Introduction: Corrosion can cause damage to the airplane's structural integrity and if it is not controlled, the airframe will carry less load than what is necessary for continued airworthiness.
(1) A CPCP is a system to control the corrosion in the airplane's primary structure. It is not the function of the CPCP to stop all of the corrosion conditions, but to control the corrosion to a level that the airplane's continued airworthiness is not put in risk.
A. The function of this document is to give the minimum procedures necessary to control the corrosion so that the continued airworthiness is not put in risk. The CPCP consists of a Corrosion Program Inspection number, the area where the inspection will be done, specified corrosion levels and the compliance time. The CPCP also includes procedures to let Cessna and the regulatory authorities know of the findings and the data associated with Level 2 and Level 3 corrosion.
This includes the actions that were done to decrease possible corrosion in the future to Level 1.
A. The Baseline Program is part of the CPCP. It is divided into Basic Task and Inspection Interval. In this manual the Basic Tasks are referred to as the Corrosion Program Inspection. This program is to be used on all airplanes without an approved CPCP. Those who currently have a CPCP that does not control corrosion to Level 1 or better must make adjustments to the areas given in the Baseline Program.
B. Typical Airplane Zone Corrosion Program Inspection Procedures.
(1) Remove all the equipment and airplane interior (for example the insulation, covers and, upholstery) as necessary to do the corrosion inspection.
(2) Clean the areas given in the corrosion inspection before you inspect them.
(3) Do a visual inspection of all of the Principal Structural Elements (PSEs) and other structure given in the corrosion inspection for corrosion, cracking and deformation.
(a) Carefully examine the areas that show that corrosion has occurred before.
NOTE: Areas that need a careful inspection are given in the corrosion inspection.
(b) Nondestructive testing inspections or visual inspections can be needed after some disassembly if the inspection shows a bulge in the skin, corrosion under the splices or corrosion under fittings. Hidden corrosion will almost always be worse when fully exposed.
(4) Remove all of the corrosion, examine the damage and repair or replace the damaged structure.
(a) Apply a protective finish where it is required.
(b) Clean or replace the ferrous metal fasteners with oxidation.
(5) Remove blockages of foreign object debris so that the holes and clearances between parts can drain.
(6) For bare metal on any surface of the airplane, apply corrosion prevention primer, refer to the Application of Corrosion Preventative Compounds.
(a) Apply a polyurethane topcoat paint to the exterior painted surface. Refer to the manufacturer's procedures.
(7) Install the dry insulation blankets.
(8) Install the equipment and airplane interior that was removed to do the corrosion inspection.