PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Tech Log (https://www.pprune.org/tech-log-15/)
-   -   Questions you had never asked before about B737 (https://www.pprune.org/tech-log/538475-questions-you-had-never-asked-before-about-b737.html)

JammedStab 1st May 2014 23:32


Originally Posted by Denti (Post 8459737)
To be honest i don't use 2 all that often, but it is sometimes useful. 10 and 25 on the other hand are normal take off flap settings and therefore used quite often. Much less often during approach though, although it can be sometimes advantageous to do so.

Flaps 2 was used a lot on the -200 in my experience for takeoff. Compared to flaps 1, it gives several thousand extra pounds of capability at some airports depending on the situation. Also, it gives about 5 knots lower v-speeds which always felt kind of fast to me.

For the newer types, I guess, it is just a holdover from the old days.

medflyer 2nd May 2014 12:18

CWS P
 
I disagree that CWS is a waste. It is merely a tool that can be useful in some specific situations.

For example, I like CWS P when the NG is doing the hobbyhorse routine in a VNAV climb. It will still level off (capture an altitude) in this mode. If you enter the mode without selecting N1 on the A/T then the power will come back to hold the selected speed. If you leave it in speed it will function like V/S, which has its place too. Although some shy away from full CWS as it will sail right through an altitude selected on the MCP, there is actually a way to ensure this will not happen: breaking out the autopilot through pressure on the controls in pitch and roll will get you into CWS but with 'CMD' on the FMA vs 'FD', which is what you will see if you get to CWS by simply pressing the button.
FD= no alt capture.

ImbracableCrunk 2nd May 2014 23:50


Although some shy away from full CWS as it will sail right through an altitude selected on the MCP, there is actually a way to ensure this will not happen: breaking out the autopilot through pressure on the controls in pitch and roll will get you into CWS but with 'CMD' on the FMA vs 'FD', which is what you will see if you get to CWS by simply pressing the button.
Or you could just de-select the current V mode. Much less muscle-y.

medflyer 3rd May 2014 01:33

Agreed, however that only gets you CWS P, not the full CWS experience :ok:

ImbracableCrunk 3rd May 2014 02:18

The only time I'd use full CWS would be severe turbulence.

Tom! 18th Oct 2014 12:10

I also have a question that has been bothering me for a while:

In the case of a loss of all generators (dispatched with APU INOP) and not recoverable.

Apart from a dozen other things you obviously also lose the elec stabtrim. Having a look at the checklist it says to land with flap 15. But since only half of you anti-skid system is working (inboard only?) it seems to be a better idea to land with normal landing flap 40? (flap indicator not working as well)

Establish and manually trim it out on long final with F40 and be careful in case of a go-around with the trim requirement, or follow the stabtrim INOP NNC and go with F15 and taking the extra speed into account for the LDR with partial anti-skid.

The loss of both generators checklist doesn't seem to have a preference.

No Fly Zone 18th Oct 2014 19:22

Say WHAT??
 
From the original: "To start with, I have an electrical question regarding its electrical system:"

I'm certainly glad that your question about the 'electrical system' was an 'electrical question and not perhaps a hydraulic question. Whew :rolleyes:. That was a close call!

More seriously, I hope you received a response that you understand. :ok:
(Tip that may help: read it out loud, even to yourself, :p -and before pushing the Send, Publish or Post buttons:confused:. Been there :( and done that:ugh:. Better luck next time.

ZFT 18th Oct 2014 20:49

Was it a bottle of red or white wine?

stilton 19th Oct 2014 09:58

' On Britannia Airways 737-200s only the Captain had HDG SEL. The F/O only had CWS in both lateral and vertical axes. Passing the Command Course meant both a pay rise and the luxury of HDG SEL! Alt Hld had to be manually engaged on reaching assigned level, having reduced the rate of climb/descent using CWS. No V/S mode either, but we did have VOR/LOC. All selected through massive rotary switches which engaged with a satisfying clunk. Ah...those were the days!
Matey is offline Report Post Reply'



Sounds exactly like a B727 :ok:

OhNoCB 19th Oct 2014 12:03

Why no check valve from the APU bleed to stop back pressure?

FlyingStone 19th Oct 2014 12:13

My FCOM shows that there is one...

OhNoCB 19th Oct 2014 12:19

Hmm mine shows that there isn't! Have just double checked to make sure. Wouldn't be the first time that I have pondered questions arising form this FCOM which have been answered by better manuals.

IFixPlanes 19th Oct 2014 16:48

I Hope you accept the AMM (Aircraft Maintenance Manual) as an "better manual".
All B737 (100-900) have a check valve in the APU bleed line.
In addition: I know it out of (more than) 25 years as a mechanic, working on this aircraft.

ManaAdaSystem 19th Oct 2014 23:22

I want to know what I am supposed to do with the yaw damper indicator?

IFixPlanes 20th Oct 2014 04:53

One thing is to check the system on ground during taxiing. You have a short movement in opposite direction the airplane drives in a curve.

BOAC 20th Oct 2014 07:10

Back in 'the old days' (73-2) it used to be part of the instrument checks during taxy ("What are they....?")

Denti 20th Oct 2014 07:23


I want to know what I am supposed to do with the yaw damper indicator?
It's not there anymore in newer planes, so i guess it can be seen as superfluous information.

ManaAdaSystem 20th Oct 2014 09:02

Yaw damper switch on, YD works. Switch off, it doesn't.
Probably why they removed the instrument. I have never used it for anything.

When you did the instrument scan, did you check the instrument or the system?
What did you look for? It moved! Thank God! :)

Have any of you found the two leading edge flaps on each wing?
I must be blind because I can only find one. I've been puzzled about this for years, but I'm scared it's just me who can't find the other one. :O

BOAC 20th Oct 2014 09:19

If you are asking as a pilot and you HAVE an indicator, what does your company manual tell you to do? If nothing, then happily ignore, stop worrying and return to blissful ignorance?

TURIN 20th Oct 2014 09:23

Yaw Damper Indicator was used every night during the Daily Check. Or was it Weekly? It's been a while.

ManaAdaSystem 20th Oct 2014 09:33

Some of our aircraft have it, some don't. I'm not worried, just curious. Our manuals doesn't tell us to do anything with it.

So, when you checked it, did you check the instrument, or could you check if the YD system was operating normally? Checking without knowing what you are checking seems rather pointless to me.

Respectfully.

framer 20th Oct 2014 09:47

What mechanism/ component moves the control yoke forward a fraction when flap is selected on the ground?
Look closely, when you go from clean to flap1/5/10 after engine start, the control yokes move forward a fraction.
( my guess is the elevator feel computer)

BOAC 20th Oct 2014 10:09


So, when you checked it,
- movement in opposition to yaw checked both damper and instrument.

Clandestino 23rd Oct 2014 07:51

Are -700 and -800 flaps and slats interchangeable i.e. same P/N?

de facto 23rd Oct 2014 08:39


Back in 'the old days' (73-2) it used to be part of the instrument checks during taxy ("What are they....?")
Was also part of Astraeus procedure a few years back.

B737900er 23rd Oct 2014 09:37

I was told the B737 had a limitation on the maximum wind speed it could taxi in.

I was told it was 65kts. I could not find this in any of my company manuals nor the AFM.
The only place on the internet i have seen it written is on B737.org.

Is there any truth?

RAT 5 23rd Oct 2014 19:56

Have you got carbon or steel brakes or only a brake parachute?

B737900er 23rd Oct 2014 20:24

Rat5

if that was directed at my question then we use both Carbon and Steel brakes and some times hopes and dreams of stopping :E

BOAC 24th Oct 2014 08:13

As far as I recall, there are two figures for 737:

1) 40kts for Airstair operation
2) NOT a limit, but if taxied or 'open' parked in wind speeds (no, Rat, not Ryanair taxy speeds:D) exceeding 65kts, an engineering check is (?was?) required.

B737900er 24th Oct 2014 12:37

BOAC,
Thanks for the answer but where can i reference this? Its not mentioned in my company manuals nor AFM?

Tom! 24th Oct 2014 15:57

It's mentioned in my FCOM2, Chapter 1 "Doors and windows"

CAUTION: Do not operate the entry or cargo doors with winds at the door
of more than 40 knots. Do not keep doors open when wind
gusts are more than 65 knots. Strong winds can cause damage
to the structure of the airplane.

RAT 5 24th Oct 2014 16:44

I once flew for an airline when hats were still in fashion. They had a temp'c limit when shirt sleeve oder was allowed. I asked about wind speed for the hated caps and was met with a dumfounded look.

B737900er 24th Oct 2014 17:02

TOM- Im not talking about the doors I'm talking about taxying!

Ive heard of Head, wind, tailing limits but never taxi.

BOAC 24th Oct 2014 22:04

I don't know where you will find it if it still exists. Ask your company? It is NOT a 'taxy' limit' - it is a wind speed above which a 737 ANYWHERE in the open needs (?used to need?) an engineering check. You could be sitting on stand;a/c parked overnight on the apron;taxying; whatever. Obviously headwinds as in 'flying' do not count. I assume it is to do with rudder maybe? Anyway, it isn't very likely to bother you.

despegue 25th Oct 2014 04:52

BOAC!

We do not have this limit so this was probably a Company Procedure.

BOAC 25th Oct 2014 07:12

Could also be one that has been withdrawn? I'm sure the airstairs limit is still there. Ask Boeing?

Jwscud 31st Oct 2014 20:06

http://www.aaiu.ie/node/667

That report regarding damage to a 738 rudder during a thunderstorm the previous evening makes interesting reading. Well handled by the crew but more significant damage could have really woken them up.


All times are GMT. The time now is 06:31.


Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.