Scotch Lock Scenario
After the BHA has been pumped down, some guns may fire without any problems, but at some point on the BHA an issue could cause one or more guns to be unable to fire. After adjustments are made to try to restore the gun to firing order without success, the BHA should be pulled out of hole to inspect.
After pulling the BHA, and disarming the guns, it should be inspected. The entire gunstring should be dismantled to find the cause of the issue. In this case, after tearing down the BHA, it is apparent that there is an opening in the scotch lock connection between the detonator and the module. After taking apart the scotch lock, there is a possibility of wiring issues as a result of wiring insulation being stretched when cut.
After the cause of the error is identified, the entire crew should be made aware of the issue and reminded of the measures that need to be taken when inspecting the scotch lock connection. This should help prevent this issue from occurring in the future. A safety alert should be sent out to all crews.