As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
2 INCH LONG CRACK IN LT AREA OF FIREWALL STIFFENER IN AREA OF THE PARKING BRAKE BRACKET MOUNTING. BELIEVED TO BE CAUSED BY FLEXING OF FIREWALL BY APPLICATION OF PARKING BRAKE. THIS IS THE SECOND AC IN FLEET WITH THIS PROBLEM. THIS AREA NEEDS ADDITIONAL REINFORCEMENT TO MINIMIZE FLEXING IN THIS AREA.