Jun 30/01 51-40-00 Page 1 EFFECTIVITY: All z SD3-60 STRUCTURAL REPAIR MANUAL SRM 51-40-00 FASTENERS 1. General Most of the repair drawings in this manual show the type of rivets or bolts required, but where this is not possible the rivets and bolts are coded as detailed in paragraphs 2 and 3. The manufacturing drawings prepared by Bombardier Aerospace (Belfast) also use this coding. For rivets the code denotes the rivet type (solid or tubular), the type of rivet head, the direction of insertion and the hole size. For bolts the code denotes the type of bolt head and the direction of insertion, and figures or dimensions are added to the code symbol to indicate holes sizes. This chapter also shows the British Standard identification and marking of U.N.F. bolts and contains information on the dimpling and countersinking of sheet metal. Data on the types of rivets used on the SD3-60 aircraft is also included.
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Jun 30/0151-40-00 Page 1EFFECTIVITY: All
zSD3-60 STRUCTURAL REPAIR MANUAL
SRM51-40-00 15.0.0.0FASTENERS
1. General
Most of the repair drawings in this manual show the type of rivets or bolts required, but where this is not possible the rivets and bolts are coded as detailed in paragraphs 2 and 3. The manufacturing drawings prepared by Bombardier Aerospace (Belfast) also use this coding.
For rivets the code denotes the rivet type (solid or tubular), the type of rivet head, the direction of insertion and the hole size. For bolts the code denotes the type of bolt head and the direction of insertion, and figures or dimensions are added to the code symbol to indicate holes sizes.
This chapter also shows the British Standard identification and marking of U.N.F. bolts and contains information on the dimpling and countersinking of sheet metal. Data on the types of rivets used on the SD3-60 aircraft is also included.
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2. Rivet Coding
Refer to Figure 1.
The use of the basic symbol indicates that insertion direction is unimportant.
The symbols above indicate solid rivets. When a tubular rivet, (i.e. Avdel, Chobert or 'Pop') is used, a 'T' is added in the N.W. quadrant thus
The rivet diameter and hole size is indicated by adding the relevant number from the Table below, in the N.E. quadrant thus
Countersunk head angle coding is not used, as Shorts have standardised on 100° angle heads.
The use of the basic symbol indicates that insertion direction is unimportant.
Bolt diameter coding is not used. The hole size is indicated thus 201 in. (5.1 mm). A group of holes of a common size may be identified and a general note added to the drawing thus
C'sk head angle coding is not used as Bombardier Aerospace (Belfast) have standardised on 100° angle heads.
Letters are added to the rivet or bolt code symbol as shown below, and are read from left to right indicating the hole types in successive sheets, and commencing with the hole into which the preformed head is inserted.
�C� indicates a cut countersink to DS.325 for rivets or DS.355 for bolts.
�D� indicates a dimpled hole to DS.325 type D for solid rivets, or DS.355, type C, for bolts.
When a tubular rivet is indicated thusdimple to DS.325 type E. Refer to para 5. for full details of the DS.325 and DS.355 type holes.
The dimpling of holes in sheet metal is a precise operation, and therefore before any operation commences the type of dimple, and the pilot hole size etc., should be carefully determined.
A. Rivetted Assemblies
The components of a countersunk rivetted joint are prepared for the acceptance of csk rivet heads by being either dimpled or cut depending on the thickness of the material and the rivet hole diameter, (see Table below) with the combination of thinner gauge and larger diameter hole facilitating the use of the dimple method.
NOTE: For calculating bonded material thickness, the compound sheet is considered as a single solid sheet, with the addition of 0.008" per glue line.
The successive thicknesses in a csk rivetted joint may, depending on their separate gauges:
- be all dimpled, or- comprise a dimpled sheet mated to a cut csk member or- comprise a cut csk sheet assembled to a non-csk component
In the original construction of the SD3-60 there are two basic forms of dimple, a constant shoulder type for the dimpling of single sheets, and a neutral angle type for sheets which are joined together. These are used in conjunction with two classes of hole as follows:-
- A DS.325E type hole for tubular rivets, and where maximum hole filling is required. Only this type is suitable for the neutral angle type of dimple.
- A DS.325D type hole for solid rivet. The rivet hole size is drilled before carrying out the dimpling process.
The two basic forms of dimple used in conjunction with the two classes of hole result therefore in three basic types of dimple as shown. Refer to Figure 5.
GaugeRivet diameter (inches)
3/32 1/8 5/32 3/16 7/32 1/4
19 SWG and thinner D D D D D D18 SWG C D D D D D16 and 17 SWG C C D D D D14 and 15 SWG C C C D D D13 SWG C C C C D D12 SWG C C C C C D11 SWG and thicker C C C C C C
NOTE: C = cut countersunkD = dimple
Transition Point between Cut and Dimple Countersinks for Rivets
Dimpling and countersinking Data for RivetsFigure 6
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B. Bolted assemblies
The components of a countersunk bolted joint are prepared for the acceptance of CSK bolt heads by being either dimpled or cut, depending on the thickness of the material and the bolt diameter (see Table below), with the combination of thinner gauge and larger diameter hole facilitating the use of the dimple method.
NOTE: For calculating bonded material thickness, the compound sheet is considered as a single solid sheet, with the addition of 0.008" per glue line.
The successive thicknesses in a csk bolted joint may, depending on their separate gauges
(1) be all dimpled, or
(2) comprise a dimpled sheet mated to a cut csk member, or
(3) comprise a cut csk sheet assembled to a non-csk component.
As is the case with rivetted assemblies there are two basic forms of dimple, a constant shoulder type for the dimpling of single sheets, and a neutral angle type where sheets are joined together. For bolted joints these are used with two classes of hole as follows:
(4) A DS 355/C type hole for use where shear conditions are applicable. Only this type is suitable for the neutral angle type dimple.
(5) A DS 355/D type hole for tensile applications. The bolt hole size is drilled before carrying out the dimpling process.
The three basic types of dimple for bolts are similar to those shown for rivets on Page 7.
Refer to Figure 7. It gives details of the DS 355/C and DS 355/D type holes, together with other relevant dimpling data.
The choice of pilot holes and preparation before dimpling is essential for accurate results. Refer to Figure 6. Refer to Figure 7. The hole category required is defined by use of the DS.325 or DS.355 tables and the required size to suit the dimple tooling pilot shank diameter is also selected from the same tables.
C. Hot dimpling process (heated die method)
Hot dimpling can be carried out using either static or portable types of machine. Both machines use the same types of dies. This process is suitable for schemes requiring 100 deg csk head fasteners in L72 and L73 sheet of suitable gauge. Hot die dimpling using constant shoulder type dies on materials which have been chromic acid anodised is possible, but local cracking of the anodic film may occur. Repair schemes requiring the hot dimpling of anodised material must be endorsed to authorise the use of the process. The dimpling machine (static or poratble type) is fitted with dies which are electrically heated and thermostatically controlled at 290° ± 10°C. The sequence and timing of the machine operations is automatic. The pre-set controls are die temperature, initial load, initial load timer, final load and final load timer. The final load and final load timer settings are given on the actual machine, for each diameter and SWG combination. The procedure is as follows:-
(1) Pilot drill. Refer to Figure 6. Refer to Figure 7.
(2) Remove burrs and remove paint from dimple area.
(3) Degrease, using trichlorethylene or other suitable agent.
(4) Install correct dies for the rivet csk dimension, and pre-set the machine controls to suit the hole dia and SWG combination.
(5) Carry out the dimpling process.
(6) Finish drill, for class DS.325E rivet holes or DS.355C bolt holes.
D. Cold Dimpling
Cold dimpling is not suitable for L73 (or any precipitation treated alloys) and is to be used on other material only when expressly permitted by the repair scheme drawing.
Cold dimples in heat treatable material must be neutral angle type, requiring dies applicable to total sheet thickness. The procedure is as follows:
(1) Drill hole size to conform to DS.325D (rivets) or DS.355D (bolts). See Figure Refer to Figure 6 and Refer to Figure 7.
(2) Clean area around hole and deburr
(3) Check angle of die for appropriate size of rivet and install with required thickness of packing washer in cold dimpling tool, and carry out the dimpling process.
The types of rivets used in the manufacture of the SD3-60, and called up in the various repair drawings and sketches are as follows:-
A. Solid Rivets
Rivet lengths are not stated on drawings and therefore the length required to produce the recommended closing head sizes for solid rivets as shown on Page 15 is determined on installation.
The length of a round or mushroom head rivet is measured from under the rivet head, but the length of a csk. head rivet is the overall length of the rivet. Also the drawings do not state rivet diameters, these are indicated as explained in the rivet coding data on Page 2 of this section.
The type of solid rivets called up in the repair schemes in this manual is as follows:-
* For use with Fibreglass Assemblies.
Material Specification Type of Head Colour ident Notes
Avdel rivets are manufactured to close tolerances, and each is secured to its mandrel during manufacture. The limitations on hole dimensions shown should be strictly adhered to, as a departure from these limits will mean that a mandrel cannot swell the rivet shank sufficiently, to fill the rivet hole, or that the mandrel will be stressed to breaking point before the rivet is correctly formed. Rivet lengths are not stated on drawings, and therefore this should be determined on assembly by use of a suitable depth gauge with reference to the thickness to be riveted and the overall length of rivet required. Also, the drawings do not state rivet diameters, these are indicated as explained in the rivet coding data.
The part numbers for Avdel rivets may be quoted by either AGS numbers or manufacturers reference numbers. Each defines the type of head.
Tucker pop rivets, manufactured by the Tucker Eyelet Co., are used for light duty applications where strength and sealing properties are not of major importance. They should not be used in shear load applications. As is the case with all other rivets used on the aircraft the length and diameter are not called up on drawings, and therefore these should be detemined prior to installation.
The length of this type of rivet is measured from under the rivet head for both raised and csk. head rivets.
Tucker pop rivets on the SD3-60 are the monel metal type. The mandrels are of break head or break stem type and are manufactured from high tensile steel. The rivets may be identified by either the AGS or the manufacturers ref. no., both of which indicate the type of rivet, raised or csk., the material and whether it is break head or break stem. Refer to Figure 11.
D. Cherry Rivets
Cherrylock rivets, manufactured by the Cherry Rivet division of the Townsend Company of California are used on the control surfaces, and wing strut.
This is basically a three part rivet, consisting of a rivet sleeve, stem, and lock ring collar, with the head being formed as the stem is pulled into the rivet sleeve. These rivets are supplied in two types, standard and bulbed, with the bulbed type being used for thin sheet and dimple applications. The design of the bulb stem is such that a head larger than the standard series is formed on installation.
For full details of this type of rivet, refer to the Cherrylock Rivet Division catalogue.
E. Cherrymax Rivets
Cherrymax rivets, manufactured by the Cherry Rivet Division of the Townsend Company of California.
This is a bulbed fastening system that improves the installed characteristics of the bulb cherrylock rivet. Cherrymax rivets are manufactured in 5056 aluminium or monel in either nominal fractional (NAS 1400 sizes) or 1/64" oversize diameter series (NAS 1740 sizes). If required solid and tucker pop rivets removed during repair action can be replaced by cherrymax 1/64" oversize diameter series.
For full details of this type of rivet, refer to the Cherrymax Rivet Division catalogue.
* Cherrymax rivets are to be used as an alternative with caution, e.g. below rivetting thickness of .040" in a repair situation, where 1/8" solid rivets are requiring replacement, the 1/8" cherrymax rivet has a lower safe working load. However the oversize cherrymax (or next rivet size - providing sufficient edge landing and/or countersink thickness is available) would be of suitable strength, and be comparable with solid rivets. If doubt exists, consult Short Brothers PLC.
This rivet used in specific locations only i.e. wing tip fairing attachment and other structures manufacured in fibreglass where soft alloy rivets are required.
7. Sheet and Fastening Devices
The following is a list of U.S. equivalents of the UK bolt fastenings used in the original construction of the SD3-60 aircraft.
Alternative bolts should be selected with care for the following reasons.
A. The plain length of US bolts may differ from the original bolts. A shorter plain length should not be selected, but if slightly longer is used an additional plain washer should be used to ensure proper tightening of the nut.
B. US bolt lengths are defined by fractional increments whereas UK bolts are defined by decimal increments and therefore overall dimensions may differ.
C. Some UK bolts used in the original construction are shortened on installation to obviate fouls on adjacent structure.
MS 20600 AD orCR3213 and CR3243MS.20601 AD or CR3212 and CR3242
TUCKER POPBreak stem and break head blindrivets (monel)
AGS.2050 (raised head)
AGS.2070 (csk hd)
MS 20600 M or CR3523 and CR3553MS 20601 M orCR3522 and CR3552
Hi-lok, Hi-shear, Hi-torque, fastening devices
Bought from USA Refer toHi-shear Corporation catalogue
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When using alternative bolts ensure that the thread projection beyond the nut is not greater than in the original construction, and check that adequate clearance is maintained relative to adjacent structure. (Minimum thread projection to be not less than 1 1/2 x pitch).
D. Bolts and screws
E. Nuts
British American British American
A 102 NAS 1303 to 1320 A 204 NAS 1219A 104 MS 20033 to 20046 A 206 NAS 1219 CRA 111 NAS 1303 to 1320 A 217 NAS 1216A 112 NAS 1303 to 1320 A 218 NAS 1216 CRA 113A 114k
NAS 1218NAS 1218 CR
A 221 Tinned plated brass screw.No equivalent.
A 116 NAS 1218A 117 NAS 1218 CR A 229 NAS 1303 to 1320A 173 NAS 1221 A 230 NAS 583 to 590A 171 No alternative. These are
Alum. Alloy bolts. Non- magnetic steel bolts (which are available) may suitthe application.
A 109A 205AS 1242
SP 63
NAS 1303 to 1320NAS 1216No equivalent, BSF or BA Threads90° c'snkSteel Woodscrews
A 205 Replaced by A 217
British American
*( A 103 S LCN 12*( A 105 S No equivalent*( A 103 T NAS 1022 A*( A 105 T NAS 1022 C*( A 103 P NAS 1021 A*( A 105 P NAS 1021 C*( A 110 T NAS 1022 A*( A 110 S No equivalentAS 8600 NAS 1291A 125 NAS 1022 AA 27 No equivalent (BA or BSF Threads)A 131 MS 20365 BA 210 D MS 20364 B 10.32
* Where these nuts (A103, A110 - steel; A105 C.Res) are used as locknuts eg on control rod ends or stops, substitute American Aerospace plain nuts: (NAS 1021A; NAS 1021C respectively).
F. High Strength Fasteners & Pins
AS 20625 LH 3417-048 Amerace Esna Co2330 Vauxhall RdUnionNew Jersey 07083 USA
65015-428Standard Press Steel CoJenkenstownPennsylvannia USA
MATERIAL UK SPECIFICATION US SPECIFICATION
HUCK BOLTS OBTAINED FROM USA M.S. 90354
SWAGE LOCKING PINS OBTAINED FROM USA Pan Head type:NAS Series 1466, 1468, 1472.Csk Head type:NAS series 1456, 1458, 1460, 1462.CollarsNAS series 1080
