« Posts tagged engine mount

Wandering aimlessly.

4 hours.

I got a call from Don Rivera at Airflow Performance regarding the quandaries of my servo installation. He said I was basically on the right track, but that yes, i’d have to make my own brackets for the throttle and mix cables. Also, there’s no reversing the butterfly. I found about $200 worth of hoses that can go back to Van’s, and I got the temperature probes installed and the extensions run back to the RDAC. I almost got the breather tube done, but I really need to get off the FWF install and go back to wiring and avionics. Basically, I puttered around, unfocused, looking for an easy way into the next step. There isn’t one. I don’t have the cables, hoses, or fittings I need to do more FWF, so screw it, I’m going back to electrical.

This is harder than you might think. Every time I walk past the engine, I find something to distract me. All these little distractions start out as “I wonder if THIS will work.” As a result, I got nothing significant done, other than the installation of a couple of probes and senders. Not that this is a bad thing, but if I had focused on avionics and panel, I could have gotten a lot more done, since I have all the stuff required to get that done.

I’m also looking at the baffles. I suspect I might have some problems where the prop governor sits, and that is going to suck.

Linkages, obstacles.

I read all the warnings. “Use a Van’s-approved engine or you’ll have a ton of trouble making everything fit.” Or this one: “By the time you convert the engine to what you want, you’ll have spent just as much money as if you’d bought new.” Tinker or fly? So, I now have a laundry list of issues related to my particular setup that will now require no small amount of customization, some of it in steel, which I haven’t had much to do with since shoehorning large snowmobile engines onto the backs of go-karts back in the mid-80’s. Here’s the list of fun so far:

-Throttle body interferes with the starter. The Kelley Aerospace starter has a retaining bolt on it that prevents the TB from being mounted in the diaphragm-up position.
-Stock brackets won’t work. Either the mixture or the throttle arm goes the wrong way when pushed, so a bellcrank is probably going to be required.
-AFP throttle body won’t play nice with the airbox. More fun with fiberglass.
-Fuel hose from engine pump to TB inlet is too short in any position except the one that won’t work because of the starter.
-Custom-length quadrant cables will be required.
-Throttle and mixture arms interfere with factory-set linkages when oriented in directions that work for me. I’ll need a straight arm from Don at Airflow.
-Right magneto interferes with battery box. Will need to be re-indexed for harness to clear and be retimed.
-Left magneto had to be removed to adjust oil cooler fitting. Timing will need to be reset.
-Breather tube is a little close to the RDAC. Should be OK though.
-Alternator interference unknown at this time, since I haven’t purchased it yet.
-Oil cooler taken off the engine when I got it is cracked. Need a new one.

Fun with the Firewall

5 hours.

I can walk around that plane all day long and find things to not do because one of the ducks isn’t in its assigned row. Problem is, the days are getting shorter and I can’t wait for everything to fall into place. The firewall has been one of those things. I still need to make holes for wire pass-throughs, and bolt various things to it, some unknown as to their specific configurations and form factors. But sometimes, you have to make a move. Today I fire-sealed the cabin heat box and installed the firewall recess.

This is halfway through the process. The cabin heat box is done, and the battery box is in place. , All the gaps and openings need to be sealed up in case there’s an engine fire. A gasoline-accelerated fire in the engine compartment fanned by a 200mph gale would make every hole, crack, and gap a 2000-degree blowtorch aimed right at the occupants’ legs, something we’d very much like to avoid. I’m using 3M Fire Barrier 2000 in all those cracks. Hi-temp RTV is rated for 700 degrees, this is rated for 2000.

Hopefully this won’t be an issue. You’re not supposed to use rigid tubing from anything fixed to the airframe to anything attached to the engine. The reason for this is obvious: the engine vibration will fatigue and split a hard line in a fairly short amount of time. This is why you’re supposed to use braided steel and flexible, firesleeved hoses for fuel lines between the firewall and the fuel pump.

Since I was fire-sealing everything, I figured why not, let’s put the engine mount on. After sealing the lower firewall corners and the brake reservoir, I got the engine mount on, permanently. I considered being a showoff and putting the plane up on the gear, but then I realized I’d omitted a rather important detail: I’d forgotten to notch out a section of the lower firewall corners to make room for the gear legs. Not one of my prouder moments. But I was able to scribe out a section to remove, which I did, and it would have been really easy if it hadn’t been for the fact that stainless steel sucks to work with. It bites, so you have to file the edges down. It also hardens if you heat it up, with something like a Dremel burr. Finally I was able to get some notches done, but they’re not that pretty. That’s what gear leg fairings are for though, right?

Here’s the firewall recess all riveted in. There’s a bead of fire seal under the flanges in addition to the seams in the recess. I hope that goop doesn’t run too much before it cures.

What happens next? I don’t know. I have the rudder available to work on, maybe I’ll do the taillight.

Let Them Eat Static.

1 hour.

Finished installing the static line. Much easier to crawl down the Jeffries tube with the flap motor bracket removed. I also made some .063 spacers for engine mount. Supposedly they weld it all up in a jig at the factory, and drill the QB fuselages with the same jig, but maybe the welding process stretches the metal a bit. Anyhoo, I had to make two aluminum washers to go behind the lower middle attach points, which, fortunately, are about .063″ off the firewall when the 4 outside bolts go on. They’re probably not exactly .063″, but they will be when everything is tightened down. I have a good feeling about it. I also got out the fiberglass cap that goes on the bottom of the rudder to see how it might accommodate the Whelen A500 position light/strobe assembly, and the answer is: not that well. There will be a need for fiberglass work here, I think. I’ll have to somehow build up enough material to drill and tap threads, or I’ll have to figure out a way to get a backing plate in there. Neither option looks like fun, but there’s gotta be some light back there or we ain’t legal. I know I promised photos, but I forgot to bring my phone. I’ll catch up with that later.