Topic Author
Posts: 151
Joined: Fri Feb 23, 2001 10:26 pm

Flaps Failure While Extending

Wed Jul 03, 2002 10:49 pm

When on approach if flaps fail to extend beyond certain units, what action is to be carried out ? Assume both the cases of flaps symmetry & assymetry. That is flaps fail to extend although they are symmetric ( as per indicator ) and flaps failure to extension in case of assymetry. Will the alternate operation be the choice in both cases ?
Posts: 225
Joined: Sat Apr 28, 2001 3:26 am

RE: Flaps Failure While Extending

Wed Jul 03, 2002 11:56 pm

Well, the first thing you do is get back up, get in touch with atc, and make sure someone is flying the ac before you trouble shoot. From your note, it sounds like you are not asking about alternative extension methods but how to proceed if there are no alternatives?

If so, the answer to both is actually the same, it's airspeed- 0 flaps is not a big deal, you just plan a long flat approach and keep speed up.

Asymmetrical extension isn't a common occurrence, but most if you can't get them in or out, I'm pretty sure that all ac will call for an increased landing speed to assure plenty of control.

This was the case with the DC-10 in Chicago (American?) where #1 pylon failed, and the engine separation caused loss of control of leading edge devices. The crew didn't realize they had anything more serious than an engine failure and going by the book, they pulled back to the speed called for in a 2 engine climb- Unfortunately, they had asymmetrical slat extension, and they dropped below the speed at which they could compensate and lost control.

Posts: 122
Joined: Sat Feb 16, 2002 11:46 am

RE: Flaps Failure While Extending

Thu Jul 04, 2002 12:35 am

If you have less than normal flaps or no flaps for landing then you will simply land faster. This of course results in a longer landing distance. In some cases then you may have to land somewhere else with a longer runway. As far as I know all transport category aircraft have detection for flap assymetry and will stop the flaps when a certain degree of assymetry is reached. You would then use a landing speed to correlate with the flap that was extended the least and use trim and roll controls to counteract the rolling tendency.
Topic Author
Posts: 151
Joined: Fri Feb 23, 2001 10:26 pm

RE: Flaps Failure While Extending

Sat Jul 06, 2002 11:13 am

Let me explain my question. What I want to ask is during extension of flaps, if flaps do not extend beyond certain units, will the alternate procedure of flaps extension be applied straight away or first will pilot confirm that its not the assymetry causing sytem to fail ?

Assuming that assymetry caused the flaps to stop, R/W length requires full flaps down, will the alternate extension be used or an alternate R/W with more length be looked for ? What if u don't hv enough fuel to go to alternate R/W ?

I hope I am clear now.

Posts: 5561
Joined: Thu Dec 13, 2001 8:27 pm

RE: Flaps Failure While Extending

Sat Jul 06, 2002 3:26 pm

A wise airline captain once told me, "if you pull a handle [i.e. flap handle] down and something wierd happens [like an uncommanded roll due to asymmetry], put the handle back where it was working correctly".
Last year 1,944 New Yorkers saw something and said something.
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Joined: Wed Jun 30, 1999 3:37 am

RE: Flaps Failure While Extending

Sun Jul 07, 2002 1:37 am

I was once on a AA f-100 from ORD to SWF that had an asymmetrical flap failure on final approach. As the captain selected full flaps, you could feel the aircraft start to bank. Flaps were immediately retracted and we executed a missed approach. After we climbed back out, the captain announced that we had a flap problem and would be making a 0 flaps landing. Since SWF has a 12,000 Ft runway and we had a 20 knot headwind, the only difference was the high speed approach and a really long rollout.

RE: Flaps Failure While Extending

Tue Jul 09, 2002 3:05 am

Gentlemen -
Asymetric flaps may present different problems, and you have to use the appropriate procedure to the specific aircraft... The 747 has alternate system to extend the leading edge and trailing edge flaps... such a situation is solved with the appropriate check lists...
On some airplanes as an example - a split flap configuration may be a potential danger of dire control problems, if no proper procedure exist, it may be better to remain in that configuration, rather than attempt to correct it... Here is a simple example for a light aircraft...
Aircraft "XYZ" has flaps which can be set at 10, 20, 30 and 40...
When extending the flaps to 10, then to 20, all goes well...
Then, selecting flaps 30, only one unit goes down, the other stays at 20...
If you try to extend further, you could end up with one at 40, one remaining at 20, worsening the situation...
If you try to retract the flaps, the one at 30 stays at 30, but the unit which remained at 20, now retracts to 10, or all the way UP... worsening again...
If your aircraft does not have an "approved" procedure to deal with asymetric or split flaps, leave it as is, and land as is...
Another advice, dont go from one flap setting bypassing each intermediate setting, i.e. selecting "flaps 40" immediately, without a stop at each position of 10, 20 and 30... with a malfunction you could end up with severe control problems... and not recognize the problem when it starts with a less severe configuration asymetry...
Happy landings...
(s) Skipper

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