74_S-F501_77751_SP_M_0001_M_NULL_0001_751_U_N_Y_N_N_Y_D.PDF

CAGE 77751 S-F501

Revision M

05 March 2020

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

ii

TABLE OF REVISIONS

Revision Changes Reason for Change Approved

Original Issue 06/09/1971

H. Kleindienst

Revision A 05/18/1973

Complete Revision. H. Kleindienst

Revision B 12/01/1973

Complete Revision. H. Kleindienst

Revision C 01/30/1977

Added alternate adhesive system. Revised destructive test requirements.

H. Kleindienst

Revision D 07/17/1979

Incorporated amendments. H. Kleindienst

Revision E 05/18/1988

Incorporated amendments D1 through D9. H. Kleindienst

Corrected pressure requirement from 10-15 psi to 15 to 20 psi to assure continuous clamping up force and positive pressure on the assembly.

Reformatted with clarification of specific requirements.

Revision F 04/09/1997

Incorporated amendment E 1. G. Leavy

Deleted use of:

O-T-620, Trichloroethane;

O-T-643, Trichloroethylene;

TT-M-261, Methyl Ethyl Ketone;

TT-T-548, Toluene; and TT-X-916, Xylene.

To remove ozone depleting substances (ODSs), and hazardous air pollutants (HAPs).

Added Foreword describing the review of this specification for toxins, pollutants and other hazardous materials, and establishing user responsibility for following all laws and regulations involving their use.

To comply with requirements of contract.

Reformatted all tables and redrew all figures. To improve clarity iii

Revision Changes Reason for Change Approved

Revision F (continued)

Updated Materials, section. 3.2: as follows:

3.2.1.1: Updated manufacturer information: was American Cyanamid; is Cytec Engineered Materials.

3.2.1.3: Updated manufacturer information in Table III: Part A: was American Cyanamid; is Cytec Engineered Materials; added full address.

3.2.2.1: Part (a): updated location for Hexcel:

was Dublin, CA; is Pleasanton, CA; added full address. Part (b): updated manufacturer information: was American Cyanamid; is AIcore, Inc.; added full address.

3.2.2.3: Deleted parts (a), Methyl Ethyl Ketone, and (c), Trichloroethane; restricted part (b), Naphtha, Aliphatic, to Type II only;

redesignated part (b) as part (a).

3.2.2.4: Deleted part (e), Altrex 1097, which is no longer available; redesignated Oakite 164 as part (e); updated corporate identities, added addresses. 3.2.2.5 part (b), replaced Frekote 33 and 44 with Frekote 48-NC, which is lower in volatile organic compounds (VOCs); added parts (c) and (d), Frekote C-200/C-210 and Frekote 710-NC, which are also lower in volatile organic compounds (VOCs); added part (e), Mold Release 225, which is specified in other A-10 documents; shifted letter designations as required; updated corporate identities, added addresses.

3.2.2.6 Deleted part (b), Ipplon DP1000; no

longer available; redesignated part (c) as part (b); updated corporate identities, added addresses.

3.2.2.7 Added address.

3.2.2.8 Added address.

3.2.2.9 Updated corporate identities, added

addresses.

3.2.2.10 Added addresses.

3.2.3:

Part (a): Added address.

Part (e): Updated corporate identity: was American Cyanamid; is Cytec Engineered Materials; added address.

Deleted part (f), Freon T-B1, which is a Class I ozone depleter and is no longer available.

Redesignated part (g) as part (f).

To reflect present manufacturers of materials, delete unavailable materials and add vendor addresses for ease of contact.

iv

Revision Changes Reason for Change Approved

Revision F (continued)

3.2.3:

Modified asterisk (*)-referenced note:

deleted carbon tetrachloride extraction;

added acetone and water extraction;

Added note that laundered materials shall not be used.

Added part (g) Rymplecloth #301;

Provided sources of supply.

Carbon tetrachloride is a Class I ODS and a HAP;

New materials are lower in HAPs or HAP-free;

To require only virgin— not laundered—gloves and cheesecloth be used.

Rymplecloth is an approved wiper for solvents;

For ease of contact with suppliers.

3.3.1.4 Expanded part (b).

Deleted part (d).

To reflect addition other alternative Frekote release agents, and provide for their unique requirements.

Release agents may not be compatible and so shall not be used interchangeably.

3.3.2.1.2 part (b), deleted Freon as a lubricant/coolant.

Freon is a Class I ozone depleter and is no longer manufactured.

3.3.2.5.1, deleted part (a), Altrex 1097;

renumbered parts (b) and (c) as (a) and (b) respectively.

Altrex 1097 is no longer manufactured.

3.3.2.7.2, modified part (a) to delete use of methyl ethyl ketone; replaced with Naphtha/MPK 50/50 ±2% blend by weight.

New solvent is lower in HAPs.

3.3.3.1.12, added "per G-R302" to instructions to use vapor degreasing for detail parts.

G-R302 is the A-10 process specification for solvent cleaning of metals.

3.4.2.1, deleted use of trichloroethane; replaced with choice of naphtha or naphtha/MPK 50/50 ±2% blend by weight.

Trichloroethane is a Class I ODS and a HAP; new solvents are lower in HAPs.

Revision G 09/30/2002

1.1 Scope added the A-l0A Aircraft. Clarification of

specification scope.

K. Grube v

Revision Changes Reason for Change Approved

Revision G (continued)

2.1 Added 0-0-670, Orthophosphoric Acid, Technical.

Military deleted Mil-S-8802 and Mil-A-83376

Chemical needed for phosphoric acid anodize process.

Obsolete and replaced by

SAE AMS QQ-A-250/4

and AMS-S-8802.

2.2 Added ASTM D2651, ASTM D3933, ASTM

D329, ASTM D740, and SAE APR 1524.

To facilitate processing of outside vendors.

Sec. 3 requirements added (Forest Products Laboratory) after FPL.

Define FPL.

Sec. 3.1 Facilities, Equipment and Tooling, Added specifications AMS QQ-A-250/4, AMS- S-8802 and AMS-A-25463.

SAE documents replace and supersede QQ-A- 250/4, Mil-S-8802 and Mil-A-25463.

3.2.1.2, Added: "except FM126 and Hysol EA9628 NW have to be certified only to the mechanical properties of MMM-A-132 and AMS-A-25463 specifications."

FM126 and EA9628 NW not on QPLs.

3.2.1.3, For Approved Adhesives, added Hysol EA9628 NW film weights .045, .060, and .080 to facilitate manufacturing and ordering of common adhesive systems at Hill A.F.B. Added Ref. to nominal thickness to denote approximate thickness vs. actual thickness.

3.2.1.4.1, Added (S-F501 and either Type I, Type II or Type III).

Clarification of type as called out in S-F501 Section 1.2.

Added: In the event type is not specified by P.O., Type I shall be marked on the container and/or roll of adhesive.

All A-10 drawings do not specify type and if type is not specified assemblies will be considered Type I in accordance with S- F501.

3.2.1.5, Added Note 3/ to table to read:

"3/ Hysol EA9628 NW shall be stored at or below 0 degrees F for 12 months max. The material may be re-evaluated for up to two additional 3 month storage lives".

Note is needed to define storage requirements for

EA9628 NW.

3.2.2.2, Added SAE specification AMS QQ-A- 250/4 to replace QQ-A-250/4.

Updated to SAE specification which is now used for procurement.

vi

Revision Changes Reason for Change Approved

Revision G (continued)

Sec. 3.2.2.3 (d), Added MEK at the request of Hill, AFB.

(e), Added Acetone.

Acetone is environmentally compliant/exempt with respect to EPA regulations.

3.2.2.4, Added Ferric Sulfate and Turco 4215 special caustic.

Chemical needed in P2 Etch process.

3.3.1.1, Added Figures 1a and 1b. To define processing and surface preparations.

3.3.2.4.1(e), Added dry nitrogen as option to dry air.

Dry nitrogen is acceptable for solution agitation and part drying.

3.3.2.5, Added "Anodize." To include anodizing process.

3.3.2.5.2, Added FPL Etch Deoxidizer Solution. To define FPL Etch Deoxidizer section.

Added Section 3.3.2.5.3, Deoxidizer Solution, P2 Etch.

To define P2 Etch chemistry, operating conditions, and solution maintenance procedures.

3.3.2.5.3, Added “(Environmentally preferred deoxidizer solution).”

Solution does not contain toxic chromate.

3.3.2.5.3.1, Added "FPL Etch per ASTM D2651 may be used in lieu of P2 Etch, as called out in Figure 1b and Appendix A-1.

FPL Etch is an acceptable alternative and the solution can be more easily maintained then P2 Etch solutions.

Added Section 3.3.2.5.4. To define Phosphoric Acid anodize Solution, make-up and solution maintenance.

3.3.2.7.1, Added statement to read:

“Pre-cleaned core may be used for test specimens provided the mechanical properties of this specification are obtained after testing.”

Hysol request.

Added new solvents to Sec. 3.3.2.7.2 (a). New solvents include Acetone, MEK, and MPK, Technical Grade.

Added MEK at the request of Hill, AFB.

Other solvents are either exempt in the case of Acetone, or Compliant at 45 mm Hg or less.

3.3.3.1.1, Added statement to read:

“The preferred surface preparation is phosphoric acid anodize per ASTM D 3933.”

The aircraft industry prefers this surface preparation, prior to structural bonding.

vii

Revision Changes Reason for Change Approved

Revision G (continued)

3.3.5.2.5 (b), Added the word production before assemblies to differentiate between test assemblies and production assemblies. Test assemblies need not have thermo-couples provided thermo-couples are within the autoclave and all the mechanical properties of this specification are obtained, after testing.

4.2.2, Changed title from “Clean Line Process Control” to “Clean Line and Phosphoric Acid Anodize Process Control.”

4.2.2.1.2.1, Added Phosphoric Acid Anodize Inspection Methods.

To include inspection criteria and methods to inspect Phosphoric Acid Anodize.

4.2.2.1.4, changed 40 ± 10 p.s.i. to a range of 30 to 40 p.s.i.

To assure excess pressure is not exceeded I.A.W. Table VI Maximum Bonding Pressures for Aluminum Core Parts.

4.3.5.2 Table VII Adhesive Test Requirements

added Note 5/.

To clarify/define the adhesive requirements for .080 lb./sq. ft.

Table VII, changed Adhesive Film to read .045 lb./sq. ft. 5 mil, was .45 lb./sq. ft. 5 mil.

To correct typo or misplaced decimal point.

Added Appendix A and Appendix B. To define process used at Hill A.F.B.

Added Appendix C. To define methods used to maintain Phosphoric Acid Anodize solution.

Revision H 03/30/2003

3.3.3.1 Added information to read: “or a

minimum of 8 hours at room temperature and the outside of the container is at room temperature with no condensation present.”

K. Grube

3.3.3.1 .5 Added note to read: “NOTE: The intent of conducting wedge crack testing is to assure the production parts have been cleaned correctly in accordance with this specification.

Hence, each rack of production parts shall have the cleaning verified by conducing wedge crack tests. The wedge crack specimens maybe prepared using a hot press, so an autoclave does not have to be used or tied up solely for specimen preparation purposes. See 3.3.3.1.7 for maximum time between air dry and cure of primer.”

viii

Revision Changes Reason for Change Approved

Revision H (continued)

3.3.3.2.1 Added to read: “Alternately the roll of

bagged adhesive may be used after a minimum of 8 hours exposure to room temperature provided conditions do not exceed those specified in 3.1.1 (k), prior to and after opening.”

3.3.6.9.3 Added information to section to read:

“At the start of the cure period, which is at 230°F for the lagging thermocouple and 260°F maximum limit for the leading thermocouple.

Caution: At no point in the adhesive cure cycle shall either the leading or the lagging thermocouple exceed the temperature of 260° F.”

To clarify temperatures and limit temperatures for bond cycle.

4.5.1(a) Added information to read:

"Manufacture and bond specimens in accordance with this specification, except an autoclave does not have to be used and a hot press maybe utilized for curing the adhesive."

To clarify crack extension manufacturing methods.

Revision J 02/22/2013

Section 2.0 Updated Applicable Documents. Deleted obsolete call outs to current specifications.

K. Grube

Section 3.1.1 added Clean Room requirements. Air Force request.

Revised section 3.2.1.2 and 3.2.1.3. Better define approved adhesives.

Section 3.2.3 Miscellaneous Materials under (c) added Nitrile Gloves.

Air Force request

Sections 3.2.2 to 3.2.3 Process Materials Updated consumables vendor data.

Deleted all obsolete callouts and replaced with current approved callouts.

Added Table IIA to better define and summarize adhesive certification requirements.

Better define approved adhesives and system requirements.

Added Section D. to Table III Approved Adhesives.

Hysol EA9696NW added in accordance with Air Force E.O. 11A0401-H.

Section 4.2.3.3 added allowance for Air Force approved document to aid with NDE (Non- Destructive Evaluations).

Define specific NDE requirements/methods.

Added Section 4.3.7 Adhesive Mechanical Test requirements.

Clarify the vendor test requirements for the process line and for part production.

Added Appendix D, vendor Qualification of Alternate Cleaning Process Line Chemicals and Methods.

Facilitate/allow Alternate vendor cleaning methods for cost reduction.

ix

Revision Changes Reason for Change Approved

Amend. K1 10/19/15

Cancelled unreleased Rev. K; released EO to add G-J901 to Sections 2.2 and 4.1.1.

To add NDI requirements. K. Grube

Revision L 10/26/17

Incorporated Amendment K1; corrected typos and made minor grammatical changes.

Specification update;

improve clarity.

M. Kassinger

Removed FPL Etch process in its entirety, affecting the following: 3.0: deleted fourth sentence in entirety; 3.3.1.1: in second sentence, deleted “preferred” as phosphoric acid anodize is now the only surface preparation method; deleted second paragraph in entirety; deleted Figure 1a in entirety; re-designated Figure 1b as Figure 1; corrected callouts to figures as required; 3.3.2.5.2:

deleted in its entirety; renumbered 3.3.2.5.3 as 3.3.2.5.2; 3.3.2.5.3.1: deleted in its entirety;

4.2.3.5.1: in third sentence, deleted “FPL Etch”;

4.3.7: in last paragraph, deleted “FPL Etch”;

Appendix B [formerly Appendix D]: Material Control Requirements, last paragraph, fourth sentence, deleted “FPL Etch.”

Per Air Force direction.

Deleted Appendices A and B in their entirety;

reidentified former Appendices C and D as Appendices A and B; updated references.

Per Air Force direction.

In 1.1, changed “A-10A” to “A-10.” Specification is applicable to all A-10 versions.

In 2.1 and 3.2.2.4, deleted sodium dichromate per A-A-59123.

No longer required due to removal of FPL Etch process.

In 2.2, added AMS 3819, cleaning cloths. Approved cloths for solvent wiping and cleaning.

In 3.1.1, changed first sentence to “Facilities shall be in conformance with Class 9 of ISO 14644-1, and when required for Air Force depot or field repair activities shall be in conformance with T.O. 1-1-690.”

Clarity.

In 3.1.1(f), deleted ASTM D2651 and ASTM D 3933.

Misplaced information.

In 3.2.1.1, changed first sentence to read: “BR 127, a one-part adhesive primer, shall be used.”

To ensure that only the one-part version of BR 127 is used (there is a two-part variant available in Europe).

In Table II, changed storage stability value to 12 months (was 6 months); changed pot life to 5 days.

To agree with supplier data; to correct error.

x

Revision Changes Reason for Change Approved

Revision L (continued)

In 3.2.1.2, revised material callouts. To correct errors.

In 3.2.1.3, revised title to read: “Approved Film Adhesives.”

Clarity.

In Table IIA, changed heading of third column to “Requirements for End Users of S-F501” (was “Remarks for End Users of S-F501”) and removed 1/ from heading; in third column, in all cells: deleted references to QPL.

Clarity; no longer required by end users; QPL references no longer required.

In Table III, retitled as “Approved Film Adhesives”; under AF126-2, deleted 0.045 lb./sq. ft. film weight material and deleted note 3/ (renumbered note 4/ as note 3/); under EA9628NW, added “(non-woven)”; reconfigured slightly to fit on one page.

Material is no longer available; clarity.

In 3.2.1.4.1, removed type designations from (a); added (b) Supplier’s product designation;

relettered (b), (c) and (d) as (c), (d) and (e);

added (f) Purchase order number; (g) Quantity;

(h) Distributor’s name and address, if applicable; and (i) Each individual package or container must be labeled with storage life expiration tags (the intent of which had formerly been Note 1/ in Table IV). Also in 3.2.1.4.1, deleted final paragraph.

To modify required supplier/distributor material information; to ensure that life expiration tags appear on each package/container;

paragraph is no longer required due to type designations being removed.

In Table IV, changed temperature requirements for all materials to Below 0°F; changed storage life: primer: 12 months (was 6 months), film adhesive: was 6 months, now provided by individual notes; deleted original 1/ (requirement relocated to 3.2.1.4.1(e)); in 1/, changed initial storage life to 12 months, and permit only one additional storage life; in 2/ and 3/, added “per lap shear requirements of Table VIII”; in 2/, changed supplier to Henkel (Hysol);

in 3/, added “AF126-2” and changed storage temp to 0°F, added 4/ for Cytec material.

Clarity and to agree with supplier data.

In 3.2.2.1, retitled “Core Material (For Test Only)”; in introductory paragraph, added “Class 2, Type N, or as specified.”

Clarity.

In 3.2.2.1(b), updated address for supplier. To reflect current supplier address.

In 3.2.2.1 NOTE, added “Type N” after Class 2 designation.

Clarity.

In 3.2.2.2, retitled “Aluminum Alloy (For Test or Solution Additions Only).”

Clarity.

xi

Revision Changes Reason for Change Approved

Revision L (continued)

In 3.2.2.2, added “0.020 and” as additional material thickness.

To reflect actual material thicknesses on the A-10.

In 3.2.2.3, completely updated solvent callouts and suppliers (where applicable); deleted MPK/naphtha blend; added methyl isobutyl ketone and isopropyl alcohol.

Ease of procurement;

blend is no longer available; to provide solvent alternatives.

In 3.2.2.4(b), added Ty. II Cl. 2 to A-A-55828. To ensure use of the proper chemical.

In 3.2.2.4(d) and (e), deleted Web URL. Web URL is no longer functional.

In 3.2.2.4(e), inserted “Aluminum Cleaner” to Oakite 164.

Current supplier product

In 3.2.2.4(f), added “Reagent Grade”; added “Source open.”

To ensure that proper quality of chemical used.

In 3.2.2.5(d), (e) and (f), updated address for supplier.

To reflect current supplier

In 3.2.2.6(a) and (b), updated address for

In 3.2.2.7(a) and (b), updated address for

In 3.2.2.8(a), updated address for supplier. To reflect current supplier

In 3.2.2.9(b), updated address for supplier. To reflect current supplier

In 3.2.2.10(a), (b) and (c), updated address for

In 3.2.3(b), changed thermocouple designation to Iron-Constantan, Type J.

To correct typo and use current designation.

In 3.2.3(c), updated addresses for suppliers;

deleted reference to Hill AFB document QSM- 0043.

To reflect current supplier addresses; per Air Force direction.

In 3.2.3, deleted (d); relettered successive items.

Cheesecloth is no longer

In 3.2.3(f), changed cloth designation to AMS 3819; updated address of supplier.

AMS 3819 cloths are the approved wipers; to reflect current supplier

In 3.3.1.1.1, last two sentences, changed approving organization to “A-10 SPO Engineering.”

Per Air Force direction.

In 3.3.1.1.1, added NOTE beneath paragraph. Per Air Force direction.

xii

Revision Changes Reason for Change Approved

Revision L (continued)

In Figure 1, first column, changed water break-free surface time to 30 seconds (was 20 seconds); in second column, changed oven drying maximum temperature to 160°F (was 175°F); removed boxes around various items.

In both instances, to agree with text elsewhere in document; boxes served no apparent function.

In 3.3.1.2, removed “white” and “cotton” in referencing gloves; replaced with “per 3.2.3(c)”;

changed beginning of last sentence to “Phosphoric acid anodized parts processed in accordance with this specification....”

To permit use of gloves other than those made of white cotton; to clarify proper handling of parts.

In 3.3.2.1.1(b), first sentence, changed “on the Engineering drawings” to “in the technical data package.”

To encompass governing documentation other than the Engineering drawing.

In 3.3.2.1.1, combined the Notes below item (b) into one Note.

Clarity.

In 3.3.2.1.2(e)(2), added to end of sentence “(e.g., core bonded to skin or potted core).”

To clarify meaning of “stabilized.”

In 3.3.2.1.2(e)(3), in second sentence, added “or” between “... foot” and “per detail....”

Typo.

In 3.3.2.4, beneath heading, deleted “(See Appendix D).”

Not required.

In 3.3.2.5.1(b), changed Oakite 164 to Oakite Aluminum Cleaner 164.

To agree with supplier

Rewrote and expanded 3.3.2.6 in its entirety. Per Air Force direction.

In 3.3.2.7.1, added Note immediately after heading.

To define unstabilized core and foam filled core.

In 3.3.2.7.1, added “in accordance with G-R302 and” before “as follows:” in introductory sentence.

To invoke the requirements of G-R302.

In 3.3.2.7.1(c), in second sentence, changed “1 or 2 minutes” to 1–2 minutes.”

To correct typo.

Re-numbered 3.3.2.7.2 as 3.3.2.8. To separate from 3.3.2.7, to which it is unrelated.

In 3.3.2.8 [former 3.3.2.7.2], removed solvent callouts by name and replaced with “per 3.2.2.3.”

Clarity.

Added CAUTION beneath 3.3.2.8(a). To clarify solvent wiping procedure.

In 3.3.3.2.1 (and elsewhere in this document), changed references to “refrigerated storage” or “refrigeration” to “cold storage.”

Consistency; to cover unrefrigerated storage such as dry ice.

xiii

Revision Changes Reason for Change Approved

Revision L (continued)

In 3.3.3.2.1, changed latter portion of third sentence and deleted fourth sentence; replaced with “... reach room temperature above the dew point (free or surface condensation) prior to opening for use.”

To clarify material normalization procedure.

In 3.3.3.2.3, titled as “Mismatch of Details”;

designated metal-to-core assemblies as

3.3.3.2.3.1 and metal-to-metal assemblies as

3.3.3.2.3.2. Moved second sentence of

3.3.3.2.3.1 as NOTE beneath 3.3.3.3.2.3; within NOTE, changed “Such” to “Mismatched”; added “metal-to-core and metal-to-metal” between “Mismatched” and “areas.”

In 3.3.2.6, added clarifying language from AF input

Clarity

In 3.3.3.2.7, added third sentence. To define time between removal from cold and cure for EA9628NW and

EA9696NW.

In 3.3.4.3, at end of second sentence, added “at the ramp rate defined in 3.3.8.4.”

To define ramp rate.

In 3.3.4.4, changed time permitted prior to cure to 240 hours (was 100 hours).

To agree with 4.3.2.1.

In 3.3.5.2.2, redefined thermocouple wire gauge as “no. 24 AWG or finer” (was “no. 30 AWG maximum”).

Clarity; to permit slightly thicker wire for ease of use.

In 3.3.5.2.3, tightened thermocouple accuracy to ± 2°F; was ± 5°F.

To require more accurate temperature control.

In 3.3.5.2.4, deleted introductory sentence;

merged former (a) and (b) into one paragraph.

Instructions for twisted thermocouple ends are no longer required.

In 3.3.5.2.5, added new (a) to better define the location and number of thermocouples;

relettered succeeding paragraphs.

Location and number of thermocouples had been only minimally defined.

In 3.3.6.7, at end of second sentence, added “and recorded at an interval of at least every six

(6) minutes.”

To ensure adequate pressure recording during autoclave cure.

In 3.3.6.8, in first sentence, changed “recommended” to “required”; in second sentence, after “over” changed to read “the range of vacuum and pressure required in the cure cycle.” (was “a range from a vacuum equal to 30 inches of mercury to a positive pressure of 100 psig.”).

To ensure complete and automatic instrumentation for pressure vacuum recording during cure.

xiv

Revision Changes Reason for Change Approved

Revision L (continued)

In 3.3.6.9.1, after “registering” changed to read “the range of vacuum and pressure required in the cure cycle.” (was “over a range from a vacuum equal to 30 inches of mercury to a pressure of 100 psig.”).

To ensure complete and automatic instrumentation for pressure vacuum recording during cure.

Replaced 3.3.6.9.3 in its entirety; renumbered and relocated as 3.3.8.8.

Succinctness; previous procedure was no longer required due to automation of recording;

more appropriate location.

Renumbered second Table V as Table VII and previous Table VII as Table VIII.

To eliminate duplicate numbering, which had resulted in two Table Vs.

In 3.3.7.5, changed to read “Pressure under the bag shall not read more than 5 psi during the cure cycle.” (was “No pressure probe monitoring the pressure under the bag shall read more than 5 psi during the cure cycle.”).

Clarity.

In 3.3.8.7.1, changed reference to “work book” to read “work order.”

Consistency.

Redesignated former 3.4.2 as 3.3.9 and relocated; changed references accordingly;

redesignated former 3.4.3 and 3.4.4 as 3.4.2 and 3.4.3, respectively.

More logical location;

specification requirement.

In 3.3.9.1 [former 3.4.2.1], changed beginning of second sentence to read “The area shall be wiped clean with solvents per 3.2.2.3...” (was “The area shall be solvent wiped with TT-N-95 Ty. II, aliphatic naphtha or naphtha/MPK 50/50 ± 2% by weight blend...”).

Clarity; consistency.

In 3.3.9.1 [former 3.4.2.1], deleted “ATTENTION: No liquid shall be allowed to wet foamed adhesive or core cells.”; replaced with “CAUTION: Minimize contact of liquids such as solvents and Alodine with foamed adhesive or core cells. Ensure that details are dry prior to proceeding to the next manufacturing process.”

To require only that the details be dry prior to further processing.

Rewrote 3.3.9.2 [former 3.4.2.2] in its entirety. Clarity.

In 3.3.9.2 [former 3.4.2.2], relocated NOTE to beneath 3.3.9.1 CAUTION statement; added second sentence “Damage exceeding 5% is subject to MRB action.”

Proper location; to require MRB action for damage exceeding 5% of bond area.

Re-titled 3.4 as “Rework and Environmental Monitoring Procedures” (was “Recommended Procedures”).

xv

Revision Changes Reason for Change Approved

Revision L (continued)

In 3.4.3.1 [former 3.4.4.1], changed “may” to “shall.”

To compel users to follow this procedure.

In 4.1, added “by End User” at end of title. Clarity.

In 4.1.1, changed first sentence, after “perform” to read “receiving inspection tests per Table IIA to ensure that material released to production will satisfy all the process requirements contained herein.” (was “, at their option, any receiving inspection tests within the scope of this document or the applicable military documents, to assure that material released to production will satisfy all the process requirements contained herein.”).

To require that receiving inspection tests per Table IIA are performed.

In 4.2.1.1, changed reference to “work book” to read “work order.”

Consistency.

In 4.2.2.1, in first sentence, added “and test” after “Process”; in second sentence, after “details” added “per AMS QQ-A-250/4 and....”

Clarity.

In 4.2.2.1.3.1(a), first sentence, expanded list of potential surface defects to include smut, stains, scribe lines, and pits.

Per Air Force direction.

In 4.2.2.1.3.1(b)(1), added “or” between mercury vapor and fluorescent.

Typo.

In 4.2.2.1.4, second sentence, after “using” revised to read “0.060-psf adhesive.”

Clarity; remove obsolete “Grade A” callout.

In 4.2.2.1.5, re-wrote to read “Test per Paragraph 4.5.1.” (was “Test per crack extension test method. Ref. Paragraph 4.5.1.”).

Clarity; brevity.

In 4.2.2.2, after “specimen” added “using material per 3.2.2.1 and 3.2.2.2....”

To clarify materials used in specimen.

Deleted 4.2.2.3 and 4.2.2.3.1. This testing is no longer

In 4.2.3.1, end of second sentence, changed “appropriate authorized agency” to “A-10 SPO Engineering.”

Per Air Force direction.

In 4.2.3.2, end of fourth sentence, changed “report.” to “reports per 4.2.3.3.”

Clarity.

In 4.2.3.2, deleted second paragraph in its entirety.

Not required; this is covered within 4.1.1.

In 4.2.3.5.1, second and third sentences and at beginning of NOTE, added references to “end user receiving inspection” testing; referenced “per Table IIA”

Clarity; to require that receiving inspection tests per Table IIA are performed.

xvi

Revision Changes Reason for Change Approved

Revision L (continued)

In 4.2.3.5.1, at end of third sentence, deleted “that will apply and quality control for” and substituted “and.”

Clarity.

In 4.2.3.5.1, second paragraph, third sentence, changed “the procuring authority” to “A-10 SPO Engineering.”

Per Air Force direction.

In 4.2.3.6, deleted second sentence (“Multi-metal-to-metal bonds shall be destructive tested.”) in entirety.

No longer required.

In 4.2.3.7, second sentence, deleted “of production”; second sentence, added “production” between “20th” and “unit”; second sentence, changed end of sentence to “an A-10 SPO Engineering approved test plan.” (was “an approved test plan.”).

Clarity; per Air Force

In 4.2.3.7(g)(3)c., NOTE, last sentence, changed end to “approved by A-10 SPO Engineering.” (was “approved by Engineering.”).

Per Air Force direction.

In 4.2.3.9, rewrote first sentence: “Tooling held as a result of requalification testing discrepancies shall be released only after final release of the cause and corrective action report.”

Clarity.

In 4.2.4.1.4(b)(3), changed to “The depth exceeds 0.001 inch.”; was “The depth exceeds

0.010 inch.”

Per Air Force direction.

In 4.2.4.1.5, changed end of sentence to “... be as defined in MIL-A-83376.”; was “... meet the requirements of MIL-A-83376.”

Correction of awkward phrasing.

In 4.3, immediately beneath heading, deleted reference to Appendix D.

Not required.

Retitled 4.3.1 as “Release of Adhesive Materials to Production” (was “Release of Adhesive to Production”).

Clarity.

In 4.3.1.1, toward end of second sentence, changed “will” to “shall.”

Clarity.

Deleted 4.3.1.2 and 4.3.1.3 in entirety. This testing is no longer

In 4.3.2.1, changed cumulative hours to “240”;

was “120.”

To agree with B-M101.

In 4.3.2.2, toward end of sentence, changed “bake” to “cure.”

xvii

Revision Changes Reason for Change Approved

Revision L (continued)

Deleted 4.3.2.3 in entirety; renumbered 4.3.2.4 as 4.3.2.3.

No longer required; intent incorporated into former

4.3.2.4 [now 4.3.2.3].

In 4.3.2.3 [formerly 4.3.2.4], second sentence, after “temperature” changed to “above the dew point (free of surface condensation) prior to opening the bag.” (was “with the bag unopened in a period taking 15 hours minimum.”).

To clarify material normalization procedure.

Deleted 4.3.4 in its entirety, including 4.3.4.1 through 4.3.4.4; renumbered successive sections/paragraphs accordingly.

This testing is no longer

In 4.3.4.1 [former 4.3.5.1], deleted “metal-to-metal” from first line.

Per Air Force direction.

In 4.3.4.2 [former 4.3.5.2], rewrote. Clarity; per Air Force

In Table VIII, added 4/ to Method cells for each test type (previously only shear testing showed 4/); modified 4/ as follows: is: “Conditioning of the adhesive prior to the fabrication of test assemblies shall be per 3.1.1(k) for any time up to 240 hours within the cure initiation.” (was:

“Conditioning of the adhesive prior to the fabrication of test assemblies shall be at 65°F to 75°F for any time up to 240 hours within the cure initiation, except that open assembly test panels shall have the adhesive at 90°F–95°F for 240 hours.”); changed 5/ to read “Adhesive film 0.080 or 0.085 Ib./sq. ft. shall meet this table’s requirements for 0.06 Ib./sq. ft.” (was “Adhesive film 0.080 Ib./sq. ft. shall meet the the Table VIII requirements for 0.06 Ib./sq. ft.”).

Conditioning for all testing is now the same; to encompass both 0.080 and 0.085 adhesives.

In 4.3.4.4, deleted end of sentence after comma.

Not required.

In 4.3.4.5.1 [former 4.3.5.5.1], second sentence, changed “lap shear” to “tensile shear.”

Consistency of terminology.

Rewrote 4.3.4.6 [former 4.3.6] in entirety. Clarity.

In 4.3.5 [former 4.3.7], third paragraph, deleted last sentence in entirety.

Not required.

In 4.5.1(a), deleted extraneous verbiage. Clarity; reference to Figure 4 is sufficient to define requirements.

In Figure 4, revised dimensioning throughout to correct inconsistent tolerances.

xviii

Revision Changes Reason for Change Approved

Revision L (continued)

In 6.2.3, changed time from “10 seconds” to “30 seconds” and changed temperature to “110°F (43.5°C)” from “170°F (77°C).”

Per Air Force direction.

In Appendix A [formerly Appendix C], added secondary heading “Preparation of Calibration Curve” immediately beneath overall heading “Procedure for Determining Aluminum Analysis by Atomic Absorption (AA)”; modified indentations throughout; in Item c of Analytical Methods section, added missing opening parenthesis in chemical formula; at end of first sentence of Item (1) of Analysis of Anodizing Solution section, changed “(10 ml into 100 ml)” to “(100 ml).”

Clarity; consistency with the rest of the document;

typo; clarity.

In Appendix B [formerly Appendix D], in Outline of Test Plan Requirements, changed first word of second item to “Select” (was “Selected”).

Typo (incorrect tense).

Revision M 03/05/2020

In Foreword, final paragraph, changed revision level to M [was J].

Per Air Force direction.

In 2.1, Military, added MIL-DTL-5541. To correct omission.

In 2.2, SAE, deleted AMS-S-8802. Not used in document.

In 3.0, last sentence, deleted reference to Appendix C.

No longer in document.

In 3.1.1(a), reworded second sentence to replace “periodically” with “monthly.”

Per Air Force direction.

In 3.1.1(h), added “vaping” to prohibitions. Per Air Force direction.

In Table II, under weight/gallon, changed requirement to “7.3 ± 0.2 Ib./gal.” [was “7.4 ±

0.2 Ib./gal.”].

Per Air Force direction.

In 3.2.2.4(g), changed to “Turco 4215 NC-LT” [was “Turco 4215 Special Caustic”].

Updated product name.

In 3.3.1.1, last sentence, changed to “The surface preparation in this specification is similar to phosphoric acid anodize in accordance with ASTM D3933.” [was “The surface preparation is phosphoric acid anodize in accordance with ASTM D3933.”].

Per Air Force direction.

In 3.3.1.2, end of first sentence, changed “primed” to “primed and cured.”

Per Air Force direction.

In 3.3.1.2., changed last sentence into a NOTE. Per Air Force direction.

In 3.3.1.6, changed “cured” to “completely cured.”

xix

Revision Changes Reason for Change Approved

Revision M (continued)

In 3.3.2.1.2(b), added “isopropyl alchol” as an acceptable coolant.

Per Air Force direction.

In 3.3.2.1.3(c), changed nominal diameter to “+0.120/–0.000 inch” [was “+0.060/–0.000 inch”].

Per Air Force direction.

In 3.3.2.4.1(c), third word in second sentence, changed to “may” [was “must”].

Per Air Force direction.

In 3.3.2.5.1, added (c). Per Air Force direction.

In 3.3.2.5.3(b), at end of sentence, added “per A-A-55820 Class I.”

Per Air Force direction.

In Figure 1, added water break check between the cold water rinse and the anodic coating inspection; rewrote 3.3.2.4(g) in its entirety.

To agree with 3.3.2.6.

In 3.3.2.6

(b) changed "160-190º" to "at temperatures listed for specific cleaners in 3.3.2.5.1"

(p) removed the words "at room temperature"

(s) changed “16 hours” to “1 72 hours” and added: "Parts should be processed as soon as possible to achieve a higher probability of success."

Per Air Force direction.

In 3.4.3, added 3.4.3.2 in its entirety. Per Air Force direction.

In Appendix A, Preparation of Calibration Curve, (1)b., after “orthophosphoric acid” added “per A-A-55820 Class I.”

xx

TABLE OF CONTENTS

TABLE OF REVISIONS ....................................................................................................... i LIST OF TABLES ........................................................................................................... xxii LIST OF FIGURES ......................................................................................................... xxiii FOREWORD .................................................................................................................. xxiv

1.0 INTRODUCTION

1.1 Scope

1.2 Classification

2.0 APPLICABLE DOCUMENTS

2.1 Government Documents

2.2 Non-Government Documents

3.0 REQUIREMENTS

3.1 Facilities, Equipment and Tooling

3.1.1 Facilities

3.1.2 Equipment

3.1.3 Tooling

3.2 Materials

3.2.1 Adhesive System

3.2.2 Process Materials

3.2.3 Miscellaneous Materials

3.3 Required Procedures and Operations

3.3.1 General Requirements

3.3.2 Processing of Details and Adhesives

3.3.3 Application of Adhesives

3.3.4 Foam Adhesive

3.3.5 Temperature, Pressure and Cure Requirements

3.3.6 Pressure Requirements

3.3.7 Pressure Allowable

3.3.8 Cure Cycle Requirements

3.3.9 In-Process Correction of Adhesive Primer

3.4 Rework and Environmental Monitoring Procedures

3.4.1 Removal of Excess Adhesive

3.4.2 Controlled Environment Requirements Exceeded

xxi

3.4.3 Voids, Disbonds or Recessed Areas

3.5 Certification of Process Operators

4.0 QUALITY ASSURANCE

4.1 Responsibility for Inspection by End User

4.2 Process Control Requirements

4.2.1 Process Documentation

4.2.2 Clean Line and Phosphoric Acid Anodize Process Control

4.2.3 First Part Qualification and Subsequent Requalification

4.2.4 Production Parts Inspection

4.3 Material Control Requirements

4.3.1 Release of Adhesive Materials to Production

4.3.4 Production Tensile Shear Tests

4.3.5 Adhesive Mechanical Test Requirements

4.4 Certification

4.5 Test Methods

4.5.1 Crack Extension Test Method

5.0 PREPARATION FOR DELIVERY

6.0 NOTES

6.1 Intended Use

6.2 Definitions

6.2.1 Batch

6.2.2 Double Countercurrent Immersion

6.2.3 Water Break-Free Surface

APPENDIX A: CHEMICAL ANALYSIS METHODS

APPENDIX B: SUPPLIER QUALIFICATION OF ALTERNATE CLEANING

PROCESS LINE CHEMICALS AND METHODS

xxii

LIST OF TABLES

Table I. Cleaning Time Intervals

Table II. Adhesive Primer Requirements

Table IIA. Certification Requirements for Adhesive Systems

Table III. Approved Film Adhesives

Table IV. Storage Conditions and Life

Table V. P2 Etch Calculation of Normality (N) of Sulfuric Acid to Percent by Weight

Table VI. Applicable Weight of Film Adhesive

Table VII. Maximum Bonding Pressures for Aluminum Core Parts

Table VIII. Adhesive Test Requirements xxiii

LIST OF FIGURES

Figure 1. Bonding Process Steps Utilizing Phosphoric Acid Anodize Preparation .. 18

Figure 2. Ribbon Direction in Core

Figure 3. Steps, Recesses and Undercuts

Figure 4. Crack Extension Specimen Configuration xxiv

FOREWORD

This specification has been reviewed for EPA 17 toxic chemicals, SARA 313-listed pollutants, as well as ozone depleting substances. All ozone-depleting substances have been removed.

Hazardous air pollutants and toxic materials have been eliminated or minimized to comply with the Air Force Pollution Prevention Program, AFI 32-7080. A reasonable effort has been made to eliminate rather than minimize pollutants and to use environmentally acceptable substitutes.

Certain substitutions, however, have not been made due to their potential unknown deleterious effects on the A-10 weapon system.

Government and other industry specifications called out in this specification have been reviewed. (See Applicable Documents section of this specification for documents reviewed.)

Ozone depleting substances and hazardous materials have been identified and reported on in accordance with Contract F04606-96-D-0021 CET SM-ALC/LAF 96- AI0-AI-9 D.O. 0016.

It must be understood that the materials, methods, applications and processes can contain toxic and hazardous materials. It is the responsibility of the user to ensure safe and proper use in accordance with all applicable OSHA, EPA, Federal, state and local regulations.

Material sources and practices utilized at Hill Air Force Base, Ogden, Utah (A-10 Systems Program Office) have been updated / completed in accordance with Contract F42620-01-D-

026, CET OO-ALC/LC A02-A10-ASI D.O. 0012.

This latest revision (Revision M) was prepared in accordance with Contract FA8202-09-D- 0003, D.O. 0006 to eliminate obsolete callouts, improve definition and further reflect current approaches utilized at Hill Air Force Base.

1.0 INTRODUCTION

1.1 Scope

This specification establishes the requirements for the A-10 aircraft structural adhesive bonding of aluminum metal to metal and aluminum honeycomb sandwich type assemblies. This specification meets the requirements of MIL-A-83376 and MIL-A-83377 to the extent specified herein.

1.2 Classification

The classification of adhesive bonded structure fabricated per this document shall be of the following types and shall be specified on Engineering drawings. In the event the structural classification is not specified, assemblies will be considered Type I (Primary Structure).

(a) Type I: Primary structure. – The primary structure shall be structure that is essential to the basic airframe structural integrity and failure of which would cause significant hazard to operating personnel resulting in loss of mission capability or jeopardizing flight safety (includes loss of major components or loss of control).

(b) Type II: Secondary structure. – The secondary structure shall be structure that is essential to the aerospace vehicle performance or mission accomplishment and whose failure would cause degradation of aerospace vehicle performance or mission capabilities.

(c) Type III: Nonstructural (limited strength). – Nonstructural shall be structure that is not essential to basic aerospace structural integrity or does not contribute directly to aerospace vehicle performance or mission accomplishment. Its failure would not significantly affect the structural integrity, aerospace vehicle performance or mission accomplishment.

2.0 APPLICABLE DOCUMENTS

The following documents of the issue in effect on the effective data 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

Federal

A-A-55820 Orthophosphoric (Phosphoric) Acid, Technical

A-A-55828 Sulfuric Acid, Technical

MMM-A-132 Adhesives, Heat Resistant, Airframe Structural, Metal-to-Metal

TT-N-95 Naphtha; Aliphatic

Military

MIL-A-83376 Adhesive Bonded Metal Faced Sandwich Structures, Acceptance Criteria

MIL-A-83377 Adhesive Bonding (Structural) for Aerospace and Other Systems, Requirements for

MIL-DTL-5541 Chemical Conversion Coatings on Aluminum and Aluminum Alloys

T.O. 1-1-690 Technical Manual, General Advanced Composite Repair Processes Manual

NOTE: Both MIL-A-83376 and MIL-A-83377 have been cancelled without replacement.

However, the A-10 OEM acceptance criteria and bonding requirements are called out in these specifications to the extent referenced in S-F501.

2.2 Non-Government Documents

A-10 Program

B-F501 Adhesives, Epoxy – General Purpose, Process for

B-M101 Adhesive, Expandable, Honeycomb Core Splice

G-J901 Non-Destructive Inspection Techniques of Metallic and Metal Bonded Parts

G-R302 Solvent Cleaning of Metals, Process for

Z-P801 Storage, Handling, Shipping

Z-R901 Finishes – General, Codes and Requirements for

American Society for Testing Materials ASTM C297 Standard Test Method for Flatwise Tensile Strength of Sandwich

Constructions

ASTM D329 Standard Specification for Acetone

ASTM D740 Standard Specification for Methyl Ethyl Ketone

ASTM D1781 Standard Test Method for Climbing Drum Peel for Adhesives

ASTM D2651 Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding

ASTM D3933 Standard Guide for Preparation of Aluminum Surfaces for Structural Adhesives Bonding (Phosphoric Acid Anodizing)

SAE

ARP 1524 Surface Preparations and Priming of Aluminum Alloy Parts for High Durability Structural Adhesive Bonding

AMS 3819 Cloths, Cleaning, for Aircraft Primary and Secondary Structural Surfaces

AMS-A-25463 Adhesive, Film Form, Metallic Structural Sandwich Construction

AMS-QQ-A-250/4 Aluminum Alloy 2024, Plate and Sheet

AMS-C-7438 Core Material, Aluminum, for Sandwich Construction

Other

ISO 14644-1 Cleanrooms and Associated Controlled Environments – Part 1:

Classification of Air Cleanliness by Particle Concentration

3.0 REQUIREMENTS

The requirements of the applicable Engineering drawings as implemented by this specification shall apply. This specification shall govern the materials, materials control, facilities, equipment, manufacturing process and quality assurance. Materials other than those shown shall not be used in fabrication of parts per this process. Appendices A and B shall apply.

3.1 Facilities, Equipment and Tooling

3.1.1 Facilities

Facilities shall be in conformance with Class 9 of ISO 14644-1, and when required for Air Force depot or field repair activities shall be in conformance with T.O. 1-1-690. Subparagraphs and/or statements subordinate to this section delineate specific facilities requirements that shall apply when deemed over and above the ISO and/or T.O. requirements.

Operations performed per this specification, from the storage of cleaned and primed parts through their assembly for final bonding, shall be conducted in a controlled contamination area as follows:

(a) Filter all incoming air. Check, clean or replace filters monthly to ensure proper operation.

(b) Maintain a positive air pressure differential, such that unfiltered air does not enter the area. Air pressure monitoring equipment capable of verifying the pressure differential shall be installed and accessible for inspection within the controlled area.

(c) Enclosed areas are required. Keep doors and other openings closed when not in use.

(d) Seal and/or cover floors with non-flaking, easily cleaned material, such as plastic, paint, vinyl tile, etc.

(e) Only the following methods may be used for cleaning within the controlled contamination areas:

(1) Water mopping – Use mops wet or dampened with water.

(2) Vacuuming – The exhaust air must either be vented outside the limited contamination area or filtered to at least the same degree as the incoming air for the area.

(3) Chemical mopping – Use mops commercially treated with either propylene glycol or slightly tacky epoxy resin.

(f) Cleaning is required when visual inspection shows any accumulated dust, dirt, or other contamination, according to the following inspection schedule, except that the maximum time interval between cleaning operations shall not exceed the limits specified in Table I.

Table I. Cleaning Time Intervals

Items Inspection Schedule

Maximum Cleaning Time Interval

Equipment, tables, floors, etc. No Inspection Required 24 hours

Walls from floor to 7-ft. height No Inspection Required 30 days

All walls above 7 ft., ceiling, beams, overhead fixtures, lights, etc. 30 days 6 months

(g) Do not allow internal combustion engines within the areas.

(h) Do not permit smoking, vaping or eating in the areas.

(i) All materials, tools, parts, or equipment taken into the areas shall be free of dirt, grease, oil or other contaminants detrimental to adhesion.

(j) Do not permit processes or operations that produce uncontrolled spray, dust, fumes, or particulate matter in the area.

(k) The temperature shall be 60°F to 85°F except the upper temperature limit of 85°F may be waived for the area adjacent to drying or curing ovens located within a controlled contamination area provided they are separated from the rest of the area. The maximum relative humidity shall not exceed 65% in the controlled contamination area.

(I) Keep the controlled contamination area used for structural bonding segregated from other fabrication areas.

(m) Do not use waxes, compounds containing uncured silicone, or any material detrimental to adhesion in the controlled contamination area.

3.1.1.1 Equipment contamination control shall meet the following requirements:

(a) Install filters for airborne dust, traps for moisture and oil on all air lines or ducts used for spraying and drying of parts in any location, or for the operation of air motors within the controlled contamination areas, at a point adjacent to the using area, but past the air source.

(b) Liquid handling facilities shall preclude contamination by grease, oil, suspended or dissolved solids, or other substances detrimental to adhesion.

(c) Design and control lubricated equipment so as to prevent any contamination of adhesives or cleaned details by the lubricant.

(d) Since some of the volatile products given off during the drying and curing of adhesives may contain toxic compounds, adequate provision must be made to vent the autoclaves, ovens, and vacuum pump outlets through the roof so as not to endanger personnel. Outlets must be more than 20 feet from air conditioning intakes.

3.1.2 Equipment

The following shall be provided for production use:

(a) Autoclaves, platen presses, and related equipment, such as temperature controls and pressure indicating devices, as required, with controllable heating rates within the range of 75°F to 260°F and capable of curing bonded assemblies as specified herein.

(b) Air circulating ovens capable of maintaining a temperature over a range of 100°F to 260°F and holding a given temperature to ± 10°F.

(c) Pneumatic spray equipment and related equipment, such as vibrating paint mixers and spray tanks with provisions for primer agitation and recirculation in hoses during application of liquid adhesive primers.

(d) Devices that indicate temperature and pressure (both positive and negative) shall have recording devices as well. These must be calibrated on a schedule and the rate of movement verified to permit time lapses to be read on the charts.

3.1.3 Tooling

3.1.3.1 The basic tooling requirements for adhesive bonding are to have tools that control the location of the details while allowing uniform pressure to be applied to the assembly during the bonding operation.

3.1.3.2 When a flexible diaphragm is used to apply pressure, care must be taken to prevent bridging. Bridging will not allow the proper transmission of pressure. Free floating pressure bars or rings may be used where bridging may occur. They may also be used where a local increase in pressure is required because of a specific part design or where the tolerances and bond line of the part are critical.

3.1.3.3 Tools and fixtures used to locate details to be bonded shall hold details in proper alignment during the bonding operation. These tools and fixtures shall permit the transfer of pressure to all surfaces being bonded and shall produce a bond line thickness within the required limits where specified on Engineering drawings.

3.1.3.4 Tools should be so designed so as to avoid the problem of thermal expansion between the tool and the part being fabricated.

3.1.3.5 Tools shall be so designed so that they can withstand the bonding pressure for the particular assembly being used.

3.2 Materials

3.2.1 Adhesive System

The adhesive system used per this…