Manual or Automaitc Speedbrakes with Antiskid U/S on 738

[SMOKER]

Interesting question was put to me the other day. Do you have automatic speedbrakes with your antiskid u/s?

My first answer was yes..... as per the Operations Manual "Compression of any landing gear strut enables the flight spoilers to deploy. Compression of the right main landing gear strut enables the ground spoilers to deploy."

Also in the QRH under the Antiskid inop checklist there is no mention of manual speedbrakes, just that ther is a fault with the antiskid system and do not use.

Smart little F?@*$r then pulled out the Airplane Flight Manual and sure enough in big bold letters it says "With Antiskid Inop use Manual Speed Brakes"

Any Ideas?

Regards

[ 23 November 2001: Message edited by: SMOKER ]

[rr892igw]

I AGREED WITH YOU THAT SPOILERS WOULD EVENTUALLY POP UP.PERFORMANCE WISE IT WOULDN'T KILL YOU IF LEFT IN AUTO(ARMED).
REFERING TO MY 734 FPPM,CAT B BRAKES,GRAPH
GIVING SAYS"ANTI-SKID INOPERATIVE AUTOMATIC OR MANUAL SPOILERS" ALSO THERE IS THIS NOTE AT THE BOTTOM"FOR MANUAL SPOILERS,ANTI-SKID
OPERATIVE,DECREASE FIELD LENGTH AVAILABLE BY
500FT".I'D THINK WHAT WAS WRITTEN IN THE AFM
IS VERY CONSERVATIVE.BOEING WANTS THE A/C
POSITIVELY ON GROUND SOONEST POSSIBLE AFTER
TOUCHDOWN.
THAT YOUNG PUNK ON THE RIGHT ALWAYS GET MORE ATTENTION FROM THE GIRLS AT THE BACK AND
NEVER FAIL TO SHOW SOME TALENT IN FLYING,LIKE IT OR NOT SWALLOW IT! HE IS THE ONLY PERSON TO STOP YOU FROM KILLING YOURSELF
IN THE AIRPLANE......SOME CR*B FROM CRM. :D

[DontSink]

Smoker!

The most probable answer is NO!
You won`t get Auto speed brakes with antiskid inop! To test this you can do the following experience on the classic 737s. You can`t do it on th 737NG since the Antiskid ARMED/OFF switch was removed. But if you fly a 737 classic, put the Antiskid switch off and then arm the speed brakes. You will get a Speed brake do not arm light!

WHY? Because the antiskid provides 60Kts wheel speed info for flight spoilers deflection! With Right strut compression the ground spoilers pop out! But since you had to acomplish the Speed brake do not arm checklist (witch says do not arm them and deploy them manually upon touchdown) you woun`t get also the ground spoilers!

However if it is only a partial antiskid failure, you may have auto speedbrakes, if the 60 Kts info is not afected!

But most cases you don`t

Cheers!
Happy landings ;)

[GoodToGo!]

Don't Sink.
Hmmm, now it's been awhile since I have had to play with the Auto-spoilers on a 737. But whenever we changed an speedbrake actuator, we could get it to 'fly-back' with either the switches on the antiskid box, or the air/ground switches in the fwd accessory compt. From what I remember (fuzzy brain time) if the wheelspeed wasn't detected (eg. aquaplaning) then once both the nose and right main gears sense ground, the actuator operates to extend the spoilers. After ground + 4 seconds, the signal was removed.
I may be wrong, I might have to hit the books again!

Cheers!

GTG! :D

[rr892igw]

Don'tSink,

I've to disagree with you.(My apology if it
sounded rude,which I do not mean to be)
Having an Antiskid inop inflight,QRH says
AUTO BRAKE SELECT SWITH...OFF,Brake with
caution.BUT it never tell you to put the
ANTISKID switch to OFF,reason being the antiskid system detected a fault in the system(as we all know),the remaining system
on other wheels may still provide you with
a wheel speed info to generate a autospeed-
brake command and antiskid protection on the remaining wheels.Thus we donot kill the whole antiskid system by putting the ANTISKID OFF.
However,Your test give you SPEED BRAKE DO
NOT ARM is because having the whole system
off,there is no wheel speed info at all. :rolleyes: