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problem: stuck rudder trim
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57NC



Joined: 29 Aug 2018
Posts: 5
Location: AL

PostPosted: Sat Jun 08, 2019 2:57 pm    Post subject: problem: stuck rudder trim Reply with quote

Hey all,

I'm new to Maules ... recently acquired an M7-235.
After a recent flight, I discovered my rudder trim tab was stuck in position, full deflection off to one side. I'd never even touched the rudder trim adjustment T-handle, so I'm baffled.

On the ground, once discovering it, I tried unlocking and adjusting the T-handle in various ways, tried wiggling the rudder, and tried a bit of pressure by hand on the trim tab. And I can't figure out how to get it unstuck. I hope it's something obvious, but I'm missing it.

Anyone have any ideas what might have happened? And how I go about solving this?

Thanks.
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57NC



Joined: 29 Aug 2018
Posts: 5
Location: AL

PostPosted: Sat Jun 08, 2019 3:04 pm    Post subject: Reply with quote

I'd post some photos, but I can't figure out how.
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VA Maule
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Joined: 03 Feb 2013
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PostPosted: Sat Jun 08, 2019 4:01 pm    Post subject: Reply with quote

Move the aeloin by hand watch the rudder tab move. ( after you put it back together) It's a servo tab to reduce the effects of adverse yaw and assist keeping coordinated.
The twist lock handle under the Rt. side yoke is spring loaded applying pressure to the Rt. rudder pedal . Pulling it out on takeoff and you don't have to push right rudder nearly as hard.
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Ron Hallmark



Joined: 21 Aug 2017
Posts: 41
Location: Tennessee

PostPosted: Sun Jun 09, 2019 2:00 pm    Post subject: rudder trim tab, "servo tab" Reply with quote

There is a previous post that might be helpful. The rudder trim tab, what some are calling the "servo tab" is connected to the aileron cable via its own cables on the left and right side. When you use the yoke to bank left or right the aileron cable not only actuates the aileron, it also actuates the rudder trim tab ("servo tab"). When the cables are adjusted properly the aileron cable pulls on the rudder trim tab cable to help coordinate the turn. The rudder trim tab cable is attached to the aileron cable just within the headliner over the pilot and co-pilots seat. Unzip the headliner and you will see the cables and their attachments. Yours may simply need adjustment.
Mine broke and needed a new cable. Good luck, Ron Hallmark
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Kirk
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PostPosted: Sun Jun 09, 2019 3:16 pm    Post subject: Reply with quote

The tab is interconnected to the ailerons as described above. When you get back to the airplane move the ailerons and you should see the tab move.

Not sure that Ron is correct on the rudder trim. (T handle). My understanding is that it applies spring tension to the rudder cable not at the aileron interconnect above.

Either way, the T handle, which is trim, does not move the servo tab that is interconnected to the ailerons.

Kirk
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Ron Hallmark



Joined: 21 Aug 2017
Posts: 41
Location: Tennessee

PostPosted: Mon Jun 10, 2019 11:28 am    Post subject: Reply with quote

I did not mention the rudder trim (T handle). I don't really know exactly how that works yet. I had enough trouble digging out the info on the rudder trim tab, and the cables that connect the rudder trim tab to the aileron cables. I think it might have been a previous poster who mentioned the T-Handle.
Ron
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Ron Hallmark



Joined: 21 Aug 2017
Posts: 41
Location: Tennessee

PostPosted: Mon Jun 10, 2019 11:34 am    Post subject: Reply with quote

I have been told by a couple of guys that VA Maule is right the Rudder Trim
T-Handle applies pressure to the right rudder via a spring that is controlled by the T-Handle on the panel under the co-pilot yoke.
Ron Hallmark
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Andy Young
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PostPosted: Mon Jun 10, 2019 8:28 pm    Post subject: Reply with quote

It seems like it might be helpful at this point to define terms, to avoid confusion.

The tab on the back of the rudder is called a SERVO tab; it is NOT a trim tab. Many airplanes have trim tabs in the same location, but Maules do not. It is not directly pilot-controllable, nor is it ground-adjustable; it responds to aileron deflection via small cables, as previously mentioned.

Rudder TRIM is accomplished via the T handle on the panel, which pulls on a cable that pulls on the right rudder pedal on the co-pilot side.


Last edited by Andy Young on Tue Jun 11, 2019 5:12 am; edited 1 time in total
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rv8bldr



Joined: 08 Feb 2018
Posts: 26
Location: Pakenham, Ontario, Canada

PostPosted: Tue Jun 11, 2019 2:37 am    Post subject: Reply with quote

Andy Young wrote:
It seems like it might be helpful at this point to define terms, to avoid confusion.

The tab on the back of the elevator is called a SERVO tab; it is NOT a trim tab. Many airplanes have trim tabs in the same location, but Maules do not. It is not directly pilot-controllable, nor is it ground-adjustable; it responds to aileron deflection via small cables, as previously mentioned.

Rudder TRIM is accomplished via the T handle on the panel, which pulls on a cable that pulls on the right rudder pedal on the co-pilot side.


Um.... that's confusing Smile The tab on the RUDDER is a servo tab, not the ELEVATOR.

Cheers
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Andy Young
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PostPosted: Tue Jun 11, 2019 5:11 am    Post subject: Reply with quote

Oh man. How embarrassing. I was trying to clear up the potential confusion from mixed usage of terms, and I just made it worse. Dang it.

Thanks for catching that. I’ll edit my earlier post to correct it.
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Ron Hallmark



Joined: 21 Aug 2017
Posts: 41
Location: Tennessee

PostPosted: Wed Jun 12, 2019 2:48 am    Post subject: Reply with quote

Okay I am still trying to learn...................so, I had to get the M-5 Parts Catalog CD, and study it to get an idea about how to install/replace a broken cable. The CD is for the M-5 so it might not apply to the M-7. When you look at the control group section of the CD it shows drawings of the individual parts and where they are located. Drawing #3173B is labeled "Rudder Tab Assembly," Drawing #3171B is labeled "Rudder Tab," other related drawings, #3018A "Rudder Tab Cable Clamp Assembly," #3019B "Rudder Tab Cable Fairlead Assembly," #3020B "Rudder Tab Pulley Assembly." I could not find any reference to "Servo Tab" on any of the drawings in the CD. Also, there seems to be a discrepancy in the quotations of the posts. When I read Andy's post it does say "The Tab on the back of the RUDDER is called a Servo Tab", but when RV8BLDR quotes Andy his quote says "The tab on the back of the ELEVATOR is called a SERVO tab." .........?????? Sorry about all of the confusion.
Ron Hallmark
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Duane
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PostPosted: Wed Jun 12, 2019 3:42 am    Post subject: Reply with quote

Ron, If you give me a call sometime, I think I can clear up the confusion. 229-985-2045 and option 2. That will put you in touch with Kasey in parts and she'll transfer your call to me. I may or may not be near the phone, but I will return your call.
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rv8bldr



Joined: 08 Feb 2018
Posts: 26
Location: Pakenham, Ontario, Canada

PostPosted: Wed Jun 12, 2019 6:52 am    Post subject: Reply with quote

Ron Hallmark wrote:

Stuff deleted...

When I read Andy's post it does say "The Tab on the back of the RUDDER is called a Servo Tab", but when RV8BLDR quotes Andy his quote says "The tab on the back of the ELEVATOR is called a SERVO tab." .........?????? Sorry about all of the confusion.

Ron Hallmark


Hey Ron

That's because Andy went back and corrected his original post after I pointed out the error. You can ignore my post (and me, if you like Very Happy ),

Cheers
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Mark
President EAA Chapter 245
'79 Maule M5-235C C-GJFK
RV-8 C-GURV (Sold)
Bearhawk 4pl - Under Construction
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Andy Young
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PostPosted: Wed Jun 12, 2019 9:45 am    Post subject: Reply with quote

I haven’t looked at the parts CD, but it sounds like Maule might not use the word “servo”, just using the more generic “tab”.

Here’s the distinction, as I understand it:

A servo tab is one that responds to the movement of one control surface to influence the movement of another control surface. In the case of our Maules, when the aileron is moved, it pulls on a small cable that deflects the tab on the back of the rudder, which then wants to push the rudder to one side.

A trim tab is one that is either controlled from the cockpit to deflect the control surface (like the one on our left elevators) or is a fixed piece that is set on the ground by bending (some Maules have had this installed on their ailerons, but the Maule factory never did this to my knowledge).

What can be confusing is that many airplanes have cockpit-controllable trim tabs mounted on the back of the rudder that look just like our rudder tabs that are NOT controlled from the cockpit, but are instead slaved to the ailerons.

This is why I find it useful to distinguish our rudder tab as a “servo” in an effort to clarify what it is doing vs. trim tabs that most people are more used to seeing.
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Ron Hallmark



Joined: 21 Aug 2017
Posts: 41
Location: Tennessee

PostPosted: Wed Jun 12, 2019 3:42 pm    Post subject: Reply with quote

Andy that sums it up very well. Mark, I didn't know Andy had corrected his error. I am thankful that we can put this post to bed...........Now I have another little problem that I'd like you guys to chew on a little. My alternator may be going bad, and I don't know how to know for sure. When there is minimum draw on the electrical system my ammeter is showing a slight positive charge, but when I turn on my landing lights the indicator goes into the negative. So, as long as I am flying along with strobes, nav lights, transponder and radio on the ammeter indicates + but when I turn on the landing lights it goes to - (negative) These are the old style halogen landing lights and there are two of them. Should I think about rebuilding the alternator????
Ron
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