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crjo
12th Nov 2018, 06:42
Hello all,

Transitioning from Airbus to the B787, I find myself in a state of constant perplexity...

Does anyone know why Speed should be maintained under 260 kts when below 6000 ft in the LIQUID COOLING L,R check-list ?

Many thanks for any input,

S

Fly3
12th Nov 2018, 12:15
We were told that it was to keep the TAT as low as possible to avoid over working the remaining PEC.

Dave
12th Nov 2018, 20:01
I promise I'm not being sarcastic..... but....

Does it matter?

Boeing designed the aircraft - they say keep the speed under 260kt under 6000ft, so probably they have a good reason for saying that!

The FAA/EASA etc certified the aircraft and the checklists.

Your operator pays you to operate IAW the Ops manual.

Most of the world has a 250kt below 10000ft restriction.

Simples :) :)

But yes I am sure there are interesting technical reasons.... and probably Fly3 is correct :)

crjo
13th Nov 2018, 05:20
Thanks for your responses.

I agree with both of you!

A Squared
13th Nov 2018, 13:39
I promise I'm not being sarcastic..... but....

Does it matter?

Boeing designed the aircraft - they say keep the speed under 260kt under 6000ft, so probably they have a good reason for saying that!

The FAA/EASA etc certified the aircraft and the checklists.

Your operator pays you to operate IAW the Ops manual.

Most of the world has a 250kt below 10000ft restriction.

Simples :) :)

But yes I am sure there are interesting technical reasons.... and probably Fly3 is correct :)

2 responses:

1), personally, I find it easier to remember restrictions if I understand the reason behind them.

2) If I should ever find myself in a situation I have to choose between abiding by a restriction and doing something to meet the needs of another emergency, it would be nice to understand the reason for the restriction in order to make an informed choice. "exceeding 260 may lead to slightly elevated oil temperatures if maintained for more than 2 hours" is different than "exceeding 260 causes the wing to fall off immediately"