AIRCRAFT SOLID SHANK RIVET IDENTIFICATION 飞机固体铆钉概述

AIRCRAFT SOLID SHANK RIVET IDENTIFICATION AIRCRAFT HARDWAREAircraft hardware is the term used to describe the various types of fasteners and assorted small parts used in the manufacture and repair of aircraft. In the aerospace industry there are over 30,000 different fasteners available. Many of these fasteners are specialized hardware specific to certain aircraft. Rivets are common to all aircraft and the types and range of sizes are standard across the industry. AIRCRAFT SOLID-SHANK RIVETSRivets are one of the oldest fastening systems known, and have been used in manufacturing for centuries. Steel and brass rivets were used in the earliest aircraft. Solid shank aluminum rivets were introduced in 1919 with the German Junkers F13, the first civil all metal aircraft. Various factors, such as cost, weight, reliability and simplicity, all contribute to the fact that aluminum solid-shank rivets are still the most common means of joining fabricated members of an aircraft structure. Because solid rivets have evolved to satisfy various aerodynamic and structural requirements, fastener details such as material, strength and head style are numerous. Aircraft designers will specify particular "standard" fasteners in blueprints and shop manuals and, if manufacture and repair is to be carried out in accordance with such data, the mechanic must be able to identify all such fasteners by their part numbers, head markings and drawing symbols.1919 Junkers F13: first strut free civil all metal aircraft.SPECIFICATIONS AND STANDARDSA Type Certificate is a government approval of the specifications for the production of an aircraft or an aircraft product. Without a type certificate an aircraft design cannot go into commercial production. Transport Canada (TC) issues type Certificates in Canada. In the USA, Type Certificates are issued by the Federal Aviation Administration (FAA). The aircraft design must demonstrate that it conforms to all the requirements specified for "airworthiness"in regards to its performance, structural strength and integrity. Airworthy can be defined as "fit and safe for flight". To be sure that every individual aircraft that is produced from that design will meet the same standards, all the material from which it is built, as well as every piece of hardware that will be used must be described in detail. Fortunately, standard aircraft hardware has been described in standard specifications set down by government approved organizations. This eliminates the need for an aircraft designer/manufacturer to write specifications and standards for every fastener and piece of hardware on the aircraft. For example when rivets are required, specifications have already been written under US Military Standards and US National Aerospace Standards and are available to the rivet manufacturer and the aircraft manufacturer. The specifications in the standards stipulate the type of material and the precise dimensions of the rivet. By adhering to these specifications and calling for certain "standard" hardware, aircraft manufacturers are able to build reproducible quality aircraft. These standards are recognized by the name of the organization that originated them. The standards organizations associated with aviation rivets in Canada and the US are: AA Aluminum AssociationMS Military StandardsNAS National Aerospace StandardRIVET IDENTIFICATION CODESPart numbers are used whenever referring to rivets and when requesting them from material stores. Solid shank rivets are manufactured in accordance with U.S. Federal Specification QQ-A-430. Subsequent part numbers and identification codes used are from both the Military Standard (MS) and National Aerospace Standard (NAS) systems. (The MS system evolved from an older United States classification system known as AN for Army/Navy). Canada officially recognizes these US standards as acceptable for use on Canadian aircraft. Both MS and NAS systems identify rivets by coding the following information into a specific part number:a. Head Styleb. Rivet Materialc. Shank Diameterd. Rivet LengthFor example an MS20470AD4-5 rivet would be described as follows:MS20= Catalogue System (Military Standard hardware category 20)470= Head Style Code (carried over from the old Army Navy/Air Force Navy standard, AN470)AD= Rivet Material Code (also used in the old Army Navy system)4= Shank Diameter in 1/32” (also used in the old Army Navy system)-5= Rivet Length in 1/16” (also used in the old Army Navy system)HEAD STYLESStock rivets are cold formed from aluminum alloy wire that has first been Solution Heat Treated to an annealed (soft) state. In this condition heads are formed. This head is known as the "Manufacturer’s Head". The most common types of manufacturer's head in use are the:Universal Head-MS20470 Flush Head - MS20426Universal Head Rivets. In 1955 the universal head rivet was accepted as the rivet head style to replace all protruding head rivets. The common protruding head rivets in use at that time were AN442 flat head rivet, AN430 round head rivet and the AN455 brazier head rivet. The universal head fastener is used primarily on internal structure, where the protruding head has no aerodynamic significance, or on the external surfaces of slow flying aircraft, where the aerodynamic effect is negligible. With the exception of older Round Head (AN430) rivets, the Universal MS20470 style rivet is the strongest of the commonly used solid rivets.MS20470The universal head rivet (MS20470) is the most common protruding head rivetAN442 AN430 AN455The universal head rivet is an acceptable replacement rivet for all the above protruding head rivetsFlush Head Rivets (Countersunk Rivets) - These fasteners are primarily intended for use on external applications where aerodynamic smoothness is critical, e.g. wing leading edges or the entire external surface of high-speed aircraft. Development of the flush-head rivet entailed experiments with many different head angles until the “426” head angle of l00 degrees was adopted as standard.The dimensions of this head style provide the best possible compromise between tension/shear strength and flushness requirements.Countersunk rivets have a lower installed strength than Universal Head rivets when installed in a machine-countersunk sheet. However, they make the strongest joint when installed in sheets that are double dimpled. Countersunk rivets are more costly to install because of the installation requirement to machine countersink or dimple the sheet.The double dimple flush rivet installation makes the strongest riveted jointFlush Shear Head Rivets. NAS 1097. The flush or countersunk shear head rivet is not as common as the regular 426 countersunk rivet. This rivet is commonly used for attaching lighter (thin) skins to underlying structure, e.g. stringers, where fasteners will not be loaded in tension. The NAS1097 rivet has the same size head as the next smaller shank size MS20426 rivet; e.g. an NAS1097 4-5 has the same size head as an MS204263-5. The “shear head” name is derived from the smaller size and load capacity of the head, which distinguishes the fastener from the standard Flush Head rivet. However, the l00 degree head angle is common to both flush style rivets.MS20426 NAS1097The 1097 rivet has the same size head as the next smaller shank diameter 426 rivet.Other solid aluminum alloy rivet styles in use, mainly on larger transport aircraft, are:Modified Universal Head Rivets - BACR15FT (Boeing Pt. No. System)These rivets were developed by the Boeing Aircraft Co. to replace the standard MS20470 rivet. By modifying the head, they have both saved weight and improved the “hole filling” or swelling qualities of the rivet. The “FT” denotes the head style under the Boeing BACRl5 part number system.BACR15-FTModified universal head(weight saving)Briles Rivets - BACR15FV (Boeing Pt. No. System)Briles “FV” rivets were also developed by Boeing. They are intended to replace MS20426 and NASl097 flush head rivets in fatigue critical areas, e.g. fuselage skin joints. The unique head shape results in less material removal during the counter sink/counterbore operation, with less likelihood of the sharp edges produced by normal countersinking in thin material. The Briles rivet requires a special installation process. (see section on Briles rivet installation)BACR15-FVBriles 120° CSK/CBRIVET MATERIALSALUMINUM ALLOYSWe will consider the six most common rivet alloys. There are more. The type of aluminum alloy determines where the rivet is to be used. Alloys are identified by a letter in the rivet part number and physically by a head marking stamped on the rivet head. An Aluminum Association number also identifies the basic alloy. The aluminum association number applies to all forms of aluminum alloys and not just aluminum alloy rivets.Aluminum Alloy Rivet IdentificationRivet Material Pt NoCodeHeadMarking1100 5056 2117 2017 2024 7050ABADDDDEPlainRaised CrossDimpledRaised DotDouble DashRaised Circle1100 (A) Rivets.1100 is pure aluminum and technically not an alloy because there is no alloying element. Rivets made from this material are non-heat treatable (they can not be made harder using heat). They are soft (approximately 15,000 psi tensile strength) and may be driven “as supplied”. They are used for non-structural applications only.For example to hold rubber seals in place, install interior furnishings, etc.5056 (B) Rivets.5056 is aluminum with a major alloying element of 5 % Magnesium and small percentages of other elements. Because magnesium is a very "active" metal, Magnesium alloy structures are extremely prone to galvanic corrosion. B rivets are used in such structure to minimize the dissimilar metal effect that would exist when using any of the 2000 (copper) series rivets. B rivets are soft enough to be driven “as supplied”. They are non-heat treatable.2117 (AD) Rivets.2117 is aluminum with a major alloying element of 2.6 % Copper and a small percentage of another element. AD rivets are probably the most commonly used fasteners in general aircraft structures. Their strength (approx. 27,000 psi) and resistance to corrosion is good. They come in a heat-treated condition and are still soft enough to be driven “as supplied”.2017 (D) Rivets. 2017 is aluminum with a major alloying element of 4 % copper and small percentages of other elements. If AD rivets are not quite strong enough then 2017 “D” rivets are available with astrength of approx. 30,000 psi. However, the larger sizes are too hard to be driven "as supplied"andrequire Solution Heat Treatment before installation. The smaller sizes (under 5/32" diameter) can be "driven hard" in the "as received" condition to produce extra strength. D rivets are used where intermediate strength between 2117 and 2024- rivets is required.2024 (DD) Rivets.2024 is aluminum with a major alloying element of 4.4% copper and small percentages of other elements. Until recent times, these were the strongest solid rivets in common use (approx. 35,000 psi). Typically, they are found installed in high-strength (e.g. 7075 aluminum alloy) primary structure or highly stressed, heavier gauge parts. All DD Rivets are too hard to be driven as supplied and require Solution Heat Treatment prior to installation.7050 (E) Rivets. 7050 is aluminum with a major alloying element of 6.2% Zinc and smaller percentages of other elements. The 7050 “E” rivet is the strongest rivet available (approx. 46,000 psi). It has the additional advantage of being soft enough to be driven in the “as supplied” condition, i.e. no heat treatment required. For this reason, they are fast replacing both “D” and “DD” rivets. However, “E” rivets must be procured in exact lengths required as cutting to size causes work hardening and prevents correct installation.Ice-Box Rivets.This is a term often used to describe 2117 (D) and 2024 (DD) rivets. It refers to the practice of storing these rivets refrigerated to delay the natural age hardening process that takes place after solution heat treatment. If rivets are used immediately following the heat treatment quench, they will remain soft enough to be driven for approx. 20-30 min. However, if after the quench they are immediately transferred to the freezer, the age hardening process is delayed up to 30 days. On removal from the freezer and returning to room temperature the aging process recommences and rivets should be driven without delay.TYPES OF SOLID AIRCRAFT RIVET MATERIALS OTHER THANALUMINUM ALLOYAircraft rivets are also available in steel, stainless steel, titanium and monel.Corrosion Resistant Steel (Stainless Steel). They are used in the as received condition for attachment of stainless steel.Monel rivets. They are used in the as received condition for attachment of corrosion resistant metals such as stainless steel and Monel where the higher strength of SS is not required.Monel Nickel-copper Alloy.They are used in the as received condition for attachment of corrosion resistant metals. They are easier to set than stainless steel rivets and are therefore used in attaching thinner stainless steel sheet.Carbon Steel. They are used to attach steel sheet and some steel parts.Titanium. They are used for the attachment of Titanium skins.RIVET SHANK DIAMETERSolid Shank Rivet diameters are measured in increments of 1/32”. Typical Part Number examples for different diameters, head styles and alloys might be as follows:MS20470AD3- 3/32” diameterMS20426A4 - 1/8” diameterNAS1097E5- 5/32” diameterMS20470B6- 3/16” diameterMS20426DD8- 1/4” diameterDiameter in 32ndsRIVET LENGTHSolid Rivet length is measured in the un-installed condition and is stated in increments of 1/16”. Rivets lengths are also available in half sizes, eg. 4 /16, 4 and 1/2 sixteenths, 5 etc. If the rivet is Universal Head, then the head is not included in the length measurement. If the rivet is Flush Head (all types), then the head is included in the length measurement.Typical Part number callouts are as follows:MS20470AD4 -33/16” longNASl097DD5 - 41/4” longMS20426E5 - 55/16” longLength in 16thsNAS—523 RIVET CODENational Aerospace Standard CodeIn addition to the MS, AN and NAS codes for rivets, technicians working on larger aircraft will encounter a National Aerospace Standard (NAS) code for the identification of rivets on drawings. Technicians will find a symbolic system of instructions on drawings for rivets or other permanent fasteners to be used in a particular location. When using the NAS 523 Symbol System the information will be found on a "cross". The fastener codes will be found in four quadrants designated NW (upperwhich it is made. In the NW section of the chart, note that the code letters BJ identify an MS20470AD (AN470AD) rivet which is a universal-head rivet made of aluminum alloy 2117-T3. Only a few codes are shown in this chart owing to lack of space. For a complete listing, the technician should consult NAS-523.The upper right (NE) quadrant- specifies the diameter of the rivet and the required positioning of the manufactured head of the rivet. The letters N and F are used to is indicate that the manufactured head be placed on the near or far side of the sheet.The lower left (SW) quadrant provides dimple and countersink information. Letters and numbers as shown are placed in the SW quadrant to show the technician exactly what type of installation is to be made.The lower right (SE) quadrant of the symbol gives the fastener length and indicates whether a spot weld may be used as an alternate method.The column on the right of the quadrant shown on the next page is included to provide additional information and examples for the student.In addition to standard code numbers for fasteners and fittings, manufacturers often design their own items of hardware and apply their own part numbers. Large manufacturers will also assign their own part numbers to standard parts. For example Boeing refers to an MS20470AD rivet as a BAC 15BB 'A'. The technician must use the manufacturer’s structural repair manual and be sure to employ the parts specified. Cross over lists are sometimes available.RIVET IDENTIFICATION WORK SHEET1. What standard systems are rivet part numbers registered under?2. What information is included in the part number?3. Describe each item of the following part number MS2O47OAD 5-6.4. What are the two common head styles?5. What is the reason for a flush head rivet?6. Which style of rivet head can produce the strongest rivet joint?7. What is the angle on the head of the countersunk rivet?8. What are three other solid rivet head styles?9. Describe in a few words an NAS 1097 rivet.10. What two rivets were specially designed for Boeing?11. List the six rivet alloy types and part number codes for the following rivet head markings; raised dot, raised cross, dimple, raised double dash, raised circle.12. Which aluminium rivet is a non-structural rivet?13. Why is a 5056 rivet used in magnesium aircraft structure?14. What aluminium rivet is the most common, why do you think that is?15. What are the two rivets that must be solution heat treated prior to installation?16. What is the purpose of refrigerating rivets that have solution heat treated?17. How long do you have to drive a DD rivet after heat treatment?18. What are rivet diameters measured in?19. What are rivet lengths measured in?20. Does the length of a universal head rivet include the head?21. What is the purpose of the NAS-523 rivet code?22. What is a BJ rivetin the NAS 523 rivet code?23. What information do you find in the North East corner of the NAS 523?24. What are the Boeing part numbers for a MS20470 rivet?25. What is the AN (Airforce Navy) number for an MS20426 rivet’?Riveting Practices for Integral Tank and Pressurized AreasThe riveting of integral tanks and pressurized fuselage areas requires special techniques and great care in order to provide good sealing. Workmanship must be the best. Standard rivets of the MS 20426 and MS 20470 types are used. However, the method of installing them varies since the problems to be met are different in different areas. Generally the trim-flush method is used for attaching skin in tank areas. Sometimes special jacketed rivets are used. A jacketed rivet consists of a standard rivet with a soft aluminum sleeve around the shank. Upon driving the jacket extrudes to fill any cavity which may exist. Special washered rivets are used in some cases. They consist of a standard aluminum flush rivet with a soft aluminum washer under the head. The washer provides good sealing where it would otherwise be poor due to the limited amount of shank swelling near the head./BCIT/Rivet%20Identification.htm。