Firewall Insulation Retrofit

[Mikeyb]

I didn’t know about DanH’s work on firewall insulation when I built my plane.

https://vansairforce.net/community/showthread.php?t=47587&highlight=firewall+insulation&page=8


80% of my firewall was bare and I decided to install the .002” stainless foil and 1/8” ceramic as best I could. The blanket weighs 3 pounds.

As an aside, my intention was to measure the change in noise level and cockpit temperature before and after. I measured the sound level with a handheld sound level meter and the temperature of the rudder pedals with an IR thermometer.

At idle, canopy closed the sound level decreased from 86 dBA to 83.
Interestingly, At full power it stayed at 98 to 100 dBA with or without insulation.

The temperature test got muddled by the difference in solar load. It was overcast when I did the before test and sunny after. It lowered the temperature of the pedals by 10 degrees or more. Qualitatively it was the first time I was ever comfortable taxiing back after landing with the canopy shut and the vent closed.

 

[N804RV]

I wonder if the full-power sound level in the cockpit has more to do with the voids above the forward belly skins. I would think on a typical Lycoming powered RV-8, those voids being just outboard of the air ramp would carry the exhaust note like a natural noise amplifier. I put some automotive sound dampening mat in mine for this reason, I also sealed this area to try and prevent water intrusion from degrading the mat.

Also, I was thinking about a firewall blanket for better fire protection. I hadn't even thought about it as a way to lessen cockpit noise.

 

[DanH]

I'm not surprised, although I've never personally measured the sound reduction.

I have about two dozen beta kits out there now, some installed, some not. These kits incorporate an intumescent insulation mat rather than the familiar Fiberfrax 970 felt.

Either increases comfort at normal inflight temperatures. The intumescent does a little better at high temperatures, as it swells to about three times its original thickness when heated over 650F. It's also higher density, so it should do better at sound reduction, and for sure it doesn't pillow as much under the rivet heads.

Photo below is 0.002 foil over 0.060" intumescent, five minutes into test. There are three thermocouples. The red meter is displaying the temperature of the aluminum angle (774F) and the temperature of the radiant heat target (200F). The black meter is displaying hot side temperature, 1101C or 2015F.

The radiant heat target (flat black square below) is 6" from the back of the "firewall", and serves as a proxy for the rudder pedals, the soles of your feet, etc. 200F is hot, but it's below the ignition temperature of most everything down in the foot area, and if you are wearing shoes, you can maintain control of the airplane. For sure it's way better than the bare firewall, which pushes the heat target above 400F in about one minute.

Of course I hope you never get to experience any of the above, and the only value is comfort in ordinary operation. Although subjective, I have a test for that too
.

 

[Freemasm]

....At idle, canopy closed the sound level decreased from 86 dBA to 83.
Interestingly, At full power it stayed at 98 to 100 dBA with or without insulation.

Don't feel surprised or alone here. Noise attenuation effects are almost always specific to a fairly narrow frequency band. Sounds like you found where your mod is tuned. Ultimately, you can't very well reduce the sound power levels in our aircraft. The construction makes them very good at passing pressure waves for your body tp absorb. You halved the sound power level at idle; a fairly substantial accomplishment. Too bad that's not where you spend all of your cockpit time.

Your aircraft is safer and you got a slight side benefit. Call it a win.

 

[moespeeds]

Dan I'd be interested to hear more about these kits.

I had some type of flammable foam from the previous builder, which I promptly removed. Would like something more than just the stainless.

 

[Ken Martin]

Is your desire for something more than stainless in the firewall to reduce ambient operating temps in the lower "footwell" area (for lack of a better term), or are you seeking increased fire protection?

Dan I'd be interested to hear more about these kits.

I had some type of flammable foam from the previous builder, which I promptly removed. Would like something more than just the stainless.

 

[Ken Martin]

I just spent two weeks in an aircraft accident investigation training course for work that is taught by the NTSB, FAA and several Subject Matter Experts. The instructors all have 35-40+ years' experience conducting aircraft accident investigations and one in particular (from the NTSB) is also an RV8 builder. I spoke with them in depth about accidents involving single engine piston aircraft that had either an inflight or post-impact fire.

All of the instructors and SMEs agreed there has been no conclusive data to support the idea that a single piece of SS used for the firewall (single engine piston) is insufficient to protect the pilot from fires. (100LL burns at around 845F, AL melts around 1,250F, Steel around 2,000F and SS around 2,500F).

Our Metallurgist Instructor stated in all of the accidents he has consulted on over the past 40 years, the single sheet SS firewall was still intact after the fire. The AL/Composite cowling and fuselage areas were the weak link.

NTSB data supports - Inflight fires were contained to the engine side of the firewall by the protection of one SS sheet and if/when post impact fires got to the cabin side, it was typically due to the impact rupturing fuel tanks or fuel lines - causing the fuel to spray aft.

The training facility also has a lab with several aircraft involved in fatal and non-fatal accidents. A few of the aircraft had pre/post-impact fire damage. Everything we inspected supported the conclusion that adding extra material to the firewall in hopes of increasing fire protection, is NOT value added. As you would expect, the plastic canopy and the AL (or composite) fuselage are going to be susceptible to 100LL fueled fires nearing the 1,000F range. (remember the SS firewall is good up to 2,500F)

Conclusion from the training (specific to single engine, piston AC) - If a pilot wants to increase fire protection for the cabin occupants, make it easy to open up the cowling to do a well-developed pre-flight inspection and carry a fire extinguisher that is easily accessible.

Cheers,

Ken

I wonder if the full-power sound level in the cockpit has more to do with the voids above the forward belly skins. I would think on a typical Lycoming powered RV-8, those voids being just outboard of the air ramp would carry the exhaust note like a natural noise amplifier. I put some automotive sound dampening mat in mine for this reason, I also sealed this area to try and prevent water intrusion from degrading the mat.

Also, I was thinking about a firewall blanket for better fire protection. I hadn't even thought about it as a way to lessen cockpit noise.

 

[Mikeyb]

If you take the time to look at the work Dan did on this it’s hard to argue that engine side insulation is not a good idea. Even if you just look at the graph in post#3 you will see that in an RV your feet could be at 400F in 30 seconds. The firewall might be fine but you not so much. A relatively inexpensive addition that gives you precious seconds in the event of a fire and improves creature comfort.

Another temperature tidbit. 10 minutes after shutdown I measured the temperature of the engine side of the firewall of 150F. The temperature of the firewall inside the cockpit 75F two degrees above the ambient air temp.

 

[Ken Martin]

In reference to static temperature measurements, certainly you can gain insulation from transfer of heat making passengers more comfortable. However, in a dynamic scenario involving forward flight, you have to consider high velocity airflow. You also have to determine what scenario will have you in the situation you are trying to prepare for. IF there was enough data to support this for design consideration, why wouldn't all of the airframe manufacturers (including Vans) incorporate the simple change? In the end, if it makes you feel more safe, it's your aircraft.

If you take the time to look at the work Dan did on this it’s hard to argue that engine side insulation is not a good idea. Even if you just look at the graph in post#3 you will see that in an RV your feet could be at 400F in 30 seconds. The firewall might be fine but you not so much. A relatively inexpensive addition that gives you precious seconds in the event of a fire and improves creature comfort.

Another temperature tidbit. 10 minutes after shutdown I measured the temperature of the engine side of the firewall of 150F. The temperature of the firewall inside the cockpit 75F.

 

[hgerhardt]

What about the bottom fuselage aluminum skin just aft of the firewall which would be exposed to a flame plume coming out of the cowl outlet (if there was an in-flight fire)?

Also, how do the aluminum rivets fare on the firewall which hold the angle stiffeners? Wouldn't those melt fairly quickly leaving a bunch of #40 holes in the firewall? I wouldn't expect those #40 holes to become mini-blowtorches, but they would let noxious smoke into the cockpit, no?

And, Ken, since when does avgas burn at 845F? I think you're missing a (1) in front to make it 1845F.

 

[skylor]

And, Ken, since when does avgas burn at 845F? I think you're missing a (1) in front to make it 1845F.

More like missing a (3). Gasoline adiabatic flame temperature is around 3880F!

 

[Ken Martin]

To your point, in the NTSB training we investigated an actual inflight fire caused by a broken v-clamp on a turbo charger exhaust tube that was mounted near the lower left section of the firewall. In this scenario the turbo exhaust temps are much higher than just burning avgas. (Turbo exhaust is approximately 1,000F hotter....1,875F) The searing heat did NOT penetrate the SS firewall. It did create a hole through the left side of the AL cowling about the size of a silver dollar. The heat was then exposed to the cooler slipstream and cooled enough to create soot and smoke down the side of the fuselage.

Unfortunately for the pilot, he lost the turbo a few minutes after takeoff and was over a congested city. He couldn't stretch the aircraft back to the runway and landed on a city street - finally striking a light pole. The light pole ruptured the left wing leading edge (Fuel Tank) and this sprayed fuel all over the canopy and fuselage. The wreckage was in the lab and we were able to inspect everything just as the NTSB did. (Fuselage had melted due to the post impact fire and the firewall was completely intact.) Again, this is heat generated by a turbo charger exhaust, which is well above 100LL auto-ignition burn temperature. (As a side note: The NTSB uses 845F as their number for 100LL ignition temperature during accident investigations to analyze physical metallurgy affects.)

Also, I did specifically discuss Van's Aircraft firewall design when speaking to the SME's about inflight fire containment. The instructors all acknowledged the AL angle and AL rivets would melt soon after exposure to 900+F. However, (their words) "The AL angle/rivets are not your real concern. Neither is the possibility of the small amount of potentially noxious smoke." "You have much bigger concerns... you have a fire that can spread and very possibly cause you to lose your engine." "Open your canopy or puncture a hole in it to let out any smoke and then focus on landing...hopefully without rupturing a fuel tank."

Remember the theory of a propane blow torch (2,000+F) aimed at a static firewall is NOT truly a representation of what NTSB accident investigation data has revealed.

For single engine, normally aspirated, piston engines, the NTSB data shows average fire temps below 1,500F. The NTSB determined this based on knowing the metallurgical make up of each part and documenting the type of damage sustained during the fire.

As the NTSB instructors explained to our class, science applied to the collected data tells the story.

What about the bottom fuselage aluminum skin just aft of the firewall which would be exposed to a flame plume coming out of the cowl outlet (if there was an in-flight fire)?

Also, how do the aluminum rivets fare on the firewall which hold the angle stiffeners? Wouldn't those melt fairly quickly leaving a bunch of #40 holes in the firewall? I wouldn't expect those #40 holes to become mini-blowtorches, but they would let noxious smoke into the cockpit, no?

And, Ken, since when does avgas burn at 845F? I think you're missing a (1) in front to make it 1845F.

 

[DanH]

All of the instructors and SMEs agreed there has been no conclusive data to support the idea that a single piece of SS used for the firewall (single engine piston) is insufficient to protect the pilot from fires.

A seamless sheet of 26 ga stainless steel is absolutely fireproof. The SS panel merely emits a lot of radiant heat on the cabin side. Care to define "protect"?

That aside, have you actually heated a two piece SS test panel, assembled with aluminum or monel rivets?
.

 

[Ken Martin]

Dan,

As you are already aware, (as it pertains to a fire) the firewall (no matter what it is made of) is providing a fire barrier between the fwd and aft side. Not for a finite amount of time, as the high temps will eventually compromise the surrounding structure. The firewall merely helps to buy time for the pilot to get the aircraft on the ground as soon as possible.

That being said, your analysis is based on aiming a 2,000F torch directly at a simulated static firewall and taking radiant heat measurements. A basic understanding of Engineering properties could easily predict the findings.

What I am trying to pass along to you and the others is the information provided to me by several SME Engineers who each have 35-40 years of actual accident investigation experience. This particular group of instructors has investigated everything from single piston fixed wing to the Space Shuttle Columbia accident.

REAL WORLD accident investigation data does NOT show single piece SS firewalls as a design deficiency being causal or contributing to fire related crashes. If the data showed differently, don't you think Van's would modify their design accordingly.

If you are advocating for radiant heat protection on the cabin side because you believe the occupants will be subjected to dangerously high temps during descent for landing or after a post impact fire, then good on you. There's just no recorded accident data to support the need.

You don't have to agree with me. Please feel free to attend the NTSB training and discuss it further with them.

Cheers!

A seamless sheet of 26 ga stainless steel is absolutely fireproof. The SS panel merely emits a lot of radiant heat on the cabin side. Care to define "protect"?

That aside, have you actually heated a two piece SS test panel, assembled with aluminum or monel rivets?
.

 

[DanH]

REAL WORLD accident investigation data does NOT show single piece SS firewalls as a design deficiency being causal or contributing to fire related crashes.

A bare, single piece stainless firewall is relatively safe. If you'll give me a dollar for every time I've sung that tune over the past 18 years here on VAF, I can probably fly to OSH free next year.

Anyway, firewall performance is never causal. Firewalls don't start the fires.

There's just no recorded accident data to support the need.

Oh, there's plenty of it, but again, it won't be listed as causal. Here's an example. Read the attached. This gentleman was a 1500 AGL over cut fields. Why were flames entering the lower part of the cockpit by the rudder pedals? Did anyone consider the question?
.

 

[Jonnyb]

Dan,

As you are already aware, (as it pertains to a fire) the firewall (no matter what it is made of) is providing a fire barrier between the fwd and aft side. Not for a finite amount of time, as the high temps will eventually compromise the surrounding structure. The firewall merely helps to buy time for the pilot to get the aircraft on the ground as soon as possible.

That being said, your analysis is based on aiming a 2,000F torch directly at a simulated static firewall and taking radiant heat measurements. A basic understanding of Engineering properties could easily predict the findings.

What I am trying to pass along to you and the others is the information provided to me by several SME Engineers who each have 35-40 years of actual accident investigation experience. This particular group of instructors has investigated everything from single piston fixed wing to the Space Shuttle Columbia accident.

REAL WORLD accident investigation data does NOT show single piece SS firewalls as a design deficiency being causal or contributing to fire related crashes. If the data showed differently, don't you think Van's would modify their design accordingly.

If you are advocating for radiant heat protection on the cabin side because you believe the occupants will be subjected to dangerously high temps during descent for landing or after a post impact fire, then good on you. There's just no recorded accident data to support the need.

You don't have to agree with me. Please feel free to attend the NTSB training and discuss it further with them.

Cheers!

Can I ask what point you’re trying to make Ken?

Is the firewall a design issue? No.

Can good quality firewall insulation improve outcomes in the event of an engine fire? I think the answer has to be a qualified yes. Qualified as in there’s not enough data comparing engine fires in single engine aircraft with insulated firewalls with those that are not insulated. However, a firewall covered in a good quality insulation will at worst be a waste of time, and at best be a life saver. I hope never to find out.

It reminds me very much of the argument around the wearing of parachutes. How many RVs have come apart in flight? How many pilots have successfully bailed out of an RV? Yet many of us still ware them, and for some are a legal requirement. The chances are the wearing of a parachute is utterly pointless, yet can only improve the chances of a successful outcome. Much like the argument around firewall insulation.

One of my biggest bug bares with light aircraft is the presence of fuel in the cockpit. That is why I will carry a fire extinguisher, and won’t ware nylon clothing. My decisions, I hope, will prove to be utterly pointless and unnecessary. But it won’t stop me making them.

 

[rv8ch]

... If a pilot wants to increase fire protection for the cabin occupants, make it easy to open up the cowling to do a well-developed pre-flight inspection ..

Reminds me of a podcast I just heard - ilafft:

https://overcast.fm/+nLF90EcEQ

https://podcasts.apple.com/us/podcast/68-hidden-hazard/id1544875746?i=1000628710321

https://podcasters.spotify.com/pod/show/ilafft/episodes/68--Hidden-Hazard-e29jije

(sorry about all the links - there does not seem to be a link to this podcast on the Flying.com website)

 

[Ken Martin]

Jonnyb, my original comment was to Moe's statement which gave me the impression he might be concerned with the ability of "just the stainless" to protect the cabin from an inflight fire. If that was an incorrect interpretation, that's on me.

My point is this:
If anyone is concerned with the ability of the current firewall design to perform its intended design intent, my posts were just to share what the NTSB and FAA, teaching Aircraft Accident Investigation, had to say on the topic.

This is experimental aviation and everyone is entitled to customize their aircraft as they see fit to contend with any perceived safety issue. If adding additional insulation or modifying your firewall makes you feel safer, great! It's your decision.

Can I ask what point you’re trying to make Ken?

Dan I'd be interested to hear more about these kits.

I had some type of flammable foam from the previous builder, which I promptly removed. Would like something more than just the stainless.

Dan - Your clip is merely a snippet from a pilot's post-accident interview. There is a lot of missing information that would be taken into consideration during the investigation to determine if the lower firewall did not sufficiently protect the cabin area. You have to consider ALL evidence gathered in an investigation. Beware of "Confirmation Bias".

Oh, there's plenty of it, but again, it won't be listed as causal. Here's an example. Read the attached. This gentleman was a 1500 AGL over cut fields. Why were flames entering the lower part of the cockpit by the rudder pedals? Did anyone consider the question?
.

 

[DanH]

My point is this:
If anyone is concerned with the ability of the current firewall design to perform its intended design intent, my posts were just to share what the NTSB and FAA, teaching Aircraft Accident Investigation, had to say on the topic.

Which current firewall design would that be?

As long as we're talking about seamless stainless or equal, I am of the same opinion. But we're not.

Dan - Your clip is merely a snippet from a pilot's post-accident interview.

Actually, from his NTSB Form 6120.1.

There is a lot of missing information that would be taken into consideration during the investigation to determine if the lower firewall did not sufficiently protect the cabin area.

Yes indeed. That's the point. Where is the information? Did anyone at the NTSB bother to ask why a pilot was burned despite optimum conditions...a cruise altitude of 1500 AGL, with a mowed hay field on the nose, and a flight duration of not much more than one minute after first evidence of malfunction?

I previously asked you to define "protect". Here we had open flame in the cockpit in less than 30 seconds, while the certified standard (23.1191) is:

(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.

BTW, I interviewed the pilot. Ex-Marine. His written self-description of "minor burns on my lower legs" may have been overly modest.

 

[Ken Martin]

Dan - It's apparent you disagree with the NTSB and potentially their processes. I am not interested in further entertaining your arguments.

Please feel free to take the training so you can communicate your thoughts directly with them.

Which current firewall design would that be?

As long as we're talking about seamless stainless or equal, I am of the same opinion. But we're not.



Actually, from his NTSB Form 6120.1.



Yes indeed. That's the point. Where is the information? Did anyone at the NTSB bother to ask why a pilot was burned despite optimum conditions...a cruise altitude of 1500 AGL, with a mowed hay field on the nose, and a flight duration of not much more than one minute after first evidence of malfunction?

I previously asked you to define "protect". Here we had open flame in the cockpit in less than 30 seconds, while the certified standard (23.1191) is:

(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.

BTW, I interviewed the pilot. Ex-Marine. His written self-description of "minor burns on my lower legs" may have been overly modest.

 

[Mikeyb]

You are the one arguing Ken. Arguing against a simple modification that has little downside and several benefits.

 

[DanH]

Dan - It's apparent you disagree with the NTSB and potentially their processes. I am not interested in further entertaining your arguments.

Further? Ken, factually, you've brought nothing to the discussion beyond a secondhand account of instructor opinion regarding a narrowly defined case, specifically seamless firewalls...an opinion with which I agree.

We disagree when you apply that opinion to the whole fleet. It's simply not true.

Look, folks want everyday inflight comfort. The most effective approach is to insulate the hot side. Make good choices in materials and technique, and you get extended fire protection in the bargain. Hopefully you'll never use it, but hey, what's not to like?

 

[Bill Boyd]

Dan's longstanding and patiently researched endorsement of insulation on the forward side of our firewalls may or may not ever gain an unfortunate victim of an in-flight fire very much margin, but I suspect his simultaneous campaign against insulating the aft side of the firewall has or will save lives someday.

You can bet the foam sound insulation promptly came off the cockpit side of my -6A after reading his original post years ago, and my -10 was built with Fib-refrax blanket and SS foil on the engine side.

Thank you, Dan.

 

[Freemasm]

Root cause, direct contributor, secondary contributor,...

and other "subjectability". Some interesting and flawed arguments.

So, if a firewall doesn't breach during an in-flight fire but the local temps _____ly prevent a pilot from effectively actuating rudder pedals. As a _____ result, the aircraft ground loops upon landing and ______ly causes major injury or loss of life.

Did the product: meet spec, meet expectations, meet design intent?

We get to build what we want in this non-cert world. Sure, risk parameters have to be evaluated and the high consequence, low probability corner of the FMEA (a far too linear process, IMO) typically makes for the hardest decisions.

Having said all that, judging someone's conservative approach regarding safety is a bit presumptuous in my opinion (which counts for nothing here.)

Be smart. Ask questions. Build safe, (drink beer, and pet dogs)

 

[wirejock]

Firewall

Further? Ken, factually, you've brought nothing to the discussion beyond a secondhand account of instructor opinion regarding a narrowly defined case, specifically seamless firewalls...an opinion with which I agree.

We disagree when you apply that opinion to the whole fleet. It's simply not true.

Look, folks want everyday inflight comfort. The most effective approach is to insulate the hot side. Make good choices in materials and technique, and you get extended fire protection in the bargain. Hopefully you'll never use it, but hey, what's not to like?

I trust Dan. Fiberfrax and titanium on my firewall. Anybside benefit appreciated for minimal weight gai

 

[skylor]

A little knowledge is...

There are a lot of terms and concepts being thrown about here, much of it incorrectly and inaccurately:

To your point, in the NTSB training we investigated an actual inflight fire caused by a broken v-clamp on a turbo charger exhaust tube that was mounted near the lower left section of the firewall. In this scenario the turbo exhaust temps are much higher than just burning avgas. (Turbo exhaust is approximately 1,000F hotter....1,875F)

Engine exhaust gas temperatures are much lower than avgas flame temperatures because some of the heat is consumed through gas expansion and resultant piston work before the exhaust exits the engine.

Turbo exhaust is not 1000F hotter than "just burning avgas". Avgas burns at over 3800F! It is typically a bit hotter than non-turbo exhaust temperatures because the exhaust gases upstream of the turbo have not fully expanded to atmospheric pressure and therefore have not cooled as much as NA engine exhaust. However, in the case of an exhaust leak upstream of the turbocharger, the gases continue to expand through the leak and cool down towards the temperature of NA exhaust when they exit the pipe- but they're still hot enough to burn aluminum!

Again, this is heat generated by a turbo charger exhaust, which is well above 100LL auto-ignition burn temperature. (As a side note: The NTSB uses 845F as their number for 100LL ignition temperature during accident investigations to analyze physical metallurgy affects.)

Auto-ignition temperature and ignition temperature are completely unrelated to "burn temperature". Auto-ignition temperature is the temperature at which something will ignite without an external ignition source, and the Conoco-Phillips MSDS for 100LL quotes that as 824F - similar to the 845F temp you quoted above. This has nothing to do with "burn temperature" which as stated above is much hotter - over 3800F flame temperature.

Also, I did specifically discuss Van's Aircraft firewall design when speaking to the SME's about inflight fire containment. The instructors all acknowledged the AL angle and AL rivets would melt soon after exposure to 900+F. However, (their words) "The AL angle/rivets are not your real concern. Neither is the possibility of the small amount of potentially noxious smoke." "You have much bigger concerns... you have a fire that can spread and very possibly cause you to lose your engine." "Open your canopy or puncture a hole in it to let out any smoke and then focus on landing...hopefully without rupturing a fuel tank."

I'm not sure what the NTSB instructors point was but considering most piston aircraft POH's call for shutting off the fuel valve at the first sign of a FWF fire, an engine out is a given. Ideally we do our best to prevent the fire in the first place by following accepted practices for FWF installation and by performing frequent inspections. Thermal protection is a last resort but following Dan's recommendations significant additional protection can be added to our planes with little weight and cost penalty.

Remember the theory of a propane blow torch (2,000+F) aimed at a static firewall is NOT truly a representation of what NTSB accident investigation data has revealed.

For single engine, normally aspirated, piston engines, the NTSB data shows average fire temps below 1,500F. The NTSB determined this based on knowing the metallurgical make up of each part and documenting the type of damage sustained during the fire.

As the NTSB instructors explained to our class, science applied to the collected data tells the story.

Well this particular NTSB instructor is entitled to his opinion, but I would want use something other than an "average" for protecting myself from something as extreme as a FWF fire. If faced with a FWF fire, I would like to not be overly distracted by my feet burning up while likely trying to make a dead-stick emergency landing somewhere. In the case of my RV-8, I followed Dan's advice and insulated the forward side of of my firewall with stainless foil encapsulated fiberfrax insulation. I also replaced the aluminum cooling air outlet ramp with stainless steel and applied encapsulated fiberfrax on the inside of that as well as replaced the stock aluminum cabin heat valve with a stainless one. Eventually other parts of the fuselage may burn through given enough intensity and time, but we try to do the best we can with what we have.

Skylor

 

[Webb]

I am one of Dan’s beta test sites for firewall insulation kit. I elected to go with the heavier SS foil (0.005) and thicker tumescent insulation (0.1). The heavier foil allowed me to score it which gave it a quilted look and almost eliminated the reflected wave look. That step was not part of the install instructions but was my touch and I hope it makes Dan a smidge proud of the outcome. The quilting also hides little dents that occur during the install.

I am delaying attaching the top skin and the flange for the Skybolts until I run the wires for the engine which will be hung in the very new future.

I also am installing 2 thermocouplers for early fire detection.

Pics are bare foil, smooth foil, foil with attachments clecoed on, and quilted foil, and quilted with attachments riveted or bolted on.

I’m looking forward to noise reduction and improved cabin comfort and pray I will never need the added level of safety.

 

[Mike S]

Remember the theory of a propane blow torch (2,000+F) aimed at a static firewall is NOT truly a representation of what NTSB accident investigation data has revealed.

But, as I recall, it is the standard the FAA uses for firewall testing. Which Is what I believe Dan was trying achieve.

 

[DanH]

I elected to go with the heavier SS foil (0.005) and thicker tumescent insulation (0.1). The heavier foil allowed me to score it which gave it a quilted look and almost eliminated the reflected wave look. That step was not part of the install instructions but was my touch and I hope it makes Dan a smidge proud of the outcome. The quilting also hides little dents that occur during the install.

I think it looks great. Probably work fine with the 0.002" stainless also. Dull plastic pizza cutter and a straightedge, roll in the crease.

But, as I recall, it is the standard the FAA uses for firewall testing. Which Is what I believe Dan was trying achieve.

Yes Mike, I have tried to stick with the FAA standard as much as practical in a non-laboratory environment. Note the standard is changing, as the specified oil burners are apparently no longer in production. A propane flame can generate the required 2000F temperature at the test surface, but doesn't deliver quite as much energy; a lot of it radiates away through the clear flame envelope. The FAA has been working on a new standard for propane test rigs. Probably complete by now; I have not checked.

Point is, a propane test rig with a simple 25 sq in hot spot at 2000F is not as severe as the old standard with the specified oil burner.