Chapter 1. General 




Chapter 1. General 


Corrosion is the electrochemical deterioration of a metal because of its chemical reaction with the surrounding environment. While new and better materials are continuously being developed, this progress is offset, in part, by a more aggressive operational environment. This problem is compounded by the fact that corrosion is a complex phenomenon. It can take many different forms and the resistance of aircraft materials to corrosion can drastically change with only a small environmental change.


Corrosion is most often thought of as a slow process of material deterioration, taking place over a significant period of time (examples being general corrosion, pitting, exfoliation, etc.). Other forms of corrosion degradation can occur very quickly, in days or even hours, with catastrophic results. These forms (such as stress corrosion cracking, environmental embrittlement, and corrosion fatigue) depend on both the chemical and mechanical aspects of the environment and can cause catastrophic structural failure without warning.


a. The possibility of an inflight mishap or excessive down time for structural repairs necessitates an active corrosion prevention and control program. The type and aggressiveness of the corrosion prevention and control program depend on the operational environment of the aircraft. Aircraft exposed to salt air, heavy atmospheric industrial pollution, and/or over water operations will require a more stringent corrosion prevention and control program than an aircraft that is operated in a dry environment.

b. In order to prevent corrosion, a constant cycle of cleaning, inspection, operational preservation, and lubrication must be followed. Prompt detection and removal of corrosion will limit the extent of damage to aircraft and aircraft components. The basic philosophy of a corrosion prevention and control program should consist of the following:

(1) Adequately trained personnel in the recognition of corrosion including conditions, detection and identification, cleaning, treating, and preservation;
(2) Thorough knowledge of corrosion identification techniques;
(3) Proper emphasis on the concept of all hands responsibility for corrosion control;
(4) Inspection for corrosion on a scheduled basis;
(5) Aircraft washing at regularly scheduled intervals;
(6) Routine cleaning or wipe down of all exposed unpainted surfaces;
(7) Keeping drain holes and passages open and functional;
(8) Inspection, removal, and reapplication of preservation compounds on a scheduled basis;
(9) Early detection and repair of damaged protective coatings.
(10) Thorough cleaning, lubrication, and preservation at prescribed intervals;
(11) Prompt corrosion treatment after detection;
(12) Accurate record keeping and reporting of material or design deficiencies; and
(13) Use of appropriate materials, equipment, and technical publications.

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