RV-4 firewall cracks

[MoonDog1]

My mechanic found these cracks during the process of replacing already cracked weldaments. Trying get some opinion as to what do with the cracks found on the firewall. Thank you!

Alex

RV-4

 

[HFS]

This is a very common "malady" on RV-4's at the lower juncture of the bends associated with the rudder pedal "kick out" of the FW necessary for full travel of those pedals. Since the FW is not structural (mostly for CO, fire & heat protection) a repair is not mandatory. If you elect not to undergo repairs, you should attempt to seal that area re/CO intrusion.

I elected to make a repair, making a thin gauge 4130 steel "glove" that covered all the interconnected surfaces down there (including MM hole), both inside & out, effectively making a "sandwich" there, using Cherry Max rivets along with 3M-2216 epoxy adhesive for added continuity.

Still flying that way (I think) 24 years later ...

YMMV - and probably will, but this is one way.

HFS

 

[MoonDog1]

This is a very common "malady" on RV-4's at the lower juncture of the bends associated with the rudder pedal "kick out" of the FW necessary for full travel of those pedals. Since the FW is not structural (mostly for CO, fire & heat protection) a repair is not mandatory. If you elect not to undergo repairs, you should attempt to seal that area re/CO intrusion.

I elected to make a repair, making a thin gauge 4130 steel "glove" that covered all the interconnected surfaces down there (including MM hole), both inside & out, effectively making a "sandwich" there, using Cherry Max rivets along with 3M-2216 epoxy adhesive for added continuity.

Still flying that way (I think) 24 years later ...

YMMV - and probably will, but this is one way.

HFS

This is very helpful! Thank you for the detailed response. I think I will opt for the repair