Broken flap indicator B737

[B737900er]

Hi,

We had an aircraft push back and select take off flaps for departure and there was no indication of any flap movement. So the aircraft went back to stand and found out that the flap indicator was busted and needed replacing.

Seeing as the aircraft is dispatched and the QRH is now the reference book to use, I couldn't find anything about it. The closest thing I found was trailing edge flaps not in the commanded position.

So my question is, what happens if this was in flight?

Also I could not find it in the MEL/CDL manual so that would mean the aircraft is AOG correct?

[sky-738]

i guess in flight ,you can use the flap warning to set the flap to 15.
for further down , may be the stall speed can help, but i haven't try that ever.

[ampclamp]

I would say you just have to trust your flap handle settings making sure you give the flaps slats time to travel to selected position. Remembering that the slat indicator panel will offer some clues for certain settings as will the instrument panel mounted lights.

[EW73]

Hey....just like a Standby Power approach....

Having no flap position indication, that is...

[misd-agin]

Does the trim change when the flap handle is moved?
Establish a constant airspeed and power, does the plane slow when the flap handle is moved?
Visual inspection?

Lots of ways to cross check.

And if your company had the AOA option...

[c100driver]

On the Legacy and the Classic the flap indicator is also the Flap asymmetrical protection device.

[de facto]

Seeing as the aircraft is dispatched and the QRH is now the reference book to use, I couldn't find anything about it. The closest thing I found was trailing edge flaps not in the commanded position.

So my question is, what happens if this was in flight?

Also I could not find it in the MEL/CDL manual so that would mean the aircraft is AOG correct?

The QRH is not to be referenced to dispatch an aircraft!
You departed with a fault that is AOG one as it flight crew procedures is not laid down on the DDG.
You operated illegaly and recklessly.

[Capt Chambo]

You operated illegaly and recklessly.

Whoa, ease up de facto!
Re-read the original post.

So the aircraft went back to stand and found out that the flap indicator was busted and needed replacing.

After push back a fault was found and the aircraft returned to the gate...case closed.
The OP then poses the hypothetical question

So my question is, what happens if this was in flight?

Personally I would be looking at doing a "Trailing Edge Flaps Up Landing".

Whereas most regulatory bodies will allow the commander of an aircraft to fly in any way (s)he sees fit for the purposes of saving lives, I don't believe we are at this stage yet. Boeing also caution about troubleshooting, in case it makes a situation worse.

[de facto]

Whoa, ease up de facto!
Re-read the original post.

The poster wrote:

Seeing as the aircraft is dispatched and the QRH is now the reference book to use

Was the aircraft not dispatched then?

Also I could not find it in the MEL/CDL manual so that would mean the aircraft is AOG correct?

Well yes,i guess then you changed aircraft...

Apologies for jumping on ya

To answer your question...
If you select flaps 1 and your indicator only is failed,which means the pdu is working normally,LE slats/slats will deploy as normal.
The initial checklist would be trailing edge flaps disagree.
This checklist will direct you to the stby electrical way to extend the TE flaps.
(Mind you,if the flaps actually went down,you would feel it and see adjustments on the speed tape from the fseu).
Now uou use the stby to extend to 15....the LE should go to full down but still no indication on the TE...
You will be directed to TE flaps up landing with LE slats and flaps at full extent.

The qrh gives some info in the airspeed unreliable,thrust/pitch for different flap setting...you may just realize then that your flaps are at 15.....

Best thing is to follow the qrh and dont guess as stated above.

[Capt Chambo]

Seeing as the aircraft is dispatched and the QRH is now the reference book to use

Different (dispatch) horses for different (dispatch) courses. I can only presume that this "dispatch" is applicable in the OPs company (or maybe under FAA regulations generally as the OP's location is Florida). Either way I cannot comment.
FWIW the last three 737 operators that I have flown for, the MMEL/MEL/DDG applied from; a) pushback, b) when the aircraft moved under it's own power, c) to the application of take-off thrust, respectively.

Widening the pattern out a bit: just because the aeroplane has "dispatched" doesn't preclude the use of other applicable checklists/memory items. (If we take the OPs definition of dispatch, we wouldn't be applying an MEL/DDG if we had an engine or APU fire as we taxiied out!). As ever common sense should prevail.

[Denti]

Now uou use the stby to extend to 15....the LE should go to full down but still no indication on the TE...

Which is not true for all NGs, some only move the LE slats to full extend when the TE flaps are at 25. Which means one has to know which tab number range has that behavior and the tab number if the plane one is sitting in. If one counts in the time for a standby electrical deployment and the required cooling times, that can take some time.

[B737900er]

Hi guys and girls thanks for the replies!

Let me clarify what I mean when I said dispatched. I ment the aircraft has been pushed back from the gate doors all closed etc tug driven away so now the aircraft is using its own power to move.

Thinking about the situation I would of used the LED panel on the over head and actually looking out the window in the cabin.

Reason being, even if you used the alternate flap switch the gauge still wouldn't move yet the flaps would be deployed.

[de facto]

2 min 39 secs from up to 40...
possible about the full positions only if flaps 25 or more,in any case the checklist make sure pilots check the status of the LE flaps on the overhead.
they may be redirected to all flaps up landing checklist...

[B737900er]

Defacto I'm not sure your actually reading the post correctly or I just don't make any sense.

I'm talking about an actual scenario that happened I.e the aircraft pushed off stand selected the flaps and found a problem and went back to stand. The engineers said it was a flap gauge problem.

My question is what happens if the gauge goes bust in flight seeing as you can't just 'pull over to take a look' and there isn't a checklist for it.

[de facto]

got it
deleted earlier post ..

BUT if you read my posts, i replied about the checklists to use...

[B737900er]

Thank I'm glad we sorted the confusion haha.

Yes the TRE disagreement was my first reaction and your post has confirmed it.

But that leads on to the question of doing a flaps up landing.
You plan to do a flaps up landing but as you said if the flaps do move then you will feel it then what?

Do you just check the LED panel and visual cues in the cabin and pitch power settings and hope the flaps are in that position once you get a strong feeling the gauge is bust.

Because I can't see planning to do a flaps up landing knowing from the above cues that the flaps are out regardless of the flap indicator.

[BOAC]

I think post #12 is the logical solution. The situation, as you say, is not really covered by the QRH. We have no reason to expect concurrent flap failure or flap asymmetry and providing you can see the position of the flaps, confirm no roll trim issues and the overhead panel works, then I would probably make a 'normal' landing after a slow speed check for safety. If I could not see, work as logically as possible through the QRH and go flaps up.