N916K

N916K

Well Known Member
After way too many months N916K is back flying with a shiny new paint job. And a new rudder, and some new elevators, and much more fiberglass.

The weight was a little higher than I expected. Maybe it's just the different scales I used this time. 1074lbs with everything attached and painted, including engine oil, interior, and a bunch of junk in the map box and in the underfloor storage.

The rudder and elevators developed cracks over the last few years. I made some fixes that I believe will take care of that problem. Plus the second time you build the tail it only takes a weekend and looks much better.

I will post some photos soon.

Cam
 
Cam,

That is great news!

Could you give us an idea of where the cracks developed and at how many hours?

I'm right at 165 hours now and just gave the tail complete inspection and found no cracks.
 
N941WR said:
Cam,

That is great news!

Could you give us an idea of where the cracks developed and at how many hours?

I'm right at 165 hours now and just gave the tail complete inspection and found no cracks.
Click to expand...

The cracks are at the last rivet of the stiffeners. First one was on the elevator close to the spar. I think that was from me pulling the skins too far to rivet the spar. That was around 60 hours.

The rest are on the rudder. After about 250 hours of flying a few showed up close to the spar. I had a few run ins with turbulence and after that I started to see the cracks in the rudder.

When I rebuilt the tail surfaces I prosealed the end of each stiffener and made a few jigs to hold the skins open to reduce the stresses around that last rivet.
 
I was looking at an RV-6A rudder the other day and it had a bunch of cracks emanating from those first rivets. Van's attributed it to the guy have a "big" engine. Yep, O-360 and CS prop. :(

Kind of makes me wonder what the O-360 powered -9's are seeing.

Anyway, in talking about the guy's next rudder, he was thinking of making the stiffeners longer and riveting them to the spar. His thinking is that it will stop the flexing there at the end of the stiffeners.

Just some thoughts from two guys who were thinking through this problem.

Maybe I should wait another year before I paint my -9. By then, any cracks that are going to show up should be there.
 
N941WR said:
I was looking at an RV-6A rudder the other day and it had a bunch of cracks emanating from those first rivets. Van's attributed it to the guy have a "big" engine. Yep, O-360 and CS prop. :(

Kind of makes me wonder what the O-360 powered -9's are seeing.

Anyway, in talking about the guy's next rudder, he was thinking of making the stiffeners longer and riveting them to the spar. His thinking is that it will stop the flexing there at the end of the stiffeners.

Just some thoughts from two guys who were thinking through this problem.

Maybe I should wait another year before I paint my -9. By then, any cracks that are going to show up should be there.
Click to expand...

Attaching the stiffeners to the spar is going to be tricky. How would you get in there and rivet them in?
 
N916K said:
Attaching the stiffeners to the spar is going to be tricky. How would you get in there and rivet them in?
Click to expand...
You would have to put a small bend in the stiffeners to step up over the spar. Rivet the stiffeners to the skins and then slide the spar on and top rivet that last rivet in place. Does that sound like it might work?
 
So I flew the RV9 this morning for the first time with everything on it. Fairings, wheel pants, everything well fitted and painted. The plane seems a bit faster than when it was a 9A. I was only level for what seemed like a few seconds before I had to full back the power to keep from over revving the prop. At 2580 rpm the TAS on the Dynon was 163 knots. I was at 8800 feet density altitude. I didn't check out the manifold pressure because I started to get into some really thick smoke so I decided to turn around and head back to the airport. I was still below a few of the mountain tops and the vis was going from bad to worse. The smoke is really quite bad now. There is a 35,000 acre fire burning a few miles away and the smoke is settling into the valley.

I'll do a full performance evaluation in the next week or so and post the results. I did quite a bit of testing when it was a 9A, so this should be one of the better comparisons between the 9A and the 9.
 
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