CORROSION PREVENTION CONTROL MANUAL

CORROSION PREVENTION — CORROSION PREVENTION

1. Standard Preventive Maintenance Methods
A. General
The information contained in this section is intended to supplement the specific preventive
maintenance recommended in the remaining chapters of this manual.
B. Aircraft Washing
(1) Washing is a means of enhancing the appearance of the aircraft and is important in minimizing
corrosion. Procedures for aircraft washing are contained in the Aircraft Maintenance Manual,
Chapter 12.
(2) The benefits of frequent washing are obvious. Primarily, washing removes any potentially
corrosive deposits that have accumulated on the aircraft. Dirt and residue retain moisture which
in turn promotes corrosion. However, other factors that must be taken into consideration when
establishing a washing program are the following:
(a) Washing, and in particular the use of high pressure water or steam, can lead to the ingress
of moisture into areas not normally contaminated and not readily dried.
(b) The detergents used for washing can promote corrosion if they are not thoroughly rinsed
off. Rinsing itself can become a problem if high pressure hoses have forced the washing
solution into small cavities where the wash chemical residues will concentrate after each
wash and moisture is difficult to remove.
(c) Any effective washing solution which removes unwanted grease and oil will also remove
the grease and oil required for lubrication. Consequently, reapplication of the lubricants is
required after aircraft washing.
(d) Frequent washing will eventually remove any corrosion inhibiting compounds, to the end
that reapplication times will be affected by the frequency of washing and detergent
strength.
(e) Excessive use of any brighteners on unpainted aluminum surfaces can eventually lead to
deterioration of the clad surfaces.
(3) Washing frequency must be determined by the operator on an individual basis, depending on
the operating environment and external appearance of his aircraft(s). As a guide the following
frequencies are suggested (see Section 20-50-00 for definitions):
• Mild zones - Every 90 days
• Moderate zones - Every 45 days
• Severe zones - Every 15 days
(4) Brighteners for unpainted surfaces may be used occasionally. Once every 18 months or 2 years
should be adequate.
C. Protective Finish
(1) Maintenance of the surface finish is important if corrosion problems are to be avoided. Damage
to paint or similar surface coatings should be repaired at the earliest opportunity. Until such
times as the finish can be restored, consideration should be given to using corrosion inhibitor to
minimize the risk of corrosion.
(2) Where damage to the finish is not confined to the paint, the metal should be protected by one
of the treatment processes described in Standard Surface Treatment Methods, 20-50-05,
Corrosion Prevention, before the paint is reapplied. Unpainted surfaces should be similarly

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treated where necessary.

(3) Specific details of the application and removal of finishes is detailed in Standard Surface
Treatment Methods, 20-50-05, Corrosion Prevention.
D. Corrosion Inhibitors — General
NOTE: Each operator should evaluate the environment of their aircraft, the inhibitor used and the
application interval to ensure adequate corrosion protection.
(1) Types I, II, III and VIII Water Displacing Corrosion Inhibiting Compounds
(a) Precautions, application / removal methods and general information for the use of water
displacing corrosion inhibiting compounds are presented in this section.
(b) Corrosion inhibitors may be used to enhance the effectiveness of protective finish
systems. These materials are volatile liquids which may be sprayed or brushed on the
surfaces to be treated. This material has the ability to penetrate into extremely small
cavities and to displace water. Consequently, corrosion inhibitor is able to enter between
faying surfaces or between fasteners and holes. The liquid carrier evaporates quickly to
leave a thin film of wax like residue over the coated surface.
(c) Type I and II materials are durable materials not easily removed by normal use. They are
generally used in areas such as those outside the fuselage pressure vessel which are
exposed to the external environment. They will withstand a certain amount of washing,
though eventual reapplication will be required. These type materials remain tacky and are
subject to adhesion of foreign material which will require periodic removal and
reapplication.
(d) Type III material is less durable than Type I and II materials. Type III material is easily
removed by washing and is generally used in areas such as those inside the fuselage
pressure vessel which are not exposed to the external environment. Type III material will
form a clear glossy ultra thin film which will completely dissipate from interior surfaces
within 12 - 18 months leaving no residue.
(e) Type VIII material is similar to Type III, but about twice as thick and will remain effective for
longer periods. Type VIII will serve as a lubricant for slow moving components.
(f) The intervals required between repeat applications of Type I, II, III and VIII materials will
vary depending upon the application location and upon the environment.
(g) General (operator selected) application areas should be monitored by the operator to
determine the specific reapplication interval necessary to maintain the effectiveness
desired.
(h) Specific (manufacturer recommended) application areas and intervals are called out in the
applicable Maintenance Manual sections for the specific areas.
(2) Compound Type Descriptions
(a) Type I - A transparent colorless film which is detectable only with ultraviolet light.
(b) Type II - A colored film which is readily detected by the unaided eye.
(c) Type III - A transparent colorless glossy film which is nearly undetectable.
(d) Type VIII - A thin transparent film that is water displacing and lubricating.
(3) Approved Materials (see Table 101)
(4) Precautions for Use

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WARNING: CORROSION INHIBITORS ARE APPROXIMATELY EQUAL TO KEROSENE

OR ALIPHATIC NAPHTHA IN TOXICITY. TO PROTECT THE SKIN, USE THE
SAME PRECAUTIONS AS FOR KEROSENE. WHEN SPRAYING THEM IN AN
ENCLOSED AREA, SUCH AS LOWER FUSELAGE, A VAPOR
CONCENTRATION OF 500 PARTS PER MILLION IS THE MAXIMUM
COMFORTABLE WORKING LIMIT. AT THIS CONCENTRATION A MAN CAN
WORK AN 8 HOUR SHIFT. VAPOR LEVELS EXCEEDING 500 PPM ARE NOT
DIRECTLY TOXIC, BUT FORCED VENTILATION MAY BE NECESSARY TO
MAINTAIN A COMFORTABLE LEVEL.
TRICHLOROETHANE IS THE PREFERRED SOLVENT AS IT IS
NONFLAMMABLE. TRICHLOROETHANE IS TOXIC. IF USED IN EXTREMELY
CONFINED AREAS MECHANICAL VENTILATION IS MANDATORY.
RESPIRATORY AND SKIN PROTECTION MAY BE NECESSARY.
WATER DISPLACING CORROSION INHIBITING COMPOUNDS AND OXYGEN
WHEN MIXED ARE EXPLOSIVE. KEEP THE COMPOUND AWAY FROM
OXYGEN SYSTEM COMPONENTS (LIQUID OR COMPRESSED). KEEP THE
COMPOUNDS AWAY FROM ANY OXIDIZING MATERIALS (PEROXIDES,
CHLORINE, ETC.).
AS A FIRE SAFETY PRECAUTION, THE MATERIAL SHOULD BE KEPT AWAY
FROM SURFACES THAT WILL GET HOTTER THAN 300°F (149°C) IN
SERVICE. THE DRY FILM FLASH POINT IS 500°F (260°C). CORROSION
INHIBITORS CONTAIN FLAMMABLE COMPONENTS. DO NOT EXPOSE
THESE MATERIALS TO OPEN FLAME, ACTIVE CIRCUITS OR OTHER
COMPONENTS WHERE A POTENTIAL FIRE HAZARD WOULD EXIST. THE
VOLATILE CARRIERS ARE ALSO FLAMMABLE. MAINTAIN SAFETY
PRECAUTIONS UNTIL THE CARRIER HAS FULLY EVAPORATED.
(a) Since these are hydrocarbons, these compounds can be dangerous when mixed with
oxygen. Oxygen system components must be shielded to protect them from direct or
indirect contamination.
(b) Precautions must be taken when using these materials which can constitute a fire hazard
when subjected to high temperature.
(c) For Type I and II materials, mask electrical connectors where there is a possibility of
contamination of electrical contacts.
CAUTION: REMOVE EXCESS CORROSION INHIBITING COMPOUNDS FROM
MECHANISMS AND MOVING PARTS WITH A CLEAN, DRY RAG. THE
RESULTANT THIN FILM IS ADEQUATE FOR CORROSION PROTECTION.
EXCESSIVE BUILDUP COULD HARDEN AT LOW TEMPERATURES AND
CAUSE OPERATING DIFFICULTIES.
(d) The use of corrosion inhibiting compounds on control cables is not considered a suitable
substitute for the cleaning and corrosion protective procedures in the Aircraft Maintenance
Manual. Overspray, as you apply these compounds to adjacent structure, should not have
a significantly bad effect on cable life. Direct application of these compounds on control
cables, pulleys, Teflon lined bearings and lubricated surfaces should be avoided. Type III
material should not be applied to composite bonded structures or assemblies.
CAUTION: THESE COMPOUNDS CAN CAUSE SILICONE RUBBER TO SWELL.

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(e) Care is to be exercised in application of corrosion inhibiting compound near door or

emergency hatch seals, grease seals in bearing assemblies or rubber lined clamps for
tubing or wiring. Hydraulic seals may also be affected, so these corrosion inhibitors are not
suitable for use on actuator rods.
(5) Compatibility
(a) As these materials are all usually hydrocarbons, new applications of a different vendor’s
compound of the same type classification only may be applied over existing corrosion
inhibitors without bad effects.
(6) Cleaning Before Application
(a) Extreme cleanliness is not required for the application of these compounds, but better joint
penetration will be achieved if the joint is cleaned before application. Loose dirt or other
foreign matter can be removed by vacuum or wiping. The surfaces can then be cleaned,
where necessary, by using normal aircraft cleaning agents and solvents. See Table 102.
(7) Application
(a) Observe the Precautions for Use, Step 1.D.(4) thru Step1.D.(4)(e). Mask or shield
components which must not be contaminated with corrosion inhibiting compounds. Do not
apply corrosion inhibiting compound to areas which will subsequently be painted or
sealed. For Type III material, do not apply within 6 months of future scheduled painting.
(b) Statically ground the aircraft per Aircraft Maintenance Manual, Chapter 12.
(c) If corrosion inhibitor is applied near batteries, electrical contacts, electrical connectors or
other components where potential fire hazard would exist, remove external power and put
the battery switch in off position.
(d) If application area contains moving components, apply a corrosion inhibiting compound
lubricant.
(e) Ensure that all primers and enamels have been permitted to cure for a minimum of 8
hours.
(f) For Type I, II, III and VIII materials, apply a continuous wet coat so that joint penetration
will be achieved by capillary action. An application rate of spraying of 1 gallon per hour at
a coverage rate of 15 - 20 square feet per minute will produce a Type I and II film
thickness of 0.0003 inches (3 mil) or all four Type materials may be brushed. For Type III
material, maximum allowable film thickness is 0.0002 inches (2 mil) and for Type VIII
material, 0.0005 inch and is to be applied to structures and assemblies only by qualified
personnel trained in the use of this material and equipment. See Step 1.D.(8) for details of
spraying equipment and procedures. The use of pressure equipment that applies these
compounds under pressure directly to a joint or lap will improve the penetration. For Type
I and II material, a soak period of 60 minutes is required before excess compound is
removed to ensure maximum penetration. For Type III material, application of excess
compound in inaccessible assemblies is to be avoided since removal from these surfaces
will not be possible.
(g) Wipe up puddles with clean gauze or rags after the 60 minute minimum soak period.
(h) If a topcoat of Type IV or Type V compound is to be added as a barrier coating over an
initial Type I, II, III or VIII application, it shall be applied after the 60 minute minimum soak
time and excess compound wipe up has been completed. Apply the Type IV and Type V
coatings per Step 1.E, Type IV and Type V Heavy Duty Corrosion Preventive Compound.
(i) Give the area a good flow of air until the volatile solvents have completely evaporated.

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Then remove the masking or shielding from the area treated.

(j) Corrosion inhibiting compound should not be used in the vicinity of oxygen system
components. If corrosion is discovered close to oxygen system components, the following
steps are recommended:
1 Clean up corrosion products and repair as required per the Structural Repair Manual
or contact Gulfstream Customer Support.
2 Chemical conversion coat unpainted aluminum or cadmium plated steel.
NOTE: Epoxy primer 3012 is an alternate for 2012.
3 Apply one coat 2012 green epoxy primer.
4 Apply additional coat 2012 green epoxy primer.
5 Top coat with 2013 epoxy topcoat.
(8) Spray Methods of Application (Type I, Type II, Type III and Type VIII)
(a) Aerosol cans can be used in conjunction with plastic nozzle extensions, but they are not
generally recommended due to cost and the amount of overspray generated. For Type I
and II materials, the preferred application method is with standard pressure pot equipment
using an airless spray gun operated at low pressure (45 psi). For Type III material
applications, a high pressure fogging system is required for application to specified
inaccessible interiors of structures and assemblies. Suitable spray equipment is available
for Type I, II, III and VIII materials, (spraying applications) from the following suppliers:
NOTE: For large areas or where confinement is not a problem, spray application is the
best method to use.
• Nordson Corporation, V07036 or V2R369
• The DeVilbiss Company, V17431
• Binks Manufacturing Company, V07334
• Graco Incorporated, V25980
(b) For Type III Material (fogging applications)
Corrosion Block Application System, Item No. 2206CB (includes fog nozzles and
extension tubes).
Greater accessibility will be provided with the use of accessories such as spray gun
extension kits and swivel adapters for variable nozzle positioning.
Standard air atomizing equipment (siphon or pressure pot) may be used when access is
sufficient to allow application of a wet coat. A spray nozzle to surface distance of no more
than 12 inches is required for wet application. When spray is operated with a pressure pot,
for Type I and Type II applications that can be visually monitored and manually wiped of
excess, suitable extension may be made as follows:
1 Remove and keep the air cap.
2 Remove the fluid tip. Solder or braze 1/8 inch annealed copper tubing of a desired
length on the end of the tip.
3 Make a nozzle at the end of the tubing by clamping tube around a 0.010 inch
diameter wire.
4 Do not connect air hose to spray gun.
5 Spray with a pot pressure of 20 - 30 psi.

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NOTE: This type of equipment is NOT an acceptable substitute for fogging

systems in Type III material applications to specified inaccessible interiors
of assemblies.
(c) Brush Application (Type I, II, III and VIII materials)
Use an ordinary paint brush or a clean cloth. This method is best for small confined areas
or where caution is necessary to keep corrosion inhibiting compound away from adjacent
equipment.
(9) Removal
(a) All corrosion inhibiting compounds must be removed from prepared surface before
painting. You must also clean with a solvent before penetrant inspection. The solvents
noted in Table 103 have been successfully used to remove these compounds.
(b) When you use solvents to remove water displacing corrosion inhibiting compounds, wipe
all accessible surfaces dry with clean cloth and give the area a good flow of air until the
solvent evaporates.
(10) Exterior Discoloration
(a) Liberal use of water displacing corrosion inhibiting compounds on the internal surfaces of
the aircraft can lead to discoloration of the external surface. Application of Type III material
should be tightly controlled to avoid overspray which will cause bleed through to exterior
surfaces from interior assemblies. Because of the excellent penetrating properties of
these materials, a bleed through can be expected at fasteners that are not fluid tight. This
is normal and does not indicate a requirement to replace or redrive the fasteners. The tiny
passages should seal themselves within a short time.
(b) Water displacing corrosion inhibiting compounds on the exterior surface may be removed
using one of the solvents listed in removal above. They will not stain or damage the
exterior of the aircraft or the decorative finish, but a noticeable difference in oxidation of
the exterior surfaces can occur between those areas which have been coated with
compound and areas that have not. Where this difference in color is apparent, it can be
buffed out.
E. Type IV, V, and VII Heavy Duty Corrosion Inhibiting Compounds
(1) General
These organic inhibiting compounds contain nonvolatile base materials dispersed in solvents so
as to form a fluid formulation and do not contain silicones. These compounds may be applied by
dipping, brushing or spraying. After drying, these materials form translucent, discernible
protective coatings. Coated panels shall be dry to the touch after 24 hours. They are durable
materials, not easily removed by normal use and where used externally, will withstand a certain
amount of washing, although reapplication will be required in accordance with service /
exposure conditions and manufacturer’s recommendations.
Precautions, application / removal methods and general information for the use of heavy duty
corrosion inhibiting compounds are presented in this section.
NOTE: Each operator should evaluate the environment of his aircraft, the inhibitor used and
the application interval to ensure adequate corrosion protection.
(a) Corrosion inhibitors may be used to enhance the effectiveness of protective finish
systems. These materials are volatile liquids which may be sprayed or brushed on the
surfaces to be treated. The liquid carrier evaporates within 24 hours to leave a medium to
heavy, wax like film over the coated surface. This material is not highly penetrating, but will

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form a barrier layer which will prevent water and moisture infiltration.
(b) Type IV, V and VII materials are durable materials not easily removed by normal use. They
are generally used in areas such as those outside the fuselage pressure vessel which are
exposed to the external environment. They will withstand a certain amount of washing,
though eventual reapplication will be required. Type IV and Type VII materials remains
slightly tacky and are subject to adhesion of foreign material which will require periodic
cleaning and reapplication. Type V material is nontacky and foreign material will not
adhere easily.
(c) The intervals required between repeat applications of Type IV, V and VII materials will vary
depending upon the application location and upon the environment.
(d) General (operator selected) application areas should be monitored by the operator to
determine the specific reapplication interval necessary to maintain the effectiveness
desired.
(e) Specific (manufacturer recommended) application areas and intervals are called out in the
applicable Aircraft Maintenance Manual sections for the specific areas.
(2) Compound Type Descriptions
(a) Type IV and VII - When applied, will form a continuous film of medium thickness with a
drop melting point of 140°F (60°C), minimum.
(b) Type V - When applied, will form a continuous thick film with a drop melting point of 200°F
(93°C), minimum.
(c) For approved materials see Table 101.
(3) Precautions for Use
Use the same precautions and warnings for Type IV, V and VII material as those listed for Type
I, II, III and VIII water displacing compound. See Step 1.D.(4).
(4) Compatibility
As these materials are usually hydrocarbons, different hydrocarbon compounds can be applied
over existing corrosion inhibitors without adverse effects.
(5) Cleaning Before Application
The surface does not need to be extremely clean before application of these compounds, but
better penetration and corrosion protection will result if the area is cleaned before application.
Vacuum or wipe away loose dirt or debris. The surfaces may then be cleaned, where necessary,
by using normal aircraft cleaning agents or solvents. See Table 102.
(6) Application
(a) Observe the Precautions for Use [see Step 1.D.(4)] and mask or shield components which
must not be contaminated with corrosion inhibiting compounds. Do not apply corrosion
inhibiting compound to areas which will subsequently be painted or sealed.
(b) Statically ground the aircraft per Aircraft Maintenance Manual, Chapter 12.
(c) If corrosion inhibitor is applied near batteries, electrical contacts, electrical connectors or
other components where potential fire hazard would exist, remove external power and put
the battery switch in off position.
(d) Ensure that all primers and enamels have been permitted to cure for a minimum of 8
hours.

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(e) Apply the Type IV and VII compounds at a wet film thickness of 0.002 inches (2 mils) for
a final film thickness of 0.001 inch (1 mil). Apply the Type V compound at a wet film
thickness of 0.008 inches (8 mils) for a final dry film thickness of 0.004 inches (4 mils).
(f) Give the area a good flow of air until the volatile solvents have completely evaporated.
Then remove the masking or shielding from the area treated.
(g) Corrosion inhibiting compound should not be used in the vicinity of oxygen system
components. If corrosion is discovered close to oxygen system components, follow the
steps recommended previously in this section.
(7) Methods of Application
(a) Use the same application procedures for Type IV, V and VII as those listed for Types I, II,
III and VIII water displacing compound with the differences noted in the following Step 1.E
.(7)(b) through Step 1.E.(7)(e).
(b) Let the Type IV, V and VII compounds dry for 60 minutes before wiping up puddles.
NOTE: Puddles are primarily unsightly and will not negatively affect the coatings
performance.
(c) If the coated surface will touch another surface (such as insulation blankets), let the
coating dry tack free.
(d) If a topcoat of Type IV or Type V compound is to be added as a barrier overcoating over
an initial Type I, II or III application, it shall be applied after the 60 minute minimum soak
time and excess compound has been wiped up as previously noted.
(e) A one step application of Type VII material may be used as a option where a top coat of
Type IV or Type V is called for as a barrier overcoating over an initial Type I, II or III
application.
(8) Removal
The solvents for removing Type IV, V and VII are listed in Table 103.
(9) Exterior Discoloration
(a) Liberal use of these corrosion inhibiting compounds on the internal surface of the aircraft
can lead to discoloration of the external surface. Because of the excellent penetrant
properties of these materials, bleed through can be expected at fasteners that are not fluid
tight. This is normal and does not indicate a requirement to replace or redrive the
fasteners. The tiny passages should seal themselves within a short time.
(b) These compounds can be removed from the exterior surface with one of the solvents
listed. These solvents will not stain or damage the exterior of the aircraft or decorative
finish. A noticeable difference in oxidation of the exterior surfaces can occur between
those areas which have been coated with the compound and areas that have not. If this
difference in color is seen, polish with an appropriate buffing material.
F. Type VI Nonsetting Corrosion Inhibiting Jointing Compound
(1) General
This jointing compound is a nonhardening and flexible, corrosion inhibiting oil base putty that is
to be applied to nonpressurized joints and surfaces that may be subsequently dismantled
without damage. This and all other corrosion inhibiting materials are designed to be used to
supplement plated and organic protective coatings and not to replace them.
Precautions, application / removal methods and general information for the use of corrosion

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inhibiting jointing compounds are presented in this section.

NOTE: Each operator should evaluate the environment of his aircraft, the inhibitor used and
the application interval to ensure adequate corrosion protection.
(a) Corrosion inhibiting jointing compound may be used to enhance the effectiveness of
protective finish systems. These materials are volatile liquids which may be brushed on
the surfaces to be treated. The liquid carrier evaporates quickly to leave a thick film of
flexible putty like residue over the coated surface. This material has the ability to exclude
water from joints.
(b) Type VI materials are durable materials not easily removed by normal use. They are
generally used in areas such as those outside the fuselage pressure vessel which are
exposed to the external environment. They will withstand a certain amount of washing,
though eventual reapplication will be required. These type materials remain tacky and are
subject to the adhesion of foreign material which will require periodic cleaning and
reapplication.
(c) The intervals required between repeat application of Type VI materials will vary depending
upon the application location and upon the environment.
(d) General (operator selected) application areas should be monitored by the operator to
determine the specific reapplication interval necessary to maintain the effectiveness
desired.
(e) Specific (manufacturer recommended) application areas and intervals are called out in the
applicable Maintenance Manual sections for the specific areas.
(2) Compound Type Description
Type VI - A thick paint drying to a flexible, nonsetting green paste.
For Approved Materials See Table 101.
(3) Precautions for Use
Use the same precautions used in applying Types IV compounds. Because of the volatility and
flammability of the solvents in the jointing compound, its container should be tightly closed and
stored below 90°F (32°C) when not being used.
NOTE: The materials specified for this procedure may have significant safety, health or
environmental requirements related their use. Safety Data Sheets must be consulted
to determine the manufacturer’s recommendations concerning exposure precautions
and manufacturer’s instructions shall be followed when using any of the specified
materials. It is the sole responsibility of the user to ensure protection of their
employees from injury or exposure, safe application of material and its proper disposal
and strict compliance with any Federal, state or local regulations regarding the use of
any materials specified in this manual.
(4) Compatibility
This material is compatible with other corrosion inhibiting compounds and should not be
exposed to direct spray during application of other corrosion inhibiting compounds.
(5) Cleaning Before Application
This material should always be applied to clean surfaces and therefore generally must be
applied before any other corrosion inhibitors. Surfaces may be cleaned by using normal aircraft
solvents. See Table 102 and Aircraft Maintenance Manual, Corrosion Inhibiting Compound -
Cleaning, 51-01-00, Cleaning / Painting.

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(6) Application
(a) All mating surfaces to be joined using the jointing compound shall be finished per drawing
requirements and be clean and dry.
(b) Surfaces to be joined shall be wiped clear of dirt, dust or foreign debris. Care must be
exercised not to remove any of the paint or finishes and degreasing shall be performed
using a clean cotton cloth and an acceptable solvent such as Methyl Propl Ketone (MPK).
Bolts, pins and solid rivets shall be degreased using the solvents listed. Fasteners,
bushings and bearings with internal recesses or if lubricated with dry lubricants shall not
be solvent cleaned. See Table 103.
(c) Application to Fasteners
Jointing compound should be applied under the head of bolts, to the threads and shanks
of studs and bolts and to surfaces under fastener heads before fitting washers and nuts.
Washers should be coated with compound before assembly over threads. Where fastener
installation (torquing) may be affected by this jointing compound (such as installing
Hi-Lites or Hi-Loks), the compound shall be applied to the exposed threads after installing
and torquing of the fasteners. For lock bolts, coat only the grip area with jointing
compound. If the lock bolt has annular grooves, wipe the compound from the groove prior
to swaging the collar. All other attachment bolts and fasteners shall have jointing
compound applied to the shank before insertion unless upon insertion, squeeze out from
faying surface application through the hole can be shown to consistently coat the shank.
(d) Application to Bushings and Bearings
Application of jointing compound to bushings and bearings requires a continuous coating
of the housing bore and a continuous bead around the surface of the hole under the flange
of the bushing. After installation a continuous extrusion of compound must surround the
bearing or bushing.
(7) Methods of Application
(a) This material is to be applied directly from the container in a thin continuous film by brush,
knife or spatula. Should thinning be necessary, a solvent solution of 80% volume Xylene
and 20% volume n-Butanol may be used. See Table 104.
Addition of only enough of the solvent mixture to produce a consistency of a thick, but
brushable paint shall be allowed. Jointing compound should be mixed to a smooth
homogeneous mixture, immediately before application. Immediately after the joining
compound has been applied to both surfaces and spread evenly, the joint shall be closed
and the surfaces brought into intimate contact by bolting, riveting or fastening as
appropriate.
(b) When the joint is assembled, a continuous bead of squeeze out of the faying surface
applied compound must be evident in the form of a fillet to give additional protection.
Excessive squeeze out beyond that necessary to form a fillet shall be removed using a
clean cotton cloth.
(c) A period of 24 hours minimum should be allowed for the volatile solvents to escape from
the joints. During this time, the area should not be exposed to sparks or excessive heat or
strong solvents.
(8) Removal
For complete removal of the compound from surfaces, wipe off with a cotton cloth dampened
with one of the solvents listed in Table 103.

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G. MIL-PRF-16173 Corrosion Preventive Compound

(1) Grades of MIL-PRF-16173
(a) Grade 1 compounds form a hard film, similar to a hard grease. This coating is dry enough
to touch in 4 hours. It does not penetrate crevices or displace water.
(b) Grade 2 compounds form a film which stays soft after drying, but does not displace water.
(c) Grade 3 compounds form a film which stays soft after drying and will displace water.
(d) Grade 4 compounds form a transparent film that is dry enough to touch in 4 hours and is
completely dry after 24 hours.
(e) Grade 5 compounds form a water displacing film that stays soft after drying. This coating
can be removed with low pressure steam.
(2) Intended Use
The corrosion preventive compounds covered by this section are intended for the following
uses:
(a) Grade 1
1 For protection of metals when exposed to outdoor weather conditions.
2 For general purpose preservation, indoor and outdoor, with or without cover, for
domestic and overseas shipment where a dry to touch film is required.
(b) Grade 2
1 For extended undercover protection of interior surfaces of machinery, instruments,
bearings or material with or without use of supplementary barrier materials.
2 For outdoor protection of material for limited periods where metal temperatures do
not reach levels which produce prohibitive flow of the corrosion protective film.
(c) Grade 3
1 For use where water or saline solution must be displaced from corrodible surfaces
and the corrosion prevented or arrested.
2 For protection of interior surfaces of machinery, instruments or material under cover
for limited periods.
3 For protection of critical bare steel or phosphated surfaces for extended periods
when packaged with satisfactory barrier materials.
NOTE: Use Grade 5 on metal(s) which may be attacked by an alkaline treatment
during the preservative removal stage. The chemical boil out is alkaline and
its use should be avoided with such materials as aluminum and magnesium
alloys.
(d) Grade 4
1 For general purpose indoor and limited outdoor preservation of corrodible metals
with or without an overwrap and where handling, stacking and counting requires a
tack free coating.
2 Where a transparent coating is required in addition to properties indicated in Step 1
.G.(2)(a).
3 Where there is no requirement for miscibility with lubricating oil and where ease of

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removal with dry cleaning solvent (P-D-680) is important.

(e) Grade 5
1 For use in place of Grade 3 corrosion preventive compound where chemical boil out
cannot be used for removal. See Step 1.G.(2)(c).
(3) Refer to the most recent revision of the Qualified Products List (QPL-PRF-16173) for a
complete listing of approved material part numbers and vendors, for all grades of MIL-PRF-
16173 compound.
(4) Precautions for Use
Use the same precautions and warnings for MIL-PRF-16173 that are listed for water displacing
corrosion inhibiting compounds previously listed.
(5) Compatibility
As these materials are all usually hydrocarbons, a different hydrocarbon compound can be
applied over existing corrosion inhibitors without adverse effects.
(6) Cleaning Before Application
The surface does not need to be extremely clean before application of these compounds; but a
more continuous film will result if the area is cleaned first. Vacuum or wipe away loose dirt or
other foreign matter. The surfaces may then be cleaned, where necessary, with normal aircraft
cleaning products (see Table 102).
(7) Methods of Application
(a) Use the same application procedures for MIL-PRF-16173 that are given for Type I, II, III,
IV, V, VII and VIII corrosion inhibiting compounds as previously listed, with the differences
noted in Step 1.G.(7)(b) and Step 1.G.(7)(c).
(b) Let the MIL-PRF-16173 Grades 2, 3 and 5 compounds penetrate for 60 minutes. Do not
attempt to wipe up puddles until 60 minutes have elapsed.
(c) If the coated surface will touch another surface (such as insulation blankets), let the
coating dry tack free. (Use only Grades 1, 4 or 5 compounds. Grades 2 and 3 compounds
form soft films which would be damaged by such contact).
(8) Removal
(a) Remove all of the MIL-PRF-16173 compound before painting the surface. Solvent
cleaning is also required before penetrant inspection.
(b) Naphtha can be used to remove these compounds. The use of MPK or acetone is not
recommended.
(c) When using solvents to remove corrosion inhibitors, give the area a good flow of air until
the solvents evaporate.
(9) Exterior Discoloration
(a) Liberal use of these corrosion inhibiting compounds on the internal surface of the aircraft
can lead to discoloration of the external surface. Because of the excellent penetrant
properties of these materials, a bleed through can be expected at fasteners that are not
fluid tight. This is normal and does not indicate a requirement to replace or redrive the
fasteners. The tiny passages should seal themselves within a short time.

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(b) These compounds can be removed from the exterior surface with one of the solvents
listed. These solvents will not stain or damage the exterior of the aircraft or decorative
finish. A noticeable difference in oxidation of the exterior surfaces can occur between
those areas which have been coated with the compound and areas that have not. If this
difference in color is seen, polish with an appropriate buffing material.
Table 101: Type I, II, III, IV, V, VI, VII, and VIII Corrosion Inhibiting Compounds

TYPE SPECIFICATION MATERIAL VENDOR CAGE CODE

Boeshield T-9
Type I MIL-PRF-16173D PMS Products OPKD8
(colored)
MIL-PRF-16173,
Type II LPS-3 LPS Laboratories Inc. 66724
GR 2
Dinitrol AV5B-2 Chemetall Oakite 0L040
Dinitrol AV8 Chemetall Oakite 0L040
MIL-PRF-81309,
Type III ACF-50 Lear Chemical Research Corp. 3AM52
TY III
LPS-2 LPS Laboratories Inc. 66724
MIL-PRF-16173,
Type IV Dinitrol AV25 Chemetall Oakite 0L040
GR 4
Dinitrol AV25B-2 Chemetall Oakite 0L040
Ardrox AV30 Chemetall Oakite 0L040
LPS B 997 LPS Laboratories, Inc. 66724
LPS Procyon(1) LPS Laboratories Inc. 66724
Ardrox 3321 Ardrox, Inc. 23373
MIL-PRF-16173,
Type V LPS B 1007 LPS Laboratories Inc. 66724
GR 1
Ardrox 3322 Ardrox, Inc. 23373
Dinitrol AV100D Chemetall Oakite 0L040
GMS-4109, Type
Type VI Cor-ban 27L Zip-Chem Products 6KCJ9
NC-1
Type VII GAC 115AD Ardrox AV30 Chemetall Oakite 0L040
Corban 35 and
Corban 35 Zip-Chem 1KQX9
(undyed)
MIL-PRF-81309,
Type VIII ACF-50 Lear Chemical Research Corp. 3AM52
TY II
DPM-5707-1 TY II D-5026NS Zip-Chem 1KQX9
Ardrox 3204 Ardrox Inc. 0HET2

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TYPE SPECIFICATION MATERIAL VENDOR CAGE CODE

So-Sure 813 LHB Industries 5602X
Type VIII Alox 2028C Alox Corp. 0FPK8
Nox Rust 212 Daubert Chemical Co. 7X108
2775 Fine Organics Corp. 05867
LPS-813 LPS Laboratories Inc. 66724
Octoil 5068 Octagon Process Inc. 82925
22028CM-Bulk Stevens Industries Inc. 0NX60
97-SX092 Selig Chemical Industries Inc. 86938
(1)
The use of Ardrox AV30, Corban 35 and Corban 35 (undyed) in lieu of LPS Procyon is preferred. Existing stock of LPS Procyon may be
used to depletion.

Table 102: Surface Cleaning Solvents For Type I, II, III, IV, V, VI, VII and VIII Corrosion Inhibitors

SOLVENT INTENDED USE ON SPECIFICATION

MATERIAL
Aliphatic naphtha Aluminum / steel / titanium TT-N-95, type 2
Solvent blend Aluminum / steel MIL-C-38736
Stoddard blend Aluminum / steel / plastics and MIL-PRF-680
acrylics
Methyl Propyl Plastics and acrylics / titanium / ASTM D329
Ketone (MPK) aluminum / steel

Table 103: Materials For Corrosion Inhibitor Removal

CORROSION SOLVENT MATERIAL VENDOR / SPECIFICATION

INHIBITOR TYPE
I, II, III, IV, V, VII, 1,1,1 Trichloroethane ASTM D4126
VIII (1)
Aliphatic Naphtha TT-N-95, Type 2
Magnaflux Corp. Solvent Magnaflux Corp. V37676
Dry Cleaning Solvent MIL-PRF-680
1,1,1 Trichloroethane ASTM D4126
(aluminum / steel)
Acetone (aluminum / steel / ASTM D329
VI titanium)(2)
Methyl Propyl Ketone (MPK) GAS115K
(aluminum / steel / titanium /
plastics / acrylics)(2)
(1)
Soap and water will remove Type III material from painted surfaces.

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(2)
Use of Methyl Propyl Ketone (MPK) or Acetone is not recommended.

Table 104: Solvents

SOLVENT INTENDED USE SPECIFICATION

MATERIAL
Xylene Type VI thinner ASTM D4076
n-Butanol Type VI thinner ASTM D304

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