Hi everybody,
to state the obvious, in a coordinated turn load factor relates to angle of bank with n=1/(cos(b.a.).
Here is my train of thought, please comment and fire at will
:
- The certified limit is 2,5g, just like any other aircraft.
- In a coordinated turn, 2,5G is reached at 66,5 aob.
- Airbus decided (hypothesis) to put a hard stop on bank at 67 deg aob, so in ideal conditions the load limit protection, aircraft certified limit, and bank angle protection intersect at a single point of the 4D situation.
- The B.A. protection indicator "=" is shown on PFD at 67 degree mark, and this was clearly stated in the older FCOM versions.
- There is no black magic about Airbus FBW. All is in the FCOM (somewhere
). Equally important is, what is not in the FCOM!
That was then, and this is now:
a) ZFT discovered that the wording have changed.
b) tubby linton points out, that with flaps out, the bank angle protection set at 67 deg AOB will not stop you from going beyond the certified (+2g) envelope. Personally I feel the FBW designers are way smarter than that.
c) villas reminds us that load factor protection should takes care of the g-loading limitations.
My questions then:
. with flaps out, will the load factor protection change its hard stop to 2g instead of 2,5?
. with flaps out, will the bank limit protection change its hard stop to 60 deg AOB (2 g in coordinated turn) instead of 67 ?
In case the answer to the second Q would be YES (another hypothesis), all snaps together:
- the new limiting angle being 60 deg, the position of green marks on PFD no longer represents where the protection activates;
- Airbus purifies the FCOM wording since ["protection stop" equals to 67°] is not really true at all times.