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Firewall Penetration Hardware

fabricflyer

Well Known Member
What is the consensus out there? How are you routing your engine control cables through the firewall? Are you using the Vans method with the two snap bushings and Proseal, or are you using a firewall eyeball? Any and all thoughts are welcome.
Allen
 
I used the eyeballs...look better, hold the cables securely at the correct angles, and are, I think (others will no doubt disagree) the right tool for the right job.
 
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What is the consensus out there? How are you routing your engine control cables through the firewall? Are you using the Vans method with the two snap bushings and Proseal, or are you using a firewall eyeball? Any and all thoughts are welcome.
Allen

There is no consensus. It tends to break down into two camps.

One camp is those who follow Van's methods unquestioningly, which in this case means a cheap and quick and dirty way of penetrating the firewall, but that's probably fairly ineffective in containing an actual fire should one ever occur.

The other camp is those of us (I count myself among this camp) who take the threat of engine fire more seriously, and want to give the firewall the best chance to do its job, should it ever be called upon. So in this case, a steel eyeball would be the better way to go, though admittedly it is more expensive and a little heavier.

Note that if you're serious about maintaining the integrity of your firewall, there is more to it than just using eyeball fittings for the control cables. Each and every penetration, from control cables to electrical to plumbing to cabin heat needs to be sealed properly, using effective methods and materials. Your firewall is only as good as its weakest link.

The topic of firewall integrity has been discussed in great detail in many threads on this forum. Use the search function and do some reading.
 
Fabricated my own

I am using an electrical fitting from the aviation section at Home Depot with a 4" section of fire sleeve. The fitting has a locknut on the back of the firewall and the fire sleeve is held on with 2 hose clamps.
 
I'm in Roee's camp ....

For some attention and a few bucks focused on FW penetrations, you get a ton of added safety.
 
I am a proponent of the tube and firesleeve penetrations per Aeroelectric and elsewhere.

I also think the eyeballs are overused. They are not automatically fire resistant. Sealant must be added. In addition, the onlypass through that needs it is a prop control.
 
I am using an electrical fitting from the aviation section at Home Depot with a 4" section of fire sleeve. The fitting has a locknut on the back of the firewall and the fire sleeve is held on with 2 hose clamps.
What was the name or intended use of the Home Depot electrical fitting with a locknut? I like the idea and it sounds like it would work nicely on my firewall.
Thanks, Eric Schlanser
 
I bet it was one of these, I saw them in the conduit section and for $1.50 I bought a couple of sizes to possibly use.
55DCFEE3-9ED1-487F-AB01-742E3892A9AD-9217-000004FAB65D7CC3_zps88761f47.jpg
 
I bought several of these. Haven't installed yet.

http://www.averytools.com/prodinfo.asp?number=SA-05

There seems to be a lot of talk about stainless (especially with the TG-10). Does anyone know of an actual fire in an RV fwd of the firewall?

Similar thing as the DIY kit but stainless instead of plated steel and a lot more $. The fires I have been aware of, the bottom skin proved to be the weak point, not the firewall. There have been very few.
For what it Is worth I followed Van's Heyco method with firestop, not proseal.
Dan H has done exhaustive testing and his results and conversations can be searched out. Worth the read.
 
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That's probably it. Definitely fireproof. I wonder if it will hold up under vibration on the thin firewall. Maybe attach it to a doubler on the firewall somehow? But I can't see how with that thin nut.
 
I made my own, similar (but with a square flange) to the Avery ones. Some tube, some sheet and a punch (and a few TIG tacks. I needed a bunch of small ones to accommodate a bunch of already placed things in my panel rebuild/rewire/firewall redo, so I couldn't swing $45 per, our whatever they get...
 
Does anyone know of an actual fire in an RV fwd of the firewall?

Thankfully inflight fire is not common, but yes, it happens. We even had one documented here on VAF, Ted Chang's RV-10.

Going to the NTSB reports, here is one example illustrating why you don't want polyester, rubber, or plastic insulation on the inside of a firewall. It happened in the pattern, at low altitude with a runway available. The pilot was well known, and competent.

http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001211X11589&ntsbno=LAX99LA063&akey=1

Returning to firewall penetrations.....a steel eyeball with the open (hollow) end facing forward and filled with something like 3M FireBarrier 2000 would seal gas tight several minutes into a fire. Welded steel tube-and-plate pass throughs can be easily fabricated and are far, far less expensive. Either will maintain an intact seal in direct 2000F flame for a significant time.

I did a firewall burn to compare various sealants, but it also serves to illustrate penetration methods. Plastic grommets covered by a glob of orange silicone don't buy much time....less than 2 minutes to total failure in this example, probably less than a minute in direct flame.

The fun starts at post 38:

www.vansairforce.com/community/showthread.php?t=72087
 
Thanks Dan, great info. Think I'll go with the 3M product.

I knew about Ted's RV-10 (ground fire in SAV right?) but was curious if there were any inflight.

The link to the NTSB report, was the ultimate probably cause because that industrial fitting backed off allowing a fuel leak? Read all the data but never saw a summary.
 
...I knew about Ted's RV-10 (ground fire in SAV right?) but was curious if there were any inflight. ...

I remember when this one happened, and it still depresses me when I think about it:(
http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001212X19358&key=1

...The link to the NTSB report, was the ultimate probably cause because that industrial fitting backed off allowing a fuel leak? Read all the data but never saw a summary.

It may just be the way I read the report, but due to how recent the condition inspection had been conducted, the fitting probably wasn't torqued adequately. I'd bet that wasn't the only "industrial" fitting on the engine, but it appears to have been the only loose one.
 
I knew about Ted's RV-10 (ground fire in SAV right?) but was curious if there were any inflight.

Inflight. He had to pop the door to clear smoke from the burning insulation, then put it in a field. The ground fire was because the insulation choice would not extinguish.

Ted was very lucky. As I recall the insulation was limited to the tunnel, so he did not face open flame. And the RV-10 has a tear-away door; he was able to ventilate.

...fitting backed off allowing a fuel leak?

Yes, for both the Chang and Dallman fires. The NTSB report for the Dallman accident indicates a loose B-nut on the pump output fitting.

There's a first person account here, page 2:

http://www.eaa292.org/ttd/ttd11.09.pdf

Mr Schelling's version of the cause (last paragraph) is not consistent with the recorded evidence.

Aggressive flame and very thick black smoke smelling of plastic or fiberglass is consistent with two tested materials sold as "firewall insulation", Soundex rubber mat and Thermozite Plus. Both are all too common in RVs and Rockets.
 
Not finding a source for a tube or two of 3M Fire Barrier 2000+. None of the box stores carry it any more. Online they all want to sell a case or a bucket and I don't think it takes that much. How many tubes does it take?

In a short phone call today, the 3M guy says their Fire Barrier 1000NS has similar properties and won't slump on a vertical surface during installation. But the data sheets show some differences in components and properties. Has this product been evaluated for our use on firewall penetrations?

Are there any more pictures of the ceramic blanket/SS foil on the firewall? The one posted in the link is just enough to be a tease.
 
Thanks. I saw the same link that Phil had posted on the other thread about this. Came back to confess and saw your post beat mine. Sometimes the most obvious place is the last one.

Any opinions on 3M Fire Barrier 1000NS?
 
I knew about Ted's RV-10 (ground fire in SAV right?) but was curious if there were any inflight.

The on the ground fire at SAV was Todd Sqezey's 10. Dan's description of my accident is accurate. When I saw the fire on the bottom of the firewall I shut the fuel. Flame was less than an inch high. Of course without fuel the fan in front stopped. I was lucky on several accounts and made it out only with hurt ego. If I had read Dan's report on firewall insulators I would not have that insulator in my tunnel and would have much less damage.


The red stuff in the picture is 3M stuff from Lowes.
IMG_1936.JPG
 
Fire

There was also the Rocket incident at San Diego where the pilot was unhurt but the airplane was badly damaged. IIRC also a loose fuel pump fitting. The AC style fuel pumps use a o ring type seal. The nut compresses this seal and prevents fuel leakage. If the nut is loose a significant amount of fuel will leak past the fitting threads. The fittings are straight thread.
If the fitting is a 90 or 45, you can try to turn the fitting/hose by hand. If the fitting moves the nut is loose. If the fitting is straight, you will have to put a wrench on it.
These should be checked at every oil change.
 
Does anyone know of an actual fire in an RV fwd of the firewall?

Yes, I saw the remains of an RV6 that caught fire due to a fuel pressure hose leak.

Firewall was fine but there was a BIG hole in the aluminum skin inder the pilots feet. I never met the gentleman but common friends indicated that his shoes were burned but he was OK.

As a result of that observation, I insulated my floorboards with the Mcmaster Carr ceramic batting discussed in other fireproofing threads here. Alternatively, a stainless sheet could be used for a few inches on the underside of the fuselage.
 
I knew you had done some SS work Dan and thats why I mentioned it. I thought you had gone all the way across.

It has been 8 years since I saw that guys plane so memory can lie. I thought the damage extended to the corner of the fuselage but that would mean the cowl had to have burned away in that area instead of the flames concentrating in the cowl exit. I do not remember seeing the cowl itself because it was removed and my attention was on the firewall and fuselage.
 
I bet it was one of these, I saw them in the conduit section and for $1.50 I bought a couple of sizes to possibly use.
55DCFEE3-9ED1-487F-AB01-742E3892A9AD-9217-000004FAB65D7CC3_zps88761f47.jpg

These are probably not a good choice with the sharp edges. In the same department you can find chase nipples which are made to not chafe the wires. They are threaded for locknuts also.
 
eyeball orientation

...Returning to firewall penetrations.....a steel eyeball with the open (hollow) end facing forward and filled with something like 3M FireBarrier 2000 ...
Hi Dan, This is a great idea - I had never thought about this orientation and I am just about at this point in my build. Regards, Mickey
 
I had never thought about this orientation and I am just about at this point in my build. Regards, Mickey

You're welcome Mickey. The 3M FireBarrier 2000 is intumescent, so even if the cable burns off the sealant will swell and fill the hole. Open side forward means if/when the silicone component chars, it will not introduce flame or smoke into the cockpit.
 
I bought several of these. Haven't installed yet.

http://www.averytools.com/prodinfo.asp?number=SA-05

There seems to be a lot of talk about stainless (especially with the TG-10). Does anyone know of an actual fire in an RV fwd of the firewall?

Yes. I am aware of one fire in an RV-10. The pilot made a great off-field landing and was able to walk away with only minor burns. Unfortunately, the airframe was a loss. I understand the tunnel floor was burned through even though the time of the fire was fairly short.
 
Dimensions?

Would anyone who has some or access to them, please give me the outer physical dimensions (the sheet metal) of the Van's options for firewall penetrations. I only need the bottom 2, I have some of the one-hole blue eyeballs.

Thanks,
GH
cat-med_one_eye.jpg
 
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