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MIL-S-8660C

MIL-S-8660B
[-’”’ 30 October 1963.

MILITARY SPECIFICATION

SILICONE COMPOUND,
NATO COOE NtFIBER S-736 ,

This specification is approved for use by all Departments

and Agencies of the Oepatlxnent of Oefense.
.?, ,
1. SCOPE f:
[!
1.1 Sco e. This specification covers one type of a nonmelting, heat
stable S1
+ cone compound for “ use in high tension electrical connections,
ignition systems and electronics equipment; for application to unpainted
mating threaded or non-threaded surfaces , and as a lubricant for components
fabricated from rubber. This, compound is effective in. the temperature range
from -54°C (-65”F) to +204”C,(+400”F) for extended periods and to 260”C
500”F) for short periods. ~is compound is identified by NATO symbol S-736
I see 6.5).

2. APPLICABLE DOWIENTS ;

2.1 Government documents. ~

“2. 1;1 Specifications, sta~dards, and handbooks. Unless otherwise

specified, he fol lowlng spec~f lcat}ons, standards, and handbooks of the issue
1 isted in that issue of the Department of Oefense Index of Specifications and .
Standards (OOOISS) specified in the solicitation form a part of this
specification to the extent s~ified herein.

SPECIFICATIONS

FEOERAL

O-A-548 Antifreeze/Coolant, Engine, Ethylene Glycol,

Inhibited, Concentrated.
O-G-491 Gljcerol, Technical (High Gravity).
QQ-A-250/4 ~ Alqminum Alloy 2024, Plate and Sheet.
QQ-8-613 - Brass, Leaded and Non-Leaded, Flat Products,
(Plate, Bar, .$heet and Strip).
QQ-C-502 - Copper Rods and Shapes and F1 at Products with
Finished Edges (Flat U~re, Strips and Ears).

Beneficial contnents (recommendations, additions, deletions) and any pertinent data

which may be of use in improving this document should be addressed to: Engineering
Specifications and Standards Department (Code 93), Naval Air Engineering Center,
Lakehurst, NJ 08733, by using the self-addressed Standardization Oocument Improve-
ment Proposal (00 Form ]426) appearing at the end of this document or by letter.

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MIL-S-8660C

QQ-L-201 Lead Sheet.

QQ-P416 Plating, Cadmium (Electrodeposited). .=)
:2-;-;;; Solder, Tin Alloy, Lead-Tjn Alloy, and Lead Alloy. :.
Zinc Sheet and Strip.
TT:1:735 kOPrOpYl Alcoho 1.

MILITARY

MI L-M-14 Molding Plastics and Molded Plastic Parts,

Thermosetti ng.
MI L-E-463 Ethyl Alcohol (For Ordnance Use).
MIL-E-480 Enamel, 8aki ng, Phenol -or-Urea-Fonnaldeh~de.
MI L-I-631 Insulation, Electrical, Synthetic-Resin
Composition, Non-rigid.
MIL-R-3065 Rubber, Fabricated Parts.
MI L-C-3702 Cable, Power, Electrical, Ignition, High Tension.
MIL-S-5059 Steel. Corrosion Resistant (18-8). plate. Sheet
I and S~rip.
MIL-I-24092 Insulating Varnish, Electrical, Impregnating,
Solvent Containing.

STANOAROS

FEOERAL

FEO-STO-313 htaterial Safety Data Sheets Preparation and the .

Sukdssion of.
FED-STO-791 Lubricant, Liquid Fuel and Related “Products,
Methods of Testing. ‘3
MILITARY

MI L-STO-1O5 - Sampling Procedures and Tables for Inspection by

,Attribu~es. .-
MIL-STO-2SQ - Packaging of Petroleum and Re 1ated Products.

(Copies of specifications, standards; handbooks, drawings, and

publications required by manufacturers in connection with specific acquisition
functions should be obtained from the contracting activity or as directed by
the contracting of,ficer. )

2.2 Other publications. The fol lowing documents form a part of this
specification to the extent specified herein. The issues of the documents
which are indicated as 000 adopted shall be the issue 1 isted in the current
00DISS and the supplement thereto, if applicable.

fJ4EKICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

AST14 A 569 - Steel, Carbon (0.15 Maximum, Percent), Hot-Rolled Sheet

and Strip, Commercial Quality.
ASI?4 O 149 - Dielectric Breakdown, Voltage and Dielectric Strength
of Electrical Insulating Materials at Commercial Power
Frequencies. “-, \._
ASTM o 150 - A-C Loss Characteristics and Petmittivity (Dielectric ..- )’
Constant) of Solid Electrical Insulating Materials.

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PS7M D 217 - Cme Penetration of Lubricating Grease.

~,.. ASTN D 257 - D-C Resistance or Conductance of Insulating Mater{a Is.
ASTM D 495

ASTt4 D 1478
-

-
High Voltage,
Electrical
Low Current,
Insulation.
Low-Temperature
Dry Arc Resistance

Torque of Bal 1 Bearin9 Greases.

of Solid
I
(@Pi i cation for cop{es should be addressed to the American soc fety for
Testing and Materials, 1916 Race Street, Philadelphia, PA 19103. )
.,
SIXIETY OF AUTOMOTIVE ENGINEERS, INC (YE)

m4s 4377 - Sheet. and Plate - 3.OAL l.OZn

(~pl icatlon for copies should be addressed .to SAE, 400 Commonwealth Drive,
Harrendale, PA 15096. )

(Industry association specifications and standards are generally available

for reference from llbraries. They are also distributed among technical.
groups and using Federal agencies. )

2.3 Order of precedence. In the event of a conf 1 ict between the text of
this specification and the references cited herein, the text of this
specff i cation shal 1 take precedence.
. -. —

.
....
.
3. REQUIREMENTS

c .,; .
Spe:i;ic$:;;f:;;;;o:.
applicable
The

qualified
silicone
e products
products
compound furnished
which are qualified
under this
for listing on the
1 ist at the time set for opening of bids (see
4.3 and 6.3). .

3.2 Materials. The materials used in the formulation of the si 1 i cone

compound shal 1 be of high quality and suitable for the intended use. The
final product shal 1 be a smooth, non-lumPY 9reaSe-1 ike c~pound.

3.2.1 Toxicit The material shal 1 have” no adverse effect on the health
of personne + when used for its intended purpose. Questions pertinent to this
effect shal 1 be referred by the contracting actl vity to the appropriate
departmental medical service who will act as an adviser to the contracting
agency.

3.2.2 Color. In its natural form, the compound shall” be translucent and
of a color=ar to light gray or cream. When specified (see 6.2c), a dye
or pigment may be i ncoworated i n the material provided the f Inished compound
meets the requirements of this specification In all other respects.
.,
3.3 Performance characteristics.
I
3.3.1 Physical properties. Physical properties of the si 1 i cone compound
shall be in accordance with the requirements in Table 1.

When tested as specified in 4.6.9, the test

~: PaP~~3~~s~a~;%~~fs~~~i~~;ests shall show no pink coloration. @lor
changes within 1/8 inch of the edges of the test discs shall be disregarded.

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MIL-S-8660C

3.3.3 Electrical properties. Electrical properties of the silicone

compound shal 1 be in accordance” with Table 11.
:3
3.3.4 Storage stability. Unworked and worked penetration of the compound
after the 6 months of storage at 37.8 + 3°C (100 + 5“F) as specified in 4.6.14
taken at 25 ~ 1°C (77 ~ 2°F) shal 1 con~onn to the-requirement in Table I.

3.3.5 Workmanship The compound shal 1 be processed to produce a

homogeneous+ m xture free from 1umps, cakes, abrasives, and foreign materials.

4. QUALITY ASSURANCE PROVISIONS

4.1 Responsibility for inspection. Unless otherwise specified in the

contract or purchase order, the contractor is responsible for the performance
of all inspection requirements as specified herein. Except as otherwise
specified in the contract or purchase order, the contractor may use his own or
any other facilities suitable for the performance of the inspection
requirements specified herein, unless disapproved by the 6overnment. The
Government reserves the right to perform any of the inspections set forth in
the specification where such inspections are, deemed “necessary to assure
SUPP1 ies and services conform to prescribed requirements.

4.2 Classification of inspection. The inspection requirements specified

‘herein are classified as follows: .,
a. @alificition inspect ion,.j(see 4.3).
.,..;.+*’
b. @ality conformance inspection (see 4.4).

4.3 Qualification inspection. The qualification inspection shal 1 consist

of all the requirements and tests specified in Tables I and II.

4.3.1 @alification inspection sample. The qualification inspection

sample shall consist of 10 pounds of the compound packaged as specified in’
Sectton 5 of, this. specification. The sample shall be forwarded to the
qualifying 1aboratory, Consnander, Naval “Air Development Center, Attention:
Aircraft and Crew Systems Technical Directorate (6062), Warminster, PA 18974.
The sample shall be plainly and durably marked with the following information:

Sample for qualification inspection

SILICONE COMPOUNO, NATO COOE Nl$iBER S-736
MIL-S41660C
Name of manufacturer
Product code number
Date of manufacture
Sihnitted by (name) (date) for qualification inspection in accordance
with the requ Irements of MI L-S-8660C under authorization (reference
authorizing letter) (see 6.3).

4.3.2 Manufactutir’s data. Two copies of the manuf acturer’s test report,
containing complete test data showing that material submitted for
qualification conforms to the requirements of this specification, shal 1 be
submitted with the qualification sample. The location and identity of the ,...,,.-Y
,
plant which produced the sample tested
safety data sheets on toxicity (see 3.2.1)
shal 1 also be supplied.
shall be prepared
Materia 1
in ‘accordance
J
with FED-STO-313 and submitted to the qualifying laboratory (see 4.3.1) .

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MI L-S8660C

4.3.3 Retention of qualification. In order to retain qualification of a

product approved for listing on the qualified products list (QPL), the
manufacturer shall verify by certification to the qualifying activity, that
the manufacturer’s product complies with the requirements of this
specification. The time of periodic verification by certification shall be in
two-year intervals from the date of original qualif~cation. The Government
reserves the right to re-exami ne the qualified product whenever deemed
necessary to determine that the product continues to meet ,any or al 1 of the
specification requirements.

4.4 @al ity conformance inspection.

4.4.’1 Lot information. Unless otherwise specified hetiin or in the

contract, a lot shall consist of al 1 the si lcone compound manufactured as one
batch (see 6.4), forming part of one contract or order and submitted for
inspection at one time.

4.4.2 Sampl inq for quality conformance inspection.

4.4.2.1 Sampling for tests. Two-6 pound samples of s i 1 i cone compound

shal 1 be randomly selected from each lot and tested as specified in 4.4.3.1.

4.4.2.2 Sampling for packaging.

4.4.2.2.1 Unit container. A random sample of filled containers shall be

selected from”each lot in accordance with Inspection Level I of MIL-STO-1O5
and examined as specified in 4.4.3.2. The lot size shal 1 be the total number
. .... of unit containers.
Q::
4.4.2.2.2 Shippinq containers. Shipping containers, just prior to closure,
shal 1 be randomly se Iected from each lot i n accordance with Inspection Leve 1 I
of NIL-STO-1O5 and examined as specified in 4.4.3.2. The lot size shall be
the total number of shipping containers.

4.4.3 Testinq arid examination of quality conformance s amples.

4.4.3.1 Testing. The sample selected in 4.4.2.1 shall be tested to the

requirements in Table III on a lot by lot basis or once in ten lots as
specified in that table. Nonconformance of a test specimen to a single
requirement in Table III shal 1 be cause to reject the lot represented by the
sample. Should the failure occur in a one in ten lot examination, the
Government may, at its option, require testing on each subsequent lot.

4.4.3.2 Packaqinq. Samples selected in 4.4.2.2.1 and 4.4.2.2.2 shall be

examined to the requirements in MI L-STD-290 and Table IV. The acceptable
quality level (AQL) for this examination shall be 4.0 percent defective.

4.5 Test conditions.

4.5.1 Standard conditions. Standard 1 aboratory conditions shal 1 be. 25°C ~

1°C (77° + 2“F) with a relative humidity (RH) of 50 + 5 pe~ent. Unless
otherwise–specif ied i n the test method, testing of the si 1ico,ne compound shal 1
be at standard conditions.
T, ,.
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MiL-S-8660C ‘“
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4.5.2 ~ecimen preparation. Unless otherwise specified, the compound
shal 1 be examined and tested as taken from the container without treatment or
preconditioning of any kind. Ho~ver, if the compound contains air bubbles,
“--)
they shal 1 be removed before testing by subjecting the compound. to vacuum and
heat.

4.6 Test methods.

4.6.1 4P earance. The silicone compound shall be visually examined for

conformance to 3.2 and 3.2.2.

A determination of the compounds insolubility in

sol%: s-using distilled water, isopropyl alcohol (TT-I-735),
ethyl alcohol (MI L-E-463), ethylene glycol (O-A-548) and glycerine (O-G-491).

4.6.2.1 Procedure. @proximately 3 grams of the compound, accurately

weighed, sham be smeared around the inside of a weighed glass beaker, 2XI ml
capacity. Prepare 16 specimens in this manner. Three for each solvent
(4.6.2) and one to act as control during the drying operation. Approximately
100 ml of the solvent, or enough to imnerse the compound; shal 1 be poured into
the container. The container shal 1 be tightly capped with metal foil and left
to stand for a period of 7 days at standard conditions. At “intervals of
approximately 24 hours, the solution shall be stirred by:moderate manual
rotation of the container. At the end of the 7 day period,. the solvent shal 1
be poured off, and the container and compound rinsed carefully with successive
. . washes of distilled water unti 1 all solvent has been removed. The container
and compound shall be dried for 20 hours in an oven’ at 70° + 1°C (160° + 2“F)
followed
of solubi Iity
by drying over calcium
in each solvent
chloride
shall
in a suitable desi~cator.
not exceed the requirement
The-degree
in Table 1. .--- ‘
“>’
1
4.6.3 Penetration. Penetration of the compound, worked and unworked,
shal 1 be determined in accordance with ASTN O 217, except that the worked and
unworked temperatu~s shal 1 be those specified i n Table 1,. TWO specimens
shal 1 be tested for each temperature condition. 1’
4.6.4 Flatnnabi lit A 10 gram specimen of the sampl~ shal 1 be placed on a
10 to 20 mes
~ s a n ess steel screen. The areas covered by the specimen shal 1
be approximately .1 inch in diameter. The underside of the screen shal 1 be
cautiously heated with a Bunsen burner in a manner that will not cause the
flame to DrOjeCt throuah or above the screen. As soon as the comoound beains
to decompose-or volat iii ze a second burner shal 1 be used to i gni~e the v~pors
evolved. The material wi 1 ~ be considered non-f lamnable if the burnina ceases
as both burners are withdrawn from the screen. Heating shall be cont;nued
unti 1 the sample is at a red heat; and both upper and under surfaces shal 1 be
examined for a self supporting f 1ame. Two specimens shal 1 be tested.
,.:
4.6.5 Corrosive effect. ,Corros,ive effect of the si 1i cone comc”ound aoainst . ..”..
various metals, combinations of metals, and non-metals shal 1 be detennin~d as
specified in 4.6.5.1 through 4.6;5.2.

4.6.5.1 Specimen preparation.

4.6.5.1.1 Metals. All metal strips in Table.- V. exceot cadmium elated ..”-..,4
,,.
steel, shall be polished to a bright finish, swabb~d with a hot sui~able
chemically pure solvent; followed by two successive 5 minute immersions in the ‘“”<”
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MIL-S-8660C

same hot solvent. Each dry, polished strip shall be coated with the silicone
~:; compound. Combination, of metals to be mated are identified in footnote 1-/ of
Table V. The mated metals and remaining Individual metal strips shall b~
exposed as specified {n 4.6.5.2. The number of strips In Table V will yield
two test specimens for each kind of metal.

4.6.5.1.2 Non-metals. All non+etal materials shall be wiped with a dry

clean, llntless cloth. Three specimens for each materl al identified in
Table V are required. The si 1icone compound shal 1 be coated on two specimens
of each material, with the thfrd piece acting as a control. Al 1 specimens
shall be exposed as specified ‘In 4.6.5.2.

4.6.5.2 Procedure. All specimens shall be placed in a convection current

air oven maintained at 100°C ~ 1°C (212” ~ 2°F) for a period of 70(+1, -O)
hours. won completion of the exposure perfod, al 1 specimens shal 1 be removed

I from the oven, wiped gently

mated strips
for evidence
shall
of corrosion
with a soft dry cloth to remove the compound (al 1
be disassembled).
or degradation
Each specimen shall be visually
as specified in Table I.
examined
Change in
hardness of the rubber specimens (ccsnpared to control) shal 1 be determined
using a Shore A durometer. The remaining non+netal specimens shal 1 be given a
scratch test, using a metal spatula, to determine apparent hardness changes.

4.6.6 Volume change. The percent change in volume of a rubber specimen

due to Swem ing ef feet of the s i 1i cone compound shal 1 be determined in
accotiance with Method 3603 of FED-STO-791, using the standard rubber N8R-L
(see 6.6 and Table 1) “within 6 months of date of, manufacture.

f.?. .!
4.6.7 High t emperature weight loss (evaporation and bleed
),< compound shal I be tested i n accordance with Method of
as follows:

a. Cone shal 1 be suspended from a rod supported on the edges of the

beaker without covering the beaker.

b. Oven temperature shal 1 be 204° ~ 6°C (400° ~ 10”F).

c. Time shall be 30(+1, -O) hours.

4.6.7.1 Evaporation. The loss in weight of the entire assembly, after 30

hours at the test temperature, divided by the weight of the sample used,
multiplied by 100 shal 1 be reported as the percent evaporation.

The gain in weight of the beaker divided by the we{ght

of %~”%pl%%$%ultiplied, by 100 shall be reported as the percent
bleeding.

‘4.6.8 Low temperature torque. Torque properties shal 1 be determined in

accordance~i th ASTM O at - 54° ~— 1°C (-65° ~ 2°F) with a 60 minute
running time. . . .=_
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4.6.9 Waterproof seal >Pl%. ?#a. i h disks of filter paper shall be dipped
in a 25 percent b y wel ght aqueOuS SOIUL?“ Oh & cobaltous chloride, blotted off
to remove ex~ess solution and then. dried at 105° + ~°C, [2210 + 20F) until
completely blue. The test paper disks shall then%e P~w=! iii five ~~a.
:;\ c
Hoffman bomb oxidation dishes and the dishes filled with
., ,.
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MIL-S-8660C

tested, avoiding incorporation of air bubbles. After leveling off the

compound to the height of each dish, the latter shal 1 be immersed in water at
25° ~ 3°C (77” ~ 5°F) for 24 hours, at the end of which time, the test paper
disks shall be examined for development of a pink color.

4.6.10 Dielectric strength. Dielectric strength shall be determined in

air at 23” + 2°C (7 3.4” + 3.6 “F) and 50 + 5 percent RH and in accordance with
ASTM O 149,-except that 172 inch hemisphe~ical electrodes shall be rigidly
mounted with the axis in a horizontal plane, in a suitable apparatus.. ne,
electrodes shal 1 be pressed into the compound i n order to f otm the specified
electrode gap. For. lot inspection testing, an electrode gap of 0.050 inch
shall be used.

4.6.11 Volume resist ivity. Volume resistivity shall be determined in

“accordance with 7, at 23° + 2°C (73.4° + 3.6”F) and RH of 50 + 5
percent. Test eletrodes shall be ifi accordance With Figure 1. Extrem= ca~
should be exercised to avoid trapping air bubbles in the compound.
,,
4.6.12 Dielectric constant and dissipation factor. Dielectric constant
and dissipation factor shal 1 be determined in accordance with ASTM O 150 with
the compound spread in a layer 1/8 inch thick on the fixed electrode plate of
the apparatus shown in Figure 1, using extreme care to avoid trapping air
bubbles in the compound. The compound shal 1 then be exposed to a temperature
of 23°C + 2°C. (73.40 + 3.6°F) and “a RH of 50 + 5 percent for 24 hours. At the
end of t~is period, t~e coqpound shal 1 be tes~ed at frequencies of 1 kilohertz
(KHz), 1 megahertz (MHz), and 10’MHz for measurements of dissipation factor
and dielectric cohstant. This test shall be performed in a suitable apparatus .
I where the ratio of sutiace to thickness of compound layer is sufficient to .:
,..
,’~.:., N i
give a capacitance of not less than 70 microfarads. .1

4.6.13 A’K resistance. llse arc resistance time shal 1 be determined in air
at 23°C + 2nC (73 4° + 3.6”F) and a RH of 50 + 5 percent RH i n accordance with
ASTM D 4~5, excep~ th~t the test shal 1 be coniltcted using a 1/8 inch 1ayer qf
the compound spread on a 1 ayer of thermal glass, such as quartz, Pyrex, etcj
The electrodes shall consist of two tungsten rods 0.186 inch diameter, with ~
tips 0.060 inch in diameter, which have conical points with a 60 degree ~
included angle. The electrodes shal 1 be mounted to an insulated ‘block at 45. .
degrees to the vertical, and shal 1 be adjusted to give a gap of 0.320 inch.
8oth electrodes shall .be in the same horizontal and vertical planes. The as%
electrodes shall be cleaned with a soft clean cloth dampened with alcohol,
then dried with a soft, clean dry cloth” before each’ determination. The time i
in seconds from the start of test unti 1 failure of the material shall be
recorded as the measure of the arc resistance of the compound. Failure shal 1 ~
be considered to have occurred at the instant that a cent inuous bright 1 ine is
completed between “the electrodes.

4.6.14 Storage stability. ‘The penetration qfter storage shail be ‘

determined on an unworked and a worked sample of compound which has been
stored at a temperature of .37.8° + 3°C (100° + 5“F) in a 1 pound oiltight
container for 6 months subsequent-to the orig~nal detenninat ion of the
,unworked and worked penetration: The unworked and worked penetration., “after
storage, shal 1 be determined. as specified in 4.6.3.
:’:y
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MI L-S-8660C

5. PACKAGING

5.1 Preservation, packing and marking. The si 1I cone compound shal 1 be

(“
preserved, packed and marked i n accordance with the provisions of MI L-STD-290
and in accordance with the detai 1s specified by the acquiring activity with
respect to the various options, choices, and alternatives indicated in
NIL-STO-290 (see 6.2.le and f).

6. NOTES

6.1 Intended use. The compound covered by ttils specif I cat ion is intended
for use, as fol lows:

I a. As a 1ubr{cant and sealant for rubber components., such as “O”

rings and gaskets.
.
b. When mixed with molybdenum disulfide powder, as a 1ubricant for
threaded connection; on piping and valves to be used with
1 iquids and gases.

c. AS a sealant to prevent galvanic corrosion due to moisture

I penetration in areas of dissimilar metal contact.

I d. For use under extreme conditions of service and st”orage, where

freezing at -54°C. ( -65”F) or exudation and deteriorate ion at
+2040C (+400”F ) “i,s not perniissible, and wherein water
insolubi 1 ity and sealing properties are essential.

For seal ing high tension electrical connections of ain’raft and

automotive engines.

f. For seal ing and insulating electronic equipment, subassemblies

and ccnnponents where it is essential that the material remain in
a soft state in order to allow easy disassembly or change.

I 9. As a sealant “to protect the threads on shells from moisture and

corrosion. Uhen used i n thls. manner, the si 1i cone compound
should not come into contact with surfaces that are to be
painted.

6.1.1 .Use restrictions. This silicone compound is not ‘intended for use as
a heat sink. Materials having more suitable properties are available
conscenially.

6.2 Ordering data. Acquisition documents should specify the following:

a. Title, n“tier and date of thfs speclflcatlon.

I .. . b. Quantity desired in pounds.

c. Color of.dye or pigment, if required (see 3.2.2).

c .. ,. “..

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MI L-S-8660C

d. Size and type of container in which silicone compound is to be <>,

furnished. - ..$. /
i~~.,’~
7..-.
e. Levels of preservation and pack’ing (see 5.1).

. Other options, choices and alternatives of MIL-STO-290 (see 5.1).

espect to products requiring qualification, awards

wi 116.3be +.
ma e on y or products ,ith r which are, at the time set for opening of bids,
qualified for inclusion in qualified products 1 ist (QPL 8660) whether or not such
products have actual ly been so 1 isted by that date. The attention of the
contractors is cdl led to these requirements, and manufacturers are urged to arrange
to have the products that they propose to offer to the Federa 1 Government tested
for qualification in order that they may be eligible to be awarded contracts or
purchase orders for the products covered by this specification. The activity
responsible for the Qualified Products List is the Naval Air Systems Comnand,
Washington, OC 20361; however, information pertaining to qualification of products
and letter of authorization for submittal of sample may be obtained from the
Cmnander, Naval Air Development Center, Attn: Aircraft and Crew Systems” Techn ica 1
Directorate (Code 6062), !danninster, PA 18974.

6.4 Batch. A batch is defined as the end product of al 1 raw materials mixed or
blended =single operation.

6.5 International standardization agreements. . Certain provisions of this

specification (see are the subject of International standardization agreement,
ASCC AIR STO 15/1, &C-NAVY STO .17, and NATO STANAG NAT-STO- 1135. When amendment, ~,:: ,.
revision, or cancellation of this specification is proposed, which wil 1 affect or .,..”::,”
vi elate the international agreement concerned, the preparing activity should take 3
appropriate reconciliation action through international standard ization channels
including departmental standardization offices, if required.

6.6 Standard rubber samp les. Samples of “the standard synthetic robber N8R-L
for the test specified In 4.6.6 may be obtained from the Precision Rubber Products
Corp. Aerospace Division, 1217 South 26 Place, Phoenix, AZ 85035.

6.7 Changes from previous issue. Asterisks are not used in this specification
to” identlf y changes with respect to the previous issue, due to the extensiveness of
the changes.
,,. .
Custodians: Preparing activity:
AmIy - 14R Navy - AS
Navy - AS
Air Force - 20 (Project 6850-071 3)

Review activities: .
Army - ER,. GL, MI ‘ “ :
Navy - 0s, Yo
DLA - GS

User activities:
Army - ME

“3’-’

10
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MIL-S-8660C

TABLE I. Physical properties.

Paragraph .,

Characteristic Requirement Test

Insolubi llty, percent weight

loss, maximum, in: 4.6.2
Oisti 1 led water 0.4
.Isoprop 1 alcohol 1;.:
Ethyl a ! cohol
Ethylene glycol 0:5
Glycerine 0.5

Penetration at standard
conditions: 4.6.3
~worked 230&30
Worked, maxjmum
Morked, after 24 hours
at 204 ~ 5°C (400” : 113°F) 310

Flansnabi lity NOnf lansnable 4.6.4

Co~osisilgffect: 4.6.5
NO pitting or other
visual evidence
“@”: of corroston.

On non-metals No change in appearance

when compared to control.

No change in hardness.

Volume change of rubber, percent ..7 4.6.6

may.lmumg after 168 hoUrS at
70° ~ 1 C (158° ~ 2“F)

High temperature, percent 4.6.7

weight loss, max$mum:
Evaporation
Bleeding ::

Low temperature torque,

gram-cm, maximum: 4.6.8
Starting 5,000
Running 1,000

I
,

11
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‘ TABLE II. _Electrical properties.

Paragraph

Characteristic Requirement Test

Dielectric strength, volts/roil,

minimum 4.6.10
0.050 inch electode gap 300
0.010 inch electode gap 500

Volume resist ivlty, Oti-cm

minimum ,at 4.6. il
23° ~ l.l °C (73.4° + 2°F) 1.0 x 1013
177°: l.l °C (350° ~ 2°F) 1.0 x 1012

Dielectric constant, maximum: 4.6.12

1 Kilohertz 3.1
1 Megahertz 3.1
10 Megahertz 3.1

Dissipation factor, maximum; 4.6.12

1 Kilohertz 0.0025
1 Megahertz 0.0025
10 Megahertz 0.0025 ..
.,.
Arc resistance, seconds, minimum 60 4.6.13

.
. ,.

..

. .

,.
:
‘>,
..”
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. . 12
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,,’
1.

MIL-S-8660C

c.
.
. .
.1
TABLE III. Quality confonnante - physical

Paragraph
tests.

Characteristic Requirement Test

Testing each lot:

Penetration “Table I 4.6.3
High temperature weight loss Table I 4.6.7
Watewroof seal 3.3.2 4.6.9

Testing every tenth lot:

Flammability Table I 4.6.4

Corrosive effect Table I 4.6.5
‘ Low temperature torque Table I 4.6.8
: Dielectric strength Table II 4.6.10
Oi electric constant and
~ dissipation factor Table 11 4.6.12
Arc resistance Table 11 4.6.13

TPBLE IV. Quality conformance “packaging inspection

:,
..
kfect ‘
....’,
.. .’.’.
, Pack:a~”i
# ng Unit “containers not as specified.

::.” Packing .“ ““ Packing materials not as specified.

Not i n accordance with contract requirements.
I .,. . Container not as specified, closure not
t accomplished by specified or requind
:, . .. methods or material s.,
i:
:!
:.
l\ Inadequate application of components, such as
.; incomplete closures of case 1iners, container
.: f 1aps, loose or inadequate strappings, bulged
or distorted containers. “

: ~ Count Less than specified or indicated quantity.

I Mei ght Individual weight of container less than indicated
or specified.

Markings Interior or exterior markings (as applicable)

omitted, i Ileglble, incorrect, incomplete, or
not i n accordance with contract requirements.
1

13
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MI L-S-B660C

TABLE V. Test specimens for corrosive effects

Required Size 21
Material Specification Number ~/ (inch~

METALS :

Aluminum alloy QQ-A-250/4 6

~ay :$:-; (): 4
-- 2 -:
~~dyrium alloy MS 4377 4
QQ-S-571
Stee 1 ASTM A 569 ;
Zinc QQ-Z-301 4 “-
Cadmium P1 ated steel QQ-P-416 2
Brass QQ-B-613
Stainless steel MIL-S-5059 :’ -

NON-METALS :

Chloroprene ignition cable MI L-C-3702, Grade C 3 6 length

Silicone ignition cable MIL-C-3702, Grade B “3 6 length
Rubber MI L-R-3065, Class RN 3 2 by 2 by 0.5
Rubber MIL-R-3065, Class RS 3 2 by :Iby 0.5
Varnish MI L-I-24092 3 <., /-.

.3
.,$ . ,
Enamel MIL-E-4B0 3 ~1
Pvc MI L-I-631, Type F,
Grade B
Molding plastic MIL-M-14, CMG ‘“ : ‘:
Molding plastic MIL-M-14, ME 3

~/ After coating all metal specimens, mate the fol lowing: 2 aluminum alloy
to 2 copper; 2 aluminum alloy to 2 cadmium plates; 2 magnesium alloY to
to steel; and 2 brass to 2 stainless steel strips. Al 1 other stri Ps
shal 1 be-exposed individually.

~/ Sizes, when “not specified, shall be of a suitable size to permit

evaluation after the exposure period.
I
I ~/ In “onler to evaluate the varnish and en~l, coat any suitable panel
with the liquid, allow to dry, then overcoat with the SI licone
ccanpound. .,,

3“
14
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~ HIL-S-8660C

.
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.188 GUARDED ELECTRODE

.250
TU MEASURING
CIRCUIT GUARD RING
1.000

[+ ~

~’%

k~~-.
TO MEASURING
CIRCUIT
I

i ELECTRODES SW BE OF POLISBED BRASS.

6~ FOR TSSTS AT FREQUENCIES OF 1 REr AND 1 ~Z

SW BE A DISK 6 INc~s ~ D~R.
PER SECOND, THE CUA@SD ELECTiODE
THE THICKNESS ‘F ‘E SPECIMEN SHALL
BE 0.125 INCII.

FOR TESTS MADE AT A FKEQUENCT OF 10 MHz PER SECOND, THE GUARDED ELECTRODE SW
BE A DISK 2 INCHES It+DIAMETER. TRE THICKNESS “OF THE TEST SPECXIEN SHALL BE
SUCH AS TO GIVR A CAF~CITANcK oF B-EN 15 ~ and 45 ~F.
;.
DINZNS1ON .JNINCHES. !
~.
~~
;i’

FIGURE 1. Test electrodes for electrical resistance (volsme) .

and dielectric constant and dissipation factor teste.

II

:.,
.
..
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.. INSTRUCTIONS: In ● cattinuias ●ffort @ Vke OUr ~~d~~tion documcn~ htf=. the DoD rmvidet thh form for w in
submitkinc .=mmenu ud MLSSCS*M for imPmvt~ n*. ~ UMm Of ~~rs -~dtdi-tion dommwt~ inrited to provide
are
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“,AM. 10black 5. be u It=lfii u xible SbOIIl P~i~~ pmblcm -- such - worditw which required interpretation, wu
(. tm @id, testricthe, 100SC. unbisumm Or =- iocemw~ble. ~.d ri~e PmP04 =m’ditu ch.ns= filch would afletite the
mblems. Enter in block 6 MY rSMM~ not ;el~t~ tO - 6Ki~c w-ph Of *C document. If blcck 7 u filled out, m
acknowledgement ~11 bs IIMUWJ to YOU *thin 30 d~y~ tO let YOU kno= Iltst Your commenti wem mceirsd md we being
considered

NOTE: lldt form IMY not b@UA to =que*t soPie~ of d.=umcn~. nor 10 request waivers, deviatiom, or cluitication Of

I ,F.ld dons lhb 11.u,

(’, ‘

, F.ld d“”, fh b Il,v,

DEPARTMENT OF TM: NAVY

(jmmandi ng Officer No ●OSTAGE

111111
I
:;aval Ai r Engineering Cen Ler NECESSAmV

(ESSD),
1P MAILEO
Engineering Specifications .~nd Stdndards Department IN THE
Code 93 LINITEO STATES
Lckehurst, NJ 08733
OFFtCIAL 8UCINE=
?ENALTV son ●n8v ATE USE Sam BUSINESS
,,“s. CL**S PEHU,, No.REPLY MAIL ,2503 WA S,<, F4. .,.,?, ,, c

POSTAGE WILL OF, PAIO BY THE LXPAF41MENTOF THE NAVV

COKEIIdIIding Officer
Naval Air Engineering Center
Engineering Specifications and Standards Oept. ~~
([ss0), code 93
Lakehurst, NJ 08733
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