Aircraft Corrosion Studies Report
CHAPTER 1: INTRODUCTION
1.0 Introduction
Corrosion is the gradual destruction of material, usually metals, by chemical reaction with its environment. The destruction or degradation implies deterioration of physical properties of the material. This can be a weakening of the material due to a loss of cross-sectional area, it can be the shattering of a metal due to hydrogen embrittlement, or it can be the cracking of a polymer due to sunlight exposure. So as long the metal is not be stored properly in condition, so the corrosion will continue to destruct the metal until the metal crumble.
Corrosion manifests in many different forms. Concentration cell corrosion, or crevice corrosion, is the most common type found on airplanes, occurring whenever water is trapped between two surfaces, such as under loose paint, within a delaminated bond-line, or in an unsealed joint. It can quickly develop into pitting or exfoliation corrosion, depending on the alloy, form, and temper of the material being attacked.
Crevice corrosion damage in the lap joints of aircraft skins has become a major safety concern, particularly after the Aloha airlines incident. On April 28, 1988 a nineteen-year-old Boeing 737 aircraft, operated by Aloha airlines, lost a major portion of the upper fuselage near the front of the plane, in full flight at 24,000 feet. The Aloha incident marked a turning point in the history of aircraft corrosion.
In 1998, the combined commercial aircraft fleet operated by U.S. airlines was more than 7,000 airplanes. At the start of the jet age (1950s to 1960s), little or no attention was paid to corrosion and corrosion control. One of the concerns is the continued aging of the airplanes beyond the 20-year design life. Only the most recent designs (e.g., Boeing 777 and late-version 737) have incorporated significant improvements in corrosion prevention and control in design and manufacturing. The total annual direct cost of corrosion to the U.S.
1.0 Introduction
Corrosion is the gradual destruction of material, usually metals, by chemical reaction with its environment. The destruction or degradation implies deterioration of physical properties of the material. This can be a weakening of the material due to a loss of cross-sectional area, it can be the shattering of a metal due to hydrogen embrittlement, or it can be the cracking of a polymer due to sunlight exposure. So as long the metal is not be stored properly in condition, so the corrosion will continue to destruct the metal until the metal crumble.
Corrosion manifests in many different forms. Concentration cell corrosion, or crevice corrosion, is the most common type found on airplanes, occurring whenever water is trapped between two surfaces, such as under loose paint, within a delaminated bond-line, or in an unsealed joint. It can quickly develop into pitting or exfoliation corrosion, depending on the alloy, form, and temper of the material being attacked.
Crevice corrosion damage in the lap joints of aircraft skins has become a major safety concern, particularly after the Aloha airlines incident. On April 28, 1988 a nineteen-year-old Boeing 737 aircraft, operated by Aloha airlines, lost a major portion of the upper fuselage near the front of the plane, in full flight at 24,000 feet. The Aloha incident marked a turning point in the history of aircraft corrosion.
In 1998, the combined commercial aircraft fleet operated by U.S. airlines was more than 7,000 airplanes. At the start of the jet age (1950s to 1960s), little or no attention was paid to corrosion and corrosion control. One of the concerns is the continued aging of the airplanes beyond the 20-year design life. Only the most recent designs (e.g., Boeing 777 and late-version 737) have incorporated significant improvements in corrosion prevention and control in design and manufacturing. The total annual direct cost of corrosion to the U.S.