737 T/O config warn question
 

Hi all,
a question for the 737 drivers among you.
Do you have in your company's normal procedues a documented requirement for the takeoff configuration warning to be tested during the preflight scan? In other words, do you have to advance the trhust levers (preflight) so you can hear the intermmitent horn?
I am only asking for a published procedure, not an individual's personnal practice.
Also let me know if this is a procedure that used to be published (say2-3 years ago) but it has been amended and not valid any more.

Thank you very much.

Yes. We do. Each lever, before every duty period. Ie twice a day.

I think gonso is asking for something official from the manufacturer , and I am also curious about it. Where does the procedure come from ?

Yes. In our Before Start flow we are required to check that the horn works. On taxi we would check, as a technique, to make sure that the horn would not sound by advancing one or both throttles prior to taking the runway. It is now a procedure for us.

I don't think you can check the take off configuration warning on the B737-200 without the engines running. To conduct this test without engines running requires a circuit breaker to be actuated in the E&E Bay I think.

Neg...this is a maint test on the 737-700, 737-800

I don't think the procedure is "documented" in most airlines operating the 737.
However, most pilots flying the plane probably do it. Just think of the benefits of doing this simple check. I would (and do) it. Simply because it helps. It's alot to say the check is a "safety net", the config warning will sound early on the takeoff and 99.9% of times, an eventual reject is easy, but why do it for this reason when you have the benefit of being able to give it a try before?

You can test it on a -200 without the engines running. Remove A/C power from the busses and advance either thrust lever. No need for pulling circuit breakers.

We could check it on the -200 at SWA by just moving the throttles up when we are at the gate.

It is required to check it on every flight at SWA (now only flying -300,-500 and -700's).

Don't you just hate it when people think up new gimmicks like this. I have observed this technique being used by a couple of captains in an airline I once flew for and there was a sudden EGT rise in the P&W JT8D engines on the 737-200. Surely this is not a standard procedure. It is just laziness.

part of our pre flight cockpit preperation!

Capts also do it once shutdown on stand just to ensure the speedbrake is seated properly. (not sop) As we fly knackered old 300/500's:ok:

Well out stator vane...I have seen it both ways!

"after an RTO or landing, (two different types of events-one an abnormal-the RTO if my english serves me correctly-the other quite normal-landing) if either thrust lever is advanced, the SPEED BRAKE lever automatically moves to the DOWN detent and all spoiler panels retract. Ther spoiler panels may also be retracted by manually moving the SPEED BRAKE lever to the DOWN detent."

As a non flying type I can only give you the way I understand the system to work.
The reason for fitting a system that moves the speedbrake lever (and so the spoilers) is not RTO but rejected landing. Theory being that speedbrakes are armed for landing, deploy on touchdown, "oh s***! who parked that on the runway?" throttles to max TO. You don't want to be trying to get airborne with speedbrakes deployed or trying to stow them manually.
You will also find that they deploy automatically as you apply reverse thrust during an RTO even if you haven't armed them.


Its been a while but I remember being able to test the config warning horn just by advancing the throttles with engines running or not. In fact it used to be a test carried out during the "Daily Check". If you are not in TO config and you advance the throttles the horn will sound. The CB is pulled during high power engine runs to stop the noise as we don't tend to extend the flaps etc.

GE90 is quite correct. The reason why the spoilers will retract when the throttles are opened beyond a certain setting is a certification or design requirement. Heavy bounced landing - speed brakes extend - full thrust go-around and of course you don't want all that spoiler drag so the speed brakes automatically retract to save you from embarrassment.

That is why the spoilers operate! Ever think what would happen if you play the gimmick and when you shove open a throttle simply because you can and Murphy's Law actuates and jams open the throttle you would look a right twit going in circles simply because you circumvented normal procedures.

Vol 1 FCOM NP.20.32 under the heading Taxi In Procedure, states in part: "When clear of the active runway, the pilot taxiing positions the speed brake lever to the DOWN detent..."
Clearly the intent of the wording is that he physically places his hand on the speed brake lever to accomplish this task - not the throttle. One could argue if the throttle was the preferred method of retracting the speed brakes, Boeing would emphasise the fact. But it doesn't. :ok:

Yes, using both levers individually before start and with the button before takeoff. Before start check was limited to (your) first flight of the day.

The original Boeing checklists on the -200 did not include a T/O warning system test. This was added by individual carriers several years after introduction. I do not know the current Boeing standing on this. Perhaps someone familiar with such a well-seasoned document could elighten us.

Well you could...but the engines would have to be running. :} On the -200 the system works on advancement of the EPR gauge indications and not the thrust levers. You can check it at the gate on the -300's on up.

(From an eye witness of a captain who made a very embarrassing call to MX!)

We operate the 737-800 and do NOT do a config test before take-off. Nothing in my Boeing FOM makes mention of a config test before take-off, so I suppose those of you who does the test must have a company/fleet procedure.