Use the right hardware.
Mechanics, the tail rotor gearbox on your Black Hawk is not the place to pick and choose which hardware to use.
Set the conditions for success before installing the tail rotor gearbox cover by inspecting the gearbox cover for missing or damaged seals. Also, double check for missing or worn anti-chafing tape. It is better to fix it now rather than later. Test fit the tail rotor gear box cover and make sure the correct length turn-lock fasteners are where you need them.
Some mechanics use a longer fastener out of convenience. But longer fasteners can cause the cover chafe against the gearbox.
Depending on the damage, you might need lo replace the tail rotor gearbox, its gearbox cover, or both.