US Mine Safety and Health Administration officials said there was concern over solenoids damaged by “side loading” due to contact with a flexed trailing cable.

To avoid the scenario, the agency recommends mines install guarding to protect valve banks, valve spools, solenoids and solenoid cables from damage and also to prevent the components from contacting other parts of the machine.

MSHA investigators also recommended positioning the unit’s trailing cable to prevent it from damaging components essential to proper operating functions.

Both operators and maintenance personnel should ensure complete examinations of valve banks, valve spools, solenoids, solenoid cables and trailing cable and to keep the related areas free of obstructions.

Officials said CMs should be de-energized and removed from service when they were found to have worn or damaged components.

Finally, MSHA said, in addition to red zone awareness, mines should develop programs, policies and procedures and train all crews to examine these areas of CM machines and operations should also both install and maintain proximity detection systems.