U

utxp

I'm New Here
Recently looked at a -6 in hopes of buying. It appeared to have been rode hard. Upper skins between the ribs were cupped upward noticeably. Also the lower nose cowl had a hole eaten thru it by the alternator pulley. The seller mentioned that it may have been caused by pulling g.

Has anyone seen this type of issues? Is this typical of an aircraft that may have been stressed more than normal?
 
utxp said:
Has anyone seen this type of issues? Is this typical of an aircraft that may have been stressed more than normal?
Click to expand...
My RV-6, with the standard cowl did not exhibit any problems until I pulled a few Gs. After a few sessions of 3 or 4 Gs the alternator pulley had worn through the cowl. I had to add a bubble to the cowl, which was not unusual with this model at that time. If this was not done, it is possible the worn through place is not other than a cosmetic issue.

If there is any permanent skin deformation the airplane has been damaged. From your description, it is not possible to tell if the skin deformation is unusual. They can poof a bit, normally.
 
Overload damage causing permanent wrinkling of the upper skins would be the result of increased dihedral. Measure the dihedral and compare it to the specs. If I remember correctly, the -6 should have 3 degrees dihedral. If it has more than that, I would be quite concerned.
Since all RV-6 spars were drilled to the center section at the factory, they should be accurate.
And I agree, it is not uncommon for the alternator to wear through the cowling with just a few Gs.
 
Could this...

utxp said:
.... Upper skins between the ribs were cupped upward noticeably.....
Click to expand...

...have been caused by bringing a cold-soaked plane out into the sun?

The skins could heat a bit and expand - especially if painted dark - while the spar, with it's much larger mass, remains cold.

This could cause the "poofing" between the ribs....
 
normal

utxp said:
Recently looked at a -6 in hopes of buying. It appeared to have been rode hard. Upper skins between the ribs were cupped upward noticeably. Also the lower nose cowl had a hole eaten thru it by the alternator pulley. The seller mentioned that it may have been caused by pulling g.

Has anyone seen this type of issues? Is this typical of an aircraft that may have been stressed more than normal?
Click to expand...
I have a 850 hour -6 and love it.
The info on alternator pulleys rubbing thru is VERY normal. The original alternator was a close fit to the cowling. The newer Plane Power unit is smaller and has more clearance, so what you are seeing could be a very easy fix with a newer alternator and a minor repair.
As for wing skins, mine and others change with temperature. I was shocked the first time I was flying along at some altitude and the light was just right and the wing skins were not flat.....but on the ground, they looked mostly perfect.
I've read where many people have tried to make the top wing skins in one big piece and or control the temperature of the skin while installing them to try to get a perfectly flat wing skin.
So I'm not saying what you are seeing is bad, because we can't see it, but maybe get another RV guy to look at it with you for another opinion.
Good Luck with your purchase, you will love the RV-6.
 
utxp said:
Recently looked at a -6 in hopes of buying. It appeared to have been rode hard. Upper skins between the ribs were cupped upward noticeably. Also the lower nose cowl had a hole eaten thru it by the alternator pulley. The seller mentioned that it may have been caused by pulling g.

Has anyone seen this type of issues? Is this typical of an aircraft that may have been stressed more than normal?
Click to expand...

The alternator pulley wearing on the cowl is VERY common. I've never seen an airplane with cupped skins, but imagine they could be caused by a number of things, anything from the build process to excess G's. Also, what color are the wings? Dark paint accentuates the appearance of any waves in sheet metal.

Have an experienced builder take a look. Chances are it'll be fine.

And check the dihedral as Mel recommended.
 
I think Bob and I saw an airplane like that at Dana's flyin.

If it happens to be the same one that I saw, I would "Run Forest Run" fast like Bob said. It had definately seen some way over G at some point.

Matter of fact, I would stay away from the flightpath of that airplane unless you like to be under raining airplane parts.....
 
Last edited:
You can solve the alternator chafing against the cowling by going to a shorter built. Usually the belt supplied is a Gates 7365 or equivalent. Many years ago I started using the 7355, and it works fine and gives more clearance.
As for the high G's, check the lower skins, too.

Vic
 
You must log in or register to reply here.