The International Cessna^® 170 Association

Yea Brad, I used that fully charged cell to jump my plane an it spun that prop like a Sky-Tech And if you believe that I got some stuff I want to sell you No! I had to take the battery up to Dave Mason's hangar & get it charged up for the trip home. I wouldn't have left it on had it not been for a 170 president having me go with him to get a couple of kegs for the flyin Glad I found the corrosion problem when I did. Had I not run down the battery I might have gone a long time before opening the battery box & by then it might have gone into the firewall so things like that sometimes work out for the best

rydfly wrote:Oh boy, sounds like fun times are ahead...

Does the EC-539 sealing compound go by another name? Google and A/C Spruce searches haven't been very helpful.

EC539 was a 3-M sealant that is no longer produced under that name. Any hi-temp RTV sealant should work just fine. Permatex makes some: http://www.aircraftspruce.com/catalog/e ... exprod.php

After cleaning out the battery box and repainting any bare spots, if you will paint the whole inside of the box with Corrosion-X or ACF-50 it will not corrode again. Paint the battery terminals and cable ends with it and they will not corrode either. It's too easy not to do it and it works for a whole year.

Sounds like great advice, thank you!

gahorn wrote:The method of repair should be found in Section 19, Para 52B of the 100 Series Service Manual, under "Structural Repair, Firewall".

"Firewall damage may be repaired by removing the damaged material and splcing in a new section of the material. The new section should be lapped over the old material and sealed with EC-539 compound or equivalent, and secured with stainless steel rivets. Damaged or deformed angles or stiffeners should be replaced. A severely damaged firewall should be replaced as a unit."

Old thread but, where does one get stainless steel rivets?
I can't locate (nor would know how to buck) a solid stainless rivet.

Unless they are referring to stainless pop rivets.

David, I think Cessna is calling for MS20613C rivets semi-tubular stainless rivets in the section of the manual George quoted. These and others I mention below are available from Genuine Aircraft Hardware Company or Hanson Rivet & Supply Co.

For what it's worth the 2 Dec. 1996 Cessna Single Engine Maintenance Manual calls for MS20450 semi-tubular steel rivets to be used on firewall repairs. (Edit: In the drawing however it specifies monel rivets which would be MS20615 rivets.) It also shows regular MS 20470 rivets being used to attach the firewall to the firewall angle.

Thanks! I should have looked it up in the repair manual myself but thought I'd ask here.
That excerpt states that the firewall is stainless which is probably true of later 172s but ours is galvanized steel.
Does that change what to use?

Do we know what type of rivets are used on the heater duct that attaches to the firewall?

I fabricated a heater duct for my '52 as well so would be interested in knowing what the later 170's used to attach it. My guess is 470's. If you are patching your steel firewall I'd follow this advice from the '77-'86 C-172 manual:

rydfly wrote:Oh boy, sounds like fun times are ahead...

Does the EC-539 sealing compound go by another name? Google and A/C Spruce searches haven't been very helpful.

Rydfly, proseal works and is acceptable. It is used for sealing fuel tanks.

If you want to keep it a FIREwall, find a sealant specified for firewalls. Proseal isn't.

Miles, please elaborate.

Perhaps it is because I broke my own personal rule of NOT using "Proseal" as a specific product used to seal fuel tanks. "Proseal" is actually a brand name covering several types of sealants, but in the RV world it is almost exclusively (and incorrectly) used to refer to a polysulfide sealant used to seal fuel tanks. P/S 700 is made by Proseal, and is obviously intended to seal firewalls. It is, however, not intended to be interchangeable with fuel tank sealant.

cessna170bdriver wrote:Perhaps it is because I broke my own personal rule of NOT using "Proseal" as a specific product used to seal fuel tanks. "Proseal" is actually a brand name covering several types of sealants, but in the RV world it is almost exclusively (and incorrectly) used to refer to a polysulfide sealant used to seal fuel tanks. P/S 700 is made by Proseal, and is obviously intended to seal firewalls. It is, however, not intended to be interchangeable with fuel tank sealant.

Miles, if it is any consolation prize, it is the same stuff! Ask me how I know.