25th Feb 2004, 15:27
hello,everyone,i am a 737-300 guy,and here is my puzzle:
during a normal approach, we reduced the speed, extended our flaps,and ready for landing.
when we set flap 10, we found a ASYMMETRICAL indication:L was pointing 10,but R stuck on 5.but it's just a indication,because we did not feel "An uncommanded roll"(in fact,we went back to cabin and checked flaps by visual,they were symmetrical!).so my puzzle is:
what should we do then?
we have to follow the QRH once we meet a abnormal situation.but in this case, i can't find the checklist we should follow.checklist "ASYMMETRICAL TRAILING EDGE FLAPS"? i don't think so,cause we don't have the feel of uncommanded roll.
we can't move flaps forward or backward anymore because of the asymmetrical protection system, unless we use the standby system.but standby system does not have the asymmetrical protection-----so it's dangerous.

so,i'm here looking for your opinion.

Right Way Up
25th Feb 2004, 16:48
I believe the checklist is being revised to cover this scenario i.e. the checklist will ask if there is any roll, and will then split into two different procedure.

25th Feb 2004, 17:04
Just out of interest, did you try tapping the guage?

Although I have never had an assymetric flap problem on the 737 it was an infrequent problem on the 747 classic where it was recommended that a 'technical tap' be applied to the flap guage in case a needle had stuck. (From dim recollection I believe that the assymetric protection came directly from the flap guage)


25th Feb 2004, 20:04
Exeng - you are correct part of the flap assymetry protection on the 747 classic is through the indicator, if the needles are more than one needle width apart you get assymetry.

Flight Detent
26th Feb 2004, 10:57
Hi all,
The obvious thing to do is land with flaps 10, there is a procedure in the B737 QRH for that, it's the same one!
Land at Vref 40 + 30, the LEs are all out, so whats the problem?

Yes, the B747 Classic did have the assy detection in the indicators as has been mentioned, but then, they also had a Flight Engineer!


26th Feb 2004, 13:19

i did tap the guage,it didn't help.but thanks anyway.

Flight Detent

thanks for your direction.but i can not find that "obvious" checklist in my QRH(maybe it's an old version?), so will you please show me the exact checklist?
just a guess,Vref40+30,so you recommend to use the checklist"ASYMMETRICAL TRAILING EDGE FLAPS",that means we'll use an checklist with its conditions not been totally satisfied.and this does not catch the principle of the checklist usage,i think.

26th Feb 2004, 14:17
I would agree with Flight Detent.

Vref 40+30 kts would equate to about 170 kts at the most. If you use about Autobrakes 2 you'd use about 2700 m of runway. No big deal. Max Autobrakes would use about 1500 m if you really felt the need. This would probably blow your fuse plugs though.

It's funny how we feel absolutely comfortable flying away from the ground with only Flaps 5, yet flying towards the ground with anything less than Flap 30 is such a big deal!

26th Feb 2004, 14:40
i don't think it's a really big deal to land an aircraft with flap10.what i wanna know is what is the correct procedure in this condition!
if i follow a procedure,i hope i can follow the one which could be the legally reference instead of a personal imagination.

27th Feb 2004, 00:00
eagle 737

the conditions for the TRAILING EDGE FLAP ASYMMETRY are:
' An uncommanded roll occurs when a flap selection is made AND/OR a difference between the left and right indication is observed'
As you see the decision to follow the orh for your situation is dictated by the 'OR' word,having no uncommanded roll .
Although it is almost sure that it was a indicator malfunction,the QRH states that you should do the checklist even without a roll indication.I have no ideea how big the roll will be for a difference between 5R-10L flap,but between 5R to 15L or even 25L you can be sure it would be much worse.
A landing with flaps 5 or up is not something to worry about,but you should think about rwy length,OAT,LW..,and not forget max tyre speed (about 195 kts , less than clean speed)
The ORH also states that the checlists 'are not intended to replace good judgement.' and also that 'in some cases,deviation from checklists may be necessary,at capt discretion.'
In this particular case,I would go around,enter some hold,burn some fuel if necessary,and if feeling somehow worried about landing with flaps up or 5 (due to any reason ,eg:OAT,airport altitude,RWY length,...) I would try to extend normally the flaps to see if any roll appear.It would be easy to try all this in hold,than on the GS :). Finally ,I'll decide what flaps I'll use for landing.
Alex :ok:

Flight Detent
27th Feb 2004, 11:00
Hi Eagle737,
My copy of the checklist, page NNC.9.8. is dated 30SEP02, but does not include that "and/or" mentioned above. (just 'and')

But that makes no difference, with respect, you have to operate with the best you have, use your 'common', and there is only one way to go.
Use max reverse on touch, and leave your manual braking until below about 100-120 kias, and you won't melt the plugs, on any reasonably long runway.


27th Feb 2004, 12:01
thank you,my friends.
i don't have the word "or" in my QRH,but just "and".
i think i can only deal with this malfunction by my "good judgment" rather than the reference directly from the QRH.
and i believe most items in QRH are come from this kind of "good judgment" situation.i hope this could be another.
btw,some people told me there was a checklist called "landing with partial trailing edge flaps" in the old version.i think that would match this situation.