Right Rudder in Cruise

[Apollo]

Hey guys, I have 4 C models I'm comparing 27U - needs right rudder in cruise to center the ball 62 m20c 26U - does Not need right rudder in cruise 61 m20c 73v needs right rudder in cruise late 60s C model 07G - does not need right rudder in cruise 27U is my plane and I thought all C's needed rudder in cruise. Do I need to rerig my airplane??

[Bob_Belville]

Rudder trim is done by bending the trailing edge. It varies some from model to model and year to year so consult the maintenance manual. It is possible there is another factor going on, I discovered the step was not retracting due to a leaking servo which caused yaw. And remember the ailerons and rubber are interlinked though that should  not affect straight and level. bottom line, the ball should be centered and if it is not you can fix it relatively easily.

[carusoam]

There is a trim tab on the rudder, no?

Iirc, my C had one and flew well centered. On the other hand what you might be seeing is uneven fuel levels in the tanks, in combination with pilot weight being slightly offset..?

Well rigged and balanced will fly straight and fast.

You can experiment by burning fuel off from the heavy side... Load some fuel into the light side to get the experiment started.

How are you measuring the need? Is the ball indicating it? Is the plane always lowering one wing?

If the ball is off, but the plane flies straight, there are a few Cs with droopy panels. Easy to fix with the proper hard ware.

Ymmv...

Best regards,

-a-

[Hank]

My C requires no rudder in cruise. Since I rewrapped one wing servo and had the other one overhauled, the PC roll knob is close to center, too. There was a 2" tear in the right aileron servo boot, not visible until after removal; my roll trim had been going more and more left until I had to add left aileron. Now she flies nice and straight, more so than when I bought her six years ago.

P.S.--I have no rudder trim tab, just bend the trailing edge carefully.

[Hector]

My 67C also flies straight with no rudder input in cruise.

[tony]

I don't think you should be bending anything.  We don't own Cessna's.....My experience was similar to Hank's.  With a correctly working PC system, the ball will be centered.  Do you have a working PC system?  If not, I would start with repairing that.

[1964-M20E]

Get with your mechanic get a set of travel boards and go through the rigging process it is not complicated and verify everything is rigged properly before you start adjusting any trim tabs.  If there are no adjustments to be made this can be done in about 4 hours.

[Bob_Belville]

Do be sure your step is coming up when the engine is running if that is a feature of your C. (You do not mention what year model.) If the step servo is bad, not only will it cause yaw it will cost you at least 6k in cruise. Voice of experience. And it appears that our mid '60s Mooneys are reaching the life of the rubber bellows in that servo, I've heard about several in the last year. It's an easy fix with a rebuilt servo from Brittain in Tulsa OK @ ~ $150-$175.

[N33GG]

A properly rigged and balanced aircraft should fly straight without the PC controlling the aircraft.  Before I even thought about bending anything, I would take that aircraft to Don Maxwell at KGGG and get it checked out by someone that knows what they are doing and has the proper tools.  Don't screw up your aircraft trying things that may be masking another problem.

 

FWIW...

[Apollo]

Thanks guys my 62 C model has a manually retractable step. It's so weird that two mooneys neeed right rudder, and my other two mooneys on the field don't!

 

 

When I buy it officially in September I guess I'll take a look!

 

 

 

Thanks for the responses everyone, and I'm mad at tapatalk for not putting in my paragraph breaks where I put them!

[Mooneymite]

Before bending /adjusting anything, check the ball with the aircraft leveled on the ground.

Could be the ball, not the plane,is out of rig.

Simple, easy fix....and cheap.

[201er]

Have you tried slowing down? The rigging is only optimal at a certain power setting. Cruising too fast or too slow can cause it to have a turning tendency.

[Hank]

I should have said corrections can be made by having a knowledgeable A&P carefully bend the trailing edges after confirming proper rigging. Doing so incorrectly can be an expensive mistake! The easiest fix is a whacky turn-and-bank.

[marks]

Having been through the rigging process twice (the second time after a perfect paint job) I have to say that the plane can certainly be rigged without bending anything.  If the boards show that the ailerons are rigged as per the manual and if the gear stows away nicely and nothing hangs down to create a right wing heavy symptom, then first put a level across the seat tracks to be sure the airplane is level on the ground and check to see that the ball is perfectly centered on the ground.  It's possible that you are only observing the ball out of level when the airplane does not need the right rudder input.  So you may have to adjust the turn coordinator on the ground.  If all the items above appear correct, then adjust the rudder position itself.  Do a half turn at a time and fly the plane until you can fly with feet off the pedals.  On the J the rudder must be 1 degree to the right of center before any finer adjustments are made.  Remember that the air spirals around the fuselage and does not flow straight back.  Bending an aileron may appear to lift a wing but the airplane will be moving in a very slight crab and won't gain any speed.  People with experience have a better idea of how much adjustment is needed and can help you in an hour or so as you fly the plane once or twice between adjustments.  Don't let anyone bend anything unless it's to correct some earlier bending someone else shouldn't have done.

[Piloto]

I agree 100% with Marks. There is no need to bend any of the control surfaces (ailerons or rudder) to rig your plane. See attached picture for the rudder adjustment. Remove the bolt, loosen the nut and turn the rod end to adjust rudder deflection. On mine I have it adjusted for centered ball at 140Kts IAS.

 

José

[FlyTester]

Going into our recent annual almost 3/4 of a ball width of right rudder was required in cruise.  Our local MSC took care of it, not by adjusting rudder nor by bending any tabs nor by an expensive rerig of the ailerons, but by simply lowering our right flap 1/2 degree. Surprised no one has mentioned this option yet.

[marks]

If you check my posting above, I said if the "boards show that the ailerons are rigged per the manual" then follow my advice.  I have no doubt that the mechanic can lower an aileron by more than the other aileron and "lift" a wing, but unless the result is to match the two ailerons, then the result will be a level airplane but with a small amount of adverse yaw that overcomes the position of the ball.  Adverse yaw means that the airplane if flying in a slight crab and is not truly flying straight and speed is lost even though the airplane is flying level.  -  Hopefully your airplane had the ailerons slightly unmatched and the mechanic corrected the error by lowering the right aileron.  However, if now the position of both right and left ailerons are not matched, then it means that your airplane needed a rudder correction and instead you now have unmatched ailerons, in which case you are flying in a very slight crab while pulling one aileron through the air at a slightly protesting position to the air.  This "double-mistake" might balance out so that the plane flies level, but the airplane is not properly rigged and you will lose a couple of miles per hour speed all the time.  This is why we can say that a properly rigged airplane can go up to 5 miles per hour faster than another Mooney of the same age and with the same equipment.  Check to see if your ailerons match one another.

[jetdriven]

The ailerons trail in flight to match each other. Adjusting aileron pushrods does nothing but lower or raise them together in cruise and displace the yoke. But they will fly at the same position on both sides. Bending the trailing edge does act as a trim tab however. Same with the flap up stop adjustment.

[marks]

As usual Byron, you are 100% correct.  If you change the pushrod adjustment relative to one aileron the ailerons will fly as if matched and the yoke will be displaced, which is another way of saying that if the yoke were held level the pilot would experience a "heavy wing".  I think what's important to understand is that if the rudder is not positioned correctly it's possible to bend an aileron and have two surfaces that act against each other and create a static balance condition, but doesn't create the best condition for speed as the airplane is flying not quite straight and the result is an improperly rigged airplane.

[bradtlew]

Apollo,

 

did you ever have any resolution on this subject?  I've noticed with the M20C I'm flying, it requires A Lot of right rudder in almost all aspects of flight, I didn't think this was normal, but others in club do, or have just accepted it.  From what I'm reading here I shouldn't have a cramped right leg after every flight in varying weather conditions?

[Hank]

Check the PC servos. I had to hold right yoke and rudder, turned out the rubber boot on an aileron servo was torn. Yours may be a torn boot on a rudder servo. What year is your C?

On the other hand, it may just be out of rig. Proper checking requires travel boards, available at your friendly local (?) Mooney Service Center, along with people who know how to use them and make adjustments.

[N201MKTurbo]

You may just need to trim your rudder. The book says to bend the trailing edge. I don't like doing that, but it works. Some of the later Mooneys had a small sheet metal tab riveted to the trailing edge to adjust the trim. It would be easy to add it.

Sent from my LG-C800 using Tapatalk 2

[tony]

Go get a vacuum hand pump from that cheap auto parts store.  Then go look on the pilots side forward of the instrument panel for two plastic tubes.  One will be red and the other one is green.  That's where the PC system ties into the airplane to control left and right.  Disconnect the PC system from the airplane, one side at a time, and install the hand vacuum pump there.  Pull no more than 5 pounds of vacuum and watch to make sure you can hold that pressure.  You will see your rudder and ailerons move.  If the pressure starts to decay, or the flight surfaces don't move then you need to go and find the leak.  Most of the time its the actuators but sometimes those plastic fittings get crappy and leak.  Brittan sells the plastic fittings for like a buck and they will trade out your bad actuator for a rebuilt one in less than a week.  If you can't find any leaks and it holds the vacuum,  then inspect (I'd just replace) the surgical tubing behind the instrument panel.  When your PC system is functioning properly, you really don't need to put in much right rudder. 

[stevesm20b]

My B model Mooney has a small trim tab riveted on the rudder. The ball is centered when flying in cruise below 150mph indicated but I need a little right rudder when the indicated airspeed gets above 155mph.

[carl]

 

This is a stock picture of a mooney tail with a bendable trim tab. Mine has one too. 

 

I can find just as many pictures without trim tabs.