Left Banking M20J and Rigging

[jamesyql]

I purchased an M20J this summer and have put 40 hours on it thus far. It has always banked left in cruise and the purpose of this thread is to journal the process to address and rectify the issue (ongoing)

 

The issue: hands off cruise the plane starts banking left within 1-2 seconds and within 10 seconds the plane will be in a 15° left bank. Furthermore: stall practice has me hesitant as it consistently seems to want to drop the right wing. My reasoning tells me this is from the relatively higher AOA of the right wing needed to fly my plane straight into a stall, but I could be out to lunch on that.

 

Diagnostic work thus far:

 

I flew today for the purpose of evaluating the issue further following the flight test guidance found here:

 

https://knr-inc.com/shoptalk-articles.html?view=article&id=75&catid=25

 

Conditions: just me in the plane (but it behaves this way with a passenger as well), full tanks (burning the left side first), 8500ft, WOT, 2500 RPM 8.5 GPH 117 KIAS

 

Wings level test (using just aileron): turn coordinator ball slightly to the right of centre, just peeking past the white line.

 

Wings level and ball centred test (used right aileron and right rudder to level wings and centre ball, then released aileron and kept rudder pressure): still banks left but not as dramatically as without rudder correction.

 

In wings level cruise I will say that I *think* I could appreciate a slight positive angle upwards relative to the flap on the left aileron but tough to say for sure.

 

So- my conclusion is that my plane is out of rig and both the left bank and yaw both need addressing.

 

My mechanic is excellent, and I am confident he will be able to rig the plane, only thing is that he does not have the Mooney travel boards. I have read literally every thread on here about travel boards and rigging, so I feel that we should really try to get these to be confident in the static rigging before we start bending servo tabs. We are working to source them. I live in Alberta Canada which makes things more complicated if needing to source from the USA. I will keep this thread updated with my progress and experience with rigging my J partially as a place to journal my thoughts and also to help future riggers!

 

James

[Ragsf15e]

35 minutes ago, jamesyql said:

 

I purchased an M20J this summer and have put 40 hours on it thus far. It has always banked left in cruise and the purpose of this thread is to journal the process to address and rectify the issue (ongoing)

 

The issue: hands off cruise the plane starts banking left within 1-2 seconds and within 10 seconds the plane will be in a 15° left bank. Furthermore: stall practice has me hesitant as it consistently seems to want to drop the right wing. My reasoning tells me this is from the relatively higher AOA of the right wing needed to fly my plane straight into a stall, but I could be out to lunch on that.

 

Diagnostic work thus far:

 

I flew today for the purpose of evaluating the issue further following the flight test guidance found here:

 

https://knr-inc.com/shoptalk-articles.html?view=article&id=75&catid=25

 

Conditions: just me in the plane (but it behaves this way with a passenger as well), full tanks (burning the left side first), 8500ft, WOT, 2500 RPM 8.5 GPH 117 KIAS

 

Wings level test (using just aileron): turn coordinator ball slightly to the right of centre, just peeking past the white line.

 

Wings level and ball centred test (used right aileron and right rudder to level wings and centre ball, then released aileron and kept rudder pressure): still banks left but not as dramatically as without rudder correction.

 

In wings level cruise I will say that I *think* I could appreciate a slight positive angle upwards relative to the flap on the left aileron but tough to say for sure.

 

So- my conclusion is that my plane is out of rig and both the left bank and yaw both need addressing.

 

My mechanic is excellent, and I am confident he will be able to rig the plane, only thing is that he does not have the Mooney travel boards. I have read literally every thread on here about travel boards and rigging, so I feel that we should really try to get these to be confident in the static rigging before we start bending servo tabs. We are working to source them. I live in Alberta Canada which makes things more complicated if needing to source from the USA. I will keep this thread updated with my progress and experience with rigging my J partially as a place to journal my thoughts and also to help future riggers!

 

James

 

There’s a good rigging article out there too… ill see if my google skills are up to the test…

found it!

https://knr-inc.com/shoptalk-articles.html?view=article&id=106&catid=25

 

Edited November 18 by Ragsf15e

[jamesyql]

There’s a good rigging article out there too… ill see if my google skills are up to the test…
 

Nice googling!

So far I have come across:

https://knr-inc.com/shoptalk-articles.html?view=article&id=75&catid=25

https://knr-inc.com/shoptalk-articles.html?view=article&id=106&catid=25

https://themooneyflyer.com/issues/2017-OctTMF.pdf

https://www.themooneyflyer.com/issues/2012-JulTMF.pdf

[Ragsf15e]

37 minutes ago, jamesyql said:

 

Nice googling!

So far I have come across:

https://knr-inc.com/shoptalk-articles.html?view=article&id=75&catid=25

https://knr-inc.com/shoptalk-articles.html?view=article&id=106&catid=25

https://themooneyflyer.com/issues/2017-OctTMF.pdf

https://www.themooneyflyer.com/issues/2012-JulTMF.pdf

 

Ahh, well you’re in good shape then!

If you’re waiting on the boards, possibly worth a close look at the flaps to make sure they are both coming up fully and equally.

[jamesyql]

Ahh, well you’re in good shape then!
If you’re waiting on the boards, possibly worth a close look at the flaps to make sure they are both coming up fully and equally.

Edited post for brevity:

We did drop the left flap as an initial attempt to fix the heavy wing, but no effect. Seems that this may be more effective for asymmetric wing drop with flap actuation.

[PT20J]

First of all, these things were rigged correctly when they left the factory. The stall strips were put on with duct tape and after a couple of flight tests to get the position correct for stall with wings relatively level they were riveted in place.

Unless the airplane has been damaged, the rigging shouldn't change. But what happens is that people mess with them over time and get the rigging messed up. 

You can check a few things yourself per the KNR article. If it's not right the best thing to do is to take it to a Mooney Service Center that has done rigging and has the travel boards and have them set it up correctly. 

[jamesyql]

First of all, these things were rigged correctly when they left the factory. The stall strips were put on with duct tape and after a couple of flight tests to get the position correct for stall with wings relatively level they were riveted in place.
Unless the airplane has been damaged, the rigging shouldn't change. But what happens is that people mess with them over time and get the rigging messed up. 
You can check a few things yourself per the KNR article. If it's not right the best thing to do is to take it to a Mooney Service Center that has done rigging and has the travel boards and have them set it up correctly. 

I am hoping to source travel boards and have it done locally if possible. I don’t have much spare time to be travelling for maintenance and I trust my mechanic and have an excellent relationship with him. Even if it takes a bit longer than an MSC, it is worth it to me to keep everything in house.

I should add that the right aileron [edit] trailing edge has also been bent downwards and correlates to a log book entry for a heavy left wing from years ago.

My goal is to get the static rigging checked and adjusted since the plane is new to me and then I will have a better starting point if needing to modify tabs any further.

Will also have engine mounts checked.

[PT20J]

11 hours ago, jamesyql said:

I should add that the right aileron servo tab has also been modified and correlates to a log book entry for a heavy left wing from years ago.

Stock M20Js don’t have aileron servo tabs. Does your airplane have an Aero-Trim installed?

[jamesyql]

Stock M20Js don’t have aileron servo tabs. Does your airplane have an Aero-Trim installed?

apologies, wrong lingo. Thanks for the clarification. I was referring to the aileron trailing edge which can be bent. Still learning all of this, new to plane ownership and Mooneys. Edited above post to avoid confusion to others.

[EricJ]

13 hours ago, PT20J said:

Unless the airplane has been damaged, the rigging shouldn't change. But what happens is that people mess with them over time and get the rigging messed up. 

Regular maintenance happens, too, and rod ends and flap hinges and control surfaces and such get replaced over time.    Every time an airplane is painted it gets re-rigged.  ADs and SBs get performed that are intrusive to flight controls, etc.  There are lots of opportunities for rigging to get disturbed over the decades that our airplanes have been around.  I'm a little surprised most of them are as good as they are.   

[Sue Bon]

I had this problem for a while, but with banking to the left. My maintainer fixed it by trimming the rudder.

[Pinecone]

Who are the best shops for rigging?

[jamesyql]

Secured travel board rental from nearby MSC.

Correction: they only have the elevator board. The hunt continues. Mechanic going to chat with Lasar.

Aaaaand, we found them locally(ish) after all. Will update back once we have had a chance to get the plane in the shop.

[Fly Boomer]

10 hours ago, jamesyql said:

I was referring to the aileron trailing edge which can be bent.

I wouldn't allow anyone near my flight controls with pliers unless more than one Mooney rigging expert told me it was the only way.

[jamesyql]

I wouldn't allow anyone near my flight controls with pliers unless more than one Mooney rigging expert told me it was the only way.

Fair enough. I am hoping that by addressing the static rigging many of the issues will resolve.

[Ragsf15e]

42 minutes ago, jamesyql said:

Fair enough. I am hoping that by addressing the static rigging many of the issues will resolve.

Getting the rigging right first is important but at the end, a very small tweak on the aileron trailing edge is very effective.  On my first (very expensive) annual, a very popular (and expensive, and knowledgeable) MSC said the rigging was all messed up.  They were also replacing a trim tube and some heim joints.  Anyway, they used the boards and got her all squared away, then told me to go fly it and see what happens.  Well, it had a pretty solid right roll (I have a video somewhere that I took to show them).  The “big boss” of the shop looked at the video, took a pair of duckbill pliers and slightly tweaked the left aileron.  You can’t see the bend, it’s very small.  Totally straightened it out.  So if you get there after the boards, it’s not the end of the world.

[DC_Brasil]

On 11/19/2024 at 12:06 AM, Ragsf15e said:

Getting the rigging right first is important but at the end, a very small tweak on the aileron trailing edge is very effective.  On my first (very expensive) annual, a very popular (and expensive, and knowledgeable) MSC said the rigging was all messed up.  They were also replacing a trim tube and some heim joints.  Anyway, they used the boards and got her all squared away, then told me to go fly it and see what happens.  Well, it had a pretty solid right roll (I have a video somewhere that I took to show them).  The “big boss” of the shop looked at the video, took a pair of duckbill pliers and slightly tweaked the left aileron.  You can’t see the bend, it’s very small.  Totally straightened it out.  So if you get there after the boards, it’s not the end of the world.

Can you share the video and perhaps a picture of how your left aileron looks now? I am having the exact same issue: a very intense right roll tendency after the shop rigged everything according to manual specs.

[PT20J]

If you are certain it is rigged correctly, it’s simple to make a fine adjustment following the procedure in the service manual.

[Ragsf15e]

36 minutes ago, PT20J said:

If you are certain it is rigged correctly, it’s simple to make a fine adjustment following the procedure in the service manual.

But before you bend anything very small… are you sure they had the boards and that both flaps are fully retracted?  A shop that did the rigging correctly should have the manual for the bend…

[PT20J]

It's pretty easy to double check the aileron and flap rigging. 

1. Strap a bar across the bottom of the yokes to hold them in the neutral position.

2. Check that the ailerons are both deflected down about 2 deg. (This allows for the ailerons to drift up slightly in flight).

3. Place a long straight edge on the trailing edge of the wing and check that the flaps are aligned with the aft section of the wing at the ends and mid-point. (The surfaces don't line up perfectly -- you're just checking for any obvious deflection of the flap relative to the wing).

4. The flaps should either be aligned with the ailerons or be slightly higher than the ailerons (because the ailerons are set down 2 deg.) But they need to be the same on both sides.

 

[jamesyql]

Mechanic got my J in for rigging today.

I was experiencing left roll AND yaw.

He went through everything step by step as outlined in the maintenance manual with reference to the very helpful article here https://knr-inc.com/shoptalk-articles.html?view=article&id=106&catid=25

Main highlights were 1. rudder left of reference and 2. asymmetrical flaps, left too high, right too low. Both these make sense, and perhaps explain the issue.

Test flight tomorrow will confirm if we are making headway

[Ragsf15e]

2 hours ago, jamesyql said:

Mechanic got my J in for rigging today.

I was experiencing left roll AND yaw.

He went through everything step by step as outlined in the maintenance manual with reference to the very helpful article here https://knr-inc.com/shoptalk-articles.html?view=article&id=106&catid=25

Main highlights were 1. rudder left of reference and 2. asymmetrical flaps, left too high, right too low. Both these make sense, and perhaps explain the issue.

Test flight tomorrow will confirm if we are making headway

The flaps are a common issue.  It could still roll, so don’t get discouraged if it does need a slight tweaking as long as everything else is straight!

[jamesyql]

The flaps are a common issue.  It could still roll, so don’t get discouraged if it does need a slight tweaking as long as everything else is straight!

Thank you! I will report back how things go

[Joshua Blackh4t]

I have a trim tab on my E. It isn't meant to, and no record, but it makes tweaking the aileron trim easy. Although the wing leveller also does it, so not too important. 

[jamesyql]

Winter got the better of my initial plans at a test flight and I had to scrub the flight. Finally got up today and pleased to report that after the static rigging issues were addressed with the travel boards my left bank/yaw is much less pronounced. Winds were strong and gusty today and I was working with my instructor on exercises so will need another flight or two before I decide to start tweaking trailing edge tabs. What a great community we have here.