Van's RV-9A in Aurora

The Big Picture

The Big Picture
Flying! 8/28/2011

Monday, May 25, 2009

8.2 hrs, 8 rivets
Worked on aileron attach and bellcrank hardware. It was a lot of work.
Cut both sets of aileron pushrods.
Drill holes for 917 pushrod endcaps.

Cut, prime, and assemble 918 push rods. There are four rivets per pushrod. These are really hard to do right. The first ones I did look like crap. I got better by the second one. No way I'm drilling the ugly ones out. Those pushrods aren't coming apart.




Install both bellcrank sets.



Install ailerons. Clamp ailerons with aileron alignment jig and tune 918 pushrods.

Tighten 918 jam nuts.

All of this work takes few words to describe. But there's a lot of details. Like trimming the bolts where the 918 pushrods connect to the aileron. Not to mention all of the tiny washers to be installed in tiny spaces. After dropping them 10 times, you finally figure out the best way to do it. Pay close attention to the nuts and washers. They are NOT all the same, and there are a couple of places where it matters. So if you used the wrong parts in another of the five AN3 aileron hardware spots, you'll get to go look at all of your to find where you used the thin washer and nut you need on the last place you'll be working.




[edit] Aileron travel looks good as far as I can tell. In the up direction, it has way more travel than required. Like 40 degrees or so when it hits the stop. There's a little interference from the push tube rivets against the spar right at the stop. But the table on 15-2 of the manual sez that the max travel is 32 degrees, so this should get limited a bit more (by fabbing new stops?) I guess up travel gets limited somehow so the stop never gets used in practice. The stop is there to prevent the bellcrank from flipping over, but other things have to go wrong before the aileron can ever get to that point.

In the down direction, the travel is close to the limits required by 15-2. I did a crude measurement of 15 to 17 degrees, which are the min and max travel limits. It appears to be limited by the short push tube rubbing against the cutout in the rear spar. As the aileron is pushed down, the bell crank is rotating outboard, and the push tube is also trending outward. At the limits of the travel, it starts hitting the spar. But there's no point worrying about it until the whole system is put together. Then the real behaviour will be be determined.


Also setup the left tank for leak testing. Tied on the balloon and tried to inflate it. The fuel cap appears to leak a lot! Taped off the fuel cap and blew the balloon up. So far, so good. I think the BNC leak is resolved.