[Learjetter]

AC 43.13b gives some good advice on making repairs to metal skins and structures. Imagine your rear non-pressurized firewall had corrosion or a crack and your remediation efforts resulted in a hole in the rear firewall. A forward-thinking A&P & IA team would be expected to fabricate an acceptable repair to that area, consulting the appropriate service manuals. The same enterprising A&P & IA team could agree to make the repair removable, thus creating an access hatch where one was not previously. Such a repair would probably be a minor repair logbook entry or at most a major repair needing a form 337 citing the appropriate repair manual as approved data.