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ask about B744 MEL

Hi, Dear

I have a question about 744 mel (maybe, diffrent from with yours)

anyway, according to our mel

If FCU (flap cont' unit) left is inoperate then no.4 demand pump is

selected ON during T/O and landing.

If FCU (flap cont' unit) right is inoperate then no.1 demand pump is

selected ON during T/O and landing.

actually, demand pump auto operation during flap operation.

So, i can't understand why turn demand pump on? also just 1 demand

pump !!!

I want to listen your valuable opinion...

thanks to listen to me :rolleyes::rolleyes:

B/RGDS

maybe due to flap load relief on approach and gear retraction on t/o just another boeing be sure technique

I believe this should clear things up !!

ADP Run Continuous Solenoid:

Placing the ADP Switch to the AUTO position, 28v DC is supplied
to the HYDIM Card so that it can energise the Run Continuous
Solenoid, when the following conditions occur;

• Whenever the Fuel Metering Unit is in CUTOFF.
• Whenever the Flap Handle is repositioned until the Trailing Edge
Flaps are in agreement with the Flap Handle.

When the Demand Pump Control Switches for Hydraulic Systems 1
and 4 are in the AUTO position, and the Flap Control Units (FCU)
are operating normally,
• The right FCU will provide the signal to System 1 HYDIM Card
to turn on the Demand Pump for System 1.
• The left FCU will provide the signal to System 4 HYDIM Card
to turn on the Demand Pump for System 4.

Although all three Flap Control Units are identical and
interchangeable, only the Flap Control Units positioned in those
specific right and left locations will automatically control Hydraulic
System 1 and 4, e.g. During flap extension with the Demand Pump
Control Switch in AUTO, the ADP’s will run when the Flap Lever is
at 5 units or greater with T/E flaps in disagreement with the handle.

FCU Failures

Whenever the left and right FCUs are inoperable, the Flight Crew
will be required to place the Demand Pump Control Switch in the
ON position during takeoff and landing.

NOTE:

The Demand Pump control feature does not transfer from
FCU to FCU when there is a Flap Control Circuit failure.

ST,

Thanks for the lucid explanation!

To save me delving into the CD as you possibly have the answer at your fingertips, can the B744 HYD #1&4 air pumps overspeed trip like those on the "Classic"?

G'day ;)

Feather #3.

Yes, ADP overspeed trip is as per the classic. Maint Manual states that it is permissible to reset the turbine drive overspeed 'once'. We normally read that as "each engineer" can reset it 'once'. Bill can reset it once, Tony can reset it once, George can reset it once, Paul can reset it once etc, etc until a spare can be sourced. It's all in the interpretation!

It's easy to do, access the ADP Turbine Drive, remove the cap on the overspeed housing (3/4 spanner I think) and push in the silver pin on the inside.

Ta muchly!!:)

G'day ;)