Control Surface Balance Checks

[cliffy]

This parallels the "polished aluminum" thread

Just thinkin'

If we have to check the balance of control surfaces after we paint them and before flight-  do we need to 

check their balance if we remove the paint and fly them that way?  

In other words, if they came off painted and in balance and we remove the paint, are they still within balance limits?

[Guest]

The manual has a note saying paint is to be stripped before re painting and that static balance limits are for painted surfaces.  I don't see why the limits would change for unpainted or polished surfaces.

Clarence

[cliffy]

Not saying the "limits" would change but that removing the paint will change the balance point (by the weight of the paint removed) and would they now be in balance "clean"?

The limits say "not to exceed" and removing paint would more than likely reduce the overcenter weight BUT-

Would one not want to (or be required to) check the balance again after the paint was removed and the surface polished if one was going to fly it that way? 

 

 

 

[Hank]

5 minutes ago, cliffy said:

Not saying the "limits" would change but that removing the paint will change the balance point (by the weight of the paint removed) and would they now be in balance "clean"?

The limits say "not to exceed" and removing paint would more than likely reduce the overcenter weight BUT-

Would one not want to (or be required to) check the balance again after the paint was removed and the surface polished if one was going to fly it that way? 

 

 

 

Yes, they should be rebalanced whether stripped and repainted or stripped and polished. The balance limits should be the same, regardless of the amount of paint applied. My own are base coated with colored stripes running front to back across the ailerons.

[Yetti]

I was under the impression that Mooney test flys the planes unpainted.   Then paints them.  Best I can tell Mooney painted with

all the control surfaces on the airframe.

Edited February 1, 2016 by Yetti

[cliffy]

I'd be willing to bet that whatever way the factory flies the surfaces they get balance checked before they go airborne.

[MB65E]

Last I checked there was no min weight published on the trailing edge. Only a max allowable weight at the trailing edge. I don't see the need to check the balance if the paint is removed. It's lighter and will be less prone to flutter. An overweight or aft edge heavy flight control will be less stable. Some manufactures list a MAX weight of the flight control. 

I have seen new airplanes from mooney with freshly painted flight control hardware. I highly doubt they balance every surface. 

The ailerons are espically hard to get in balance with paint on them. I'd always recomend a full strip of flight controls during a repainted. I pulled 6 layers of of some in the past. They were heavy when I pulled them off, but never had any issues in flight. 

If you paint them, please check the balance.

-Matt

[Guest]

I just checked the C,E,F,G manual, it list a minimum and maximum weight for trailing edge heavy.

Clarence

[MB65E]

Thanks Clarence, I'll check the other J material I have. Some have minimum weights, and that's where the confusion was I believe. 

-Matt

[1964-M20E]

OK I'm reviving this thread.   just out of curiosity

I just watched a highly sped up time lapse sequence of an Emirates passenger jet 737 or similar get repainted.  They stripped the plane cleaned it and repainted it.  I never saw the control surfaces removed for balancing??

1. Is this a Mooney thing? (FAA regs I believe call for this)
2. Do they do it another way on the plane that was not show?
3. Is the ratio of the mass of the control surface to the mass of the paint so much greater on a 737 that it is negligible and does not need to be considered?
4. Did I just miss the step due to the time lapse or camera angles?
5. Emirates doesn't need to comply with FAA regs (they fly outside US airspace) and it is not required over there?

 

[ArtVandelay]

Do they paint the control surfaces or even the wings, thought it was fuselage and tail only.



Tom

[1964-M20E]

No they stripped everything and repainted the whole plane

[RLCarter]

Maybe the control surfaces get balanced in a different way (on the aircraft) than our little bug smashers?

[Prior owner]

Technically, you’ve got to weigh the aircraft after painting it, as well... no other way to accurately determine the weight change.

[PT20J]

Control surfaces are mass balanced primarily to prevent flutter. There are other methods that may be used. For instance, analysis might show that a particular configuration will not flutter without balancing. Modern airliners have irreversible controls which might be less prone to flutter. So, there is no general rule except to do whatever the maintenance manual calls out for your airplane.

[Prior owner]

I have read somewhere in this site that an old Mooney test pilot stated that the tail  control surfaces on our planes will not flutter because the trailing edges are swept forward... 

[PT20J]

6 minutes ago, PilotCoyote said:

I have read somewhere in this site that an old Mooney test pilot stated that the tail  control surfaces on our planes will not flutter because the trailing edges are swept forward... 

Another interesting Mooney Myth  If it were true, Mooney wouldn't need to specify control surface balance.

[boeingroam]

controls that are hydraulic dont need balance(737,etc) just the controls with cable control.

[N201MKTurbo]

30 minutes ago, boeingroam said:

controls that are hydraulic dont need balance(737,etc) just the controls with cable control.

https://www.ndt.net/article/aero2013/content/papers/11_Hinken.pdf
 

This document describes how to balance the control surfaces on a 737 after painting.

[Hector]

Finished quite a bit of painting on my bird last weekend (everything you see white) but avoided the ailerons because I did not want to remove them for balancing.


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[EricJ]

7 minutes ago, Hector said:

Finished quite a bit of painting on my bird last weekend (everything you see white) but avoided the ailerons because I did not want to remove them for balancing.


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Tell me you really put a window in your hatch. 

[Hector]

Tell me you really put a window in your hatch. 

No, it’s just painted brown there to give the illusion of a third window


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[Raymond J1]

I also painted windows in addition... To have more natural light...

For the balance of the control surfaces, the manufacturer's values are maximum tolerated static moments, to be checked after painting or even varnishing. After stripping, you are rather on the minimum side. On some aircraft, especially those with cable controls, there is also a maximum gap in mass between the ailerons that should not be exceeded.

 

[carusoam]

10 hours ago, boeingroam said:

controls that are hydraulic dont need balance(737,etc) just the controls with cable control.

Welcome aboard br…

Mooney controls are neither… hydraulic or cable.

The service manual has the instructions for painting and balancing requirements…

PP thoughts only, not a mechanic…

Best regards,

-a-

[A64Pilot]

Cable or push pull tube they have to have the balance checked, but as one poster said removing the paint will most certainly push the balance towards nose heavy which means it becomes even more resistant to flutter, but check to be sure

Flutter is terrifying, flutter can cause a surface to be torn off, or even an entire empennage, and sometimes there is nothing at all you can do about it, so check the balance.

Good friend of mine doing one of the velocity dive tests of the 114 Commander for Certification had the elevator get into flutter, Rockwell recreated the incident in the wind tunnel, the time between flutter initiation and complete empennage failure was supposedly less than 1 sec.

‘If you want to look up the accident report the aircraft tail number was 114AC. 114 was the model number and AC for Aero Commander, pretty sure it was the 114 and not the 112 .

 

On edit, if you have to rebalance after painting, balance towards being within range, but nose heavy as any repairs in the future or repainting will most likely add more weight to the tail as there is way more surface area there and if you start nose heavy, maybe you will be within limits still.

Edited October 3, 2021 by A64Pilot