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apuneger
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Tests Conducted Before To

Thu Jul 12, 2001 7:01 am

I know that, every time a crew is preparing an aircraft for takeoff, they test the ailerons, spoilers, elevators and rudder.

But, my question is: how do they know they work? From the outside it's easy to see, but how do you see this from the inside?

Yesterday, when I jumpseated a Sabena 737, I noticed that the crew took a look outside, so I think it's possible on a 737 to see the wing, but then how about the elevators and rudder?

Ivan
Ivan Coninx - Brussels Aviation Photography
 
JETPILOT
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RE: Tests Conducted Before To

Thu Jul 12, 2001 7:15 am

There are two ways to tell if the control surface is moving when called for.

1. A respective drop in hydraulic pressure when the surface is moved.

2. A control surface indicator relaying the position of the control surface.

JET
 
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apuneger
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RE: Tests Conducted Before To

Thu Jul 12, 2001 4:44 pm

Thanks for the answer, JETPILOT.

Ivan
Ivan Coninx - Brussels Aviation Photography
 
FBU 4EVER!
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RE: Tests Conducted Before To

Thu Jul 12, 2001 9:08 pm

In addition to JETPILOT's reply,which is valid for planes with hydraulically operated flight controls,there are other ways to tell,as well:
On the DC-9 and MD-80/90 series with manual flight controls,a "SPOILER DEPLOYED" light will appear on the Annunciator panel when the ailerons are tested.Elevators have no indication except for a green "ELEVATOR POWER" light which comes on when the control column is pushed fully forward (nose down) indicating that the Stall Recovery Augmentation System is working.
The MD-90 has a fully hydraulically operated elevator,and full forward and aft motion of the control column will activate an "ELEVATOR AT LIMIT" sign.
The checs are mainly performed to check that the controls move freely without obstructions.
"Luck and superstition wins all the time"!
 
M80
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RE: Tests Conducted Before To

Fri Jul 13, 2001 1:18 am

A very small correction to FBU 4EVER!'s good explanation: DC-9/MD-80 annunciator panel has no green lights: advisory lights are blue, for example ELEVATOR POWER ON, IGNITERS ON and ANTI-ICE lights. (Caution lights are amber and warning lights are red.) And some additional info for DC-9/MD-80: Spoiler deployment starts when control column is moved 5 degrees from its neutral position, spoilers remain retracted with down aileron. Also the elevator power test (DC-9/MD-80) aligns the elevator surfaces (normally performed before takeoff to make sure that there are not any control column forces affecting takeoff.)

M80
 
ILOVEA340
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RE: Tests Conducted Before To

Fri Jul 13, 2001 9:46 am

smaller private planes it is stil visual though.
anyone know about regional planes like Saab 340's or ERJ's?
 
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apuneger
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RE: Tests Conducted Before To

Sat Jul 14, 2001 7:18 am

Thx for all the answers, guys...

But, as already mentioned, I saw the FO looking out of the window, to the back of the plane, when he was testing his control surfaces. The plane was a Boeing 737-329. Does this mean that he could still see the (end of) the wing, and preferred to see (some of) the surfaces work visually, instead of looking to some anunciators.?

Ivan
Ivan Coninx - Brussels Aviation Photography

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