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Question for B747 classic pilots and engineers

I posted this question in this video's original thread in spectator's balcony, but received no response so far.

YouTube - The Belly of the Beast

Anyway, shouldn't the inboard slats stow when the thrust reversers are deployed during landing ? Or is this function found only on the 744s ? Was of the impression that it affected all B747s as it had something to do with hi-frequency vibration damaging the slats (krueger flaps) during thrust reverser deploying.

Not all 747 Classics have that happen. I haven't flown one for a couple of years so I can't remember which ones it is sorry.

Not fitted to all aircraft - standard/optional depending on
A/C and/or engine combination - early Pratt powered aircraft also had
hot section reversers.
Below is taken from the Maintenance Manual (My highlighting),

On airplanes with leading edge flap retraction by reverse
thrust levers,interaction between leading edge flaps and thrust reverser is
as follows:
.
1) Under normal operating conditions, the leading edge flaps
will automatically retract upon application of reverse
thrust. The reverse thrust levers actuate microswitches
on the control stand which bypass trailing edge flap
control inputs to allow flap retraction regardless of
trailing edge position.

2) When the reverse thrust levers are stowed, the
microswitches de-energize time delay relays which allow 5
seconds for engine stabilization before flaps are
re-extended.
.
3) No. 1 and 4 reverse thrust levers operate group A flaps
No. 2 and 3 levers operate group B flaps.

Both levers must be operated to retract flaps.

Just to clarify - the above is from the "Classic" manual.
ALL 747-400's do have L/E flap retraction on reverse BUT only group 'A'
Having said that, the 'Groupings' between -400 & Classic are also different.
Still love the old girl - so simple, yet so complex and no 2 are the same!
Queen Of The Skies.

:ok:
.

Thanks for the insight guys !:ok: