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744 Slat Configuration

AC_B777 From Canada, joined Aug 2000, 784 posts, RR: 13
Posted (11 years 2 weeks 2 days 7 hours ago) and read 887 times:

Hey all,

I was looking at the picture below and was wondering about the Kruger flap configuration set for landing.
This KLM 744 has landed with only the outboard Kruger slats deployed. Why would'nt the mid and in-board sections be deployed?
Obviously the a/c is still travelling fairly fast as shown by the spray, and too early to retract the flaps.
What kind of performance would the 744 have in this configuration? Is this a normal practice for KLM or any airlines? I ask because I have never seen a plane land or takeoff with only a partial flap/slat setting.
Thanks.

AC_B777

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Photo © Peter Unmuth - Vienna Aviation Photography

In life, some days you are the bug..... some days you are the windshield!

13 replies: All unread, jump to last

Hkniceguy From Hong Kong, joined Jun 2001, 130 posts, RR: 0
Reply 1, posted (11 years 2 weeks 2 days 5 hours ago) and read 822 times:

On 747-400, inboard Kruger slats will retract when applying reverse during landing, to avoid the structure damage to the slats. This information is from a book about 747-400.

Hkniceguy From Hong Kong, joined Jun 2001, 130 posts, RR: 0
Reply 2, posted (11 years 2 weeks 2 days 5 hours ago) and read 813 times:

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Photo © Felix Sieder

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Photo © Allan Rossmore

Cx flyboy From Hong Kong, joined Dec 1999, 6341 posts, RR: 56
Reply 3, posted (11 years 2 weeks 2 days 5 hours ago) and read 815 times:

That is correct, this can be seen inside the cockpit as an indication. Normally the little flap indicator sign is marked 25 or 30 (As appropriate) and is in green, indicating the flaps are in position. Select reverse on the ground and the indication will turn magenta coloured, indicated not all flap groups are in the right position they should be. When reverse is deselected, the indication turns green again, as the leading edge extends again (Only for you to put them back in again!).

AC_B777 From Canada, joined Aug 2000, 784 posts, RR: 13
Reply 4, posted (11 years 2 weeks 2 days 5 hours ago) and read 803 times:

Huh, I never noticed that before.
Thanks for the info guys.

AC_B777

In life, some days you are the bug..... some days you are the windshield!

Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 23
Reply 5, posted (11 years 2 weeks 2 days 1 hour ago) and read 758 times:

Cxflyboy:

Sorry I didn't really get you there. You mean it's normal for the middle slats and inboard slats not to extend and only to extend after retracting reverse thrust on the ground? (Flaps 25/30 both have slats extended?) Wonder why the slats don't extend? Thanks a lot for the further explanation.

Boeing747 万岁!

AJ From Australia, joined Nov 1999, 2376 posts, RR: 27
Reply 6, posted (11 years 2 weeks 1 day 20 hours ago) and read 736 times:

The aircraft has Flap 25 or 30 set for landing, including all leading edge flaps extended. The flight deck indication is a green line at 25 or 30. When the reverse thrust levers are raised to the interlock the inboard and midspan leading edge flaps retract whilst the engine reverser system is activated, giving a magenta line on the flap indicator (Boeing code for commanded but not yet reached). After the reversers are stowed the leading edge flaps redeploy giving a green indication.

Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 23
Reply 7, posted (11 years 2 weeks 1 day 16 hours ago) and read 711 times:

Thanks AJ... but any explanation to why the inboard and middle slats retract when the reverse is activated?

Cheers

Boeing747 万岁!

Hkniceguy From Hong Kong, joined Jun 2001, 130 posts, RR: 0
Reply 8, posted (11 years 2 weeks 1 day 15 hours ago) and read 701 times:

Mr.BA: Is to avoid the structure damage to the slats when applying reverse. Becoz the oppsite thrust effect on the slats area very strong, the slats will damage if it's not retract

Aerosol From Germany, joined Oct 2000, 543 posts, RR: 0
Reply 9, posted (11 years 2 weeks 1 day 14 hours ago) and read 694 times:

I have flown on a Boeing 744 of LH (FRA-HKG); during approach the middle slats were retracted. No Idea why this was, never seen that before.

A388 From Netherlands Antilles, joined May 2001, 9077 posts, RR: 13
Reply 10, posted (11 years 2 weeks 1 day 14 hours ago) and read 689 times:

I didn't even notice this, nice to know and thanks Smile/happy/getting dizzy

AC_B777 From Canada, joined Aug 2000, 784 posts, RR: 13
Reply 11, posted (11 years 2 weeks 1 day 12 hours ago) and read 675 times:

Hey guys,

Thanks for the info, but I was wondering is this feature only found on the 744 or is it on all series of the 747?
If it is only on the 744, then what would the difference be from all other series? Does the 744 engines have different characteristics than the 741, 742 and 743 when it comes to reverse thrust?
Here is a picture of a Orient Thai 742 in reverse and the Kruger flaps are still deployed.

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In life, some days you are the bug..... some days you are the windshield!

Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 23
Reply 12, posted (11 years 2 weeks 1 day 6 hours ago) and read 643 times:

Was at the airport yesterday. Noticed this no all the landing B744s except the classics. Would be interested to know why too! Thanks!

Boeing747 万岁!

Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 23
Reply 13, posted (11 years 2 weeks 1 day 6 hours ago) and read 641 times:

Sorry I meant on not no.

Boeing747 万岁!

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