Aviation Maintenance Practices II Prelim A PDF

Aviation Maintenance Practices II Prelim A  Learning objectives: By the end of this week, learners will be able to: Define aircraft riveting and its significance in aircraft construction. Explain the concept of riveted joints and their role in joining aircraft structures....

Aviation Maintenance Practices II Prelim A  Learning objectives: By the end of this week, learners will be able to: Define aircraft riveting and its significance in aircraft construction. Explain the concept of riveted joints and their role in joining aircraft structures. Understand the importance of rivet spacing and pitch in aircraft construction. Apply his knowledge in a practical manner using detailed procedure. Aircraft Riveting Blind rivets Solid Shank Rivet  Solid Shank Rivet Solid shank rivets are the most commonly used fastener in aviation today. When a solid shank rivet is “driven” or installed in a hole, several things change: The diameter of the rivet’s shank increases The bearing strength increases The shear strength increases Solid Shank Rivet Solid Shank Rivet Rivet Head Shape  Rivet Head Shape Universal head rivets were developed specifically for the aircraft industry and designed as a replacement for both the round and brazier head rivets. Countersunk head rivet is primarily intended for use when aerodynamics smoothness is critical, such as on the external surface of a high-speed aircraft. Rivet Codes  Rivet Codes Different types of solid shank rivets are used for different applications. To help identify the type of rivet you are working with, rivets are given codes to identify their size, head style, and alloy material  Rivet Codes The rivet codes breakdown like this: Example: AN470AD4-5 AN 470 AD 4 - 5 Specification (Standard)  Rivet Codes – Specification (Standard) There are several common system used to identify standard: AMS - Aeronautical Material Specification. AN - Air Force-Navy AND - Air Force-Navy Design AS - Aeronautical Standard ASA - American Standard Assoc.  Rivet Codes – Specification (Standard) There are several common system used to identify standard: ASTM - American Society for Testing & Materials MS - Military Standard NAF - Naval Aircraft Factory NAS - National Aerospace Standard SAE - Society of Automotive Engineers  Rivet Codes The rivet codes breakdown like this: Example: AN470AD4-5 AN 470 AD 4 - 5 Style of Rivet Head  Rivet Codes – Rivet Head Style The rivet head code will always be three numbers The most common rivet head style are the: AN426 Counter sunk AN442 Flat Head AN470 Universal Head AN430 Round Head  Rivet Codes – Rivet Head Style Countersunk Rivets: Flush with the aircraft skin Aerodynamic and reduce drag  Rivet Codes – Rivet Head Style Universal Head Rivets: Not flush with the aircraft skin so will cause drag Usually used on slower aircraft Sometimes called “button head” rivets  Rivet Codes The rivet codes breakdown like this: Example: AN470AD4-5 AN 470 AD 4 - 5 Alloy or Material  Rivet Codes – Rivet Alloy Code The alloy code tells you the type of metal the rivet is made from.  Rivet Codes – Rivet Alloy Code The AD rivet is the most commonly used. It is sometimes called the “field rivet”.  Rivet Codes – Rivet Alloy Code The D and DD rivets are called “icebox rivets” because they are stored in freezers after annealing to prevent them from becoming to hard to drive.  Rivet Codes The rivet codes breakdown like this: Example: AN470AD4-5 AN 470 AD 4 - 5 Shank Diameter (1/32” increments)  Rivet Codes – Shank Diameter The diameter of the shank is measured in 1/32 of an inch. For example: AN470AD6-8 has a diameter of 6/32” or 3/16”  Rivet Codes The rivet codes breakdown like this: Example: AN470AD4-5 AN 470 AD 4 - 5 Shank Length (1/16” increments)  Rivet Codes – Shank Length The diameter of the shank is measured in 1/16 of an inch. For example: AN470AD6-8 has a diameter of 8/16” or 1/2” Rivet Size to Material Thickness  Rivet Size to Material Thickness The diameter of the chosen rivet should generally correspond to the thickness of the material being riveted. NOTE: use rivets with a diameter at least 2 ½ to 3 times the thickness of the thicker sheet being riveted. Material Compatibility  Material Compatibility Whenever possible, it’s recommended to select rivets with the same alloy number as the material being riveted. Installation of Rivets Rivet Spacing  Rivet Spacing Rivet spacing refers to the distance between the centerlines of rivets in the same row. The minimum spacing between protruding head rivets should not be less than 3 ½ times the rivet diameter. NOTE: These specified dimensions serve as the minimum spacing unless otherwise specified in a specific repair procedure or when replacing existing rivets Edge Distance  Edge Distance Edge distance is a critical factor in riveting that influences the structural integrity and durability of the joint. The recommended edge distance typically falls between 2 and 4 times the diameter of the rivet.  Edge Distance For universal rivets, the minimum edge distance is specified to be 2 times the diameter of the rivet. Countersunk rivet, the minimum edge distance increases to 2 ½ times the diameter of the rivet.  Impact of Incorrect Edge Distance Too close edge distance – it can lead to issues such as cracking or pulling away of the sheet from the rivets. Too far edge distance – the sheet might turn up at the edges, causing alignment and structural problems. Quiz