PDA

View Full Version : A320 Vle Vmo/mmo Relation


bflyer
14th Sep 2008, 00:10
HI everybody

In our FCOM 3 operating limitations/gear down it states that VLE( max speed with the landing gear extended ) is 280 kias/0.67
While in FCOM 2.04 special operations/flight with landing gear down...it states under PROCEDURES/PREFLIGHT that VMO/MMO with the landing gear down and doors closed is 235kts/M 0.60
The question is how can a VLE value exceed VMO/MMO which may not be exceeded deliberately in any regime of flight for the same condition which in this case is a flight with the landing gear down and doors closed?
Thanks in advance for all inputs
Bf

Mad (Flt) Scientist
14th Sep 2008, 19:48
Is the FCOM the right vehicle for limitations - shouldn't there be an AFM to be the definitive source?

My own guess at the apparent discrepancy comes from inferring the intent of that "special operations/flight with landing gear down" bit - which sounds like the case where you conduct an entire flight gear down (ferry to maintenance with a gear problem, say).

IF that's the case then there may be fatigue issues restricting your gear down speed for an extended period, whereas the VLE is for "normal ops" of only a few minutes with gear down, and so the fatigue issue is smaller and already factored into your inspections and such.

In other words its safe to fly at VLE with gear extended - but maybe not for two hours.

bflyer
14th Sep 2008, 20:15
thanks mfs

The point is that the special ops specify that revenue flight ( no time limit set) is permitted with gear down and it is not permitted to exceed VMO/MMO deliberately in any regime of flight and that is what i don't understand about it
i'll check the FM and get back to you
bf

TyroPicard
15th Sep 2008, 09:48
bflyer
mfs has it right - on a normal flight VLE applies, and the FCOM 2.04.25 limit applies to only two situations:
1. "dispatch with landing gear down" and
2. "in case of an inflight landing gear retraction failure".
On a normal flight you can exceed the FCOM 2 "special procedures" VMO/MMO because it does not apply to your flight.
Hope that helps.
TP