Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for CFM International CFM56-5 and -5B series turbofan engines. That AD currently requires exhaust gas temperature (EGT) harness replacement or the establishment of an EGT baseline and trend monitoring. That AD also requires replacement, if necessary, of certain EGT harnesses and EGT couplings as soon as a slow and continuous EGT drift downward is noticed after the effective date of that AD. This proposed AD would require the same actions but for an increased population of affected EGT harnesses. This proposed AD results from CFM International adding subsequently certified engine models to the list of engines that could have affected harnesses installed. We are proposing this AD to prevent unexpected deterioration of critical rotating engine parts due to higher than desired engine operating EGTs.