The FAA missed a problem with the 737MAX during its original certification process.
The problem is a group of wires in the wing root that don’t meet standards and if something chafes could result in a short circuit and fire.
Boeing says it doesn’t need fixing as the likelihood is so remote.
The FAA is faced with either doing nothing or asking for a delicate, complex and expensive fix for a problem that’s unlikely to happen but still isn’t impossible.
Boeing says the 737NG has the same wiring and the rules when that was certified weren’t as stringent as they are now and it’s never been a problem. They also so doing something about it in 800 MAX’s already built will potentially cause insulation damage and create the problem the FAA wants solved.
Engineers for the FAA want it fixed, and the FAA won’t want to be seen as taking risks, but still hasn’t decided what to do.
By all accounts there are up to 12 sites on the MAX that wiring is considered sub standard under current regulations, from the tail to under body areas and the wings.
Boeing says it won’t make any difference to the recertification process. But it will affect the date existing aircraft are able to get airborne, and that won’t make airlines happy.
The fact is there is a remote possibility it could become a problem. Should it occur an aircraft would be forced nose up or nose down and a short circuit would prevent remedial action.
How did the FAA miss this originally is another question?