[swisseagle]

Hello

I made a pre buy inspection on a 2001 RV-4, 410+h flown, 500 landings. O-320, FP Prince prop. Lightweight Tailwheel

The plane is in good condition, except the area where the tailwheel strut is mounted. There at the fuselage are smoking rivets on the bottom and on the lower radius. The rivets are from the bulkhead F-411 and F-412 to the skin bowl F427 where the tailwheel structure/weldment gets screwed onto the bulkheads. The paint is cracked around the rivets and coming off, strains of black dust come out around the rivets. I'm not sure if the skin is dimpled or countersunk. Interesting is, that it is only shown in the area of the F-427 skin.

RV-4 plan page 30/31

The homestrip where the plane is flown from, is grass wit Perform plates on it. Those plates are pressed into the ground, grass is growing throu the holes, but still there is a "structure" that makes landings "noisy". I think the perforation in the plates bring the tailboom to vibrate and then it starts to harm thestructure. Do you think that this can make those rivets "smoke" and come loose?

What does the new owner of the plane can expect, regarding the smoking rivets:

- Does they get worse until the rivets get more and more loose?

- How to prevent any further damage?

- How to repair? (unrivet this section, clean inside, glue with scotch weld the flanges of those bulkheads to the skin and re-rivet)


Thanks for any input!

 

[F1Boss]

Not difficult

Hello Eagle:

Dis-assembly and re-riveting will not likely be a permanent fix, considering your runway surface. I would recommend a change to 470-4 rivets for any type of repair your choose to make.

You can re-rivet (one rivet at a time) with 470-4 rivets, but bucking bar access will be difficult, unless you remove the 417 deck plate. As an alternative, you can re-rivet using Cherrymax rivets - likely the std -4 size - but be sure to get the correct lengths for each station.

The original -3 rivets are obviously no up to the job of controlling the vibration - we had a similar problem with some of the Rockets (heavier tailweight, combined with non-paved runways), and the change to the 470-4 rivets on that skin fixed the problem.

Carry on!
Mark

 

[swisseagle]

Hi Mark

Thank you for your input. I hoped to be able to take out the welded structure ... but without taking off the deck plate, no chance.

I have experience in this area on a RV-7, but there it is much wider!

 

[Taildrgr]

If the shop heads will allow it, you can try re-bucking the existing rivets a little bit to expand them in the holes. Probably a temporary fix, but could buy you some time.