cockpit videos.
The elevator tips are REALLY vibrating a lot during the routine!
I cannot believe that these weights simply screw in with no lock-tite, no compression washers, no safety wire, no retainers of any kind. No way that these coarse threaded weights would stay put just on their own under extreme vibrations.
Those screws aren’t weights, they are just aluminum plugs that allowed for addition and removal of lead shot into the counter-ballences. Nevertheless, a screw without a locking feature in an area that can cause a control surface to jam is not a good thing!
Lead shot?? I would like to se a demonstration of pouring lead shot into a horizontal cavity.
The more significant issue is changeing the weight of a counterweight. Improper balancing of a control surface has killed a lot of people over the years.