Warning about Flaps Adjustment

This has always been sort of a problem. I usually recommend that people set the "full flap" to somewhat less than 40 degrees. I have mine set at about 37. If the flaps are set correctly this will NOT happen in flight because flight loads keep the flaps from going down so far.

hevansrv7a said:

I'm posting this very embarrassing account in the hope it will prevent anyone else from experiencing it.

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You are to be commended for posting this so others may learn, it is not embarrassing, it is the honorable and right thing to do. This reminds me of the RV driver that flipped his tri gear. He posted alot of great pics and subject himself to possible ridicule. We all learned from it and I will guarantee you there are some A model RV's flying today that would have been wrecked if he did not post the pics. We all have "embarrassing" aircraft moments. It is a true aviator that shares them so others may learn.

If only..

Mel said:

This has always been sort of a problem. I usually recommend that people set the "full flap" to somewhat less than 40 degrees. I have mine set at about 37. If the flaps are set correctly this will NOT happen in flight because flight loads keep the flaps from going down so far.

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I wish I had consulted Mel. If Van's instructions mention this then I missed it.

draw triangles

I drew black triangles on the UHMW tape that is on the flaps. The triangles point aft. As soon as the tips of the triangles are visible, that is about full flaps(had been having trouble with the flaps not wanting to retract if extended too far--probably the motor, though).

Sorry to hear about the cosmetic problem. Glad to hear it still flies well.

Flap Adj.

H:

Sorry to hear about your problem. Met you at Franklin Co. (GA.) airport when you stoped for fuel on your way down to Florida a couple of weeks ago. Your post has prompted me to double check my flaps to see if they can be forced down past the position to where they can pose an interference problem.

Thanks!!!!!!!!!!!!!!!!!!

I am having trouble visualizing...

As a new member to this community, I haven't read about this issue yet in the forums. I am having trouble visualizing how this problem occurs. Would someone please humor me and explain it to me. Perhaps it was the way it was stated in the first post. Is the issue that the flaps can over-extend, and the leading edge/lip of the flap, when retracted, actually goes over the top of the upper wing skin, instead of under it?

Thanks for the help,

James

Good post

You are not the first to have something like this happen.

hevansrv7a said:

snip...I don't know exactly why or how it happened but,
A. There were high winds and it may have pushed the flap down past it's usual position. The right flap was on the windward side....snip

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This was probably it.
I have manual flaps and if I bump into the flap rather hard before getting in I can sometimes get that curved piece to catch the trailing edge of the wing skin like you described. When I go to raise the flaps...they won't. Massaging that piece w/hands and getting it to poke back down under the wing skin fixes it. Has happened three times in five years.
Sorry about the damage and thanks for sharing.

b,
d

Clarifying Attempt

FlyinFife said:

As a new member to this community, I haven't read about this issue yet in the forums. I am having trouble visualizing how this problem occurs. Would someone please humor me and explain it to me. Perhaps it was the way it was stated in the first post. Is the issue that the flaps can over-extend, and the leading edge/lip of the flap, when retracted, actually goes over the top of the upper wing skin, instead of under it?

Thanks for the help,

James

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James, you have it about right. The leading edge of the flap is curved and then the last approximately 1/4" is bent. Also, like many, I have rubbing tape protecting the paint on the top of the curved surface. If the flap comes down too far it can pop out or just catch on the edge of the trailing edge of the top wing skin. I have marked, on the left, ten degree increments with a sharpie, but that did not prevent this. I haven't seen the flap go over the skin - that might have been better. It's the wing skin aft of the rear spar that bent upwards. I have some pictures but they wouldn't help explain what happened, only what is now the situation.

Bent wing

H. check PM's

Thanks...

H,

Thanks for the reply. What can e done to prevent this? I know some mentioned stopping the flaps from extending the full 40 deg. Can you roll the leadong edge more or make a sharper bend for better clearance?

James

Prevention

FlyinFife said:

H,

Thanks for the reply. What can be done to prevent this? I know some mentioned stopping the flaps from extending the full 40 deg. Can you roll the leadong edge more or make a sharper bend for better clearance?

James

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From my first post..
"I've since adjusted my flaps so they won't come down so far. As far as I can tell, this must be done by running the screw fitting at the end of the flap motor assembly OUT."

In other words, since the down limit of the flaps is the up limit of the jackscrew, you lengthen the net length of the black tube that extends from the motor/gear housing plus the screw fitting on the end, the one with the hole in it through which the AN bolt goes to hold it between the ears of the weldment. Make sure you have enough screw threads into the black tube and the locknut. Make sure the locknut is tight and safety wired per plans. You can also shorten up the rods that control the individual flaps. They stop moving when the upward limit is reached where the overlap hits the belly and at the down end when the jackscrew is fully retracted into the motor.

I don't think I'd change the leading edge of the flap's roll, but it's a thought to consider. You just want to make sure that you don't lose the contact seal when they are up all the way because that gives a drag/speed advantage over systems like Cessna's.

There is inherently less danger of the flaps popping out in flight because flight loads make at least 3 degrees difference. (at least on mine, anyhow) You can take the extra precaution of not fully extending them when parked, too. I certainly will from now on!

A similar flap retraction problem.

This must surely be synchronicity!
I had been noticing a scuff mark developing on the plastic chafe tape and yesterday it wore through.
The problem was the doubler plate used to strengthen the walkway. It protrudes about 1 inch or so beyond the aft spar(I think I followed the plan on this) and after much climbing in and out of "Rough Red" (RV-6) it had bent slightly down and away from the underside of the wing skin and was now rubbing on the leading edge of the flap. I believe that the tape could have been partially solarized from leaving the flaps down in the sun.
Finally the tape scuffed through . Luckily, I caught it while raising the flap during the walkround check though not before a flap jambed.

Ted.
After taking off the aileron and removing the flap, I have cut back the doubler to the aft spar line.
The Job took about two hours and I will probably do the other side for good measure.
Had I not noticed this, I would have been an unhappy chappy.

In my case it was not the 40 degrees of flap extension which caused the problem, it was the doubler plate applying high rubbing pressure to the tape.
I'm not convinced that the plastic chafe tape is the best material. It used to be thin stainless steel which doesn't solarize in the sun.

I would advise people to have a good look and see if there are any tell tale signs of chafing and replace the tape before it wears through or scuffs up. It's a whole lot simpler to replace the tape than to remove the flap.

What about putting the "Tape" on the underside of the wing skin instead of the top leading edge of the flap skin.

Has anyone ever tried this ?

Wicked Stick said:

What about putting the "Tape" on the underside of the wing skin instead of the top leading edge of the flap skin.

Has anyone ever tried this ?

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Yes, it works fine and I think looks better when flaps are down.

Wicked Stick said:

What about putting the "Tape" on the underside of the wing skin instead of the top leading edge of the flap skin.

Has anyone ever tried this ?

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YES,
I used "mouse tape" teflon. From your favorite online auction house, a fellow from Wisconsin, D. Johnson, He does special orders and no I don't know him. I used 1/2' wide, orderd 1' and split it. Order extra very handy stuff!

Edit-- His web site http://www.mousetape.com/ I think I paid about $20??

I measured my extension today (6A) at 37 degrees. I have nearly 3/4 inch of upper flap skin overlap on the upper wing skin. Even at 40 degrees extension, there is no way mine would be close to having the edges grab. Are the RV7 parts a lot different?

Same....

rv6ejguy said:

I measured my extension today (6A) at 37 degrees. I have nearly 3/4 inch of upper flap skin overlap on the upper wing skin. Even at 40 degrees extension, there is no way mine would be close to having the edges grab. Are the RV7 parts a lot different?

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Mine acutally go a touch past 40 deg. and I have at least 1/2" still under the wing skin. Has anyone seen this happen on a 6?

Flaps Catching Wing Skin

Folks,

I also had this happen to me, I believe I even posted somewhere here about it. I think what causes this to happen is bumping the flap while in the down position far enough for it to catch the upper wing skin. I called Van's about it when it happened and they were quite familiar with the problem.

To prevent it from happening again I adjusted them so bumping them cannot cause them to catch the skin.

The only fix for the bent skin is replacement as far as I can tell.

Now whenever I go to retract the flaps on the ground I am looking to make sure all is OK!

Randy C