Flaps Display

[Remys 4]

There's something weird happening, whenever lowering the flaps or retracting them , on the displays sometimes the flaps shows as two columns [each flap for each wing, not 1 column as usual] and sometimes 1 column for both wings.

This occurs whenever we arm the ALTN Flaps.

and whenever the ALTN Flaps are armed, a warning sound occurs and on the display two warnings show up:

1- Flaps Control

2- Flaps Primary

 

any idea how to overcome/bypass this problem in order to be able to see the flaps position on each wing? 

and what is the ALTN flaps used for ?

 

thank you

[Captain Kevin 586]

Have a look at the FCOM, starting from section 9.10.10 for flap indication. Not sure if this helps, although seeing only two columns is unusual. It's normally one, but if you have an abnormal situation, you should see four columns. I'd have to see a screenshot to see what you're looking at.

[Remys 4]

9 minutes ago, Captain Kevin said:

Have a look at the FCOM, starting from section 9.10.10 for flap indication. Not sure if this helps, although seeing only two columns is unusual. It's normally one, but if you have an abnormal situation, you should see four columns. I'd have to see a screenshot to see what you're looking at.

yes you're right 4 columns my mistake.

This occurs whenever we arm the ALTN Flaps.

and whenever the ALTN Flaps are armed, a warning sound occurs and on the display two warnings show up:

1- Flaps Control

2- Flaps Primary

 

any idea how to overcome/bypass this problem in order to be able to see the flaps position on each wing? 

and what is the ALTN flaps used for ?

 

I wish I could insert the media but unable to find where to upload a pic. anyhow i believe that we're talking now about the same thing

[skelsey 765]

The expanded flap display that you are talking about comes up when there is a fault with the flap system, which in this case you are inducing by selecting the alternate flap controls.

3 hours ago, Remys said:

any idea how to overcome/bypass this problem in order to be able to see the flaps position on each wing?

No, because it's not a problem, it's the aeroplane functioning as designed. The normal flap display shows you the position of the slowest flap group. I don't really understand what you are trying to achieve...

The alternate flaps are only ever used when there is a fault with the flap system -- and, in all honesty, even then it is pretty rare and I can't think of too many QRH situations that require you to use them. Most of the time even with a fault the flaps will still come out in secondary mode, just a bit slower than normal.

[Captain Kevin 586]

4 hours ago, Remys said:

This occurs whenever we arm the ALTN Flaps.

If you go to the FCOM on page 9.10.12, you will note that the plane is doing exactly what it is supposed to.

4 hours ago, Remys said:

and whenever the ALTN Flaps are armed, a warning sound occurs and on the display two warnings show up:

1- Flaps Control

2- Flaps Primary

And if you go to the QRH on page 9.4, 9.6, and 9.12, you will note that the plane is doing exactly what it is supposed to do.

4 hours ago, Remys said:

any idea how to overcome/bypass this problem in order to be able to see the flaps position on each wing? 

Sure, leave the alternate flaps alone. I don't know why you're messing around with it in the first place.

4 hours ago, Remys said:

and what is the ALTN flaps used for ?

If you go to the FCOM on page 9.20.14, it tells you, but basically, unless you have a major problem with the flaps, there's no reason why you should be touching it in the first place.

4 hours ago, Remys said:

I wish I could insert the media but unable to find where to upload a pic. anyhow i believe that we're talking now about the same thing

No, I don't need it anymore, as your updated description confirmed what I suspected. In any event, for future reference, go to a photo hosting website like Photobucket or Imageshack, upload the picture there, and post the link here.

[Remys 4]

Thank you All for your Replies. it was a pleasure reading them and very useful

 

 

[berts 97]

On 25/06/2017 at 4:57 AM, skelsey said:

The alternate flaps are only ever used when there is a fault with the flap system -- and, in all honesty, even then it is pretty rare and I can't think of too many QRH situations that require you to use them. Most of the time even with a fault the flaps will still come out in secondary mode, just a bit slower than normal.

The amber EICAS caution message FLAPS CONTROL is the one abnormal B744 QRH procedure which will always require the use of Alternate Flaps.  This message means that three identical Flap Control Units (FCU) have all failed to operate correctly, so Simon is quite correct in saying that it is pretty rare.  It can occur if a trailing edge asymmetry is detected during primary mode operation, because the FCU's will immediately shut down the asymmetric group and not use the secondary mode.  However, even if all three FCU's have failed in their control function it is still possible for the EICAS flap indications from the FCU's to remain valid.

The three FCU's normally monitor and sequence the flap operation based on flap lever position and any one FCU is capable of performing all or any of the three basic flap functions (i.e. flap position indication and annunciation to EICAS and other systems; primary and secondary mode operation; as well as trailing edge flap asymmetry protection).  They also control the Flap Load Relief function in primary mode only. 

The QRH procedure for this particular failure is quite involved operationally and it will require careful execution and good teamwork; especially if the expanded flap position indication is inoperative because the autopilots will be inoperative, the outboard ailerons are unlocked (a high speed issue) and there is a 20kts crosswind limit for landing.  Manually pushing the Alternate Flaps Arm Switch to ALTN enables the flaps to be extended and retracted using the Alternate Flaps Selector and the Flap Lever is inoperative.  Extra time must be allowed for flap extension and retraction, simply because it takes up to 6 minutes for the TE Flaps to move from the UP position to Flaps25 (max for landing) and vice versa using this system.  When armed, the alternate control mode also bypasses the FCU's, brings on the FLAPS CONTROL message (if it is not displayed due to this failure) and there will also be no flap asymmetry protection.

Bertie Goddard