737NG a few questions

[Tom4]

Dear colleagues,

If you are so kind to help me out with these questions related to B737NG:

1.) Is there any indication that you have a ground air unit connected to cabin heating / cooling in the cockpit instead of a stronger sound of air circulaton? Is it possible to regulate this air from cabin or cockpit?

2.) Do you have any procedure in your company manuals regarding climbing thrust? Or just leave it on "fmc" automatic selection? And how is this selection done?

3.) The main undercarrage is equipped with a small device which detects if you get tire puncture and the destroyed tire is going up to retract. Is there any cockpit indication or something if you do not have a tire temp kit on your b737?

[FlyingStone]

1. No and no.
2. Depends on the company, so you can get a million different answers here. Derated climb can be "deleted" on N1 LIMIT page of the CDU.
3. The cockpit indication should be a "gear disagree" indication (both red and green light illuminated) on the MLG that had a burst tyre.

[Tom4]

FlyingStone:

Thank you very much for answers.

Do you know where is it possible to study about last question? 737 technical manual? I tried to check AFM and FCOM but nothing about this.

[B737900er]

The undercarriage has a breakable fuse around the edge of the wheel well. When it has broken, the landing gear leg will extend back down. You will know it has happened because the landing gear indication lights will read Red and Green, and there will be a reduced amount of Hydraulic A quantity.

Ref: FCOM2 / OMB.

[ice2x01]

The red/green will be due to the disagreement, but where in the fcom does it say loss of hyd A qty? I couldn't find it in the ldg gear chapter

[B737900er]

Ice - Approximately 15% or 1 USG is spilled.

[RAT 5]

Loss of = reduced indication.

[ice2x01]

Yeah, I get that. Where does it say this in the fcom though?

[B737900er]

Thanks RAT5, I have edited accordingly.

[Tom4]

Thank you for answers!

Have a nice day.

[Yeelep]

There is no cockpit indication of a tire puncture. What is being discussed is the MLG frangible fitting (not a fuse). Its purpose is to prevent flailing pieces of tire from entering the gear well if a fault in the gear retract braking has occurred. No fault, the gear will retract normally with a punctured tire.

[Chesty Morgan]

Not if the flailing bits of rubber frange the frangible fitting which will then release hydraulic pressure and allow the MLG to free fall down.

[Yeelep]

But if there is no fault in the retract braking, there won't be any flailing pieces of tire to break the fitting.

[Denti]

Indeed, normal retraction with normal braking, been there done it with a completely destroyed tire.