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trichos
Topic Author
Posts: 22
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What's The Wheel On The Center Console?

Tue Jun 22, 2004 6:14 am

I was wondering what the wheel-like thing (looks like a small solid flywheel on each side) is that spins in the console between pilots. I have videos of cockpit views and this wheel seems to spin at random intervals, making a slight click at each revolution. I have noticed it especially in a B727 video. I have not found a picture that has this thing clearly labeled. The only hypothesis I have is that it have something to do with the yaw damper (am I close to the ball park?).
 
LMP737
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 6:18 am

What you are probably referring to is the pitch trim wheel.
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meister808
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 6:19 am

I think it is the trim wheel. It moves of it's own accord from time to time because most autopilots control the pitch with the elevator trim.

-Meister
Twin Cessna 812 Victor, Minneapolis Center, we observe your operation in the immediate vicinity of extreme precipitation
 
N766UA
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 6:30 am

Trim. Every airplane has it in that general area, right down to the smallest Cessna.
 
airplay
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 6:34 am

Trim. Every airplane has it in that general area, right down to the smallest Cessna.

You've obviously never been on a Beech A100...

 Smile

 
Blackbird1331
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 7:24 am

I recall a DC8 accident that was determined to be caused by a nose-up trim setting to aid in the takeoff and climb. The nose-up setting from the previous flight was not reset to zero and resulted in a stall and crash because the pilots added to the existing trim setting. Could this have been the culprit? Is it so easy to miss the existing setting on the DC8?
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RduBE90Pilot
Posts: 62
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RE: What's The Wheel On The Center Console?

Tue Jun 22, 2004 5:00 pm

Good one Airplay, the Beechjets don't have a manual wheel either.
 
trichos
Topic Author
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RE: What's The Wheel On The Center Console?

Wed Jun 23, 2004 12:58 am

Wow, fast responses. Thanks for the answers. For some reason I thought trim was a lever, like the flaps.
 
LimaFoxTango
Posts: 1003
Joined: Wed Jun 16, 2004 11:33 pm

RE: What's The Wheel On The Center Console?

Wed Jun 23, 2004 1:45 am

In the B777, the trim is actually a lever. see photo below...


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Click here for bigger photo!

Photo © Juliano M. Bergmann



[Edited 2004-06-22 18:49:31]
You are said to be a good pilot when your take-off's equal your landings.
 
744lover
Posts: 207
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RE: What's The Wheel On The Center Console?

Fri Jun 25, 2004 1:14 am

Hi LimaFoxTango,


No way!!! The levers of pitch trim that you see are there only for visual aid. You may give a quick glare into them and have an idea if you trim if too AFT or FWD. They were there too on the classic 747s..... There are two levers cause you can check the positions of both elevators; if they are simectrical!


View Large View Medium
Click here for bigger photo!

Photo © Billy Wong


View Large View Medium
Click here for bigger photo!

Photo © Philipp Bruland



For checking the TRIM setting (numeric scale) you check the small indicator just right of the Parking Brake lever (on the 777) or the indicator on the inner side of the trim well (on the classic 747s)

For you to ajust the TRIM, you have the knob on the yoke!


See ya,
GHN
 
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HAWK21M
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RE: What's The Wheel On The Center Console?

Fri Jun 25, 2004 1:16 am

Stab trim wheel.
regds
HAWK
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LimaFoxTango
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RE: What's The Wheel On The Center Console?

Fri Jun 25, 2004 3:09 am

i stand corrected....
You are said to be a good pilot when your take-off's equal your landings.
 
dc10hound
Posts: 460
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RE: What's The Wheel On The Center Console?

Fri Jun 25, 2004 3:11 am

The levers of pitch trim that you see are there only for visual aid.

From the B777 SDS, 27-41-00-0006:

"HORIZONTAL STABILIZER CONTROL - ALTERNATE PITCH TRIM LEVERS AND FORWARD QUADRANT ASSEMBLY"

"AAL ALL

Purpose

The alternate pitch trim levers give the pilots mechanical control of pitch trim. The forward quadrant assembly transmits the movement from the levers to the control cables.

Physical Description

Two alternate pitch trim levers supply arm and control mechanical commands to the STCMs. The two levers are independent of each other. Springs move the levers back to the center position. Each lever connects by rod to its own forward quadrant. Each quadrant has three alternate pitch trim lever switches. Cams on the quadrants operate the switches. A pair of cables connects each quadrant to the aft control module in the stabilizer compartment.

Location

The two alternate pitch trim levers are on the captain's side of the P10 control stand. The forward quadrant assembly is just below the levers in the aisle stand.

Functional Description

To command pitch trim, the pilot moves both alternate pitch trim levers together in the same direction. The pilot moves the levers forward to command nose down trim, aft for nose up trim. Movement of the left lever supplies the control command, the right lever supplies the arm command. Movement of the alternate pitch trim levers causes rotation of the forward quadrants and movement of the two pairs of cables. The forward quadrant rotation causes cams to move the three alternate pitch trim lever switches on each quadrant. The switches send these discrete signals to the AIMS:

Up command

Down command

Actuation command."
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Georg
Posts: 27
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RE: What's The Wheel On The Center Console?

Fri Jun 25, 2004 3:58 am

Absolutely correct, the extremely neccessary pitch trim it indeed is. The "klak-klak-klak" sound comes with 727 and 737 type planes, where manual trimming is possible by turning the rotating wheels by hand. In normal situations, pilots use the electrical trim buttons on the yoke, then the wheel is rotated by electric motor. I am not a 747-777 guru, but I think that the handle trim they have in the pedestal is also electrical, not manual anymore.
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smcmac32msn
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RE: What's The Wheel On The Center Console?

Mon Jul 05, 2004 7:28 am

The nose-up setting from the previous flight was not reset to zero and resulted in a stall and crash because the pilots added to the existing trim setting. Could this have been the culprit?

If I remember the accident you are referencing, it was actually traced back to a mechanic who had removed the wheel for servicing, but never indexed properly as to the correct position. He reinstalled the wheel in a nose-up position and had it marked as the centerline (level flight). The accident occured on the first flight after maintanance had been completed on the aircraft.

Sorry, don't remember the year of this accident.
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exPratt
Posts: 306
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RE: What's The Wheel On The Center Console?

Wed Jul 07, 2004 11:02 pm

I recall a DC8 accident that was determined to be caused by a nose-up trim setting to aid in the takeoff and climb. The nose-up setting from the previous flight was not reset to zero and resulted in a stall and crash because the pilots added to the existing trim setting.

There was a DC-8 freighter crash, I believe, at DTW. The airplane pitched up immediately after takeoff, stalled, and crashed. During the crash investigation, they found the trim in an extreme nose up position. They also found the flight engineer sitting in the captain's seat. The captain was known to use the elevator trim rather than the elevator when landing to "grease" it on. IIRC, the f/e had been a captain, but had been relegated to the engineer's seat for either age or medical reasons. The benevolent captain apparently let the engineer make the takeoff, but the engineer apparently missed the extreme nose up trim position and never reset if for the correct takeoff position.
 
n685fe
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Joined: Fri Dec 12, 2003 7:01 am

RE: What's The Wheel On The Center Console?

Fri Jul 09, 2004 11:56 am



The MD80 doesn't use the manual trim wheel. They use the thumb control buttons and the suitcase handles on the left side of the center counsel with the indication right beside it.

BTW, the manual trim wheel has been known to take out a persons knee. If the manual handle is left out and the A.P. makes an adjustment or the yoke control is used, there goes your knee cap. Watch out!
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XFSUgimpLB41X
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RE: What's The Wheel On The Center Console?

Fri Jul 09, 2004 1:24 pm

No wheel at all on the CRJ..just a trim display on the secondary EICAS and the little rockers on the yokes.
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JetMechMD80
Posts: 370
Joined: Fri Jul 09, 2004 2:27 pm

RE: What's The Wheel On The Center Console?

Fri Jul 09, 2004 3:14 pm

Stab Trim,
And make sure the handles are stowed when you move it with the thumb switch on the yoke, if not, you shin will be a-hurtin!
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