737 Configuration alarm

[KiloDeltaYankee]

Hi all,

I was a passanger on a Boeing 737 this morning that aborted a take-off due to a "Configuration Alarm"

What are the most likely/common reasons for this alarm?

KDY

[flyfish]

The config warning is armed on the ground and when one or both thrust levers are advanced for takeoff. it will sound under the following conditions.
1 the trailing edge flaps are not in the 1 to 25 position for take off or
2 the leading edge devices are not configured for take off or
3 the speed brake lever is not in the down position or
4 the spoilers are not down with the speed brake lever in the down position or
5 the parking brake is set or
6 the stabilizer trim is not set in the take off range.

The above list is not real problem just abort the take off (going to be slow speed reject) and re configure.
Its in the air that that particular horn will indicate a far more bum twitching problem as its indicating a cabin altitude exceedance

hope that answers it for you
Flyfish

[KiloDeltaYankee]

Thank you Flyfish, that makes sence with what happened.

KDY

[BelArgUSA]

Tell the pilots to do their "3 killers" check when they roll onto T/O position...
Trims-Flaps-Spoilers... Old fart trick...
:D
Happy contrails

[wileydog3]

6 the stabilizer trim is not set in the take off range.

It is this one that caught a good friend of mine. The trim was correct but as the aircraft increased speed on takeoff the elevator loaded up and when that happened, the trim was near the forward limit and the config horn sounded. His F/O said, "We aborted for a trim problem..." The FAA violated the crew for failing to conduct a proper pre-flight. Only after lawyers got involved was the crew exonerated.

[PantLoad]

Yes, I remember getting a line check....when I was a line check airman, myself, by some snot-nosed, "ninety-day-wonder" of a check airman. This was back in the old days when I flew the 737-200 (both basic and advanced).

He criticized me for for making such a non-standard callout as we were taking the runway for takeoff: "Killer Items Checked".

In addition, he also had a big problem with my callout for takeoff thrust set. (This was on the P & W JT8D.)....."Thurst Set, all gauges at the nine o'clock position". (This was shortly after Air Florida dumped one in the Potomac River....for those who remember.)

I suspect this guy is still sitting behind some desk touting his flying skills and expertise.....all of his maybe 5000 hours total flight time amassed over 30 years in the business.

I also remember, as a new international captain, making my first over-the-pond flight. I told the senior F/Os....."I know the book. I know the book inside and out. But, based on your experience, tell me how to stay out of trouble."

I took their advice....and I never had a problem......

Fly safe,

PantLoad

[HAWK21M]

When thrust levers moved forward,T/O configuration warning comes on if the following are not adheared to:-

Flaps in T/O range
Stablizers in Green band.
Spoilers retracted.
Parking brake released.

Normally its an indication problem that triggers the warning.mostly observed to be the slat proximity switches.

regds
MEL

[IFixPlanes]

@ HAWK21M
please start reading the threads before writing.
Posting #2 have listed the conditions already (and more precisely) :ok:
Yeah.... pushing up the postcounter.... :ugh:

[HAWK21M]

@Ifixplanes....
Post count raising.....you have double the posts in 1/3rd the time since you joined up here in comparism......:bored:Maybe I should be saying the same thing.

Cheers & think positive.Rather than one liners of sarcasim as in your many posts,share your knowledge with the forum.:)

Guess what....I don't need to hide my profile.:=

cheers.

regds
MEL

[captjns]

Mr. Fixer...

Chill dude.... it’s a free forum for one and all.

Hawker was pointing out the fact the more common cause of the T/O

Another common problem is the micro switch associated with the speed brake lever wears out, which is a pain in the butt to change.

[IFixPlanes]

Post count raising.....you have double the posts in 1/3rd the time since you joined up here in comparism......Maybe I should be saying the same thing.
Except of 4 postings in 2001 your postings start at 2006. ;)

Hawker was pointing out the fact the more common cause of the T/O Configuration Warning Horn is a micro switch associated with the LEDs. Well, the edit-function is a nice tool...

[gone_fishing]

Just out of interest, would it also sound if the autobrake was not set to RTO?

[ampclamp]

No.Not on the 73's I've worked.
Usually (in my experience) speed brake lever not fully stowed.Only takes a poofteenth out of the detent to set off the config warning.
And yes they are a bit of a pain to change.

[gone_fishing]

OK, thankyou.:)

[BelArgUSA]

What I definitely admire here, is the use of modern technologies -
That you replace the "3 killer" check... by a gizmo that, never fails.
Never fails - no CB - no 28 DC - no 115 AC... never fails.
xxx
:eek:
Happy contrails

[A37575]

as the aircraft increased speed on takeoff the elevator loaded up and when that happened, the trim was near the forward limit and the config horn sounded

Providing the stab trim is in the green band the config warning should not sound. Can't quite see how an elevator "loading up" causes a config warning. It is not a C of G warning, but a stabiliser position warning, isn't it?

[BOAC]

I have experienced several - mostly due to tail trim on the 'edge' of the band but detected as out by the config system and speedbake mis-setting as described.

BA's wonderful fleet of old 737-200's used also to have LED proximity reed switch problems with monotonous regularity (they were knackered:)) and the config would sound as speed got towards V1 which always made the 200 take-off brief interesting!

[lunav]

hello, just a little addenda:
Classic vs NG TO conf warning:
-TE flaps not in TAKE OFF range which is F1 to F15 for 733 / F5 to F15 for 734&735 / and F1 thru F25 for 737 ng.
- LE DEVs Not extended for TO : Classics take the signal only from LE DEVs 1 and 4 while the NG has a FLAP/SLAT ELECT UNIT (please correct me if I'm wrong)
- I am not really sure of the point 4 of flyfish "4 the spoilers are not down with the speed brake lever in the down position or"...never herd that and no trace on books but maybe for the classics is a different story
- TAKE OFF conf warning sounds when either or both THRUST LEVERS pass 30° for classics and 53° for NGs

During the take off roll, building up speed, the aerodinamical loads on the elev and stab could create a dual failure of the brake sys thus giving you a STABILIZER RUNAWAY and a TO CONF WARNING. Really dunno if aerodinamical loads on elevator moving upwards could effect a little stab position!I'd be glad to have info! Grazie

ciao.

[Denti]

The above list is not real problem just abort the take off (going to be slow speed reject) and re configure.
Its in the air that that particular horn will indicate a far more bum twitching problem as its indicating a cabin altitude exceedanc

It might be an option, but newer NGs have two additional lights that tell you if its a config or cabin altitute warning.

[flyfish]

If that’s the case Denti, I have learnt something there, so glad I am involved in this thread.
Cant see why you would want the lights though, if its on the ground it’s a config, if its in the air, my Oxygen mask is going on. The config light would never illuminate (well never say never) airborne, you don’t need the lights as the two problems are worlds apart in terms of operations. That said I guess with the onset of hypoxia a second more clear warning light with the words ‘cabin alt’ may save the day, but cabin alt on the ground? Contradicted myself there a little as I explored the reasoning while typing, so sorry if this is waffle.

[hoover1]

you can get a config in the air as well. so it isn't only the cabin. due to the mistake made by another 737 operator we all have to breif the warning horn before every flight. although it is already a memory item.

[wileydog3]

A37575 said Providing the stab trim is in the green band the config warning should not sound.

Lots of stuff isn't supposed to happen that does...

[Flight Detent]

My understanding of the inclusion of the mod to install those two "unnecessary" inst panel lights to differentiate between the CONFIG and CABIN ALT horn warning, is an FAA requirement following the Helios crash, as is that briefing sillyness.

Cheers...FD...:)

[HAWK21M]

Some folks need to start being positive & share knowledge or learn some.One liners of fault finding negative thought don't do professionals any good.cheers & start living.:)

On the topic.....True.The Speed brake lever down/detent sw at times needs a recycle.A good lub serves well,if it is not a proximity sw adjustment issue.As the constant lever movement can cause the proximity sense to drift from position over time.

regds
MEL

[Cornish Jack]

Re Wiley Dog's point and the 'green band' - don't know about the 37 but, on the 474, having the trim in the green band is not necessarily a sign that all is well! If, for example, the FMS input is incorrect giving an incorrect green band indication , the config will NOT sound - the trim is where the FMS says it should be! Unlikely, perhaps, but Murphy is alive and well in the land of the unlikely. :=sxz

[Blip]

Cornish Jack.

I think Mr Boeing says somewhere that if the trim is in the green band, the elevator will always have enough authority to rotate the aircraft and get it airborne.

It may be way out of trim, but it won't kill you.

[wileydog3]

Cornish Jack is right and one needs to accept the old laws are still valid. Regardless of what The Book says, time and use has a way of introducing new problems.

I like the old sequence that is a time line for going on a new airplane...

1) What is it doing now and why? (1-3 months)
2) I have never seen that before! (3-9 months)
3) It does that some times... (after a year)

In the USAF we used to write stuff up and occasionally the mechanics would puzzle through trying to find the problem only to write, "CND" which stood for "Can not duplicate". It was a way to say they had researched the problem and could not find 1) the problem and 2) could not solve the problem.

So, I guess my point, not meant as a 1-line negative response, is that I knew the Capt who had the problem with the config and trim, knew of the FAA violation and knew of of the subsequent resolution of the violation. And from that event, whenever a crew aborted at my former airline, most NEVER explained to tower or ground why they aborted... just 'we are taxiing back', end of explanation.

[framer]

It always amazes me that I learn stuff from prune threads that I thought wouldn't teach me anything, it often sends me to the books to figure stuff out when the original picture in my head was not accurate. Nice.

[despegue]

On the Classic (300-400-500), if your trim is set near the end of the green band, often you will get a T/O config warning the moment you spool up your engines. A little forward trim solves the problem.
It's a good idea to move one throttle towards the T/O position ( vertical is fine) momentarily to check your configuration and trim settings. Avoids a possible warning on the runway.

[rubik101]

Now SOP in the cheap airline when cleared to taxy, to release the brakes and advance both throttles to the bug and quickly return them to idle, or thereabouts, to commence taxy.
Good time to find out if the config warning goes off and remedy the config.
Incidentally, why do we say go off, when we mean come on?

[masalama]

flying the 737 NG for an airline in India...
have to admit I do the quick advance of one thrust lever to vertical and back to check the config ...although it's not SOP or authorized in the FCOM ....

did have one low speed reject earlier in my 737 flying due to a faulty speedbrake lever microswitch and this quick check just before lining up saves a lot of trouble me thinks....

take care and masalama.

[Denti]

Be careful when only using one thrust lever. Depending on FMC Version that can switch the FMC into OEI mode and give you very low speeds later on.

[Ollie268]

Just in addition to to post number 2 -
Config warning also goes off due;
TE flap asymetry or uncommanded motion
LE uncommanded motion
If there is pressurised hydraulic fluid in the spoiler control valves

and just to correct the speed brake (number 6 i think) -
Speed brake lever NOT in the down detent.

If the speedbrake lever IS down but spoilers are not stowed then a light is illuminated in the f/d "Speedbrake Extended" however im presuming that if they were not stowed then there must be hydraulic fluid keeping them from doing so in which case - in a round-a-bout way WOULD cause the config alarm.

:ok:

[D O Guerrero]

Would changing the flap setting during the takeoff roll cause the TOCW to activate? For example, you set takeoff thrust with say Flap 10, when you wanted Flap 5. This is still in the range for takeoff flap setting so there would be no TOCW right? So you then decide to set Flap 5 during the roll. Would it go off? I would have thought that it would stay silent, but someone was telling me different recently.