The International Cessna^® 170 Association

ghostflyer wrote: ↑Mon May 27, 2024 12:56 am… there was a recommendation of sealing the firewall with Proseal [PRS 1422 B1/2 ] and then riveting in . …

I’d be reluctant to use PRS 1422 as a firewall sealant as it is designed to be used as a fuel tank sealant. According to Kitplanes Magazine

… fuel tank sealant is not suitable for sealing firewalls—it’s flammable. Nor is it suitable for any other use in the engine compartment.

There are a dizzying variety of firewall sealants available on the market. From Dow Corning there’s 736 High Temp Sealant and DOWSIL 3-6077. 3M makes Fire Barrier Silicone Sealant 2000+. (It’s designed more for the construction industry rather than aviation). Dapco has 2100, 2200, and 18-4F. PPG products include PR-812, P/S 700, and PR-1995. Another one is Flamemaster CS-1900. The latest revision I have to the C-172 Service Manual is dated July 3, 2006 so they may have updated this information since then, but in the manual they have a section entitled “Fuel, Weather and High-Temperature Sealing - Maintenance Practices”. There they recommend Dapco 2100 for “firewall and wire bundle sealing”, Pro Seal 700 for “firewall sealing (except wire bundles)”, and Dow Corning Q3-6077 for “wire bundle firewall sealing”. DanH at Van’s Air Force has done a lot of testing on a variety of firewall sealants. See this thread.

Despite the “correctness” of whichever sealant is used…. I can’t imagine it makes any difference whatsoever if a blazing engine compartment fire develops in-flight.

Any in-flight fire …should provoke the thought that “This airplane now belongs to the insurance company…and it’s my job to get it on the ground and GET OUT of it….regardless of any damage incurred to the airframe I no longer own.”

JMO

The sealant is between the firewall rim and the edge of the fuselarge and is not to stop fire invading the cockpit area but to stop oil migrating into the cabin area and carbon monoxide. i was told years ago [I can’t remember who]
but if you have a uncontrollable engine fire in the single engine cessna you have 4 mins to get on the ground . I do not know how that time figure originated or where it came about but i am not wanting to test it out.
I will stand corrected about the sealant used. I always had the idea it was PRC 1422 B1/2 . That’s a dark brown in color . Just looking at my aircraft now and the sealant used is a light cream. seeing that, i can’t not recall what we used.

When I was an Aeronca owner I had an accident report and photo taken of an airplane on-fire with the pilot standing on the landing gear outside the cockpit while reaching inside to manipulate the controls…an attempt toward a landing… which unfortunately did not succeed.

This was before personal computer and internet so I can’t share it, but it was a discouraging item.

There was also an Aeronca from Texas on it’s way to Tenn which supposedly suffered an inflight fire…the pilot crash-lands in a forest…survives for a day or two…then with a broken leg hobbles for miles…only to succumb to exposre in the snow.

I have spilt fuel while refueling…. it’s not just disappointing…. it’s dangerous if it gets inside the wing-root fairing. Subsequent flight….is NOT the way to evaporate or get rid of that fuel. (A place to consider placing Gorilla Tape or similar beneath that fairing. I did that after it sat tied down during a drenching downpour…to keep water out of the doorposts and down into the interior…. but it also has prevented gasoline fumes when I spilt fuel.)

I do not believe those little half-pound fire extinguishers sold at Sporty’s, etc. will be of any use whatsoever in-flight. I cannot emphasize enough…. if you have an in-flight fire…Do Not try to “save the plane”. Get it DOWN and Get OUT. NOW.

https://data.ntsb.gov/carol-repgen/api/ ... /41443/pdf

For many years we had to carry a small brass cylinder fire extinguisher and had carbontetrachloride [hope that’s the right spelling ] in it. We later found the extinguisher agent is highly toxic to life . So maybe it put the fire out but killed you any way. These days I do not carry a fire extinguisher . NEVER have a dry powder extinguisher as that is nearly as bad . I also had a BCF fire extinguisher in my aircraft for a while and found that is bad for your health if used plus I was threaten with massive fines if i used it . I had a massive argument with a “greenie” inspector on the subject . So the “correct “ way of disposing the BCF extinguisher was to take it down to the local fire station and surrender it and with obtain a receipt . We were not allowed to throw it in the trash. [Thats a life in prison ] Now this is hush hush just between us guys OK. The fireys then opened the value to the atmosphere and then placed the empty cylinder in this small crusher . I watched them do this . These days I have a a number of CO2 fire extinguisher cylinders and a a couple of foam extinguishers in my hangar plus the mandatory fire hoses .