Rear QB fuselage Questions

2 Questions....I am building a -7 QB.

1. I am having trouble match drilling the tail spring mount. It is very hard and my normal bits won't penetrate it. What method have others used?

2. The instructions mention "keeper rivets" through WD-409 and F-712. I would like to know what these are. The QB fuse has some temp rivets installed but I don't know if these are the same "keeper rivets" or which ones they used when they installed them.

Thanks in advance.

Ed N767EW
working on fuse

You're right, that stuff is very hard. I used a very sharp, good quality bit, cutting fluid and low speed with light pressure. Spinning too fast or pressing too hard will only make the material harder. Stay with it, it will eventually get through.

Steve Zicree

bamarv7 said:

2. The instructions mention "keeper rivets" through WD-409 and F-712. I would like to know what these are. The QB fuse has some temp rivets installed but I don't know if these are the same "keeper rivets" or which ones they used when they installed them.

Click to expand...

The keeper rivets hold the aft part of the WD-409 in place until you can match drill the VS to it, which will happen much later. That's why you have to use CS rivets with the flat side aft.

The forward part of WD-409 is held in place by some AN bolts.

Ron Davis QB 7

I also had a heck of a time. Use drilling fluid and work slowly. Follow up question: Is the aft section of your 409 sitting flush against the aft bulkhead (F-712)? Mine makes contact in the middle, but the edges are 1/16" from the bulkhead. It's almost as if the F712 is warped forward when cleckoed to the aft fuselage.

Ron

I had to make a shim to go between 409 and F711 to make up some space between F712 and the aft part of 409. Just like yours, I don't have perfect contact between 409 and 712. I am hoping the vertical stab bolts will pull it all together.

Ed

Spring mount gap

Ed,

If you get there before I do please let me know how it goes. My concern is that when installing the Vertical Stab it will all pull together alright however, the gap must be filled from someother location. I am thinking it may distort the aft fuselage skin. Tom at Van's suggested I not rivet the aft bulkhead in place until I have fitted and match drilled the VS to the 712 and weldmount. This sounds like good advise and I will wait. That way if anything needs to be redone, I will be able to access it much easier.