Rigging M7 235B

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Cash
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Rigging M7 235B

Post by Cash »

Ball centered in cruise however left wing slight heavy. What’s best to adjust, left flap down or wing?
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Kirk
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Re: Rigging M7 235B

Post by Kirk »

Try pulling the rudder trim out a notch first. Might fly level with the ball unchanged or slightly out.

Failing that, well the best answer is to follow the detailed rigging instructions and start from scratch. A lot of planes end up with years of “slight tweaks” that counteract each other. Control cable tensions are a commonly skipped item at annual also and is a possible cause. Takes time but…

Jeremy posted rigging instructions years back. Try a search of the forum. I had a printout but lost track of mine.

Kirk

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Re: Rigging M7 235B

Post by Kirk »

Here's a copy from Jeremy’s post in 2017. It’s the one I was thinking of, though I believe someone also had a good one describing using a laser level that was very clear description.

It seems about once a year the rigging comes up.
It is pointless chasing a rig problem without starting from scratch.
Yes, you can fix a situation but at the expense of drag from the next situation.

1. Level the plane laterally using wing root carry through tube behind top of windshield, and by jacking the gear.
2. Check that the tailplane hinge line matches laterally.
3. Run a stringline from inboard edge of composite wing tips and check it is level laterally.
4. Adjust front wing struts to achieve level lateral stringline, and a 3" gap above wingspar roots.
5. Adjust rear struts to achieve the washout in each wing, 1/2 degree trailing edge up at outboard rib.
6. Check the vertical stabilizer is 90 degrees to the elevator hinge line which you have leveled by checking and if necessary changing tail struts.
7. Run a stringline from top of rudder and vertical stab when faired and the line should extend to a point 1 3/4" to left of centre of wing root carry through tube.(This combats left turning tendency in cruise).
8. Adjust the elevators so that the balance portion is equal and flush with stabilizers at BOTH sides otherwise it will roll the plane.
9. Place light upward hand pressure on flap trailing edge and adjust with pushrod until faired correctly with bottom of wing.
Check Both ends of each flap.
Do Not use wing root fairing for reference.
10. Tie a stick across bottom of both control yokes catching four points.
Adjust with turnbuckles.
11. Using above headliner turnbuckles adjust ailerons individually until flush with bottom of wing, checking at both ends of aileron.
IF any of flaps and ailerons is not close to flush with wing bottom at BOTH ends, there is a twisted control surface and the correct rigging will be compromised.
12. Adjust rudder trim bungee so that the spring is slack with T handle fully in (this is for right turn tendency in descent) and light tension on spring when T handle is at one and a half marks on shaft showing.
13. Adjust tail steering springs correctly with a little slack or they will affect the rudder trim.
14. Adjust the rudder servo tab flush with rudder when ailerons are locked together with the stick.
15. Be sure that with no load on either the tailwheel or the nose wheel, the swivel is not too sticky otherwise the wheel will act as a rudder.
It can be kicked loose to go in trail when in flight prior to setting rudder trim.
16. Adjust the rudder centering springs (not on M4 and M5) to be no shorter than 4.5" and to hold the rudder centered when no load on the tail.

Only now can you test fly the rigging as you will be starting from square One, and fine adjustments can be done for roll or yaw.

All the above is in your Maule Maintenance Manual

Cash
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Re: Rigging M7 235B

Post by Cash »

Thanks Kirk you got me motivated. Thanks. We checked the rigging per Maule maintenance manual and now flys straight and level.
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Kirk
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Re: Rigging M7 235B

Post by Kirk »

Glad to hear that worked! Some jobs like that turn into a seemingly endless game of Whack-a-Mole and never turn out right. More often, it’s like yours and flies pretty, might even pick up a knot or two.

Just out of curiosity, how many hours did you have into that. Any tips for others?

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Cash
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Re: Rigging M7 235B

Post by Cash »

I would say six or seven hours over two days. Re advice you must have a digital level as one setting is 1/2 of a degree on wing tip washout. Also read instructions for each step several times to make sure you got it. I thought my rudder springs were two short( no shorter than 4 1/2 inches) until I reread the last three words in paragraph “rudder at neutral’. I had rudder full deflected. They were right on. Les
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Gary Raser
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Re: Rigging M7 235B

Post by Gary Raser »

I have a M7-235C
I hope this question make sense, I am trying to find out where the elevator trim tab should be for take off.

When the screw (the one that is the trim tab elevator indicator)
Is set to take off) where should the trim tab be?

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drak130
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Re: Rigging M7 235B

Post by drak130 »

Gary,

I had my M7-235 rigged by the factory 2 years ago during annual. On my plane, when set for takeoff, the elevator tab is exactly neutral or perfectly fared with the elevator.

Tim

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Re: Rigging M7 235B

Post by asa »

Drawing for trim control placard specifies making the takeoff mark when the trim tab is neutral as Tim said.

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Andy Young
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Re: Rigging M7 235B

Post by Andy Young »

Probably obvious to most, but there is a possibility here (as in all rigging operations) of transposing the cart and horse, so to speak.

The proper hierarchy of things is:

1. Ensure that trim cables are rigged such that at full travel in each direction, the trim tab angle matches spec.

2. Turn trim wheel until trim tab is streamlined with elevator.

3. Verify that indicator (screw that moves with trim) is aligned with the “Take Off” mark.

Of course, where one actually sets the trim for take off varies with load/CG. Heavier/further-aft load requires setting trim forward of mark.

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Gary Raser
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Re: Rigging M7 235B

Post by Gary Raser »

Thank everyone

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