I think you can order the part from Vans no problem. I do think you may be too worried about the specific dimensions of the part. It's a 1/8" piece of aluminum with a hole drilled in it. The purpose of the washer is to provide enough material thickness so that the bulkhead fitting nut can be tightened fully.
Not sure what you are trying to do here but as builders we see this as a trial task. The washer I assume is just part of a much bigger problem that you are trying to address. I would be more concerned about your skills for that issue than the washer itself. Perhaps you could share that info.
I did order the part from Vans as I mentioned above. And I know what it's there for. I just want the right part.
Plus I didn't understand the nomenclature on the plans - I like to understand things.
To be honest I don't see the need for a big long explanation of what I'm doing just to find out what that part is. I try not to waste people's time with lots of verbiage about something no one cares about and that often never gets read.
But here you go:
The AN833 Ell has a little bit of gas leaking around it. You can turn the Ell a little. A previous owner globbed some Proseal on the outside of the AN833 but that has failed.
Therefore it's not tight - not installed properly. Also, the fact that you can turn it means that either the vent line is turning with it or the vent line B nut is loose.
So my intention is to open up the access plate, remove the AN 833, clean the area, and install a new AN833 properly with a new washer, new nuts and some Proseal. Then screw on the vent line B nut, check the fuel sender and re-attach the access plate.
2 years ago I had a problem with a dripping vent line (the very same one )- it was dripping gas out the vent air intake. I attached a fitting and a plastic hose to the intake and while blowing some air into the intake and with my ear on the wing I heard bubbles coming out of the end of the AN833 that is inside the tank. That mean the vent line b-nut was loose.
Sure enough after removing the access plate and looking in with a borescope the b-nut wasn't even started. I'm not sure it ever was. I tightened the B-nut and the problem was solved.
However I should have also checked the nut securing the AN833 to the rib - it, too, may have been loose. I wish I had thought to check it because now I have to remove the access plate all over again, which is a pain. But it should go faster this time having done it once before.
If I'm going to remove a part and then put it back, I like to use new parts when possible and reasonable. I have no idea if the builder even used a washer there. There have been a few things on this plane that gave me pause. So I want to have washer on hand.
What if the nut that's there is rounded some? A new one would be better.
So, in order to get this job done as quickly as possible, while doing it properly, I'm assembling all the parts I may need, beforehand. If I don't need them then it's a small expenditure. If I do - they are right there, brand new, ready to go. In order to have a couple of those washers on hand I have to understand what they are. I recognized that they are 1/8" thick but that's all. The washer did not have a standard name which you can look up on AS .
So I asked if anyone here would clue me in as to dimensions. Pazmanyflyer gave me good info, as did others, but not the OD. If you look at his picture you will see the washer is close to the wing skin - so it cannot be too big.