Originally Posted by
N1 Limit
No it’s not i was just wondering why?
It is an MMEL question. The dispatch release using its provisions must be conservative, taking into account the possibility of a single independent failure on the same system (don't quote me on this verbatim).
You can depart with 1 brake (of 2+2) inop, because (after applying the penalties) a failure of another one (1+1 or 2+0) still works.
You cannot depart with 2 brakes inop (2+0 or 1+1) because a subsequent loss creates an unsafe state (1+0).
Sometimes the required 'survivability' after MMEL release is achieved by not pushing all the corners of the envelope. That is your case.
One failure in flight is expected.
- if you are departing with -1 already, need to make provisions for -2
- if you depart fully operational and encounter -1 inflight, another failure is not expected but will be dealt with using the appropriate EMERG C/L - should it actually occur.