B737NG N1 or N2 overspeed
 

Considering the CFM56-7 is fully FADEC with dual channel EEC control and protection, under what circumstances other than a technical fault could an engine N1 or N2 overspeed.

If on climb out at N1 ref, the aircraft experienced turbulence, would this be an example of non-fault overspeed? This question has been driven by the fact the FMS CDU lists exceedences on its engine maint page.

regards, an engineer on a NG course.

From memory, shoud really check before writing, but recall FADEC does not limit N1 while using thrust reverse.

There are different degrees of overspeed and protection logic.

The lower end is performance related while the upper end is structural. It's kind of like your hearbeat, not all of us are the same, some more efficient than others and some of us are protected by medicines (as I am) and some of us are also protected by absolute cielings by a sort of FADEC (defrib).

As always in technical questions there is room for interpretation of what is being asked vs what information is contained in our answers.

The FADECs do have absolute protection levels for the higher end before you really blow something and once triggered you can't even start the engine again (I can't even think of an event where this was triggered legitimately)