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RV Fire

Vern

Vern

Well Known Member
Yesterday was sobering experience for me!

I got a call from a local A&P/AI who needed advice about an RV-6 that he had been asked to rebuild. I went over to have a look at the RV-6 and was shocked by what I saw, which I share for your safety.

This older RV had just had an IO-360 and blended prop installed professionally at another airport. The owner had flown to our airport (KFFC) and was about to depart for his homedrome. He was in the runup area beside an avionics shop. While performing his runup, his RV engine area burst into flames. Several mechanics rushed out with extinguishers, put the fire out, and got the pilot out with some burns on his legs.

When I looked at the RV yesterday, the tip up canopy, cowl, seats, and all instruments and radios had been removed.

Another mechanic and I surmised that a small 1/8" copper tube from the rear-mounted mechanical fuel pump to a fuel pressure sending unit broke during the runup, allowing fuel from the 1/8" copper line to spray out above the exhaust. This fire only lasted a few minutes due to the quick response by the mechanics. In that short time, every wire and hose firewall forward was either melted or damaged. The entire panel wiring was a melted mess. The interior floorboard 1" black insulation was mostly melted.

Apparently, the fire was like a blow-torch as the windblast from the runup caused the lower firewall and lower cowl exit area to direct the fire down and underneath the RV.

Incredibly, the canopy and cowling are useable. The cowl will need some repairs, but it did not burn thru.

Even though the paint under the airplane did not burn off, and no rivets 'popped' I am concerned that the thick bottom skin in front of the wing spar may need replacing due to tempering from the heat. Certainly the mags, fuel pump, and prop gov need overhauling due to possible heat damage. The firewall seems OK.

My points: if this plane had taken off, the heat from the fire would have really burned the pilot, possibly incapacitating him quickly. His instruments and accessories would have failed shortly. An aluminum airbox would have soon allowed flames inside the cockpit. All this from the fuel spray from a 1/8" line! What would the main fuel line do? (I know-I've witnessed that also)

So, next time your cowl is off, take a critical look at your systems. Everything firesleeved? Have you got any stiff copper lines? Do lines have service loops/slack in them? Any 'stiff' lines used to join the shaking engine and the fixed firewall? All B-nuts tight? All openings in the firewall sealed? Any hidden chafing ready to wear through?

Another area we RV'ers might look at is at our brake lines and fittings which is another potential fire source for our RV design. What about leaking fuel tanks allowing fuel to seep in under our seats and ignite due to electrical devices under the floor boards?

In my AF days I survived a number of inflight fires and explosions. It's no fun when the smoke is so thick and pungent you can't see the fire handles glowing bright red!

We have a fun hobby and we all want to fly safe. Join me in taking another look at your RV to keep it that way!

Yesterday was sobering experience for me!
 
Thank you for posting this, Vern!!! My cowl is off now and I'm going over this area again when I go out to the airport next.
b,
d
 
Thanks for the post. You said that the panel wiring was melted, and the pilot was burned. Did flames actually penetrate the firewall, and via what route?
 
Thanks

Thanks Vern,
My big concern is that more guys may be using that same, thin, copper tubing to run to the pressure sender, just waiting for a catastrophe, since it's always under pressure if the engine's running. That line should be a Mil-spec braided hose and firesleeved.

I'm reminded of the guy who bailed out of his burning -8 a few years ago, with no parachute, from almost 1000 feet!

The only place I can see using copper tubing for fuel is on a primer line that is only under pressure during priming and not in flight.

Be safe guys,
 
Thanks for posting this. It points to reality of fuel or oil fires. An article in an aviation magazine a couple years back was talking about firewall security and having everything last 20 minutes with flame on the engine side of the firewall! This is crazy. No matter how you seal wiring and if you use a SS heater valve or not, smoke and flames will be inside the cockpit in seconds. SCAT hose and Tefzel are gone at 800-1000F pretty quickly and the fire spreads very rapidly with a 150mph gale feeding it.

We had a fellow killed up here last year in a Canard (American aircraft and pilot). Cause appeared to be a fire caused by an exhaust pipe failure right after takeoff. He tried to return to the airport but was overcome by smoke and fire in less than a minute and crashed on a road nearby. This was with the engine behind him.

Yes, check integrity of all hoses, lines and exhaust systems often. Don't use copper lines for flammable liquids as it work hardens and can fracture in a pretty short time.
 
More info...

i just talked to the pilot. He's a retired airline captain.

His feet and legs are blistered and hurting.

No actual flames got inside the cockpit. It was all heat... like being in an oven being cooked alive . There was 1" floor insulation but no carpet.
 
Glad he is ok and quick action on the mechanics part. I keep 3 CO2 (not dry chemical) fire extinguishers in my hangar. Two 15lb and one 30lb. With CO2 extinguishers you can put the fire out on someone if they are on fire and it is easier on airplanes too.

Wow, that much heat through 1" insulation!
 
Fire Sleeving

pierre smith said:
That line should be a Mil-spec braided hose and firesleeved.
Click to expand...

My plane has a Mil-spec, braided, firesleeved, hose going to the fuel pressure sender; but the sender is not firesleeved. Since I have seen a number of posts stressing the need to firesleeve fuel flow transducers; should not the fuel pressure transducer also be firesleeved?
 
BillyBob said:
My plane has a Mil-spec, braided, firesleeved, hose going to the fuel pressure sender; but the sender is not firesleeved. Since I have seen a number of posts stressing the need to firesleeve fuel flow transducers; should not the fuel pressure transducer also be firesleeved?
Click to expand...
Not sure about all fuel press xducers, but mines almost 2" in diameter and hard-mounted to a block on the firewall. Would be tricky to firesleeve. Certainly shielding from radiant energy wouldn't be a bad idea.

Couple of other points to consider...

1. Keep an eye on all components in the fuel delivery system, not just hose versus tubing. Check to make sure your fittings are substantial, not in a bind and not subject to excessive vibration. I've got a tee fitting on my carb feed pt. that I plan to change to steel during my next annual. It's AN aluminum, but I'm just not comfortable with the overhang possibly allowing for cracking at the carb.

2. Use some type of restrictor in the fuel pressure transducer sender line. Even with small dia. hose, I have a homemade ~.032" dia restriction orifice in my fuel transducer sender line at the carb.
 
This seems to be an oppertune time to put in a PLUG for firesleeve, especially to you guys using the Eggenfeller engines. Jan seems to think that firesleeve is optional on his engines. These are fuel injected engines with high pressure fuel systems. If you choose to NOT use firesleeve on fuel lines forward of the firewall, don't call me for an airworthiness inspection.
 
Mel said:
This seems to be an oppertune time to put in a PLUG for firesleeve. If you choose to NOT use firesleeve on fuel lines forward of the firewall, don't call me for an airworthiness inspection.
Click to expand...

So then what would you suggest for this installation?

2002-09-22_23-01-06.jpg


It's hard pipe, but both ends are solid on the firewall and not moving anywhere. Is there value in putting firesleve over the alu tube and some how securing the ends near the b-nuts?

This has been working fine this way for 500 hours thus far, but I'm always looking for upgrades.
 
Mel said:
This seems to be an oppertune time to put in a PLUG for firesleeve, especially to you guys using the Eggenfeller engines. Jan seems to think that firesleeve is optional on his engines. These are fuel injected engines with high pressure fuel systems. If you choose to NOT use firesleeve on fuel lines forward of the firewall, don't call me for an airworthiness inspection.
Click to expand...

Good point and remember that rigid aluminum fuel lines need firesleeve also as they will melt through quickly in the case of a fuel fire. Aluminum AN fittings will also go in less than a minute so maybe we should consider steel fittings firewall forward. All food for thought.
 
akarmy said:
So then what would you suggest for this installation?
Click to expand...

Hi Andy,
I did something similar and the local technical counselor recommended firesleeving it. You made yours from the same type of soft aluminum tubing as the cockpit fuel lines, right?

After some discussion here I didn't use firesleeve clamps (needs a special tool), and just safety-wired around the sleeve at both ends. Seems pretty secure. The hard part is getting the firesleeve over the tubing with the flares (and perhaps the fittings too)

I don't know about yours, but my tubing is a bit close to the cowl. Not enough to touch in flight, but could be banged when putting the cowl on and you might not notice. I'm a little worried about that.

Paul
 
Firesleeve is normally used on flexible fuel & oil lines and not required on metal lines. There is certainally nothing wrong on firesleeving metal lines but it is not required. Some one is going to say that firesleeve is not required by FARs. That's true, but the inspector can reject anything he considers unsafe.
 
I guess the purpose of fire sleeve is ultimately to keep other critical parts from melting or burning through in the case of fuel or oil fires and making the situation even worse.

If we logically consider other fuel and oil lines as vunerable to 1400F flame, all aluminum or rubber lines should be fire sleeved irregardless of convention. A rigid -6 aluminum fuel line with .035 wall will melt through in less than 30 seconds if exposed to a 1400F flame so it doesn't make sense in thinking these are ok just because they are metallic. Steel or steel braided lines are the only really safe bet- using steel fittings. An aluminum AN fitting will just take a bit longer to melt through than a thin line.

How far do we carry what is acceptable? How long do we need to be fireproof?

I've seen more fires started in race cars with improperly supported heavy braided hose hung off mandrel bent AN fittings. The vibration and mass fractures the fittings. In racing, I used more rigid steel line and steel fittings in high stress/ vibration areas.

The potential for failure and fire is to be found in the weakest link in the chain.
 
Spruce sells this economy tool for firesleeve clamps...

Economy Firesleeve Clamp Tool ..P/N 12-00684 ..$16.90

It is really an automotive CV joint boot clamp tool so you get dual use. Perhaps you could find it locally.

Thinned down silicone will help protect the firesleeve ends. The real sealant is very expensive.
 
flexible hoses, aluminum, and steel tubing, and fire sleeve

In general, flexible hoses are most susceptible to heat (fire) damage and need the fire sleeve. Otherwise the heat will melt the material under the steel braiding and fuel will leak out, further feeding the fire that is causing the heat.

I have fogotten the regs, but I thought, and someone can easily correct, that steel tubing or firesleeved flexible hose are required in front of the firewall on certified airplanes.

Steel tubing can withstand higher temps even with static fuel in the tube.

However, aluminum tubing resistance to burn-through improves significantly if fuel is flowing through the tubing. I'll bet that makes you feel good, fire impinging on an aluminum tube flowing fuel.

The aluminum arrangement shown in Andy's photo is probably not that bad in that the tube would be flowing fuel and thus have some protection from fire impingment until the engnine is shut down. If the fuel is subsequently shut off at the fuel selector, the tube could burn through without fuel feeding the fire from the tank.

Aluminum tubing is allowed in the wing and wheel well areas on twins (or used to be) because of the so-called fire resistance when they are flowing fuel. Of course, that is not a high risk area like an engine compartment.

A fire impinging on the front of the firewall will autoignite combustibles in contact with the backside of a firewall so make sure your insulation has fire retardant properties. I have use the black and red RTV on the front side of the firewall. Guess I need to reevaluate RTVs fire resistant properties.
 
tubing

The other day on the ramp at LZU a rv-4 pulled up and the owner hopped out and said he had an exhaust leak... well he was correct. He also had blue stain in his engine compartment.... After looking around I touched the copper tube that came up vertically from his fuel gascolator. It popped off and fuel started comming out.... It had been leaking for a while and I'm glad I found it.... It had been overflared and broke as soon as I touched it. Another rv-4 I did a condition inspection on had chaffing on the oil dipstick tube on the motor mount and chaffing on the flap pushrods.... There is no Magic Bean under the hood gentleman..... and the pilot of the rv-6 was very lucky to get out alive... I give some free time to pilots who are not mechanics.... not my entire schedule... but enough to get them out of trouble... or if they have questions... I've seen some stuff that has really scared me so I'm always available for consultation.... If I dont know the answer... I know who to ask for the answer....
Lets be safe please....
Brian Wallis
404-405-1315
AP/IA
 
Ruin your whole day

I have nightmares of inflight fires, which can bring down anysize plane. Note to self, do everything possible and tripled check to avoid potential for fuel leaks, especially around the exhaust.
 
GMC - I think that might be your shortest post EVER! :D :D :D

I am following this thread with interest... how much info / instruction is there with the finish / FWF kit regarding safety issues like this?

T.
 
If I recall correctly the standard for firewall materials is 2000F. It's one thing to read specs and imagine results. Its a whole 'nother thing to see stuff with your own eyes.

Some years ago I did some simple testing for a proposed vehicle configuration (a pusher) with primary structure in the engine compartment. The question was how to protect that structure, IF possible. The test is easy to duplicate, and a real eye opener for a homebuilder. Not precise scientific method, but it works.

Set up a clamp to hold your OA torch. Put a rosebud tip in it. Set up another clamp arm with a clip or something to hold the subject material. Your "calibrator" is a square of copper shim material maybe 6"x6"; I think I used some .010" or .015" I had laying around. Copper melts at 2000F. Fire up the torch and find the distance from the torch head that just barely lets the copper survive in the flame for a few minutes. Now using that set distance, try some of your familiar construction materials (stainless firewall sheet, various AN fluid fittings, firesleeved hose and aluminum line, Fiberfrax, whatever).

Trust me, you'll form some opinions about lines and fittings, as well as radiated heat from the back side of a hot firewall.

Dan Horton
 
Excellent post. I did some of this a couple of years back. Tefzel wiring, fire sleeve, SCAT hose and aluminum lines and fittings survive way less than one minute. This was at more like 1500F in my tests. These materials merely delay burn through or melting, they don't prevent it.
 
So we've established that lots of stuff doesn't hold up in fire (including firesleeve, which was a little surprising...) What does hold up, besides steel?

In particular, I'm wondering about sealing small gaps in the firewall (around wiring runs and the like)...is red RTV the way to go, or is there something better to use? I've noticed a lot of fire-resistant sealers and mortars at the local aviation/home store...
 
pitting report on copper

Hey Guys!!! I just found a report on aluminum reacting with copper and causing holes to form!!!! its under the maintenance section... please read!
Thanks
Brian
 
Ceramic batting type barrier materials will survive at typical fuel fire temperatures and steels will as well. Industrial type ceramic batting as used in the foundary business (and Space Shuttle) is magic. You can have red heat on one side and hold your hand against the other side on 1.25 inch thick material. Amazing.

Anything with silicone covering like SCAT and firesleeve -well the silicone part burns and charrs well below these temps and the inner part of firesleeve survives but falls apart because there is nothing to hold it together. Aluminum tubing- this melts with a simple propane torch in about 30 seconds. Firesleeve is worth using as it gives a shielded line more time to burn or melt through.

Best defence in the practical world is good building practices (support, strain relief, don't use rigid lines between firewall and engine etc.) , choice of materials and maintenance. Have a good look at everything during your oil changes. Give lines a good tug. Don't wear synthetics (like polyester suits). I always fly in a Nomex flight suit. Second backup would be a Halon fire bottle with a nozzle in the cowling and one in the cockpit. Spruce has these, not too heavy or expensive. You'll probably never need it but...
 
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I've been a volunteer firefighter for almost 25 years now, and the thought of getting badly burned scares the dickens out of me! I always wear Nomex when I am doing any flight testing, or when I have pulled major maintenance forward of the firewall - and sometimes just becasue I find a flight suit to be comfortable and convenient. If I'm not wearing Nomex when flying, I'm wearing cotton - I've just seen too many people burned by polyester melting into their skin.

We lost a wonderful person here at JSC a few years back because she was in the right seat of a high-wing, tube and fabric homebuilt that hit a tree on take-off. The impact was very survivable, but she was burned over 90% of her body in the post-crash fire. She lived two or three days in the hospital, but couldn't survive the damage. If she'd been wearing her nomex that day....who knows? (We now have an annual aviation safety symposium in her name.) :(

I'm one of those people that has held a glowing shuttle tile, fresh out of the furnace, in my fingertips, without getting burned. Incredible material - but I'd hate to get a quote on a firewall blanket made out of the stuff! :eek:

In building the Valkyrie, I treated every connection forward of the firewall very, very seriously, and generally pull the cowl every fifty hours (oil change time) to check everything for rubbing, cracks, and leaks.

Fly safe!

Paul
 
Ridged lines and engine vibration... good idea?

TShort said:
GMC - I think that might be your shortest post EVER! :D :D :D I am following this thread with interest... how much info / instruction is there with the finish / FWF kit regarding safety issues like this? T.
Click to expand...
Awww shucks, :D . Seriously ridged lines, copper or aluminum, hanging off the engine scare me. I know they have been done like this for ever and ever, even on certified planes, but that does not make me happy. Tshort, I have an answer about other safety issues like this, but my post would be too long. :eek:
 
Having been in the Aircraft firefighting business for the last 26 years as well as a recreational pilot, I have come to the conclusion that prevention is the key. Even if the integrity of the firewall is not compromised the surrounding aluminum would fail in seconds in the event of a wind driven, fuel fed fire.
The industry standard for aircraft skin burn through is three minutes on an airliner (thick stuff) but from what I've seen that appears to be a little optimistic. The thin materials we use wouldn't last very long. I would say that the general trend of the responses are on the right track , use the proper material as correctly as possible and check it often.

RV 8 Fuselage
 
Paul Tuttle said:
Having been in the Aircraft firefighting business for the last 26 years as well as a recreational pilot, I have come to the conclusion that prevention is the key. Even if the integrity of the firewall is not compromised the surrounding aluminum would fail in seconds in the event of a wind driven, fuel fed fire.
The industry standard for aircraft skin burn through is three minutes on an airliner (thick stuff) but from what I've seen that appears to be a little optimistic. The thin materials we use wouldn't last very long. I would say that the general trend of the responses are on the right track , use the proper material as correctly as possible and check it often.

RV 8 Fuselage
Click to expand...

Amen to all of that!

Rv6ejguy reported some very interesting test results at 1500 degrees but the bloody reality is if there is 1500 degree fire roaring up front, you can kiss your butt good bye (if you can reach it) no mattery how encased everything is foreward of the firewall. Your best chance is to turn off the fuel valve, zip up the nomex flight suit and hope to land before things melt completely. For sure the fiber glass cowling will be gone quick.

The only thing that gives me a warm and fuzzy feeling doing what we do are decent fuel lines that are not likey to break and a good quality electric system. (I had not considered a nomex flight suit but am thinking about it.)

Some may think the high pressure fuel lines with the Subaru are not acceptable in an aircraft, but look at it from this perspective. When was the last time you heard of one rupturing in a car or airplane? They are used in millions of installations everywhere on the planet. The OETIKER clamps that hold them in place are about as bullet proof as anything can be. (never use screw clamps!)

Aeroquip is "aircraft" quality plumbing. But don't rest your laurels on it. Years ago, I had a Long EZ with a troublesome primer and when testing the system with the cowl off, notice the little 4-7 psi Facet pump was pushing fuel through the Aeroquip hose like a sieve. The entire line was wet with 100LL. It turned out to be a bad batch of rubber, fuel was desolving it and I'd been flying the airplane for some time in that condition. With the pump off, the hose dried quickly and a visual inspection revealed nothing. Most everyone switched to 666 teflon after that fiasco. There was an AD on that batch of hose.

There should be a federal law prohibiting copper primer lines. I had them on a 0360 and they broke.

Ignition source concerns me a lot. A fuel leak is a relevant non event unless something lights it off. Exhaust systems must be checked regularly. Also electric leads to the starter and altenator must be secure. I believe most car fires are electrical due to battery failure and/or alternator failure. I have my batteries mounted on the cabin floor just forward of the fuel valve. If they act up - like get hot - I will know it right now.

All this, just my 2 cents worth. We all face the same risk and deal with it in our own way. So far, so good. :)

dd
 
Put it out!

Lots of fire fighters on this forum and they will all tell you what you need for a fire. Fuel, Oxy, Ignition.
Whilst prevention is the Holy grail, puting it out comes next.
Not to comment on the fire discussed here (which is reported to have burnt for "few minutes") as the full details have not been printed, but if fire is evident, airborne or on the ground, TURN THE FUEL OFF.
With a fuel injection system there is not much fuel in the lines to burn and only a little more if a carby bowl releases its contents, so turning the FUEL OFF should extinguish the fire. It will certainly stop a torching type fire continuing whilst being supplied with high pressure fuel.
We would all love to have an engine bay fire system, if it weighed nothing and was free. If you do install one and you have a fire; ensure you turn the fuel off and give the fire time to die down before dumping you precious extinguishent. 30 sec delay is the airline standard.
Pete.
Gee George. Never thought I would write more than you. Dunder Pete.
 
Although the report that began this thread (of the RV-6) indicated the cabin was not penetrated, I did see the after effects of a similar failure on an RV-4 last year. The fuel pressure sense line failed on crosswind approach and the fire melted the aluminum floorboards under the rudder pedals before the pilot got out. This event will cause me to improve the cabin protection over and above what is provided in the kit.
 
Alarming

This is pretty alarming. I'm thinking like Bill.
I know one of the Vans boys had an exhaust pipe fail, but the exhaust gases though impinging on the cowl -at low power drift down- did not burn through the cowl, which has fire resistant impreg.
So I assume these fires exits the engine bay via the cowl outlet.
If this is the case, would it be sufficient to cover the lower Al. skin in this area with SS?
If so, how far back?
Pete.
It also highlights the point in my last post. It may be better to close the throttle, pull the mixture lean, turn of the fuel, turn the fuel pump off and maybe the master and dead stick it.
Pete.
 
Fire

Whilst (down under for "while", gotta love it!) we're fighting this fire; thought I'd throw my $.02 in.

Before shutting down after my last flight a couple of weeks ago, I briefly smelled raw av-gas. Last week I had the cowl off, finally getting around to installing the cabin heat on my -8 when I read Vern's post about the fire.

I thought I would pressurize the fuel system to look for a leak. When I did, I found fuel leaking out around the mixture shaft on the FI Servo Unit. Only happened at the middle of the mixture range, not at ICO or full rich. Wasn't much, but enough to scare the Bejesus outa me and think Crispy Critter.

Needless to say, the Servo and Flow Divider is now with Don Reviera at Airflow Performance in Spartenberg, SC. being overhauled.

Mannan Thomason Msgt USAF (Ret)
RV-8 N161RL (No. One Girl)
Almost 50 hrs Saving For Paint
(Gonna take longer now with this setback)
 
fire...all-stainless fuel lines?

I occasionally ask aero parts places, and auto stores about all stainless fuel hard tubing and fittings. I never get a good lead. It seems that correctly mounted and designed, stainless would be worth the pound or so it adds to the plane. Lots of posts prase steel, but never stainless? I'm not interested in decorating with shiny braid. Wool is a low toxic fire resistant barrier. It's used in some heavy duty welding uniforms.
 
Stainless is (relatively) cheap and easy to work - I use a large amount of 1/4" OD 316 stainless for high pressure air work, rated for 10,000 psi, .180" ID, that should flow enough fuel for our purposes. I also occasionally use 3/8" OD with a .290 ID rated for 7500 psi, that would work as well with less pressure drop. Easily formed by hand, but a real tubing bender makes it look professional. I buy the stuff for about $1.50-$2 (depends on size of order) per foot. Flareless compression fittings for the ends average around $3 each. It is absolutely tops in my book, and I will use it for all fuel and oil lines. Speaking of which - I also have 1/8" OD stainless for oil and fuel pressure gauges. I'll still put fireproofing wrap on it, just to avoid heat transfer with vapor lock in mind.

PM me if you need a chunk, I buy it in 20' sticks and have LOTS of scrap laying around.
 
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airguy said:
Stainless is (relatively) cheap and easy to work - I use a large amount of 1/4" OD 316 stainless for high pressure air work, rated for 10,000 psi, .180" ID, that should flow enough fuel for our purposes. I also occasionally use 3/8" OD with a .290 ID rated for 7500 psi, that would work as well with less pressure drop. Easily formed by hand, but a real tubing bender makes it look professional. I buy the stuff for about $1.50-$2 (depends on size of order) per foot. Flareless compression fittings for the ends average around $3 each. It is absolutely tops in my book, and I will use it for all fuel and oil lines. Speaking of which - I also have 1/8" OD stainless for oil and fuel pressure gauges. I'll still put fireproofing wrap on it, just to avoid heat transfer with vapor lock in mind..........................What I'm still hurting for is the fittings, valves, and tools. Is there a catalog that will satisfy all-stainless fuel handling? I know to use flexible hose to the carburetor.
Click to expand...
 
Flex hose only!

I can't be sure from some of the posts........so I want to post a clarification of what I understand to be the facts in this accident. Rigid metal tubing running between the moving engine (because of rubber motor mounts) and the stationary firewall was the cause. Van's clearly calls for flexible hose on all of these connections, but people don't seem to understand how much the motor moves around, especially during start and shutdown, and many people have made this compromise.

Fire sleeve wouldn't/couldn't keep a rigid tube from failing in this location.
 
Back to question stainless fittings &fuel line

The question is about everything else. I would love to know how to buy stainless fittings, fuel line, tools, valves, and hardware for a fire resistant crash resistant fuel system. I figure it's utterly worth the extra pound for safety. I've had no luck finding stainless steel based hardware, but someone must make it. thank you
 
I buy all my stainless fittings (and some line, 1/8", 1/4", and 3/8") from a high-pressure air systems dealer in Dallas, at August Industries, 972-245-7000. The guys name is Porter Stiles, top notch guy, knows high pressure inside and out. He handles the tubing and all-stainless fittings for the ends.

There are other places to get the same stuff, but they will only sell in much larger quantities than builders like most of us would be interested in. I usually buy the tubing in 1000+ feet orders for my stuff, and I use a lot of carbon-steel fittings on the end (for air), but you'll want to get true stainless fittings for fuel use.

The point was made about vibration - it should indeed be noted that this tubing will NOT last if coupled directly between the frame and the motor - you MUST have some piece of flexline somewhere, even if it's only 6 inches long, to take the strain relief. I would suggest running two pieces of stainless, one on the motor itself, one on the firewall, and connecting them with a flexline as close to the crankshaft centerline as possible (behind the engine) to minimize lateral movement. Directly on the shaft centerline you'll be seeing mainly torquing movement, not lateral displacement.

The only exception would be the 1/8" OD tubing - it is designed to be very flexible and will take a great deal of vibration. The small bore makes it ideal for pressure indicator lines where a blown gauge won't dump all your fluid immediately. Many shops refer to this size tubing as "gauge tubing".
 
I plan to use 316SS 3000 psi Swagelok, Full Port Stainless on my fuel system.
Can withstand fires in a Refinery, should hold up to a severe enviroment under the cowling. The Swagelok connections do not work harden like flared Al and the weight delta is small for the piece of mind it will bring me. I estimate an extra 2 ~ 3 lbs over Al for the fuel system.

I think its downright crazy to have copper under the cowling or anywhere transporting combustibles.

I will stick with the Al inside the fuel tanks. Stainless inside the Fues and under the cowling where required over Stainless braided (Fire Retardant wrap)/
 
Swagelok stainless fittings, while not cheap, are the absolute best, no doubt. I use them in locations where it will be difficult or impossible to gain access to the joint again, while easy-access locations get the cheaper carbon steel.
 
Fire Detection??

I sounds like part of the problem is detecting a fire in the engine compartment fast enough to turn the fuel off and limit the fire to only the available fuel. I suspect with the fuel flow stopped the fire would quickly consume what fuel is available , maybe not putting out the fire but limiting the speed with which it can move to the cockpit. With that said I am looking at temp sensors (switches) which would close or open when the temp in the engine compartment rises above a certain temp, say 350 ? 450 F . (would have to check to see what the normal temp is. These sensors would then set off a loud horn and bright light on the panel to tell the pilot to take action. Possibly connect the mag switch to shut down the engine pump as well as the boost pump. (An over ride switch would let the pilot keep things running if need be)??? Its an idea that would not take much to install and would not cost a lot????? What do you think????
 
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Engine Fire Detection System

I had a Twin Cessna that had a fire detection system installed, it had a loop of sensing wire that was near to the cowl exhaust supported by several Adel clamps. The normal flow of cooling air would pass by the sensing loop, not sure what the activation temperature was but must have been in the 500-degree area.

From the 1982 Cessna T303 POH
?A fire detection system for each engine is installed in the airplane. The system consists of a temperature sensing loop in each engine compartment, two red warning lights labeled L. ENG. FIRE and R. ENG. FIRE on the annunciator panel, an audible warning tone, and the associated wiring and control boxes. ?

Just thoughts, many of the new engine monitors have extra positions to monitor temperatures. Example, turbine inlet temperature, what if a extra position was used to monitor this temp, a thermocouple could be placed in the area of the cowl exhaust and the monitor set to alarm on out of norm temps. This system could be installed for a very low cost and provide valuable protection from this threat.

Don
RV7
Finish Kit
 
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I sounds like part of the problem is detecting a fire in the engine compartment fast enough to turn the fuel off and limit the fire to only the available fuel. I suspect with the fuel flow stopped the fire would quickly consume what fuel is available , maybe not putting out the fire but limiting the speed with which it can move to the cockpit. With that said I am looking at temp sensors (switches) which would close or open when the temp in the engine compartment rises above a certain temp, say 350 ? 450 F . (would have to check to see what the normal temp is. These sensors would then set off a loud horn and bright light on the panel to tell the pilot to take action. Possibly connect the mag switch to shut down the engine pump as well as the boost pump. (An over ride switch would let the pilot keep things running if need be)??? Its an idea that would not take much to install and would not cost a lot????? What do you think????
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I'm paranoid about fire in my airplane. It's one of the few situations in flying where there are almost no options, especially if it breaks out at a higher altitude. The time to get down and make a safe landing could be too long to survive. As a result I decided to install a firewall temperature sensor. I have a GRT EIS4000 system. One of the great things about this unit is that there are a couple of extra inputs available that you can configure with whatever you want. I called GRT about a sensor that I could use for this purpose and they suggested a FT-1827-02 sensor. I installed this through the firewall near the cowl exit and set the alarm limits at 400F.
In addition to this I bought a safecraft fire extinguisher system from AC Spruce. This is a 4lb bottle that I installed behind the panel and is activated by a "T" handle on the instrument panel. Discharge nozzles are located in the high pressure area above the cylinders, above the lower pressure area behind the aft wall of the baffles and finally down near the carb.

Note that the grizzled airport bums at my home base think I'm nuts to invest the $$$ and weight for this system but I'd rather be nuts than dead!!

Doug
RV6
Warminster PA
 
Fire

Vern, My RV-6 was involved in a fire. The fire was different in that it was in a hanger that started burning. My plane was damaged and I'm in the process of fixing it up. As far as the plane your talking about: That plane needs to be tested. You need to make sure the temper on the aluminum was not affected. I had mine tested at the Lawrence Ripack co. here on Long Island next to republic arport. They do testing for the aerospace industry and in fact were testing F-18 bulkheads when I was there. My plane checked out fine but there was no flame only heat on my airframe. My canopy and cowl were melted. By far the worst damage was the smoke. It corroded anything not painted. I have changed every nut and bolt in the plane! All new fabrics and rug. New canopy, cowl, tips and spinner. Please get back to me if you have questions or concerns. I would be glad to help in anyway I can.
[email protected]
My Plane After The Fire
Getting Fixed Up
 
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The problem with "roll your own" fire detection and extinguishing systems is how do you know they work? I've flown many aircraft types with engine fire detection systems, all of which would have undergone extensive ground and flight testing in an attempt to have a system that worked properly. And I've had several false fire detection indications on these aircraft types, where the system said there was a fire when there wasn't. I've had at least a half dozen false fire indications, and never had a real one.

I'm also aware of the results of fire extinguishing flight testing, where the fire bottles are fired at various flight conditions, and the extinguisher agent concentrations are measured. It is quite common to have to tweak the design of the extinguishing system to get it to put the agent where it is needed at a high enough concentration to be effective.

To the folks who have fire detection systems - what will you do if it indicates a fire, but there are no other obvious indications of a fire? It is good to think this through while on the ground, so there is no hesitation in the air.

If you have a fire extinguisher - if the fire detection system says fire, and there are no other indications, will you shut down the engine and activate the extinguisher? Does it make a difference what sort of terrain you are over?
 
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