boeing flap question

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wwwayward
Posts: 20
Joined: Wed Feb 08, 2006 10:02 am
Location: Toronto,ON Canada

boeing flap question

Post by wwwayward »

Hello all !!

a quickie question with regards to boeing flap handle.
on the widebody aircraft there is a gate at position 1 and also at position 20, anyone have an explanation??
no i'm not gonna stay awake tonight thinking about it, just curious as to what it is and why.

Cheers
Steff

Don
Posts: 65
Joined: Sun Nov 09, 2003 6:00 am
Location: New Zealand

Post by Don »

Hi

Whilst it is true that these flap positions are not commanly used, they are necessary for various configurations.

Flap 1 for instance, I often use to comply wit ATC imposed speed restrictions, whilst not wishing to slow down to flap 5 speed.

Flap 20, I occasionally use for takeoff, it gives a beater regulated takeoff weight (RTOW) from some shorter runway lengths.

I refer here specifically to the B777.

Hope this helps
Don

chrisw
Posts: 244
Joined: Wed Jul 14, 2004 12:32 pm
Location: England, United Kingdom
Contact:

Post by chrisw »

Steff,

If you mean the 'lug' which sticks out on those flap positions I once wondered that myself. They are not just on the widebodies - the 737 has them at positions 1 and 15 (I'm staring at a real 737-200 quadrant as I type, sad, I know).

I believe they are in place so that you cannot move past those flap positions in one (possibly erronous) movement of the flap lever. The lug stops the lever moving until you lower the lever a little, pass the lug and then lift the lever again.

On the 737 for example, the leading edge slats deploy at flap 1. So, moving down from flaps 15 through 10, 5 etc. I am physically stopped from taking off all flap (and so stowing the slats) until I manouvre the lever around the lug - something I have to intentionally do. It's a safety device basically.

Cheers
Chris

wwwayward
Posts: 20
Joined: Wed Feb 08, 2006 10:02 am
Location: Toronto,ON Canada

Post by wwwayward »

Thanks for the quick answers Guys!
i thought it might be a safety restricting device. and thought i'd ask anyways

Cheers
Steff

chrisw
Posts: 244
Joined: Wed Jul 14, 2004 12:32 pm
Location: England, United Kingdom
Contact:

Post by chrisw »

No probs. I took a pic to try to illustrate what I meant. Not the clearest, but you can see the pin on the flap lever which would normally sit in the gate slots, and the 'lug' which stops it progressing past 1 / 15 degrees until you lower the lever a little.

Image

Cheers
Chris

MarkusPilot
Posts: 314
Joined: Fri Jan 09, 2004 3:42 am
Location: YSSY Sydney - Australia
Contact:

Post by MarkusPilot »

The notch is to prevent inadvertant or incorrect flap selection.

example:-
On a go-around you call "Go-Around Flaps 15"

Thus the PNF (Pilot Not Flying) selects the flaps from 30 or 40 to the 15 position.
You dont want to select Flaps 10 by mistake.

The notch will prevent the flap lever moving to the 10 position.
When the flap lever enters the 15 position the notch moves the lever down preventing the movement past the 15 position.

Also works the other way to prevent too much flap extension on approach.

In either direction a definate action is required to move past or thru the flap gate.

M
If it aint a Boeing,..I'm not going!
Sydney Aust.
S33 56.6 E151 10.8
www.markuspilot.com

Don
Posts: 65
Joined: Sun Nov 09, 2003 6:00 am
Location: New Zealand

Post by Don »

Hi
For info, it is now no longer PNF (Pilot non Flying), but PM (Pilot Monitering)!!
No doubt from the Boeing legal deparetment!
Regards
Don

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