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B737-800 AUTOBRAKE Adjustments

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B737-800 AUTOBRAKE Adjustments

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Old 30th Jul 2014, 01:06
  #21 (permalink)  
 
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Originally Posted by safetypee
LSM, 3250psi hydraulic pressure might be available to the braking system, but not necessarily the pressure used for RTO, thus 3000psi is max? Yet even this may be reduced due to anti-skid protection – which is a function of runway surface etc. Is this what you were implying?
That's the way I understood it. Our manuals state that RTO uses 3000psi. So if your system is producing >3000psi and you override RTO with manual brakes you'll get X amount extra.

Now, however, I suspect that whoever wrote our manuals used 3000psi for RTO as that is what the hyd. system normally produces as a maximum.

Maybe we used the same authors as Denti's mob!
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Old 30th Jul 2014, 10:32
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RTO uses all available brake pressure and maintains the additional capabilities of the auto brake system with their advantages.

Overriding the auto brake will allow you to put more than the available pressure onto the braes but you will loose the additional safety functions integrated within the system.

Due to the loss of the additional safety features, it is recommended NOT to override unless required, in other words, let the RTO function do its job, it's what it's designed for after all and your performance calculation is based upon that capability. Sometimes overriding is not a better option..., even if it enables additional pressure to be applied.
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Old 30th Jul 2014, 11:42
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How can you get more than available pressure?

You may be interested to know that our EFB take off performance is predicated on using max manual braking for an RTO.

additional safety functions integrated within the system
Such as?
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Old 30th Jul 2014, 20:34
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Such as:
- Symmetrical braking
- controlled antiskid protection (when changing pressure using manual braking the antiskid system needs to re-adjust before engaging once more)
- engagement and proper use of the Brake Modulating Valves (Left and Right)
- autobrake shuttle valve working as commanded
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Old 16th Aug 2014, 09:47
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Fact: Too many aircraft of any type are over-running the landing surface due to inadequate braking in some of these accidents.

Just stop talking about it and DO it, if the cicumstances so require?!?!
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