Firewall mounting/strengthening

[Nev]

My Bearhawk has got the titanium firewall.

Should I be adding a strengthening doubler behind heavier items such as the oil cooler and battery (if it’s mounted there) ? What are others doing ?

Thanks.

[BTAZ]

I welded tabs/brackets on to the tubing for everywhere something mounted to the firewall so the weight would be on the mounting tabs and not the thin firewall.

Tabs for the oil cooler, battery, solenoid, and probably a couple other items I have forgotten about.

[whee]

I welded tabs to the tubes behind the firewall. If I had a kit and didn’t want to weld I would: 1. Used clamps and angle aluminum to put brackets behind the firewall. 2. Rivet doublers on the firewall. IMO, there is sufficient strength in the firewall if you attach it to the fuselage well.

[robcaldwell]

Same as the others... I utilized all of the existing tabs for mounting heavier items such as the oil cooler and battery box. .06 AL doublers behind other components that I felt need more rigidity.

[svyolo]

I used Ti also, and it is pretty flimsy, more so than the kit SS one. It is called "commercially pure" titanium. I will put some .032 bent angles to support the oil cooler and battery in a way that the tubes will take most of the load. I don't think it will take a lot.

[Battson]

The remote oil filter is the one to watch Nev.

I don't have experience with the Ti firewall, but even with stainless steel - you are REALL leaning on the firewall when you unscrew the remote oil filter. Getting it started turning can be a little scary. The firewall really bends.

I installed a doubler (mostly by good luck, not good knowledge) and I am always glad I did!

Using the correct Dowell-Corning grease on the filter seal makes a huge difference though, much less force required. Using clean oil is a lot less satisfactory.

[svyolo]

I hadn't considered that yet. Thanks.

[AKKen07]

So the doublers that you install on the firewall - are they just flat pieces of thicker aluminum - say .04 or .05? I would guess you'd make them a bit larger than the fastening outline and install them on the... engine side of the fw?

[Battson]

That is all I did, except I put the Aluminium on the inside so the parts are mounted directly onto the stainless

[AKKen07]

Cool, thanks!

[Nev]

Another firewall related question……

The AN3 bolts that attach the firewall to the airframe lugs, is it ok to use nylocs on the cabin side of the firewall? What’s best practice? This is clearly an afterthought for me as I’m going over everything and questioning if I’ve done up every bolt etc.

[Mark Goldberg]

Using AN365 nut on the cabin side of the firewall is acceptable. Mark

[Nev]

Thanks Mark !