This article focuses on failure analyses of aircraft components from a metallurgical and materials engineering standpoint, which considers the interdependence of processing, structure, properties, and performance of materials. It discusses methodologies for conducting aircraft investigations and inspections and emphasizes cases where metallurgical or materials contributions were causal to an accident event. The article highlights how the failure of a component or system can affect the associated systems and the overall aircraft. The case studies in this article provide examples of aircraft component and system-level failures that resulted from various factors, including operational stresses, environmental effects, improper maintenance/inspection/repair, construction and installation issues, manufacturing issues, and inadequate design.

In addition to failures in shafts, this article discusses failures in connecting rods, which translate rotary motion to linear motion (and conversely), and in piston rods, which translate the action of fluid power to linear motion. It begins by discussing the origins of fracture. Next, the article describes the background information about the shaft used for examination. Then, it focuses on various failures in shafts, namely bending fatigue, torsional fatigue, axial fatigue, contact fatigue, wear, brittle fracture, and ductile fracture. Further, the article discusses the effects of distortion and corrosion on shafts. Finally, it discusses the types of stress raisers and the influence of changes in shaft diameter.

The types of metal components used in lifting equipment include gears, shafts, drums and sheaves, brakes, brake wheels, couplings, bearings, wheels, electrical switchgear, chains, wire rope, and hooks. This article primarily deals with many of these metal components of lifting equipment in three categories: cranes and bridges, attachments used for direct lifting, and built-in members of lifting equipment. It first reviews the mechanisms, origins, and investigation of failures. Then the article describes the materials used for lifting equipment, followed by a section explaining the failure analysis of wire ropes and the failure of wire ropes due to corrosion, a common cause of wire-rope failure. Further, it reviews the characteristics of shock loading, abrasive wear, and stress-corrosion cracking of a wire rope. Then, the article provides information on the failure analysis of chains, hooks, shafts, and cranes and related members.

This article focuses on common failures of the components associated with the flow path of industrial gas turbines. Examples of steam turbine blade failures are also discussed, because these components share some similarities with gas turbine blading. Some of the analytical methods used in the laboratory portion of the failure investigation are mentioned in the failure examples. The topics covered are creep, localized overheating, thermal-mechanical fatigue, high-cycle fatigue, fretting wear, erosive wear, high-temperature oxidation, hot corrosion, liquid metal embrittlement, and manufacturing and repair deficiencies.

The 206.0, A206.0, and B206.0 alloys (aluminum alloys 2xxx) are structural castings in the heat-treated temper for automotive and aerospace applications where high tensile and yield strengths with moderate elongations are needed. This datasheet provides information on key alloy metallurgy and fabrication characteristics of these 2xxx series alloys, as well as the effects of processing on their typical physical and mechanical properties.

This datasheet provides information on key alloy metallurgy, mill product specifications, processing effects on physical and mechanical properties, and applications of high-strength aerospace alloys 2024 and Alclad 2024. It contains tables that list values of tensile property limits for 2024 sheet, plate, and round product forms. Figures illustrate the effect of stretching and aging on toughness of the 2024 sheet and the effect of temperature on tensile properties of 1.0 mm thick Alclad 2024-T3 sheet.

This datasheet provides information on composition limits, fabrication characteristics, processing effects on physical and mechanical properties, and applications of the high-strength extrusion aluminum alloy 6069.

Alloy 2027 is an Al-Cu-Mg-Mn-Zr alloy providing improved mechanical properties compared with those of alloy 2024. Alloy 2027-T3511 extrusions are typically used for stringers to stiffen wing skin panels machined from damage tolerant 2xxx alloy plates. This datasheet provides information on key alloy metallurgy and processing effects on mechanical properties of plate and extrusions of this 2xxx series alloy.

Alloy 7055 is widely used in the aerospace industry in applications as plate and extrusions. This datasheet provides information on key alloy metallurgy and processing effects on fracture, mechanical, tensile, and compressive properties of this 7xxx series alloy.

Alloy 6156 is an Al-Si-Mg-Cu-Mn weldable alloy, developed for the lower portion of the fuselage, which required a T6 temper strength level and high damage tolerance properties. This datasheet provides information on key alloy metallurgy of this 6xxx series alloy. Fatigue crack growth and material toughness for various thicknesses of alloy 6156 clad T62 are illustrated.

Alloy 2055 is an Al-Cu-Li alloy developed as a replacement for high-strength 7xxx and 2xxx alloys in applications such as fuselage stringers and floor beams. This datasheet provides information on its key alloy metallurgy and illustrates the damage tolerance of 2055-T84 extrusions and 7xxx extrusions.

The aerospace extrusion alloy 2065 has excellent corrosion resistance compared with high-strength 7xxx alloys. This datasheet provides information on key alloy metallurgy and processing effects on density and mechanical properties of this 2xxx series alloy.

This article illustrates the relationships among commonly used 2xxx series alloys. It contains tables that list values for composition limits of aluminum-lithium alloys, and aerospace alloys and their temper conditions according to primary design requirements.

Alloy 2124, aerospace plate alloy, is a high-purity version of 2024. This datasheet provides information on key alloy metallurgy, fabrication characteristics, processing effects on physical and mechanical properties, and applications of this series alloy.

Alloy 2196 is a higher Li-containing alloy registered in 2000 for various aircraft extrusion parts. This datasheet provides information on composition limits and applications of alloy 2196 and 2296 as well as processing effects on mechanical properties of 2196-T8511 extrusions. A performance comparison of 2196-T8511 extrusion with alloy 2024 is also presented.

Alloy 2198 is an Al-Cu-Li alloy that is used in combination with 2196-T8 stringers for the fuselage skins of the Bombardier C-Series. This datasheet provides information on composition limits of the alloy 2198 and provides a performance comparison of 2198-T8 and 2024-T351 alloys.

The aluminum alloy 7099 is a Kaiser aluminum high-strength Al-Mg-Zn-Cu alloy with zirconium that offers a less quench-sensitive alloy for properties in thicker sections for airframe structures such as wing ribs, spars, and skins, as well as fuselage frames and floor beams. This datasheet provides information on key alloy metallurgy and processing effects on mechanical properties of this 7xxx series alloy.

Visual inspection (VI) is the oldest inspection technique man has used as a quality-control tool to evaluate products, assess their final form in terms of fabrication accuracy and external features based on experience, and decide on their acceptance or rejection. This article discusses the basic principles of visual inspection in terms of direct visual examination and indirect visual examination as well as advantages and limitations of visual inspection. It reviews the factors affecting the effectiveness of VI as a nondestructive testing (NDT): lighting conditions of observation, condition of surface under inspection, physical state/condition of inspector, proper training of personnel and level of expertise, and knowledge of applicable standards. The article provides schematic illustrations of rigid borescopes, fiberscopes, and videoscopes. It concludes with a discussion on automated optical inspection systems.

This article focuses on friction and wear of automotive and aircraft brakes. It provides a comparison of friction and wear behaviors, frictional characteristics, and frictional performance of the friction materials. The article describes the components of brake friction materials and the classifications of brake lining materials. It discusses the effect of formulation compositions and manufacturing processes and the effect of braking operation conditions. The article provides information on aircraft brake linings, which operate under a wide range of kinetic energy conditions. The morphology effect of graphite on automotive brake drum and disk is explained. The article also describes the characteristics of specific wear rates for both normal and local cast iron in automotive brake drums and disk rotors. It provides information on noises, vibrations, and harshness caused by brake pads. The article concludes with information on physical and chemical testing of brakes and toxicity of brake formulation and regulations.

Liquid impingement erosion has been defined as progressive loss of original material from a solid surface due to continued exposure to impacts by liquid drops or jets. This article focuses on the core nature of erosion by liquid impingement, due to the greater appreciation of the distinctions between the different forms of erosion. It discusses steam turbine blade erosion, aircraft rain erosion, and rain erosion of wind turbine blades. The article describes the mechanisms of liquid impact erosion and time dependence of erosion rate. It reviews critical empirical observations regarding both impingement variables (velocity, impact angle, droplet size, and physical properties of liquids) and erosion resistance of materials, including the correlation between erosion resistance and mechanical properties and the effects of alloying elements and microstructure. The article also provides information on the ways to combat erosion.