Capt.Fantastic
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Flying With Air-brakes Deployed

Mon Jul 10, 2006 2:29 am

Recently I was flying on a United 737-500 from O'Hare to Detroit. Throughtout almost the entire flight, the air spoilers were deployed. We were cruising at FL 260 - Why would the spoilers be deployed for this long of a period even at cruise altitude? Could this have been due to cross-winds?



I look forward to your replies
 
CosmicCruiser
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 3:00 am

Quoting Capt.Fantastic (Thread starter):
Could this have been due to cross-winds?

No relation. The only times I've ever had to fly with the spoilers extended was when we were going to be above max ldg. wgt at touchdown and we were trying to burn extra fuel by adding this drag.
 
n8076u
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 3:49 am

Were both sides deployed? If they were, then they were the flight spoilers, and what CosmicCruiser stated could very well have been the case.

If only one side was deployed, then that could be part of the roll control system. The spoilers will proportionately deploy on the one side to assist the aileron that is moving upwards (which is the wing that needs to go downwards). If the aileron trim is set to the left, this may cause what I am seeing in the photo, but I am skeptical of this explanation in this particular case because in the photo, the aileron appears to be completely neutral. But I thought I'd throw it out there anyways.  Wink

Chris
Don't blame me, I don't work here...
 
Capt.Fantastic
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 3:54 am

Thanks for your comments - The plane was completely full - Is there any case in which they would they carry more fuel than required (plus reserves) for the 240 mile trip?
 
ilikeyyc
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 4:38 am

There are some good pictures of how the speedbrakes work on the B737 technical site:

http://www.b737.org.uk/flightcontrols.htm
Fighting Absurdity with Absurdity!
 
flymatt2bermud
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 4:51 am

Quoting Capt.Fantastic (Reply 3):
The plane was completely full - Is there any case in which they would they carry more fuel than required

240 nm is a pretty short trip for a 737. Sometimes airlines will tanker less expensive fuel when conditions warrant. It could have been another airline cancelled a similar flight at the last minute and transferred their pax to your flight, creating an unexpected full capacity situation and thus the potential for an overweight landing. I'm only guessing but I think they probably didn't expect a full flight. They may have decided to try to burn it off enroute rather than defuel and take a delay.

One factor against my theory is your cruising altitude of FL260, if they were intending on burning off fuel I would think they would have opted for a much lower altitude unless there were storms or moderate turbulence at the lower levels.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
CosmicCruiser
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 4:57 am

Quoting N8076U (Reply 2):
If only one side was deployed, then that could be part of the roll control system.

By the amount of deflection if it were a flight control input for the whole flight that would be one out of trim jet.

Quoting Capt.Fantastic (Reply 3):
Is there any case in which they would they carry more fuel than required (plus reserves) for the 240 mile trip?

Carrying more than required is not the problem but short trips are usually max ldg wgt limited so a few hundred extra pounds more than flight planned fuel may have them heavy at ldg as well as the fact that flt. planning is usually on the conservative side meaning they have the predicted burn higher than actual burn.
 
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HAWK21M
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RE: Flying With Air-brakes Deployed

Mon Jul 10, 2006 8:06 pm

Could it have been an out of trim Flight Spoiler.Since the Aileron looks Neutral.
Only #3 & 4 are Raised.How was the other side.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
flymatt2bermud
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RE: Flying With Air-brakes Deployed

Tue Jul 11, 2006 5:58 am

Quoting HAWK21M (Reply 7):
Only #3 & 4 are Raised.

The flight spoiler position shown is normal on a 737 with the speedbrake lever pulled back to the 'half' deploy position. The 737 design also uses the flight spoilers as part of the aileron augmentation system. With the speedbrake stowed, the spoiler simply rises on the down-going wing with aileron. With the speedbrake applied, not only do the spoilers on the lowering wing rise but simultaneously the spoilers on the up-going wing return to neutral until the ailerons are returned to the neutral position.

What was happening could have been intentional or a malfunction as there are several Airworthiness Directives effecting the Boeing 737's flight spoilers. I am not criticizing, after all this is part of being mechanical and we all know Boeing builds some great aircraft.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
pilotaydin
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RE: Flying With Air-brakes Deployed

Tue Jul 11, 2006 11:51 am

I doubt you would tanker fuel, then burn it to land under the max landing weight. You can perform an overweight landing in the 737 series without any problem at all, flaps come to 30 and you're all set....

it could have been training, or the captain showing a new F/O something, with the flight spoilers up, it takes 50% less ground distance in the 737 to slow down to most speeds from cruise speed.

A captain once showed me the flight spoilers like this : he put them up, and made me manually trim to see how much the pitch changed, incase they would ever be stuck in the flight detent position...good training to see how the plane reacts...
The only time there is too much fuel onboard, is when you're on fire!
 
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HAWK21M
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RE: Flying With Air-brakes Deployed

Wed Jul 12, 2006 1:25 am

Quoting Pilotaydin (Reply 9):
A captain once showed me the flight spoilers like this : he put them up, and made me manually trim to see how much the pitch changed, incase they would ever be stuck in the flight detent position...good training to see how the plane reacts...

The posters statement of it being Raised throughout the Flight is raising a doubt to as Why.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
pilotaydin
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RE: Flying With Air-brakes Deployed

Wed Jul 12, 2006 4:22 pm

Quoting HAWK21M (Reply 10):
The posters statement of it being Raised throughout the Flight is raising a doubt to as Why.
regds

i dont get what you're saying....
The only time there is too much fuel onboard, is when you're on fire!

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