Cracked firewall tube, below cluster

[hobrecht]

Got a big problem we found at annual yesterday. The IA discovered a cracked tube on the left diagonal tube on the cockpit side of the firewall, about 1.5"
below the cluster at the top of the panel. Has anyone encountered this before? Any suggestions on the fix?

Many thanks,
Holliday Obrecht

[Steve Pierce]

I would repair it like Figure 4-35 in the AC43.13-1B with a sleeve over the tube.

http://www2.tech.purdue.edu/at/cours...3-1B/CH4_5.pdf

[hobrecht]

I would repair it like Figure 4-35 in the AC43.13-1B with a sleeve over the tube.

http://www2.tech.purdue.edu/at/cours...3-1B/CH4_5.pdf

Thanks, Steve. It looks like the real issue is going to be access. The firewall is stainless steel. If the portion of the firewall that lies just in front of the cluster could be removed, that would give ready access the damaged tube for welding. Do you know if we can legally patch the firewall after the weld repair is completed? If we can, then access to the repair site will not be a big deal. If we have to remove the engine and firewall to get to the cluster, THAT will be a big deal. Please let me know what you think about opening up a section on the firewall and repairing it later. Might not look pretty, but would get the job done.

Many thanks for your (usual) very good help.
Holliday

[Steve Pierce]

I see no issue at all pat bing the firewall. I have done it on spam can firewalls where the firewall is structural. Just use a good overlap. Steel or stainless steel rivet would be good. I have some old firewalls I can cut a patch out of if you need to mat h the beads.