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.
Unavailable or Get-There-Itis? Loctite is available at every Home Depot, Lowes and hardware store that I have ever been in. And if it’s critically important, one would think there would be an ample supply in the hangar, as in back-ups for the back-ups.
You expect flight controls to be as “free and correct” when you land as when you take off. Whether or not this cap was the cause of his accident or not remains to be seen, but all of us need to be aware af the risks that come from flight control jamming including the havoc a $1 plastic water bottle can wreak when it gets jammed behind a rudder pedal.
There is a possibility that his negligence was the primary reason for the events that led to his death. As noted already, a version of locktite or safety wire or similar method to prevent that plug from coming out was probably prudent. Then you have to wonder how much it would back out on a non-aerobatic flight from his home airport to Langley. Did he even pre-flight that plug?
IF an expert decided that the variable weight was acceptable, here is a proper way to do it: A stud welded to a washer epoxied into the outboard portion of the elevator counterweight area. Formed lead weight with a hole thru the center. Lead slides over the stud and a lock nut and washer. Cover the access with a piece of tape.
There were several loose screws involved, two of them on the airplane.
Does the experimental category of aircraft exclude hardware such as this machined aluminum flat head screw without a means of securing it against vibrations that might cause it to back out? I am by no means an expert on aircraft fasteners and how they’re held in place. However, it would seem an oversight by everyone(?) involved in aerobatic aircraft maintenance working on this one. Unfortunately, another life is lost from the possibility of not securing fasteners on aircraft and experimentals.
Flight controls free and correct is part of any checklist IIRC. Until they are not, because they are jammed. Could be a screw, bolt, nut or a coke bottle cap. That screw remained in place for quite a few previous flights. Lets try not to be too judgmental… shit happens.