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  #81  
Old 03-13-2017, 11:53 AM
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Av8rRob Av8rRob is offline
 
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To those who have bought the ss shim stock, were you happy with the .003 thickness or did you buy .002 or something thicker and are you happy with your decision? I'll need 100" of it for my -14 and that stuff is kinda pricey.
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  #82  
Old 03-13-2017, 04:24 PM
868RM 868RM is offline
 
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Location: lena, il.
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Default ss

Used stainless steel "tool wrap" from McMaster Carr. It is used for heat treatment.
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  #83  
Old 03-08-2019, 08:19 AM
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DanH DanH is online now
 
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This report has been linked in at least two threads. Read it again, carefully.

https://www.atsb.gov.au/publications...n/ab-2018-124/

Most readers focus on the battery meltdown. Although thermal runaway does appear to be the initial issue, it was not the proximate emergency. The emergency was fire in the cockpit, resulting in burn injury to the pilot, his exit of the still moving aircraft, and the ultimate total loss of the airframe due to fire.

Ok, so there was an ignition source (a hot battery) on the engine side of a firewall. The question investigators fail to ask is how did a hot battery result in open flame on the cockpit side of the firewall?

The J170 has a firewall assembly typical of composite aircraft, a bonded-in plywood core faced with a ceramic fiber sheet (fiberfrax) or similar, then covered with a stainless steel sheet. Here's a link to the construction manual; check pages 45 to 53:

https://jabiru.net.au/wp-content/upl...Manual-WEB.pdf

I've never burn tested a SS/fiberfrax/plywood assembly, but I suspect the bare stack-up would do moderately well. The problem is practical detail. As noted in this thread and elsewhere, steel fittings and bolts are both capable of point heating. They can glow red and transmit (by conduction) more than enough heat to provide an ignition hot spot.

Look at the photo at the bottom of page 53, a view of the cabin side after installation of all the bolts and fittings:



Now jump to page 234:



Yes, that's foam insulation glued over all those ignition point sources.

Folks, I cannot absolutely state that in this case the fire transfer mechanism was hot battery-->hot hardware-->foam ignition. We just don't have enough information, all too typical for an EAB crash report. I have watched bolts glow red in an otherwise relatively cool firewall, and if it walks like a duck and quacks like a duck...

So, two lessons.

(1) For the umpteenth time, don't put stupid stuff on the cabin side of firewalls, even when properly insulated on the forward side.

(2) Lithium battery runaways can get very hot. The mere fact that the battery is on the opposite side of the firewall, or within a containment box, does not guarantee adjacent objects will remain below ignition temperature.
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  #84  
Old 03-09-2019, 12:46 AM
rv8ch rv8ch is offline
 
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Default RV8 baggage area

Quote:
Originally Posted by DanH View Post
...
(1) For the umpteenth time, don't put stupid stuff on the cabin side of firewalls, even when properly insulated on the forward side.
...
This is a very good point, and something I have not given a lot of thought to. One thing I need to consider is the RV8 forward baggage area - I was assuming I could just toss backpacks or other baggage in the forward baggage area, but I think it would be wise to consider the flammability of anything I put up front, or think about a good layer of insulation.
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  #85  
Old 03-09-2019, 05:11 AM
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DanH DanH is online now
 
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Quote:
Originally Posted by rv8ch View Post
This is a very good point, and something I have not given a lot of thought to. One thing I need to consider is the RV8 forward baggage area - I was assuming I could just toss backpacks or other baggage in the forward baggage area, but I think it would be wise to consider the flammability of anything I put up front, or think about a good layer of insulation.
We can insulate the forward face of course. We can limit or protect steel hardware penetrating the engine-side insulation. However, the real key is that fire (or to be more precise, heat) goes with the air flow, which is significant, in the ballpark of 20-25 cubic feet per second. Highest temperatures will be within the combustion zone (think just downwind of the fuel source), extending to and through the cowl exit, because that is where the vast majority of the air is going. In comparison, the airflow through the cowl-to-fuselage joints is minuscule. I think (opinion) the probability of a really hot upper firewall is low...assuming a builder doesn't bolt a potential heat source like a lithium battery directly to it.
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  #86  
Old 03-09-2019, 09:28 AM
F1R F1R is offline
 
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Default Observation

I have read a lot of incident and inflight fire reports where the fire goes either un detected for critical moments (or minutes in the case of several airliners) or un responded to for periods of time that would often have allowed safe landings.

I have to consider that in RV type airframes, an over temperature / fire detection and alert system near the cooing air exit would provide improved odds of a faster reaction and landing.
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  #87  
Old 03-19-2019, 12:20 PM
Richard2364 Richard2364 is offline
 
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Location: Friendswood, TX
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Default Cabin firewall insulation

After reading through the posts about firewall forward insulation I have decided to go the Fiberfrax/.002 SS direction. In ordering the .002 SS I found that it comes in almost exactly twice as much as I need so.... What about using the extra to to a Fiberfrax(or other people friendly insulator)/.002 SS on the cabin side also?
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  #88  
Old 03-19-2019, 12:25 PM
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DanH DanH is online now
 
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Quote:
Originally Posted by Richard2364 View Post
After reading through the posts about firewall forward insulation I have decided to go the Fiberfrax/.002 SS direction. In ordering the .002 SS I found that it comes in almost exactly twice as much as I need so.... What about using the extra to to a Fiberfrax(or other people friendly insulator)/.002 SS on the cabin side also?
There are very few people-friendly insulators (smoke, flame, cancer, etc). Fiberfrax is not people-friendly. Bare stainless is quite safe.
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  #89  
Old 03-19-2019, 12:50 PM
Richard2364 Richard2364 is offline
 
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Location: Friendswood, TX
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Default Cabin firewall insulation

What comes to mind based on "bare stainless is quite safe" would be to lightly spread stainless wool behind the cabin side covered by the SS foil held in place by SS rivets. The intent is to make a slightly more comfortable cabin while not introducing bad things.

Or

Is this a waste of time and materials?
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  #90  
Old 03-19-2019, 02:44 PM
rv7charlie rv7charlie is online now
 
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If you just 'gotta' use it, why not outside the belly under your feet?
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