Tuesday, May 25, 2021

Started bolting the left gear weldment - 3.5 hours

I need to get the weldments bolted in if I want to start on the fuel system. Can't be bent over reaching into the plane without something sturdy to put my weight on. 

I had some last minute adjustments to make on that pesky rivet interference. Fit wasn't there yet, so out the left weldment came for more filing.  Its ugly, but nobody ever see it and most important it now fits great.


Once I was ready to bolt the weldments in, it becomes very apparent that the hardware callout in the plans is not correct. The AN4-12A bolts with the AN960-416 washer is clearly too short. 

 


Even with the thin AN960-416L washer, its just too short still.



So without question I need to go up a bolt size to AN4-13A. With that, I am now battling the bolt size being just a tad too long. 


I want to be careful that I do not bottom the nuts out on the bolt...and it looks close. So, I ran the scenario of adding an additional thin AN960-416L washer.
At this point its important to note that I do not have a washer under the bolt head with this two scenarios...So then the choice is obvious that the bottom option with two washer is the one to proceed with. An AN4-13A bolt...A AN960-416L washer under the head. Through the weldment and spar. An AN960-416 washer and the nut. The result is perfect. 

 

Getting the washer slipped in behind the weldment on the one hole along the bottom was a true pain the the rear. I ended up making a washer holder out of safety wire and I was then able to slip the washer into place and then slide the bolt in. I make it sound so quick and easy....it wasn't, but it worked.

I used this washer arrangement for all of the weldment holes, except for the one hole that requires the long AN4-34A bolt. That bolt also gave me a bit of grief...it was a tad too long. I added a second AN960-416 washer and that is excellent.

So the weldments are nearly all bolted in. I will drill the sides and bolt those in at a later date.