Firewall Forward

October 21, 2012

More Parts on the Firewall - Heater Box - 4.0 Hours

Well, my new heater box showed up in the mail, so it's time to get motivated and get it on! I wanted an upgraded all-stainless steel unit, since the ones from Vans are aluminum. So I shopped around and ended up ordering this one from Plane Innovations. They shipped it immediately, and it arrived here quickly. Nice experience, doing business with them. This is a very good unit. It came with the hardware for attaching the control cable, and even a small tube of sealant to seal it to the firewall and prevent engine compartment fumes, etc from leaking into the cabin. Nice!

So it was time to enlarge the pilot hole in the firewall to a 2" size. My new Greenlee knockout punch came in very handy for the job. However, I had been reading about how the thin stainless steel firewall might have a tendency to bend into the punch rather than sheer off. So I thought about it, and decided to use a pair of aluminum sheet scrap pieces, one on either side of the firewall. I reasoned that the punch, cutting through the aluminum-stainless-aluminum "sandwich", if you will, might just do a better job on the thin stainless steel, than if I tried to punch through the stainless firewall alone. As I suspected, this took more muscle to tighten up the bolt and bring the punch through the material, but it did work beautifully! I only had one little area where some of the metal bent into the punch, leaving a small piece roughly 1/2" long and about 1/8" of extra material. It wasn't too hard to grind that off. I spent some time with my files, emery paper, and my Dremel tool to deburr the hole and smooth it all out. Here it is, ready to mount the heater box. As you can see, the holes for the bolts have also been located, drilled and deburred.

I cleaned it and the heater box surface with some MEK before applying the sealant. Then I bolted it on, and that was that. A sharp eye will see a nylock nut showing in the picture below. I ordered some stainless steel hardware, bolts, washers, and self-locking stainless nuts to replace this hardware. So it's only on there temporarily. I'll swap it out for the permanent hardware when it arrives.

Next, when I was at Vans recently, I bought the Transducer Manifold that bolts onto the firewall near the top on the left side. Hoses from the oil system and the fuel system come into this unit, and sensors go out from here through the firewall into the cabin to the instrument panel, allowing you to monitor your fuel pressure and your oil pressure. Neat! It's fun learning how all this stuff works, things that I've taken for granted in all my automotive experience. The third position, at the top, may or may not be used for the manifold pressure, depending on what kind of instrumentation you end up with in the panel, according to the guys at Vans. If you don't use this port you can cut it off, but I probably will use it. We'll see. I located the position on the firewall where this will go, and drilled the mounting holes for it. Once again, it involved drilling out one rivet and enlarging the hole to #12. The only reason I didn't bolt it on yet is because I need the 90° AN fitting on the bottom port, and I'd like to know whether or not I'm going to use the top position so I can get whatever fitting I might need into that place as well. You can't get the fittings on if the unit is mounted; there's no room to turn the part into the hole. So it will wait until I'm ready. The 3 little brass plugs go into the holes on the other side to seal it up, but the fit of these is not tight enough on it's own. I ordered some loctite, and when it gets here I'll install those plugs and be ready to install this whole unit in place.

Finally, when I went to Vans, I dug real deep and nearly choked when making one more purchase. I bought the motor mounts for my engine, and the bolt kit that goes with it. You get screwed royally on this deal, but there's nothing you can do about it. It's not Van's fault.

This was very hard for me. I've been choking back my reaction to spending money on these for weeks now. It goes so deep against the grain in me to pay through the nose for something. Anything. I hate getting ripped off, and these items have to be one of the biggest rip-offs in all of aviation. Yes, they're very nicely made and all. And I appreciate the seriousness of the job they do to hold your engine in place. But at the end of the day, it's just a couple of pieces of rubber, some nice metal end caps, and a squishy spacer that goes in the middle. There's no way these should cost as much as they do. Come on! I'd be interested in knowing what the company's bottom line cost of manufacturing is on these pieces. You should be able to get all 4 of them for the price of one, it seems to me. The problem is twofold, as I see it. One, they're "certificated" for certified aircraft. Everyone knows that ups the price into the stratosphere right there. Second, the company has a monopoly. They can set whatever price they want and there's nothing you can do about it. The guys at Vans were very sympathetic to my groans. They explained that they used to be able to get them from another company when there was some good competition. It was a good product, too, at a much better price. But that company isn't making them anymore and Vans now has no choice but to get them from Lords. Apparently, there isn't a big enough market to attract some competition into the arena. Anyway, it's done. So this will be the end of my whining. I can't hang my engine without them, and I now have them on my shelf.

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