737 Questions
 

Hey friends,


talking about a 737 classic.

1.)In case of dual generator failure. Starting APU and you should connect the GEN 2 first to charge the battery through the TR3. Why? Don´t understand because GEN 2 powers the mainbus and the battery charger is then supplied? Where´s my fault?

2.) How long can the speedbrake be deployed. I mean with which flap setting? up to flaps 15?

3.)Where in the MEL can I find wether i have to have the athr engaged during the CAT III or not?


4.) Imagine ATHR is okay during CATIII approach and it does not retard. Can i retard the thrust levers on my own? So disconnect the autothrottle and pull them back?


5.) Is a cat III II landing in contaminated runway allowed? Which penalty must be applied?


6.) When the ATHR is in HLD during takeoff till 400ft AGL and i get a windshear in 200 ft AGL and pressing the TOGA buttons, nothing will happen right?

I'll have a crack:

1.)In case of dual generator failure. Starting APU and you should connect the GEN 2 first to charge the battery through the TR3. Why? Don´t understand because GEN 2 powers the mainbus and the battery charger is then supplied? Where´s my fault?

What else does TR3 do?

2.) How long can the speedbrake be deployed. I mean with which flap setting? up to flaps 15?

No limit but best not more than F5 due to tailplane buffet - don't want it falling off, do we?

3.)Where in the MEL can I find wether i have to have the athr engaged during the CAT III or not?

Not in MEL - in your AWOPS limitations section - A/T mandatory IF AVALABLE.

4.) Imagine ATHR is okay during CATIII approach and it does not retard. Can i retard the thrust levers on my own? So disconnect the autothrottle and pull them back?

Yes, (or just close them) just do not press TOGA

5.) Is a cat III II landing in contaminated runway allowed? Which penalty must be applied?

LDA check plus what are your AWOPS crosswind limits in your OM?


6.) When the ATHR is in HLD during takeoff till 400ft AGL and i get a windshear in 200 ft AGL and pressing the TOGA buttons, nothing will happen right?

Are you not at TOGA already? What does QRH say you should do?

1.)In case of dual generator failure. Starting APU and you should connect the GEN 2 first to charge the battery through the TR3. Why? Don´t understand because GEN 2 powers the mainbus and the battery charger is then supplied? Where´s my fault?

What else does TR3 do?
737 Electrics

2.) How long can the speedbrake be deployed. I mean with which flap setting? up to flaps 15?

No limit but best not more than F5 due to tailplane buffet - don't want it falling off, do we?
Not recommended more than flap five due increased roll sensitivity.

3.)Where in the MEL can I find wether i have to have the athr engaged during the CAT III or not?

Not in MEL - in your AWOPS limitations section - A/T mandatory IF AVALABLE.
Under the MEL for the autothrottle, I would think. Autoland with manual throttle permitted in my company.

4.) Imagine ATHR is okay during CATIII approach and it does not retard. Can i retard the thrust levers on my own? So disconnect the autothrottle and pull them back?

Yes, (or just close them) just do not press TOGA

5.) Is a cat III II landing in contaminated runway allowed? Which penalty must be applied?

LDA check plus what are your AWOPS crosswind limits in your OM?
My company has a requirement for edge and/or centre lighting to be visible on any contaminated landing. More restrictive crosswind limits apply. Other than that, there are no specific restrictions.


6.) When the ATHR is in HLD during takeoff till 400ft AGL and i get a windshear in 200 ft AGL and pressing the TOGA buttons, nothing will happen right?

Are you not at TOGA already? What does QRH say you should do?
TOGA is a Flight Director and autopilot mode. The autothrottle will be in THR HLD. If you're in performing a reduced thrust take-off with the N1 bugs in Auto, the calculated reduced thrust will be bugged on the N1 gauges. Pressing the TOGA button below 800feet will change the thrust limit mode to GA, and the GA thrust limit will bug on the N1 (to give you something to aim at should you have pressed the TOGA due to a need to increase thrust) - you have to manually increase thrust. Above 800 feet the autothrottle will advance to GA thrust (as it exits THR HLD to N1 mode automatically at 800').

- any answers yet, Speedwinner?
That's a new one for me! Boeing say no limit but 'should' be avoided at F15+. Nothing about roll - any reference for that? - not in any MEL I have seen. OM AWOPS limits - where is it in yours, Speedwinner?

can you start apu at any alt? bear in mind start and have allready running apu`s are very different things
most apu`s that i know can be run in the air but not started in the air
its all down to windmilling you know



gs

I was thinking of it not being prohibited.

quote from my company's Ops Man:
(Note: autothottle isn't on the list :) )

I believe the APU should be stabilized for 1 min before using bleed. No limitation on using either one independently other than the altitude limits. So, yes you can use the APU bleed without the APU GEN. The only problem I can see is the possibility of the ground crew disconnecting GPU without notifying you if they hear the APU.

No altitude limitation on starting the APU on the the Classics and NGs. All operation all the way up to the ceiling.

Bally - I know that 'cabin service' is an archaic notion, but in the days when that fine airline DanAir ran a superb business class cabin service we found that whilst the 'econ' LGW-CDG sector showed FL300+ for a light 737 (with about 1 min at cruise), stopping at FL240 gave a much easier ride for the c/c for heaving trolleys up and down the mountain. Fuel burns were little affected and there were sometimes routing benefits too in the lower sector.

APU-wise
1) Boeing (737) 'recommend' starting below 250 for better start reliability but as IC says, no limit there.

2) DanAir (because of the way our APU maintenance was costed) found the improvement in 'life' by leaving it running LGW-CDG outweighed the fuel costs by eliminating rapid hot-cycling.

With all this cost saving being the go, it is a wonder that the ops people haven't twigged that locking the forward toilet from the punters will force them to queue down the back to the rear toilet and thus edge the CG aft. Less download on the tailplane and better fuel burn:ok:

DUAL GENERATOR FAILURE
 

Classic: Select Gen #2 first to be back on-line.

Why? Well Gen #1 cannot provide power to TR3.

While Gen #2 can provide power to ALL TR's.

You might not get a second chance otherwise.

Regarding APU on the classic: either the Garret or the Sunstrandt has a operational ceiling of 35000ft. Beware as the aircraft certified ceiling is Fl 370...So there is a limitation. On NG, all APU versions work untill aircraft certified ceiling.

But at FL410 you have only electric up to 66 KVA.
You get the full 90 KVA until FL 320.
Bleed is only available until FL 170.
Bleed and electrical load until FL100.

and before you can use it you have to start it which is better to do below FL250
above it's possible to start but a bigger chance it won't start

I talking about 737 NG

APU can be started at all level, the only problem is in case of no AC power available ( loss of both EDG), the fuel boost pumps are not powered.

The Fuel supply to the APU will be by feeding line only which reduce the chance of a succesful start.

And you are only on battery power, any unsuccessful start will affect your battery endurance by 7 min i heard

So for me any reference not to start APU above FL 250 is only applicable to this specific scenario and has to do with fuel boost pumps not powered anymore

Most 737 operators have a APU (DC) boost pump installed.
It will run with tank 1 (FWD&AFT) boost pump relays OFF and APU SW in ON.

are there any other reasons to start the apu above 250 unless you lose both edg's?
i don't have that much experience yet but i can't think of anything else as you can't use bleed above 170

i looked it up in my manuals and couldn't find it as a limit anymore
it was probably somewhere during the ground course they told us

missing windows
 

I have another question about the -800

I've noticed that on the right hand side there is 1 "missing" window around the engine. I'm thinking it's extra protection in case of an uncontained engine failure but if you look to the left of the aircraft it has also a window missing in the same row AND a 2 rows more to the front.
Does anyone know the reason for this?

we don t. :(

Riser for the air system is what I've heard.