G-F604_REV_D__DOC_14_approved_OEMimages.pdf

2017-12-20

PCO LETTER REQUEST

A-10 TLPS

Legacy VI 12/20/2017

Contract/Delivery Order Number: FA8202-15-D-0001

Program Manager: Edie Messina

Letter Number: A10-CDM-0001-E-17-0092

Date of Letter: 12/5/2017

CDRL Number: A129

Document Title:

Fastener, Threaded Pin and Collar, Installation of

Document/ Drawing Number: G-F604 Rev D

NOT APPROVED (See comment below)

X APPROVED

APPROVED Subject to inclusion of attached comments

OTHER (please identify below)

Notes:

Program Manager Signature and Date:

X

MESSINA.CARRI

E.E.1023771388

Digitally signed by

MESSINA.CARRIE.E.1023771388

Date: 2017.12.21 12:54:42 -07'00'

CAGE 77751 G-F604

Revision D

09 August 2017

Data contained on this sheet is subject to the restrictions on the title page of this document.

ii

LIST OF REVISIONS

REV. CHANGES REASON FOR CHANGE APPROVED

D

08/09/17 Incorporated Amend. C1. Specification requirement. M. Kassinger

Re-drew figures and cleaned up tables.

To improve clarity.

Updated Section 2.0, Applicable Documents:

• AN960 became NAS1149.

• MS21042 became NASM21042.

• Added PW220T0040 and QATB M-40.

Updated titles as necessary;

updated callouts/references where required throughout document.

To reflect latest applicable documents.

Removed all information and references to Eddie-Bolt fasteners, impacting the following sections, paragraphs, figures and tables, as applicable (renumbered subsequent sections/paragraphs as required):

• Sections 1.1, 1.2, 2.2.4 (deleted in entirety), 3.2.1.2, 3.2.2 (title),

3.2.10.1.4 (deleted 3.2.10.1.4.1 and 3.2.10.1.4.2), 3.2.10.2.1 (deleted title), 3.2.10.2.2 (deleted in entirety), 3.2.10.2.3.1 (deleted title), 3.2.10.2.3.2 (deleted title),

3.2.11 (modified title), 3.2.11.2.1,

3.2.12 (deleted in entirety), 3.2.13.1, 3.3.3.1, 3.3.3.2.

• Figure 2, Figure 4, Figure 5A (renumbered as Figure 5, retitled), Figure 5B (deleted in entirety), Figure 6A (renumbered as Figure 6, retitled), Figure 6B (deleted in entirety), Figure 8 (deleted in entirety, renumbered successive figures accordingly).

• Table III.

Eddie-Bolts are not used on the A-10 aircraft; no impact to program.

iii

D (Continued)

Updated supplier information in Sections 2.2.2 and 2.2.3.

To reflect current suppliers.

In Section 2.2.2, renamed “Threaded Fasteners”; added

HL114, HL115, HL116, HLT50,

HLT51, HLT52, HLT71, HLT420,

HLT421, ST3M758, ST3M759 and

ST3M761.

To include fasteners used on EWA and as alternates on legacy wings with A-10 SPO Engineering approval; per Air Force direction.

In Section 2.2.2, deleted titanium Hi- Loks HL10, HL11, HL12 and HL13.

Titanium Hi-Loks are not used on the A-10; no

Added Paras. 3.2.1.3 and 3.2.1.3.1. To cover rivet definition methodology and provide alternate fasteners with A- 10 SPO Engineering

Deleted Paragraph 3.2.2.2, which addressed titanium Hi-Loks only.

Titanium Hi-Loks are not used on the A-10; no

In Table II, replaced “circumferential scratches” with “circumferential grooves”; added “grooves” to list of unacceptable surface defects.

To be consistent with surface defect descriptions in

PW220T0040.

Changed references for Kaynar to K-Fast, in Sections 3.2.11.2.1 and 3.2.11.2.1, and in Table I, Note 2.

Former Kaynar products are now manufactured by Alcoa, which uses only the K-Fast designation.

In Section 3.2.4, added NOTE as follows: “Where either QATB M-40 or PW220T0040 is referenced on a drawing or applicable to designated hole(s), the inspection requirements of PW220T0040 shall supersede the requirements of this document.”

To invoke the document that controls inspection requirements for holes.

iv

D (Continued)

In Table III, deleted HLT335 and HLT336, which are titanium.

Titanium Hi-Tigue fasteners are not used on the A-10; no impact to program.

In Paragraph 3.2.8.5, converted original AN960 washer callouts to NAS1149 callouts.

NAS1149 replaces AN960 for specified washers.

Added NOTE beneath Paragraph 3.2.8.5.

To alert users to the substitution/cross-reference table within NAS1149 to the obsolete

AN960.

In Paragraph 3.2.10.2.1.2, converted original AN960 washer callouts to NAS1149 callouts.

NAS1149 replaces AN960 for specified washers.

Added NOTE beneath Paragraph 3.2.10.2.1.2.

To alert users to the substitution/cross-reference table within NAS1149 to the obsolete AN960 part numbers.

Added Paragraph 3.3.1.3. To provide flushness acceptance criteria for crown-head fasteners used as alternates with A- 10 SPO Engineering v

TABLE OF CONTENTS

LIST OF REVISIONS ........................................................................................................... i LIST OF FIGURES ............................................................................................................. vi LIST OF TABLES .............................................................................................................. vi

1.0 SCOPE

2.0 APPLICABLE DOCUMENTS

2.1 Government Documents

2.2 Non-Government Documents

3.0 REQUIREMENTS

3.1 General

3.2 Detail

3.3 Acceptance Criteria

4.0 QUALITY ASSURANCE

vi

LIST OF FIGURES

Figure 1: Fastener Code

Figure 2: Grip Length

Figure 3: Pin Insertion

Figure 4: Collar/Nut Application

Figure 5: Power Tool Insertion

Figure 6: Hand Tool Installation

Figure 7: Pin Protrusion Limits

Figure 8: Inspection Shim

Figure 9: Head Gaps—Protruding-Head Pins

Figure 10: Countersink Exposure

LIST OF TABLES

Table I: Allowable Nut/Collar Substitutions

Table II: Surface Defects in Fastener Holes

Table III: Hole Sizes

Table IV: Torque Values for MS21042 Nuts

Table V: Pin Protrusion Limits

Table VI: Allowable Gaps Under Collar/Nut

Table VII: Shim Thickness

1.0 SCOPE

1.1 This specification establishes the requirements and acceptance criteria for the installation of the Hi-Lok threaded pin and collar system.

1.2 For the purpose of this specification, the Hi-Lok threaded pin/collar system is defined as a fixed grip length pin with threads to be used with a break-off wrenching pad, a self-locking collar, or a torque controlled self-locking nut that preloads the pin mechanically.

2.0 APPLICABLE DOCUMENTS

The following documents of the issue in effect on the effective date of contract shall form part of this specification. In the event of conflict between the contractual documents referenced herein and the requirements of this specification, the contractual documents referenced herein shall govern.

2.1 Government Documents

2.1.1 Federal

None

2.1.2 Military

None

2.2 Non-Government Documents

2.2.1 A-10 Program

A-F302 Cold Working of Holes, Process for G-F101 Deburring and Blending—Metals PW220T0040 Post Production A-10 Inspection of Holes in Critical Structural

Components QATB M-40 Inspection of Holes in Fatigue and/or Fracture Critical

Structures SP664 Flush Fastenings—Structural (Rivets, Bolts and Screws) Z-P101 Smoothing and Sealing of Exterior Surfaces Including Form-in-

Place Door and Fairing Gaskets Z-P102 Sealing, Environmental—Requirements and Methods for

2.2.2 Threaded Fasteners

Lisi Aerospace – Hi-Shear Corporation 2600 Skypark Drive, Torrance, CA 90509-2976 www.lisi-aerospace.com

Part No. Nomenclature Material

HL18

HL114

Hi-Lok Pin

Protruding Shear Head (1/16 Grip Variation) Alloy Steel, Cad. Plated

HL19

HL115

100° Flush Shear Head (1/16 Grip Variation) Alloy Steel, Cad. Plated

HL20

HL116

Protruding Tension Head (1/16 Grip Variation) Alloy Steel, Cad. Plated

HL21 100° Flush Tension Head (1/16 Grip Variation) Alloy Steel, Cad. Plated

HL70

Hi-Lok Collar

Shear (1/16 Grip Variation) Aluminum, Anodize, Red

HL73 Tension (1/16 Grip Variation)

CRES 17-4PH, Silver Plate, Blue

HL75 Tension, Self-Aligning (1/16 Grip Variation)

CRES 303, Cad. Plated Collar, 17-4PH Washer

HL79

Shear, Auto Feed (1/16 Grip Variation, for Std. & 1/64 Oversize Dia. Pins)

Aluminum, Anodize, Red

HL82 Shear, Self-Aligning (1/16 Grip Variation)

Aluminum, Anodize, Collar, Red, 17-4PH Washer

HL86 Tension (1/16 Grip Variation)

CRES 303, Cad. Plated, Blue

HL87

Tension (1/16 Grip Variation, for 1/64 Oversize Dia. Pins)

CRES 303, Cad. Plated

(Table continues) http://www.lisi-aerospace.com/

Part No. Nomenclature Material

HLT50

Hi-Lok Hi-Tigue

Pin

Protruding Shear Head (1/16 Grip Variation) Stainless Steel

HLT51

100° Flush Crown Shear Head (1/16 Grip Variation)

Stainless Steel

HLT52 Protruding Tension Head (1/16 Grip Variation) Stainless Steel

HLT420 Protruding Shear Head (1/16 Grip Variation) Inconel 718

HLT421 100° Shear Head (1/16 Grip Variation) Inconel 718

HLT71

Hi-Lok

Hi-Tigue Collar

Shear, Self-Aligning (1/16 Grip Variation)

Aluminum, Stainless Steel Washer

ST3M758

Rivet Pin

100° Shear Head Per Engineering Callout

ST3M759 Protruding Shear Head Per Engineering Callout

ST3M761 Protruding Tension Head Per Engineering Callout

2.2.3 K-Fast Nuts

Alcoa Fastening Systems & Rings Aerospace 800 South State College Boulevard, Fullerton, CA 92831 www.alcoafasteners.com

Part No. Nomenclature Material

KFN536

K-Fast Nut (8-Spline)

Tension, Self-Sealing (Std. & 1/64 Oversize Dia. Pins)

Alloy Steel, Cad. Plate, Aluminum, Anodized, Dark Blue

KFN604 Shear (Standard, 1/64 & 1/32 Oversize Dia. Pins)

Aluminum, Anodized, Dark Blue

KFN606

Shear, Self-Aligning (Std., 1/64 & 1/32 Oversize Dia. Pins)

Aluminum, Anodized, Dark Blue

KFN616

Tension, Self-Aligning (Standard, 1/64 & 1/32 Oversize Dia. Pins)

A286 CRES Nut, 17-4PH CRES, Cad. Plate Washer

KFN617

Tension (Standard, 1/64 & 1/32 Oversize Dia.

Pins)

A286 CRES Nut, Silver Plated

KFN631

Shear, Self-Sealing (Std.

& 1/64 Oversize Dia.

Pins)

Aluminum, Anodized, Teflon Seal, Yellow

KFN644

Tension (Standard, 1/64 & 1/32 Oversize Dia.

Pins)

Alloy Steel, Cad. Plated

2.2.4 Industry Documents

NAS1149 Washer, Flat NASM21042 Nut, Self-Locking, 450°F, Reduced Hexagon, Reduced Height, Ring Base, Non-Corrosion Resistant Steel http://www.alcoafasteners.com/

3.0 REQUIREMENTS

3.1 General

3.1.1 All threaded pins and collar/nut systems shall comply with the respective Standard Part drawing as listed on the Engineering drawing for material and configuration. Part numbers listed herein are representative of typical fasteners for application of this specification.

3.1.2 Equipment and tooling shall be suitable for and capable of performing the installation of pins and collars/nuts consistent with the requirements of this specification.

3.1.3 Equipment and tools for the inspection of the threaded pin and collar/nut installation must be capable of performing the specified function.

3.14 Cadmium plated fasteners shall not be used in contact with titanium parts.

3.2 Detail

Each fastener called out on a drawing will be represented by a basic code tabulated on the face of the drawing. Figure 1 is an illustration of the symbols and method of specifying the coding.

Ref: Engineering Manual Vol. III, RA900Y1300, Part B, Section 5.

Figure 1: Fastener Code

3.2.1 Codes

Each fastener called out on a drawing will be represented by a basic code tabulated on the face of the drawing. Figure 1 is an illustration of the symbols and method of specifying the coding.

3.2.1.1 Code letters and other fastener installation requirements will appear within the fastener quadrant symbol used on the drawing and will be coded as illustrated in Figure 1.

3.2.1.2 An example of a coded fastener symbol:

Flush shear head, steel, Hi-Lok pin HL19PB with aluminum alloy Hi-Lok collar HL70; 3/16-inch diameter with head on far side; 1/4-inch maximum grip.

3.2.1.3 Enhanced Wing Assembly (EWA) fastener definition is not accomplished through the symbol/code system described in 3.2.1.1, 3.2.1.2 and Figure 1. Definition is accomplished through complete fastener part number (including diameter and grip length), model orientation (manufacturer head location), and fastener attributes (e.g., hole number, countersink information, etc.).

3.2.1.3.1 Fasteners other than those used during original A-10 design and production are now called out in specific locations (e.g., EWA). Therefore, it is important that the drawing callouts are used and substitutions made only when authorized by the A-10 SPO as different fasteners may directly affect the design life of the A-10 aircraft. The following Boeing fasteners are currently authorized for use in locations authorized by A-10 SPO Engineering:

ST3M758, ST3M759, and ST3M761.

3.2.2 Substitutions

3.2.2.1 The following Table I nuts (collars) may, at the option of Manufacturing, be used in place of the noted drawing part callout.

(Table continues)

Table I: Allowable Nut/Collar Substitutions

Drawing Callout Hi-Lok and Noted

Substitute K-Fast Nuts 2/

Torque for K-Fast Nuts 1/

HL70-5 7/

HL70-6

HL70-8

HL70-10

HL70-12

HL70-14

HL70-16

KFN604-08

KFN604-3

KFN604-4

KFN604-5

KFN604-6

KFN604-7

KFN604-8

15–25 35–45 3/ 85–100 3/ 130–160 200–240 270–330 370–430

HL82-5AW

HL82-6AW

HL82-8AW

HL82-10AW

HL82-12AW

HL82-14AW

HL82-16AW

KFN606-08

KFN606-3

KFN606-4

KFN606-5

KFN606-6

KFN606-7

KFN606-8

15–25 35–45 100–120 130–160 200–240 270–330 370–430

HL86/HL87-5 4/, 6/

HL86/HL87-6

HL86/HL87-8

HL86/HL87-10

HL86/HL87-12

HL86/HL87-14

HL86/HL87-16

KFN644-08

KFN644-3

KFN644-4

KFN644-5

KFN644-6

KFN644-7

KFN644-8

30–40 40–50 115–130 200–250 360–440 550–625 725–825

HL75-5AW

HL75-6AW

HL75-8AW

HL75-10AW

HL75-12AW

HL75-14AW

HL75-16AW

KFN616D-08

KFN616D-3

KFN616D-4

KFN616D-5

KFN616D-6

KFN616D-7

KFN616D-8

30–40 40–50 115–130 200–250 360–440 550–625 725–825

Table I: Allowable Nut/Collar Substitutions (continued)

Drawing Callout Hi-Lok and Noted

Substitute K-Fast Nuts 2/

Torque for K-Fast Nuts 1/

KFN536-3 5/

KFN536-4 5/

None None

40–50 115–130

KFN631-08 5/

KFN631-3 5/

KFN631-4 5/

None None None

15–25 35–45 85–100

HL73/HL273-6 8/

HL73/HL273-8

HL73/HL273-10

HL73/HL273-12

HL73/HL273-14

KFN617-3

KFN617-4

KFN617-5

KFN617-6

KFN617-7

40–50 115–130 200–250 360–440 550–625

NOTES:

1/ Installation torque shall be preset into installation tools. Tool calibration shall be accomplished or verified and interval established by Quality Assurance.

2/ KFN604, KFN606, KFN616 and KFN617 were H604, H606, H616 and H617, respectively. This is a K-Fast part number designation change only. The parts are identical and interchangeable.

3/ These values can be reduced to 25–35 in.-lbs. for the -3 size and 60–80 in.-lbs. for the -4 size where installations do not have a faying surface sealant for fluid leak prevention.

4/ An MS21042 nut may be used as a substitute for the HL86/HL87 Hi-Lok collars (see Para. 3.2.10.2.1). Installation torque for the MS21042 shall be the same as that listed for the equivalent KFN644 nut size.

5/ Do not use these self-sealing nuts as substitute for KFN604-3, -4 and HL70-6, -8 non-self-sealing parts. These nuts are intended for fuel sealing applications only.

6/ An HL73 collar may be substituted for an HL86 collar only, and only when a critical shortage occurs. An HL87 collar may be substituted for an an HL86 collar when a critical shortage occurs or due to cost considerations.

7/ An HL79 collar can be substituted for an HL70 collar when critical shortages occur.

8/ An HL273 collar may be substituted for an HL73 collar when a critical shortage occurs or due to cost considerations.

3.2.3 Fit-Up

3.2.3.1 All details shall be surface treated for corrosion protection as required by drawing or op sheet for that stage of assembly.

3.2.3.2 Parts shall be held together during hole preparation. There shall be no evidence of dirt or chips at the interface. Maximum permissible faying surface gap is not to exceed 0.015”, unless otherwise specified on the Engineering drawing or for holes generated and cold worked per A-F302.

3.2.3.3 Burrs that could prevent seating of the fastener head shall be removed, or if deburring of the fastener hole is specified by the drawing or op sheet, then the deburring shall be done in accordance with G-F101.

3.2.3.4 For sealing applications, compound shall be applied to faying surfaces at the locations specified by the drawing before fastening.

3.2.3.5 Dissimilar metals insulation and hole treatment shall be in accordance with drawing requirements.

3.2.3.6 Remove all temporary coatings from mating and faying surfaces prior to assembly.

3.2.3.6.1 Countersunk-head fasteners can be installed through temporary protective coating if fastener flushness requirements are met.

3.2.3.6.2 Temporary protective coating remaining after countersinking may remain under manufactured head of countersunk fasteners providing head gapping allowances are met.

3.2.4 Holes

NOTE: Where either QATB M-40 or PW220T0040 is referenced on a drawing or applicable to designated hole(s), the inspection requirements of PW220T0040 shall supersede the requirements of this document.

3.2.4.1 Fastener holes shall be drilled perpendicular within 2° to the surface against which the installed fastener head will bear using controlled tooling or drill blocks. Gap inspection in accordance with paragraph 3.3.3 will verify hole perpendicularity. Actual measurement of the hole perpendicularity shall be a method of inspection. All (100%) close ream holes prepared for the installation of fasteners in accordance with this specification shall, unless otherwise noted on the drawing, have a surface roughness of 125 RHR or smoother. See Table II for acceptable limits.

Table II: Surface Defects in Fastener Holes

Acceptable Not Acceptable

1. Circumferential grooves that are a minimum of 1/16” or 10% of the part thickness from the surface of the part, whichever is smaller.

2. Spiral scratches that are a minimum of 1/16” or 25% of the part thickness from the surface of the part, whichever is smaller.

3. Longitudinal scratches not more than 50% of length of hole in any one part that can neither start nor end within 1/16” or 25% of the part thickness from the surface of the part, whichever is smaller.

4. Any visible defect that does not exceed the specified surface roughness.

1. Grooves, scratches, nicks, or cuts intersecting a part surface or exceeding limits specified as acceptable.

3.2.4.2 The cleaning of drilled, dimpled, and/or countersunk holes that require sealant coverage of the installed fastener shall be accomplished per the cleaning requirements specified on the drawing and/or sealant application specification.

3.2.5 Hole Sizes

3.2.5.1 Hole sizes shall conform to Table III as noted, unless otherwise specified on the Engineering drawing.

3.2.5.1.1 Type I hole sizes, in Table III, are to be used for non-fluid tight requirements.

However, at Production’s option, Type II can be used with Type I size applying for inspection purposes.

3.2.5.1.2 Type II hole sizes, in Table III, shall be used for fasteners that are a potential fluid leak and loss path (e.g., wing center section integral fuel cells).

3.2.5.1.3 Type III hole sizes, in Table III, are to be used in fiberglass or graphite composite structures.

Table III: Hole Sizes

Nom.

Pin Dia.

Examples of Typical Basic Part Numbers

First Dash No.

Shank Diameter

(Ref)

Hole Size

Type I Type II Type III

5/32

Hi-Lok/Hi-Tigue:

HL18, 19, 20, 21, etc.

or equivalent parts with same shank diameter

-5 0.1635/0.1625 0.161/0.164 0.161/0.1635 0.164/0.167

3/16 -6 0.1895/0.1885 0.186/0.190 0.186/0.1885 0.190/0.193

1/4 -8 0.2495/0.2485 0.246/0.250 0.246/0.2485 0.250/0.253

5/16 -10 0.3120/0.3110 0.308/0.313 0.308/0.311 0.312/0.315

3/8 -12 0.3745/0.3735 0.371/0.375 0.371/0.3735 0.375/0.378

7/16 -14 0.4370/0.4360 0.433/0.438 0.433/0.436 0.437/0.440

1/2 -16 0.4995/0.4985 0.496/0.500 0.496/0.4985 0.500/0.503

9/16 -18 0.5615/0.5605 0.558/0.563 0.558/0.5605 0.562/0.565

5/8 -20 0.624/0.623 0.621/0.625 0.621/0.623 0.624/0.627

3.2.6 Countersinks

3.2.6.1 Countersinks shall be in accordance with SP664 or as required to achieve the flushness requirements.

3.2.7 Head/Shank Fillet Radii

3.2.7.1 Where the fastener fillet radius between the head and the shank interferes with the proper installation of the fastener, Manufacturing shall use a radius or chamfer on the edge on the hole. This relief shall not exceed the nominal fastener under-head radius.

3.2.8 Grip Length

3.2.8.1 Grip length tables are contained in the applicable Hi-Lok standard pages.

3.2.8.2 Grip lengths are graduated in 1/16” increments and are specified by the second dash number of the part number. The grip length of the pin is the distance between the bearing surface of the head and the thread shank junction. The pin length is the grip length plus the nominal thread length. See Figure 2.

Figure 2: Grip Length

3.2.8.3 The grip range of the pin is the grip length less 0.062 inch through the grip length (e.g., for a -8 grip length, the grip range is 0.438 through 0.500 inch). If the pin length must be changed, an adjustment of one size longer or shorter is permitted, as required.

3.2.8.4 Under no circumstances shall a pin be reworked to a shorter grip length.

3.2.8.5 To compensate for grip variations, one NAS1149D( )J or NAS1149D( )K washer may be installed under an aluminum collar or nut; one NAS1149F( )P cadmium plated carbon steel washer under steel collars or nuts; or one NAS1149C( )R under CRES collars or nuts, thickness in all cases as required. For self-aligning collars, use the next-diameter washer for clearance, with suitable I.D. to provide for self-alignment.

NOTE: Older Engineering drawings will call out washers per AN960. Within its replacement document, NAS1149, there is a substitution list that cross-references the obsolete AN960 callouts with their NAS1149 equivalents.

3.2.9 Collars or Nuts

3.2.9.1 Collars/nuts, as received, are lubricated by the manufacturer. Degreasing or additional lubrication are not allowed.

3.2.10 Methods of Installation

3.2.10.1 Power Tool Installation

3.2.10.1.1 Insert the pin into the hole until pin is seated. The manufactured head shall not be deformed to meet seating requirements (see Figure 3).

Figure 3: Pin Insertion

3.2.10.1.2 After inserting the pin into the structure, the threads shall be wiped to remove excess sealant or foreign residue before collar/nut is installed. Wiping shall be done with a cloth that is damp with a solvent that is approved for use in Z-P101 or Z-P102, as applicable.

3.2.10.1.3 For single-shot tool installations manually screw the collar/nut onto the pin a minimum of two threads (see Figure 4).

Figure 4: Collar/Nut Application

3.2.10.1.3.1 When an automatic feed driver is used, Steps 3.2.10.1.3 and 3.2.10.1.4 are eliminated. Interference fit holes are required in metal structure.

3.2.10.1.4 Insert the power driver’s socket hex tip into the pin’s hex recess (see Figure 5).

Female Fastener in Magazine When Automatic Feed Driver is Used

Figure 5: Power Tool Insertion

3.2.10.2 Hand Tool Installation

Seat pin and pin collar as in 3.2.10.1.1, 3.2.10.1.2 and 3.2.10.1.3. Place wrench on the wrenching flats of the collar. Insert hex wrench into the pin’s hex recess (see Figure 6).

Torque until hex breaks off.

Figure 6: Hand Tool Installation

3.2.10.2.1 MS21042 Locknut Substitution

3.2.10.2.1.1 In limited access areas where the HL70 collar cannot be used, it is permissible to use MS21042 steel locknuts on steel pins. Torque values to be used when installing the MS21042 nuts are per Table IV.

Table IV: Torque Values for MS21042 Nuts

Diameter and Thread Size

Torque, inch-pounds

0.1640-32 15–25

0.1900-32 25–35

0.2500-28 60–80

0.3125-24 130–160

0.3750-24 200–240

0.4375-20 270–330

0.5000-20 370–430

3.2.10.2.1.2 When installing MS21042 steel locknuts on pins, one standard NAS1149D( )J or NAS1149D( )K washer (0.062 in. thick) shall be used to protect the surface from injury while tightening and to allow for the 1/16-in. grip variation provided by the standard collar.

NOTE: Older Engineering drawings will call out washers per AN960. Within its replacement document, NAS1149, there is a substitution list that cross-references the obsolete AN960 callouts with their NAS1149 equivalents.

3.2.11 Pin Protrusion

3.2.11.1 Pin protrusion shall be within the limits shown in Table V and measured in accordance with Figures 7(a), (b), (c), (d) and (e).

Table V: Pin Protrusion Limits

First Dash No.

Fastener Nom.

Dia., in.

Nominal Thread

Minimum Protrusion

P

Maximum Protrusion

P1 -5 5/32 8-32 0.302 0.384

-6 3/16 10-32 0.315 0.397

-8 1/4 1/4-28 0.385 0.467

-10 5/16 5/16-24 0.490 0.572

-12 3/8 3/8-24 0.535 0.617

-14 7/16 7/16-20 0.625 0.707

-16 1/2 1/2-20 0.675 0.757

Figure 7: Pin Protrusion Limits

3.2.11.2 Collar/Nut Angularity

3.2.11.2.1 Hi-Lok collars and K-Fast nuts may be used on Hi-Lok pins where there is a backside taper of up to 2°. When the backside taper exceeds 2° and up to 7°, then a self-aligning collar/nut should be used. The applicable Engineering drawing must be revised to add a self-aligning collar/nut if required.

3.2.11.2.2 There are no self-aligning sealing collars. However, the K-Fast self-sealing nuts, KFN536 or KFN631, may be used on up to a 6° backside taper.

3.2.12 Removal

3.2.12.1 Hi-Loks may be removed with an Allen-type hex wrench and pliers.

3.2.12.2 Collars or nuts shall not be reused. Pins may be reused if threads are not damaged and pin has not been removed from its hole.

3.3 Acceptance Criteria

3.3.1 Flushness

3.3.1.1 Flushness limits shall be in accordance with drawing requirements.

3.3.1.2 No head shaving is permitted.

3.3.1.3 Flushness of ST3M578 fasteners shall be checked from the top of the dome. To compensate for the dome, the maximum allowable dome height shall be 0.013” greater than the maximum flushness specified by the applicable smoothness requirement. The minimum allowable dome height shall be 0.012” greater than the minimum flushness specified by the applicable contour smoothness requirement.

3.3.3 Gaps

3.3.3.1 There shall be no measurable gap under the collar/nut of an installed self-aligning collar/nut.

3.3.3.2 Gaps under standard (non-self-aligning) collars/nuts of installed Hi-Loks shall not exceed the values shown in Table VI when measured at the outer periphery of the collar/nut.

These gaps shall not be continuous for more than 40% of the circumference of the collar/nut.

Table VI: Allowable Gaps Under Collar/Nut

Nominal Fastener Diameter, inch Allowable Gap, inch 5/32 0.003

3/16 0.004

1/4 0.005

5/16 0.006

3/8 0.007

7/16 0.008

1/2 0.009

3.3.3.3 The heads of protruding-head pins shall seat in at least one location on the periphery of the head and the remaining gap shall be in accordance with Figures 9(a) and 9(b) using the shim thickness shown in Table VII.

Table VII: Shim Thickness

Nominal Fastener Diameter, inch T, inch +0.0005 / –0.0000 3/16 0.004

1/4 0.005

5/16 0.006

3/8 0.007

7/16 0.008

1/2 0.009

3.3.3.4 The heads of all flush-head fasteners shall seat to meet the requirements of 3.3.3.4.1 and 3.3.3.4.2.

3.3.3.4.1 A 0.002-in.-thick shim cannot be inserted between the fastener head and the countersink for more than 40% of the circumference of the head.

3.3.3.4.2 A 0.002-in.-thick shim, of the configuration shown in Figure 8, does not contact the fastener shank when inspected as shown in Figures 9(c) and 9(d).

Figure 8: Inspection Shim

NOTE: Angularity shown facilitates gap definition only. Such a condition is not

(Figure continues)

Figure 9: Head Gaps—Protruding-Head Pins

NOTE: Angularity shown facilitates gap definition only. Such a condition is not

Figure 9: Head Gaps—Protruding-Head Pins (continued)

3.3.3.5 Manufacturing tolerances on the heads of flush-head fasteners may result in partially exposed countersinks. Exposed areas around the fastener head are acceptable if the fastener tolerances, hole tolerances, and flushness requirements are met. See Figure 10.

Figure 10: Countersink Exposure

3.3.4 When installing fasteners in transition fit holes and cadmium plating from the fastener shank collects under the head, the condition is acceptable providing the requirements for flushness and gapping stated herein are met.

4.0 QUALITY ASSURANCE

Shall ensure compliance with this specification.