Cockpit fuel lines and fire prevention

[logansc]

Sorry Lee it was my fault!

Hahahaha! Todd, you are too cool. I (like you) was just siding with the guys who are cautioning a little conservatism here. Since it is NOT raining flaming RV's, I think we might consider holding off on the Toyota-style recall for a bit. This puts me in opposition to the most knowledgeable guy on this stuff that I know (you know who you are!), but simple logic tells me I can afford to wait for further developments before I tear the tunnel out of my airplane and replace all the hard aluminum tubing.

I plan a detailed inspection when I get to the point of pulling my tunnel cover (for other reasons), but I'm not planning an immediate stop-everything, effort. I'm going to replace my aluminum stick first...;>)


Lee...

 

[David-aviator]

Ok there are a lot of unsubstantiated opinions floating around in this thread. If you are going to offer an opinion, state it as such. If you are going to state a fact, back it up.

Fact: Flexible hose is a "specialized" product, generally used by exception. Because of it's expense, weight, bulk and yes, relative unreliability and fragility, it is used only when hardline can't be used. Examples include high relative movement between connections, or in some cases, to facilitate periodic maintenance (like engine removal). Aircraft designers go to long lengths to avoid flex line because except for a few specialized uses, hardline outperforms hose in every way. I doubt there is an aero engineer alive that dreams of someday building an aircraft plumbed exclusively with hose (..."if only it wasn't for the darn bean counters, I could finally do this aircraft right"...) This information is simply common aerospace practice.

There are a few good reasons to use hose assemblies - but replacing hardline in a misguided attempt to increase system reliability is not one of them. Yes, that part is my opinion, but I doubt you will find an aero engineer who will disagree.

We all have a lot to learn? Let?s make sure we learn the ?right? things.

Mike,

When you say "hardline out performs hose every day" does that include 3003 aluminum tubing mounted in an area subject to some vibration?

 

[woxofswa]

About two weeks before the first of the most recent two fuel related incidents, I was on the phone speaking with an engineer at the company that manufactures the "red cube" fuel transducer.

He was adamant that no hard line should be connected into or out of their product. He said that components of different mass will vibrate at varying levels and that hard line between them will be stressed accordingly. He commented that in his opinion hard line should not be used anywhere in the fuel system unless vibration is not an issue, and that the shorter the line, the more vulnerable it is.

He also stated that the cube should not be located in the designated spot that Van's depicts, but should be placed forward of the firewall, and that they have mentioned that several times to Van's.

I am just repeating what he said. What he said made sense at the time and was a week or two before two fuel related incidents that really drove it home.

 

[rvbuilder2002]

What I'm hoping to hear is someone who can provide a clear reason not to run it and I haven't heard that yet.

Phil

One reason is feasibility.

Hard line has a much tighter bend radius than most hose and a smaller cross section area. There are a lot of aircraft with fuel systems that just could not be done with hose for the entire flow path.

I can't say for certain, but I think Todd had implied in the past that his fuel system required a duplex fuel valve to allow for running return lines to each fuel tank. That makes for a crowded tunnel in the vicinity of the fuel valve that may not be possible with hose installed with proper bed radii. Not saying it can't / couldn't be done, just that it would definitely be more difficult.

As a reverse point many people install hose sections with a bend radius tighter than recommended.

 

[RV7Guy]

Not just me

Darwin brings up some good points. However, at least to me, he is tarring ALL braided hose with his experience.

Not JUST my experience but that of several others. Not tarring all braided lines. As I noted, there is no real good reason to used braided if you take the time to learn hard line fabrication and flaring. Then have your FWF lines made by a professional aviation fuel line fabricator. As Mike R. also stated, braided line should not be used as a solution to a difficult installation.

Also, the line I used was made by a company that builds lines for many of the top NHRA folks. I used with confidence and almost had a major issue. I don't want to others to fall into the same trap thinking that they have "braided" line so all is good. Might not be the case.

 

[Phil]

Thanks Scott.

That's a very valid point and not one I had come up with on my own. Fortunately I haven't ran into a tight bend issue yet, so I haven't had to think about it. But it does make perfect sense that the hose can't be bent as tightly.

On that topic, it's my understanding that there is a gauged ball you can run through the lines to make sure you haven't collapsed the liner in a bend. If the ball passes through, you know you're okay. If not, you need to replace the line.

Has anyone used one or know what the acceptable size is?

Thanks again, Scott. As usual, good info.

Phil

 

[Toobuilder]

Michael, happen to have a public link to that technical order in PDF?

I wish I did Dan, as it would make things a whole lot easier to explain. The best that I have found is a variety of sites that offer it as a download (for a fee). I suspect that you have Googled the titles and seen many of these sites. I have access to the books because I own hardcopies at home and they are available as engineering references here at work. For those that have not seen these books, they are invaluable sources of reference. There are entire chapters dedicated to self locking nuts, for example. Tubing is a separate chapter as are hose assemblies (...and bolts, rivets, washers, heim joints, etc, etc, etc).

Also note that my fat fingers got in the way in my original post. The two pubs you are looking for are T.O: 1-1A-8 and T.O 42E1-1-1. These are Air Force pubs, but their NAVAIR counterparts are NAVAIR 01-1A-8 and NAVAIR 01-1A-20. I did find a pretty decent copy of the NAVAIR 1-1A-1 here:

http://www.tinker.af.mil/shared/media/document/AFD-070314-040.pdf

But this is not nearly as comprehensive an engineering manual as the others I mentioned.

 

[Toobuilder]

Mike,

When you say "hardline out performs hose every day" does that include 3003 aluminum tubing mounted in an area subject to some vibration?

Yes, with a disclaimer. What I'm saying is, generally, if it is determined that hard line (of the appropriate material) is acceptable for a given location, substitution of that hardline for hose would be a step backwards. It would be heavier, cost more, and be less reliable.

So how?s that for a ?non answer?

 

[Toobuilder]

About two weeks before the first of the most recent two fuel related incidents, I was on the phone speaking with an engineer at the company that manufactures the "red cube" fuel transducer...

Question:

What engineering degree did this guy hold?

I suspect that he was "covering his 6" because he has no idea how his product is going to be used by the end builder. Using hose is an easy way to transfer a problem installation to another component, thus getting him off the hook.

As an aside, I have spent many hours in the engine bay of aircraft performing hydraulic system checkouts, and I can tell you that a 3000 PSI hydro pump can generate so much high frequency vibration that you can?t even put your hand on the line. Hard line works just fine in a vibration environment if properly designed and installed. I?d say there are very few places on a general aviation aircraft where flex hose is the ONLY choice.

 

[DanH]

...the line I used was made by a company that builds lines for many of the top NHRA folks. I used with confidence and almost had a major issue. I don't want to others to fall into the same trap....

Ok, so tell us the brand and product line.

 

[Toobuilder]

Hey Paul,

What I'm hoping to hear is someone who can provide a clear reason not to run it and I haven't heard that yet. Every objection is pretty easily defended.

Cost? Money isn't a safety item.
Weight? Weight, isn't a safety item.
Inspections? Every fuel line needs inspected.
Not Airworthy? 43-13 says they are and they're TSO'd too.​

It seems like there's no silver bullet. I'm hoping someone can shoot it down with more relevant and scientific data. "Because" isn't a good enough explanation and that's really all that we've heard.

Once again, the acceptance of unnessesary weight on an aircraft simply boggles my mind. My "company" airplane weighs 40,000 pounds. Engineering has made a deviation from standard practice and allows zero thread protrusion (flush) on threaded fasteners instead of the normal two thread minimum. Yes, this is in an attempt to save weight... Yes, a few grams of weight per fastener on a 20 ton airplane...

but I digress...

I suspect that you will never find your "silver bullet", but I'll try one last time: How about the fact that hose can fail simply because of age. There is no inspection for that. You simply have a replacement schedule and hope the hose meets that limit. Seems like an awful risk to take when a properly installed hardline will last the life of the airframe with ZERO maintenance.

In my many years in the aircraft business, I have replaced far more failed hose assemblies than tube assemblies, despite the fact that airplanes typically have about 10-20 times the footage of hard lines to hose. This fact alone, even if you ignore all the standard aviation guidance, indicates hose is "fragile" compared to hard line.

 

[Ron Lee]

Michael, location matters. Let us assume that your post just prior (post #111) to mine is a good guide for fuel lines AFT of the firewall. I will also assume that this does not apply to the engine compartment. Correct me if wrong.

I have firesleeved hose in the engine compartment but aluminum lines in the cockpit.

 

[RV7Guy]

Loper's

Loper's in Mesa AZ.

The hose failed in the middle of an approximately 14" run. The fittings were fine.

Note that Kevin Eldredge of Reno fame, with Breathless had all of his lines made at Brown and Miller Racing Solutions. Race car hoses. They look just like the ones I had made and later replaced!!!

http://www.bmrs.net/index.htm

 

[Toobuilder]

Michael, location matters...

...More to the point, environment matters (temperature, working pressure, resonance, corrosion, external damage, etc). Any given installation from plastic hose to titanium hard line either meets the minimum requirement for the application or it does not. If a given material meets the requirements of the designer, then "extra" serves no purpose. It is also important to note that this always assumes proper fabrication and installation - a huge variable!

Will 3003 aluminum tube survive in the basic FWF environment? Under normal conditions, sure! Thousands of airplanes stand testament to this fact. BUT, if you start throwing in additional requirements like high relative movement (engine connections) or fire resistance, then that changes things. You are forced to come up with a new material (easier) or engineering approach (harder) to satisfy the requirements.

For me, the possibility of fire drives me to stainless hard line FWF, but fire is MY additional requirement that needs to be satisfied. If I could be assured that I would never have a fire or exhaust leak, then 3003 would work just fine (again, if properly fabricated, and installed/supported)

 

[Ron Lee]

I should have been clearer. You would not use solid line to carry fuel from a point on the firewall to a point on the engine would you?

 

[akschu]

I'm guessing a brushless equivalent would be less likely to spark if a sealed version isn't available.

Phil

Given that brushless motors don't have any electrical parts that move I can't possibly see how they could spark unless the coil somehow failed.

This is why I went with the andair pump over the afp. It is a brushless design which not only can't spark but is generally a more reliable motor. Also there is less tubing and fittings.

schu

 

[Toobuilder]

I should have been clearer. You would not use solid line to carry fuel from a point on the firewall to a point on the engine would you?

... Only if the engine was solid mounted...

 

[GaryStofer]

Flammable Gas sensor

I have put together a flammable gas sensors that activates an external beeper and/or indicator light when the threshold is reached. The device consumes about 2.5W from the battery and is mounted on a ~ 1"x2" pcb. The sensor responds to various flammable gases, hydrocarbons, alcohols, etc.

If there is a demand I can order parts and put a few units together for ~ $75 a piece. Send me a private message if you think you'd like one.

Gary -- Happily flying an RV8 with PZL350

 

[RV7Guy]

Just Curious

Stein and I were talking about this today. So you've got your sensor in there and the light goes off, the horn sounds.

Now what do you do? Just curious.

I have put together a flammable gas sensors that activates an external beeper and/or indicator light when the threshold is reached. The device consumes about 2.5W from the battery and is mounted on a ~ 1"x2" pcb. The sensor responds to various flammable gases, hydrocarbons, alcohols, etc.

If there is a demand I can order parts and put a few units together for ~ $75 a piece. Send me a private message if you think you'd like one.

Gary -- Happily flying an RV8 with PZL350

 

[TSwezey]

Stein and I were talking about this today. So you've got your sensor in there and the light goes off, the horn sounds.

Now what do you do? Just curious.

I have gone over this a thousand times in my head and my best answer on the -10 is lose a door. Dive her as fast as possible and don't touch a single switch, land and let all passengers out, unbuckle you seat belt , kill the engine with the fuel valve and get away from the plane. My biggest mistake was not listening to my daughter when she wanted to bail out on the runway.

 

[Toobuilder]

Stein and I were talking about this today. So you've got your sensor in there and the light goes off, the horn sounds.

Now what do you do? Just curious.

Reminds me of a recent "upgrade" to the company jet...

A new glass cockpit display allowed the ability to see engine oil tank quantity, where as for the prior 40 years the aircraft was flying there was none. - the oil was checked on the ground only. Would you believe that as soon as the pilots got a new "toy" to play with, the maintainers started getting discrepancies? It took YEARS for engineering to finally convince the flying community that the wild swings in oil quantity were perfectly normal operation. There was even talk of disabling the oil quantity indication from the new display as the solution to the "problem".

Sometimes too much info is a bad thing.

 

[flion]

Stein and I were talking about this today. So you've got your sensor in there and the light goes off, the horn sounds.

Now what do you do? Just curious.

Illuminate the 'No Smoking' lamps.

Sorry, this thread needed a little levity. I'd say it depended what equipment you had in the tunnel. Close cabin heat, turn off boost pump, land flaps up as soon as possible. Be prepared to evacuate on landing. Turn fuel selector to Off as soon as practical on rollout and let the engine suck the system dry (or drier, anyway). I'm just guessing, really, but I think those would be prudent actions.

One thing that occurs to me; any way (short of a 'match' test, of course) to verify that such a warning light wasn't giving a false positive? I'd hate to have a light that cried 'Wolf!'; it'd probably take more years off my life than an actual incident like Todd's.

 

[Bavafa]

For what ever it is worth:
After reading the Todd's horrifying experience and reading all the thoughts every body had in this subject, I got some what paranoid can decided to replace my 3003 fuel lines with 5052 lines. I should have done this when I built it but I didn't really know. So, yesterday I took the old lines out, all with the exception of the runs from the tank to the valve which I had less worry about and fabricated very carefully new lines. I inspected all the old lines and they all looked good with no sign of fatigue or bad flare. The plane has 185+ hours on it.

Gary,
Which flume detector are you using? Could you give us some feed back and have you tested it with AVGAS? I guess I am still some what paranoid and are considering installing one.

 

[Phil]

Regarding the sensor, I think the response is pretty simple.

1) Don't turn on anything electrical inside the tunnel.
2) If you can shut off all electrical, go ahead and do it.
2) If you can shut off the fuel go ahead and do it.
3) And of course get on the ground.

The false positive indications are just something you'd have to test over time. Could the hydrocarbons in the exhaust activate it? Maybe; since we don't have a catalytic converter to aid in reducing them. Could adhesives set it off until they've really had time to cure? Yeah. Could fairly new resin set it off? Yeah. The boat sensors installed if fiberglass boats warn of false positives for the first year of the boats life.

Until you've spent time testing it, I don't think anyone is going to panic the first time the light comes on. Now if a 100 hrs have gone by and then the sensor light decides to come on? That's a whole new ballgame and sense of urgency. Everyone understands the possibility of a false positive and already knows how they would respond to a warning light early in the unproven sensors life.

Before I committed a hole for the lamp in my panel, I'd want to spend some time evaluating it first and make sure it's a feasible sensor for the application.

With two electrical motors (one is which isn't sealed and has brushes), the additional electrical items being added (or already installed) by the builder, and maybe O2 lines running through the tunnel, having the information is pretty critical. I'd like to know if gas vapors are circulating around my electric motors, wires, and devices. I'd hate to be 5 miles out at 3000 AGL and dropping flaps to find out I had vapors surrounding them.

One of the topics that hasn't been addressed is the possibility of static building in the airplane. The faster RV's can strip electrons out of the clouds and add them to the airframe. This could cause some arcing too. Not much you can do here to reduce it except for adding static wicks and bonding the surfaces of the airframe. But it is an ignition source that hasn't really been addressed yet. I'm not installing them on my airplane until I experience some issues with static.

It's best just to keep the fuel system tight and control what you can control through brush-less or sealed motors.

Phil

 

[TSwezey]

If the leak has more vapor than liquid, think tiny leak under high pressure, then the vapor is going to fill the entire cabin not just the tunnel. So you have to watch every electrical device. We did have static wicks on our airplane.

 

[Phil]

Yeah I agree, Todd.

A high pressure pin hole leak could aid in vaporizing the fuel.

 

[DanH]

With two electrical motors (one is which isn't sealed and has brushes),...

Phil, have you looked at simply sealing the motor you have? At the low end of the scale a plastic bag and a few wraps of tape might do the job. Or a few dabs of silicone over the holes in the case. Doesn't need to be complicated, and I seriously doubt the motor needs ventilation for cooling purposes.

 

[Mike S]

IIRC, these holes are threaded------alternate use mounting holes it would seem.

 

[Pat Stewart]

I have been watching this thread for a few days and have finally decided to add my 2 cents.

I have seen dozens of certified and experimental airplanes with blue streaks down gear legs, cowlings, belly?s and inside aircraft.

I make it a regular practice to keep a white cloth in my airplane to occasionally run under fittings just to see if there is any fuel residue. Hard fuel lines work well and have a proven track record.

IN MY OPINION the problem is the tunnel. In my tunnel I have the standard setup, filter, pump and FF transducer and lots of electrical wiring. That?s 7 connections in the tunnel not including the fuel selector valve; one will eventually leak from a sub standard flare or over tightening.

I also have insulation in my tunnel that will soak up fuel from a leak.

Here is my plan.

1. Move the filter out of the tunnel and hopefully into the wing root or if that?s not practical one under each front seat. This will require two filters vs. one. I see that as an improvement even without the fuel leak issue. I have never liked both tanks feeding to one fuel filter anyway. This will also eliminate the tight turn requirements between the fuel filter and fuel pump that can add to the problem.

2. Replace all hard lines with flex lines. Yes more expensive, yes weigh more, yes must be replaced over time, yes piece of mind is priceless. The flares are significantly less likely to leak but I will also say flex lines can and do sometimes fail. Not sure about fire sleeve as it can also soak up fuel.

3. Find a way to ventilate the tunnel. I have an extra port on my avionics cooling fan that could supply interior air to the forward end of the tunnel but I would need to find some way to provide an exit path in the rear of the tunnel. Also ventilating with interior air may not add any value after a few minutes unless the exit path is outside the airframe.

4. Remove the insulation.

Feel free to jump in and tell me the flaws in my ideas, that?s the real value of this forum.

Pat Stewart

 

[rvbuilder2002]

IN MY OPINION the problem is the tunnel. In my tunnel I have the standard setup, filter, pump and FF transducer and lots of electrical wiring. That?s 7 connections in the tunnel not including the fuel selector valve; one will eventually leak from a sub standard flare or over tightening.

Feel free to jump in and tell me the flaws in my ideas, that?s the real value of this forum.

Pat Stewart

I think one flaw is that you are still flying an airplane that you feel has substandard flares or flares that have been over tightened.

If you believe that, then by all means make new lines and correct the problems that you think are lurking in your airplane.

As for the other stuff...I don't see any point in going to all of that work modifying your fuel system when there is not a shred of evidence to point to anything at all specific as a cause of Todd's accident. It is very possible that his fuel system was not even close in design to what the standard fuel system in an RV-10 is.

Moving the fuel filter(s) (it would require you modifying to use two) under the seats? I am not sure what that would gain. This entire area is common with the tunnel. There are structural partitions, but they are full of holes so it is one common area as far as fumes go.

It has already been said in numerous posts but I will repeat it once more in case some people missed it...
It makes no sense to modify a fuel system only out of speculation that there might be a design problem. Any modification you do has the potential to induce an unanticipated problem, all in the interest of fixing a problem that may not even exist.

 

[Pat Stewart]

Im really not even saying there is a design problem, I am thinking of a design improvement. I am still building although almost finished so I am not flying yet. Both tanks into one filter means if there is a clog both tanks are clogged, switching tanks will not help. The vans design in the tunnel makes for a tight bend radius from the fuel filter to the pump, let's elimate that. Flex lines vs. hard lines again in my OPINION are better, they just cost more, weigh more and will require replacement.

Pat
RV8
RV8A
J3
RV10
A&P

 

[rvbuilder2002]

Both tanks into one filter means if there is a clog both tanks are clogged, switching tanks will not help.

I can't disagree with that statement, but if we are to analyze the fuel system in the context of contamination, consider that each fuel tank has a finger screen which will catch all but very small particles. The fuel filter it self has a very fine mesh screen of probably at least 10 square inches (maybe more, though I have never measured it).
If a pilot properly sumps the fuel tank(s) to verify there is no contamination after refueling, it is extremely unlikely that there could ever be a high enough concentration of contaminates that it could clog 10 square inches of filter screen. Even then, if the highly unlikely happened, I am pretty sure that the AFP fuel filter is designed in such a way that if the screen began to clog, pump suction will cause the filter to displace against against a light spring and allow the flow to bypass the screen.

 

[DanH]

I have access to the books because I own hardcopies at home and they are available as engineering references here at work.... T.O: 1-1A-8 and T.O 42E1-1-1.

Nothing like a good reference library.

Mind posting one detail about .035 304 stainless steel lines? Minimum bend radius for dash 3, 4, and 6, please. The rest we can figure out.

 

[N427EF]

No improvements needed

Pat,
Scott is right, there is no need to change anything about the original design
and the use of aluminum tubing.
However, the priviledge of experimental category aircraft allowes you to make changes if you want to.
Here is what I did and why.
2 fuel filters under the seat, heavier more expensive but much easier to service and a short piece to connect to the tanks.
Elbow fittings entering the tunnel, more expensive more chances to leak but much easier to fabricate 2 short pieces versus one long piece and very accessible for service.
In the tunnel, fuel flow and fuel pressure sensors installed in a rigid fashion on the cool side of the firewall.(the drainplug is where the fuel pressure goes) I just plugged it for pressure tests.
As you see its full of bent aluminum tubing and there is no way I would substitute with hoses.

 

[rvbuilder2002]

2 fuel filters under the seat, heavier more expensive but much easier to service and a short piece to connect to the tanks.

Since the filters are located between the the fuel tanks and the fuel shutoff valve, how do you clean/inspect each filter without fully draining the fuel tanks?
If the tanks must be drained, it doesn't sound like it is much easier to service.

 

[Phil]

Phil, have you looked at simply sealing the motor you have? At the low end of the scale a plastic bag and a few wraps of tape might do the job. Or a few dabs of silicone over the holes in the case. Doesn't need to be complicated, and I seriously doubt the motor needs ventilation for cooling purposes.

Yeah I've thought about that, Dan. I think some silicone would do the trick, you just have to be sure to shut off the flap motor and can't leave it running.

If you had something like TCW's intelligent flap controller, you could prevent the motor from an accidental long-term run. I agree that venting is probably not required for the short cycles that we'd be using during a full up and down series.

 

[N427EF]

Physical access

Good point Scott, I did not think about that, you see what happens when
builders start making "improvements".
Maybe I will use a hose from the tank to the filter and clamp it shut for service.
Seriously, I was thinking about the convenience of accessing the filters without sticking my head and arms into a crowded tunnel plus 2 filters reduce the number of filter checks in half.
In addition I have a fuel return system with control over which tank the fuel goes to and it could be pumped over to one tank or the other. AFP fuel pump will transfer 5 gallons of fuel in just a few minutes.
My point was really on the suitability of aluminum lines for a fairly complex fuel system installation. There is no way you would have room for all of that in the tunnel if you were to use hoses.
BTW all that complexity in the tunnel allows for a very tidy FWF installation.

 

[DanH]

It's pretty work Ernst. Now if I could just convince you to replace those two aluminum bulkhead fittings with steel

 

[rvbuilder2002]

In addition I have a fuel return system with control over which tank the fuel goes to and it could be pumped over to one tank or the other. AFP fuel pump will transfer 5 gallons of fuel in just a few minutes.

No offense Ernst, but adding this type of complexity (two fuel valves) is what many of us here on VAF caution people about.
You now have a fuel system that gives the pilot more opportunity to screw up.
You could sometime forget the second valve, you start pumping fuel into a tank that maybe only had 5 gal burn off of it. Once the tank is full you will be dumping fuel over board through the vent. I can think of a number of other "mistake" scenarios as well.

Andair makes a duplex valve just for this type of installation. It switches the main feed and the return at the same time.

Good luck and be careful

 

[Pat Stewart]

Very nice Ernst, the filters look great.

Pat

 

[N427EF]

Fuel Valve Compromise

Scott, none taken.
It is really quite simple.
The Andair 4 way fuel valve is simply too much of a stack and obstruction
to still be able to run the heater hose.
I used the 2 way Andair valve about $200 cheaper than the 4 way and Van's valve for the return, leaving enough vertical clearance for ease of installation and heater hose passage.
The apparent complexity is simply all of the fuel system components in one place.
I have the same system in my 8 and it provides rock solid fuel pressure and
instantaneous flow information.
You are right about the 2 handles, make sure they point in the same direction
as simple as that.
I am drifting this thread sorry.
There is great advantages to my fuel system but that would be another thread.
Dan, always appreciate your thoughts. In what way would a steel fitting improve the the installation.

 

[Mike S]

In what way would a steel fitting improve the the installation.

Ernst, lookin good.

Steel fitting on firewall maintains the integrity of the firewall.

This is why many of have up graded the heater boxes to stainless steel.

 

[TSwezey]

Trust me aluminum burns very easily.

 

[Phil]

Ditto on the firewall, Mike and Dan...

My aluminum heater boxes are in the scrap pile and I've swapped them out with stainless.

The aluminum bulkhead fittings on the firewall have been swapped out for steel.

The last bit of aluminum penetrating my firewall (other than rivets) is the brake fluid reservoir. Anyone know of a SS upgrade that is available out there for it? I'd jump at the opportunity to swap it out.

Phil

 

[DanH]

The last bit of aluminum penetrating my firewall (other than rivets) is the brake fluid reservoir.

Relocated mine to a location in the baggage compartment (RV8). No inverted systems so I don't expect spillage, but another option is a sealed diaphram style reservoir. Source it from a motorycle rear brake system. Or there are individual reservoirs that mount on the master cylinders.

Other than traditional location, I can't figure why the darn thing penetrates the firewall.

 

[L.Adamson]

Relocated mine to a location in the baggage compartment (RV8). No inverted systems so I don't expect spillage, but another option is a sealed diaphram style reservoir. Source it from a motorycle rear brake system. Or there are individual reservoirs that mount on the master cylinders.

Other than traditional location, I can't figure why the darn thing penetrates the firewall.

The way I bleed the brakes on my "slider" 6A, I'm quite happy to have the reservoir on the firewall. I replace the top cap with a fitting and a clear hose that runs into a clear bottle. I then fill the brakes with a pressurized weed sprayer from the bottom (brake caliper)... up. It's quite an automatic process as the clear red fluid escapes from the reservoir, through the tube, and into the bottle. I then drain some fluid from the reservoir by holding my thumb over the end of the tube.

For this operation, I prefer having the reservoir accessible.

L.Adamson --- RV6A

 

[L.Adamson]

Trust me aluminum burns very easily.

As does the cowl & windscreen, as well as the lower fuselage pan. That's why I don't buy into all this firewall protection. I figure that a sustained 2000 degree "flame thrower" will effect much more than the firewall ---- rather quickly.

I'm more for eliminating the main source of the flame thrower; such as turning off the fuel supply with a conveniently located "fuel knob". With all the talk of exterior fuel lines, pumps, and solenoid valves to eliminate in-cockpit plumbing and "fuel knobs"...............I just don't know..

Could be my "day job" up-bringing. I've worked on gas furnaces, gas lines, and shutoff valves for nearly 40 years.

L.Adamson --- RV6A

 

[rvbuilder2002]

Scott, none taken.
It is really quite simple.
The Andair 4 way fuel valve is simply too much of a stack and obstruction
to still be able to run the heater hose.

I admit it is tight but is also very doable.
The second RV-10 prototype with the Continental IO-360 has the andair duplex valve installed with fuel returns to each tank (required by the Continental fuel injection system), and still has the duct for the aft cabin heat running through..

 

[DanH]

Todd, after the flash what sort of fire problem did you have? What caught fire and where?

 

[N427EF]

No hose barred

You see, when the tunnel heat issue made its way around the forum circuit,
I felt the need to jump on the modification "improvement" bandwagon.
If you look closely on my picture you will see a double floor in the tunnel.
That modification raised the floor 2 inches and effectively ruined my chances to install the 4way Andair valve and have room for a 2" heater hose.

So this time I am sticking with the suggested and tested methods of using aluminum tubing.