I would surgest your your manager obtains a copy of BSEN60079:17-2007 INSPECTION AND MAINTENANCE OF ELECTRICAL EQUIPMENT IN EXPLOSIVE ATMOSPHEREs. He will find that all mobile equpiment should be inspected every 12 months to comply with ATEX and DSEAR It also states that a compitant person should carry this work out and the the compitance should be proven by suitable traning and experiance. So unless you are trained to work on Ex eqipment and and fully experianced not only on a standard FLT but EX equipment the dont touch it, its your name on the paperwork not your managers and it not his life your are putting at risk.