Mistakes I Made!

Mis-Drilled the HS-610/HS-614

October 7, 2001

If you look on page 3PP of the plans for the empennage you'll see the detail for the forward spar showing where the HS-610/HS-614 attaches to the HS-602s. The drilling pattern is shown on the drawing, and at four stations there is a big oval which says "Drill in Assembly with Fuselage". What that means is "DON'T DRILL IT NOW, DUMMY". I, of course, did drill it early. Fortunately I drilled it only with a #30 drill and these holes are NOT for rivets, but will later be assembled with bolts. Therefore, I can clamp and align with the fuselage and THEN drill them out to the actual size when the time comes. Whew! I'm not totally screwed on this one! :)

Drilled Ribs to Forward HS Spar

October 28, 2001

I am still working on getting the hang of aligning the ribs when I drill. I was drilling through one of the HS-608 ribs and I got the holes WAY too close to the web. This resulted in me having to order a replacement. My first replacement part! (I knew it had to happen eventually!) Update ... it wasn't my last. I continued to have problems with alignment on the HS, and kept not being happy with it, and finally ended up replacing more parts until I was happy. I chalk this up to the HS being my "construction classroom" and, in that light, it was cheap training. Ribs for the HS really are quite inexpensive. :)

Cut Stiffeners Wrong

May 18, 2002

Ok, this was just plain stupid. The rudder stiffeners need to be tapered, and they are pre-marked to show just how the tapers should be cut. This should be a no-brainer, but the first pair I did were arranged such that the mark in the middle of the stiffener which indicates the ending point of the taper really was about right in the middle. I didn't cross-check with other stiffeners before I marked, and cut, these two. When I went to do the next two (Marilyn was doing the marking of these next ones .... while I trimmed on the bandsaw) I saw that they were marked in the opposite direction! I wasn't SURE this was wrong, but it certainly seemed wrong, and the only smart thing I did during this whole affair was to stop immediately and make sure we were doing the right thing. We weren't. :) Just remember ... "If it looks wrong, it probably is wrong." That kind of thinking saved me in this case. I "stole" some stiffener material (not pre-cut, but just simple aluminum angle) from the elevator stiffener stock and fabricated replacements. It was very easy to do, and I used the messed-up stiffeners as a drill guide. Piece of cake. All I need to do now is make sure I still have enough stiffener stock for the elevators, and order another length if I don't.

Mis-Drilled Skin!

August 16, 2002

I started on finishing the drilling of the stiffeners to the skin, and made a tragic mistake. I grabbed the wrong stiffener, not realizing, and drilled it to the wrong position. The mistake was severe enough (and when combined with the other mis-drilling above) I decided to replace the skin. Damn. Aside from the obvious not-paying-close-enough-attention stupidity in evidence here, I think there is a critical issue at play which caused these mistakes. Complacency. I built the right elevator with NO problems at all ... and in doing so became complacent in building the left. A (somewhat expensive) lesson learned. On the up-side, I'll get to start fresh on the left elevator and do it right, and will at the same time re-work the stiffeners to correct a rivet hole spacing issue that I was unhappy with. Still, it sucks to make a mistake and screw up parts. Truly sucks.

Mis-Drilled Tiedown Bar

March 2, 2003

We got moving too quickly and mis-drilled the tiedown bar. We drilled before we measured to the outboard edge of the spar to insure that the edge of the tiedown bar was parallel with the spar end. This caused us to mis-drill the lower holes by about 1/8 of an inch! Stupid, but there you have it. Measure twice, drill once ... should be the motto. The trick is sticking to it and never cutting and/or drilling too soon!

Too Many Rivets!

May 18, 2003

This was a simple case of not reading ahead, or having read ahead and then forgetting critical items. Except for those places on the plans where it explicitly said "rivet in assembly with ...", I set rivets where I should not have put them yet. This was where the W-724 aileron gap fairing, W-721 flap gap fairing, and the 712 outboard rib main spar attachment goes. These need to be left empty for now. The W-724 and the W-721 because they are installed later, and the W-712 outboard rib because those same holes are used to install both the main and nose ribs. A hint (for the W-721 and W-724, at least) is when you get to a spot like that and there is a different rivet callout than all the rest of the rivets on that rib ... it means something else goes there which likely is making the assembly thicker! Pay attention! Fortunately, the drilling out went easily and nothing was harmed. *whew*

Mis-Drilled Wing-Walk Doubler

June 7, 2003

Ok ... here is another reminder to read the directions carefully! I thought I read them, and clearly read them too fast. I was left with the impression that the doubler was to be aligned flush with the top of the skin. Why? I can't tell you. But, it isn't. It is sad to figure that out after you drill (and debur!) all those holes. I'm getting a replacement piece of aluminum for the doubler, and I'll come back to that work when it gets in. Annoying, this is!

 

<< General	Previous/Next Chapters	General >>