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  #1  
Old 06-22-2017, 08:53 AM
bobhope2505 bobhope2505 is offline
 
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Location: Carmichael, CA
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Default Pro-Seal vs. RTV sealant for firewall fittings

I didn't have any Pro-Seal available when installing the fuel line fittings in the firewall, so I used RTV sealant. I've now seen posts from two others hinting they did the same. My adviser suggested that I redo it because standard RTV sealant will burn away when exposed directly to flame and compromise the firewall. (It really wasn't a "suggestion.")

He did, however, suggest an alternative to avoid dealing with Pro-Seal--3M Fire Barrier Silicone Sealant. There may be other options, but I didn't check. It proved to be very useful when I wanted to tweak the angle of the elbow in the fuel line.
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Old 06-22-2017, 09:50 AM
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N941WR N941WR is offline
 
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I used 3M Fire barrier Sealant and it has held up well. Of course I have not "tested" it in an actual fire and hope never to do that.
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  #3  
Old 06-22-2017, 03:01 PM
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See the sticky thread at the top of the Safety forum page.
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  #4  
Old 06-22-2017, 04:12 PM
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RV6_flyer RV6_flyer is offline
 
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Quote:
Originally Posted by DanH View Post
See the sticky thread at the top of the Safety forum page.
Here is the Link to the Sticky "Firewall sealant and Fire Safety" Thread on the Safety Forum.
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  #5  
Old 06-22-2017, 05:45 PM
rv7charlie rv7charlie is online now
 
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Just out of curiosity, what did he think would happen to proseal in a fire, if you'd used that? (Might help evaluate his 'advice'...)
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Old 06-22-2017, 06:18 PM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by bobhope2505 View Post
I didn't have any Pro-Seal available when installing the fuel line fittings in the firewall, so I used RTV sealant. I've now seen posts from two others hinting they did the same. My adviser suggested that I redo it because standard RTV sealant will burn away when exposed directly to flame and compromise the firewall. (It really wasn't a "suggestion.")

He did, however, suggest an alternative to avoid dealing with Pro-Seal--3M Fire Barrier Silicone Sealant. There may be other options, but I didn't check. It proved to be very useful when I wanted to tweak the angle of the elbow in the fuel line.
Perhaps I don't understand. If you are using a bulkhead fitting for the fuel line, why do you think sealant is required with the fitting?

Carl
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Old 06-22-2017, 10:39 PM
bobhope2505 bobhope2505 is offline
 
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Quote:
Originally Posted by Carl Froehlich View Post
Perhaps I don't understand. If you are using a bulkhead fitting for the fuel line, why do you think sealant is required with the fitting?

Carl
Because the instructions called for it. I presume the aircraft designer had his reasons.
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Old 06-22-2017, 10:53 PM
bobhope2505 bobhope2505 is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Just out of curiosity, what did he think would happen to proseal in a fire, if you'd used that? (Might help evaluate his 'advice'...)
He said it swells when exposed directly to flame to maintain the seal instead of converting to ash and reducing in volume.
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Old 06-23-2017, 07:06 AM
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Quote:
Originally Posted by bobhope2505 View Post
He said it swells when exposed directly to flame to maintain the seal instead of converting to ash and reducing in volume.
No he didn't.

Intumescent sealants swell to close gaps and openings. The usual ingredient is vermiculite, and required "swell temperature" is about 600F. There are also other ingredients in use. 3M FireBarrier 2000 appears to be intumescent. In addition, many products form a char on their surface, which is an insulator, and thus desirable. Some firestop products depend entirely on char-based protection. Char alone is a poor protection for an airplane firewall. The chars are fragile, and firewalls vibrate while being blasted by cooling air at high velocity.

Proseal is a polysulfide sealant. It was not included in the burn test earlier in this thread. I'm sure it would be a fine gas sealant when enclosed between the fay surfaces of a sheet metal joint, but I would not allow any to be exposed inside the cabin, as outgas, flame, and smoke results are unknown.
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Last edited by DanH : 06-23-2017 at 07:11 AM.
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  #10  
Old 06-23-2017, 10:03 AM
rv7charlie rv7charlie is online now
 
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Or maybe he did, and you know who not to listen to....
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