747-400 Fly By Wire?

[777300ER]

Recently while reading through a Boeing document which detailed the differences between the older generation 747s to the 747-400 I noticed that Boeing claims the 400 incorporates Fly By Wire technology. My understanding of the Flight Control system on the 400 is that Elevator and Aileron systems are connected mechanically to actuators.

Is the 747-400 Fly By Wire? If so, what part of the Flt Control system utilizes this technology?

Thanks.

[Intruder]

Is the 747-400 Fly By Wire? If so, what part of the Flt Control system utilizes this technology?

Not in the generally understood sense. All flight controls are connected to the cockpit with cables, pushrods, etc.

OTOH, the engine controls (thrust levers) are connected to the engines via electronics only.

[CV880]

TE Flaps were converted to all electronic control on the -400 and the Stab Trim was all electric (no manual stab trim levers in the cockpit). Primary Flight Controls were largely unchanged from classic with conventional cables.

[18-Wheeler]

Yes, the wires go from the control column to the tail & wings, hence they are Year 2000 BC compliant.
(One of my fave jokes ....)

[777300ER]

Thanks for the responses. This confirms that the info in the document I saw is inacurate.

[Intruder]

TE Flaps were converted to all electronic control on the -400 and the Stab Trim was all electric (no manual stab trim levers in the cockpit).

"Fly by wire" usually refers to primary flight controls -- ailerons, elevators, and rudder. In this regime, the 744 is strictly conventional.

While control of TE flaps may be electric/electronic, actuation is still by hydraulics, and there is NO automatic adjustment of LE or TE flaps (as in the F/A-18 and other "fly by wire" aircraft).

The bottom line is that by any conventional measure, the 744 is NOT a "fly by wire" airplane.

[used2flyboeing]

747-400 IS NOT FLY BY WIRE .. IT IS FLY BY CABLE CONNECTED TO HYDROMECHANICAL prime movers .. It has computers that can drive all that clap-trap - those are the autopilot, flight management system and autothrottle.. but it is a very conventional airplane .. A320 & A340 are more advanced from that stand point ..

[NSEU]

While control of TE flaps may be electric/electronic, actuation is still by hydraulics, and there is NO automatic adjustment of LE or TE flaps

What about the Flap Load Relief system on the 747-400? What about the automatic retraction of certain LE flaps during reverse thrust operation on the 747-400?

I'd say YES

Rgds.
NSEU.

[Intruder]

In that case, the 742 is "fly by wire" too!