Hi Josh,
I used some high-temperature red silicone sealant from a local auto supply store.
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Hi Josh,
I used some high-temperature red silicone sealant from a local auto supply store.
Did the same as john on our plane for firewall penetration points....
Have to admit it is kinda fun putting blobs of various materials on a test plate....let them cure and turn the torch on them to see what happens.
Ditto what John and Dave did.
I used this stuff. It supposedly chars in place and supposedly doesn't generate smoke or toxins. Only problem is it isn't really a sealant, as it never "cures". It's rather like clay, moldable and sticky.
Josh,
There are two things I want to comment on. First you mention that you fed a fuel line through a 1" hole. Does that mean that you ran a hose or aluminum tubing through the firewall. Normally firewall fittings are used for any fluid and air lines going to/from the engine compartment and there are removable B nuts on both sides of the firewall. Running tubing or a hose through a fire wall hole can lead to them being chaffed or cut by the firewall. Fittings eliminate the need for sealant too.
My Model 5 kit came with aluminum firewall fittings, but I upgraded them to steel fittings. Why?
1. That is the standard for certified aircraft [CFR 23.1191 (h)(5)]. Steel fittings are fire resistant and can hold up to a fire, whereas aluminum ones will melt at a much lower temperature than steel (1220 F vs. 2500+ F).
2. If the nut holding an aluminum bulkhead fitting were to come loose in its hole the fitting can vibrate against the firewall, cutting through it and causing a leak.
3. Fuel or oil leaks can lead to fire, fuel exhaustion or engine seizure. Nobody wants these emergencies to happen, especially if it was preventable by putting in steel fittings.
The second thing I wanted to mention was sealing the firewall, which is also mentioned in CFR 23.1191 (c). You want to seal up every firewall penetration. There shouldn't be many holes that need sealant, primarily where wiring and cables go though. I used 3M Fire Barrier Silicone Sealant 2000+, which can be bought on Amazon. It doesn't show a temperature rating, but it is made to withstand fire for a long period of time. I would not suggest using the red high temp RTV that is available at the automotive stores, it is only good to 600-700 degrees and would melt or burn away immediately in the event of an engine fire.
One more thing. You mentioned riveting a carry through to the firewall. Make sure you use stainless steel or monel rivets, not aluminum rivets. Aluminum rivets may not hold up to a fire and melt away if there is an engine fire.
An engine bay fire in any aircraft is definitely something to do your best to mitigate. That said, the cowl is fiberglass and the stainless steel fuse lower cover is only 6 or so inches long. If the fire is that hot in a Kitfox engine compartment, It's likely the cowl will melt before anything made of metal whether stainless, aluminum or 4130. Then the glareshield and windshield - next is the covering and wooden floorboards. Then you.
Make SURE your fuel system is perfect. Nothing less.
I was told by G&N engines that they use and recommend steel AN fittings on engines because they are stronger than aluminum and therefore much less likely to break. The same could be said for firewall fittings. I am using steel fittings for fuel line penetrations on the firewall.
I Have not seen a line run through a firewall, but that doesn't mean they don't exist.
I have been picking away at small stuff, nothing major enough to warrant a post. I put the engine stuff on hold for now that the weather is nice as I have some jobs that involve sanding and trimming etc.
I sanded the extrusion lines out of the strut fairings and rough fit one side so far.
Thanks Josh
Helped me get my minds eye on how that is done.
Eddie
Josh, I wouldn't bother with those two small pieces of fairing above the upper crossbar.