Most Airbus (A330/A340) aircraft have additional fuel storage in the horizontal stabiliser that can be used to actively trim the aircraft. The Boeing 744 can also carry additional fuel in the stabiliser, but this cannot be used to actively trim the aircraft.
My question is, does the pilot of the 744 have to manually trim the aircraft when fuel is moved out of the stabiliser tank? When you refuel a 744 to high fuel loads, you must be careful to maintain a 5.2:1 ratio of fuel weight between the Centre Wing Tank (CWT) and Horizontal Stabilizer Tank (HST). That is, for every 5.2 kg of fuel in the CWT, there must not be more than 1 kg of fuel in the HST. This prevents the aircraft tipping up, and also maintains the C of G within limits. I dunno what the ratio is with Airbus as the fuelling is automatic.
IIRC, when fuel is consumed from the CWT and HST of the 744, this ratio is not maintained, I seem to remember that fuel is used down to a certain level in the CWT, then all the fuel is transferred from the HST. This indicates to me that there is a trim change.
I think that Airbus aircraft automatically adjust the incidence of the stabiliser when fuel is transferred out of the HST, but does this occur with the Boeing?
I apologise if this has been asked before, but a search did not yield any similar threads. I though it was about time to get some juicy, in-depth discussion going in Tech/Ops !
[Edited 2006-09-29 05:38:10]
[Edited 2006-09-29 05:38:41]