B737 leading edge flaps transit

[dishwasher]

Hi guys,

Maybe some of you can help me out with this:

If this light comes on, and you have one or more lights on the LE DEVICES ANNUNCIATOR PANEL lit,

do you have to go through the ASYMMETRICAL OR NO LEADING EDGE DEVICES checklist yes or no?

I think yes, result is that you have to make a flaps 15 landing, even if you have only 1 light....

Thanks

[BOAC]

I agree with what (I think) you are saying! The cklist is not well written.

The way I read it, it runs in two parts:

1) In flight ie clean a/c

Follow drill for number of lights on o/head panel.

2) Then PLAN a F15 landing (ie runway length) because you do NOT know what is going to happen when you run the flap out

When you extend the flap, the cklist says " if the light remains .......", "carry out ........"

If the light is out with landing flap out, land normally. I would also have a 'shufti' at the o/head panel!

[TR4A]

Our procedure is to go to Flaps 1 and then up to see if the flaps will come up.

Then:

When configuring for landing, the pilot should be prepared to refer to the Asymmetrical, Partial, Or No Leading Edge Devices Checklist in the event that a malfunction still exists and a asymmetry develops. If the leading edge devices move to the full extend position when configuring for landing, a normal Flaps 30/40 landing may be made.

[dishwasher]

see your point, once beyond F5 you will have all LED's to their fully extended position.

If the LE flaps transit light is still on continue with F15,

If not normal landing....

It might be the problem that the will not retract fully, but will extend normally.

thanks, made my day!

[pancho]

Be careful, the checklist says:

If any light(s) for only ONE LED is illuminated Limit max airspeed to 300kts(280 for turbulent air penetration) or .65MACH whichever is lower. (Note it says ONE)

And then;

If any light(s) for MORE than ONE LED Limit airspeed to 230Kts and then accomplish the Asymmetrical or no LED checklist.

You do not have to carry out a F15 landing as per the Assymetrical or no LED checklist if only one LED light is illuminated.
In this situation you proceed normally except limit the airspeed as defined.

This assumes that No Roll has been encountered and you have recycled the flaps as per the checklist.

[BOAC]

Pancho - don't forget - and I suspect this is where 'dw' was pointing, that the asym cklist is actioned WHENEVER the Transit light is ON, with flap extended, REGARDLESS of the number of LED lights that were or were not on at the time. The flap extension check (below 20,000ft) is carried out for any number of LED lights. My reading is that the only influence the NUMBER of LED lights has is on the limit speed. It is a shame there is no 'flow chart' to clarify the drills!

I suspect that if it was unscheduled LED deployment that caused the Transit light in the cruise, then IF the LEDs eventually went to correct extension the Transit light would go out, thereby enabling a normal landing. In case it didn't, that is why I say have F15 'up your sleeve' in planning/thinking terms, then there will be no nasty surprises as you try to land in Jersey!

[purr]

You would have to do the LEADING EDGE FLAPS TRANSIT checklist first.:ok:

[pancho]

BOAC- That is absolutely right, but to clarify, there are two possibilities depending on wheater the TE flaps are extended or not. If the LE Transit light comes on then you use the LE FLAPS TRANSIT check. Then you decide if the light (or lights) came on with TE flaps extented or not. If it happened with the TE flaps extended you then use the ASSYm or NO LED checklist which leads to a F15 prep. As you say, if the LED subsequently behaves correctly then you can have another look at the snag or lack of.

The assumption is that if the LED Transit light is on, there is a disagreement between TE position and LE positon. Which in the takeoff scenario means that one or more have remained in an EXTENDED positon when the TE flaps are selected up. If only one is out then no big deal. If more than one then you have to follow the limits and the ASYM or NO LED checklist. On the other hand, if the light comes on when TE flaps are EXTENDED when slowing down for approach, it now means the one or more LEDs have failed to move to the required position, which could mean they are still retracted. This is considered more serious hence the reason for the F15 approach irrespective of how many LEDs have failed or not.