More assembly of firewall #2 - 2 hours

I’ve come to the dreaded F-601J angles. I sure didn’t like riveting these on the first firewall. I really don’t like how close the inboard rivets sit in the inside radius of the angle. Not an easy rivet job. A combination of gun/backing bar and my shaved down backrivet set did the trick. Unfortunately I’m short on AD-9 rivets, so I’ll put in an order to Aircraft Spruce for more of those.







On a side note. The spring pin in my back rivet set broke. I’ll have to find a new spring pin to fix it and it appears to be an odd size - 7/64", not going to be easy.

Started assembly of firewall #2 - 2 hours

Very excited and nervous to get the firewall riveted...Again. Much quicker process now that I’ve been through it once before and know how best to set up the back rivet plate

I managed to get a few angles back riveted onto the firewall. All of the rivets are upsized by half or a full rivet size compared to what the plans called for. (Plans rivet spec’s are a tad short in this area)

Primed Firewall #2 pieces - 2 hours

A short day in the garage today, managed to get all of the pieces prep’d. Washed with maroon scotchbrite, cleanbrite acid wash, MEK and prime. Same old story.

Countersink, Debur and Dimple Firewall #2 - 3 hours

Fairly easy night in the garage. I deburred all of the parts and pieces. Made sure all edges where cleaned on the 3M wheel. All pieces are countersunk, I made sure to countersink slightly shallow and not too deep. I’m quite happy with the result.

Finished match drilling firewall #2 - 4 hours

Never missing an opportunity to drill on the drill press whenever I can. I match drilled as much of the #30 holes on the drill press that I could. Yes a slow process....but they are perfect.



I am pondering drilling pilot holes for the engine mounts now as it is incredibly easy to do on a drill press now.A few things come to mind about doing it now; 1. The firewall has pilot holes for the engine mount already. 2. It is extremely easy to drill those pilot holes on a drill press now before I mount the firewall to the fuse. 3. According to some build logs, it seems folks have used the firewall pilot holes as a mounting point for the rotisserie. 4. I really, really don't want to try and drill those holes by hand down the road.

Before I do anything I will pose the question to the builders group to see what the general consensus is.

I finished the rest of the match drilling using the palm drill and the ATS drill guide.

All I need to do now is countersink the angles, debur and clean things up and I will be back on track!

Finished drilling F-601J angles and F-601P spacers - 4 hours

Another tedious day in the garage. Managed to finish drilling the F-601J angles. Lots of back and forth; Fitting to the firewall, clamping, checking, removing, adjusting drilling.

One item that I've decided to drill at this point was the pilot holes for the F-772B stringers. I've omitted the holes on the original firewall thinking I would drill them in the assembly as directed on the plans. However drilling these nice a straight will be challenging. After confirming that there won't be edge distance issues on my original firewall....I opted to drill 1/8" pilot holes now allowing for an easier go at it later.

Next I need to work on finishing the F-601P spacers.Careful work is needed to round the corners to get a good fit.I can then drill the first #30 hole.

Re-clecoing the assembly I can then check alignment of the spacers with the rest of the assembly and then begin drilling the rest of the #40 holes.

Started fitting firewall #2 - 4 hours

Well, I'm diving into firewall #2. I quickly noticed that I cannot get clecos into the engine mount brackets due to the powder coating. So I set up the drill press and I opened the holes with an 1/8" drill bit. At least I can cleco those holes allowing my to use a #30 later.

After all the drilling was done, I could cleco all of the engine mounts to the firewall.

Next step I shaped the top of the F-601N stiffeners to next into the F-601L angle. Slow and steady makes for good work and fit.

I double checked the fitment of the F-601D and F-601N angles. Made very slight adjustments here to ensure rivet holes line up.

All done and clecoed.

Next I need to work on drilling the F-601J angles. Now this is not the most fun part and I find the process for getting it right quite tedious. I have started by using scotch tape to place the gussets and spaces that are located under the angles. Then I carefully clamp the angles on the the bulkhead checking for proper spacing (3/32" below).


Once clamped, I flip the assembly over and use the drill to start a pilot hole in the backside F-601J angles. This way I can ensure proper edge distances before I drill through. Once I am happy everything looks right, I can then complete drilling holes to 1/8" on the drill press.