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747 Spool-up

Thu Jan 28, 2010 7:09 pm

The thrust levers are advanced (around half-way?) and then slammed back.
Their is an aural warning in the clip @ "0.40/41.
What is that sound?
Does the 744 have that sound too?
How far can you push the levers for an agressive spool-up?
Many thanks!
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RE: 747 Spool-up

Thu Jan 28, 2010 8:33 pm

The aural warning is the takeoff configuration horn. If the thrust levers are pushed beyond a certain point the horn sounds if LE flaps, body gear steering, speedbrake, etc are not in the correct position. That wouldn't sound if the aircraft was correctly configured for takeoff. The video is shot in a 747 sim and they probably forgot to set takeoff flaps during filming, hence the warning. In theory you can slam the thrust levers to the firewall. The engine is protected by the fuel control unit which limits acceleration and prevents stall or surge. Normal procedure on a classic Boeing is to "stand up" the throttles (position them about halfway in the quadrant so the levers are vertical) and wait for all engines to stabilise before advancing them to takeoff power.

All modern airliners have a form of takeoff configuration aural warning.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
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RE: 747 Spool-up

Thu Jan 28, 2010 8:36 pm

Quoting Kimon (Thread starter):
Their is an aural warning in the clip @ "0.40/41.
What is that sound?

It sounds like the configuration warning horn.

Quoting Kimon (Thread starter):
Does the 744 have that sound too?

If it's the configuration warning horn, then yes, the 744 has that sound.

Quoting Kimon (Thread starter):
How far can you push the levers for an agressive spool-up?

With FADEC engines, all the way to the stops. With non-FADEC's, it depends on the particular engine.


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