TASK 70-43-05-380-005
1 . General.
CAUTION:
DO NOT APPLY THIS PROCESS TO ALUMINUM OR ALUMINUM ALLOY HARDWARE OR ASSEMBLIES, UNLESS APPROVED BY GEAE ENGINEERING.
WARNING:
THESE COATINGS CONTAIN ALUMINUM PARTICLES IN THE 5 TO 10 MICRON RANGE, WHICH REACT LIKE PURE ALUMINUM POWDER IN THE DRY STATE, FORMING EXPLOSIVE MIXTURES WHEN DISPERSED IN AIR. TAKE PRECAUTIONS TO AVOID THE ACCUMULATION OF OVERSPRAY AND THE FORMATION OF DUST CLOUDS. ALUMINUM COATINGS REACT WITH ALKALINE SOLUTIONS AND MANY ACIDS TO LIBERATE HYDROGEN, WHICH FORM EXPLOSIVE MIXTURES WITH AIR. BE SURE THAT PAINT-STRIPPING TANKS ARE THOROUGHLY VENTILATED BY A FORCED-AIR EXHAUST SYSTEM WHILE PROCESSING ALUMINUM-COATED PARTS.
WARNING:
THE UNCURED BINDER OF THESE COATINGS CONTAINS HEXAVALENT CHROMIUM, IS TOXIC IF INGESTED AND REQUIRES CARE IN HANDLING. AVOID CONTACT WITH SKIN, EYES, AND MUCOUS MEMBRANES. IN CASE OF CONTACT, IMMEDIATELY IRRIGATE AFFECTED AREA WITH RUNNING WATER. IF CONTACT IS SEVERE, OBTAIN MEDICAL ATTENTION. WHILE SPRAYING AVOID BREATHING THE MIST OF THE ATOMIZED COATING. WELL VENTILATED SPRAYING AREAS WITH A HIGH EXHAUST RATE (150 FEET PER MINUTE OR GREATER) SHOULD BE USED AND RESPIRATORS SHOULD BE WORN.
A.These coatings are applied to surfaces that are subject to corrosion.
2 . Equipment and Settings.
Subtask 70-43-05-380-051
A.The following spray equipment (1) and settings (2) or equivalent are recommended for this coating procedure.
(1)Equipment.
(a)Spray Gun, Devilbiss Model JGK IN-641FX with nylon tipped needle and either air cap number 263 for 6-8 inch (152-203 mm) spray pattern or number 265 for 8-12 inch (203-305 mm) spray pattern.
(b)Pressure Tank, Devilbiss Model QMR-HTS 1414-55p stainless steel fitted 5 gallon (19 liter) pot with high efficiency stainless steel mixer and air motor drive.
(c)Fluid Hose Devilbiss H-1996-PHC-4548-XX (specify length) 0.375 inch (9.5 mm) ID nylon lined.
(d)Air Hose. Devilbiss H-1641-PNC-4527-XX (specify length) 0.312 inch (7.9 mm) ID with static grounding wire.
(e)Grounding Wire For Pressure Pot. Justrite 8-501, 3 grounding wires with clamps.
(2)Settings.
(a)Pressure Tank: 10-12 psi
(b)Fluid Pressure: 5-7 psi
(c)Atomizing Air Pressure: 40 psi
(d)Spray Distance: 5-8 inches (127-203 mm) from the part while making up-and-down passes. Do not make passes in a circular motion.
3 . Materials.
Subtask 70-43-05-380-052
A.Inorganic Aluminum Coating
 
Description
Ref No.
 
Paint, Inorganic Bonded Aluminum
C03-038  
 
Paint, Inorganic Aluminum
C03-055  
 
Paint, Inorganic Bonded Aluminum
C03-039  
 
Paint, Inorganic Aluminum
C03-091  
 
Paint, Inorganic Aluminum
C03-093  
4 . Preparation Procedure.
Subtask 70-43-05-380-053
A.Strip the old coating. Refer to TASK 70-23-02-110-019, Stripping Method No. 2 - Stripping Inorganic Bonded Aluminum Paint.
B.If the part has been inspected or repaired after the coating was stripped, clean the part. Refer to TASK 70-21-22-110-042, Cleaning Method No. 22 - Light Duty Aqueous Cleaning - Method No. 1, or TASK 70-21-22-110-050, Cleaning Method No. 22 - Light Duty Aqueous Cleaning - Method No. 2.
C.Mask all areas not to be coated, following the detailed part instructions.
D.Grit-blast the part. Refer to TASK 70-21-04-120-001, Cleaning Method No. 4 - Dry Abrasive Blast Cleaning. Use aluminum oxide grit particles in the 120-240 mesh range as the abrasive material. Remove the remaining grit particles by air-blasting the area with clean, dry shop air.
NOTE:
Do not handle prepared parts with your bare hands; wear clean, white cotton gloves. Unless the parts are to be coated in less than 4 hours, they should be stored in clean, sealed polyethylene bags.
5 . Spray Application and Cure Procedure.
Subtask 70-43-05-380-054
A.Apply a minimum of 2 separately cured spray coats of C03-038  , C03-055  , C03-091  , or C03-093   to get the required thickness. The total thickness after curing is to be 0.0015-0.0030 inch (0.038-0.076 mm) unless otherwise specified in the detailed part instructions. For coating material, refer to Subtask 70-43-05-380-052, Materials.
NOTE:
When it is possible, apply the coating in shop areas where the relative humidity is not more than 60%. If humidity is more than 60%, special drying procedures are required after spraying. Refer to Step 5.D. Mix the coating material thoroughly before and during the procedure to make sure that solids do not collect in the bottom of the tank. Viscosity shall be 16-18 seconds, as measured with a Model S-2 Meylon stop watch and a No.2 Zahn cup.
B.Unless otherwise specified, use the spray parameters and method specified in the Engine/Shop manual to apply the coating. Refer to Subtask 70-43-05-380-051, Equipment and Settings.
C.Remove the masking, plugs, caps and sealing fixtures from the part.
D.Air-dry the coating at room temperature until the coating is a uniform gray-white color. When the relative humidity is more than 60%, dry the part with one of the following processes to accelerate the drying time.
- Dry in an oven at 150-200°F (79°C ± 14°C)
- Dry with heat lamps at 150-200°F (79°C ± 14°C)
NOTE:
Temperatures reflect metal temperature required to satisfactorily dry and bake the coating.
E.If dark green areas exist and will not dry, remove the coating by pressure-rinsing with cold water. Dry the part thoroughly. Replace the required masking, plugs, caps, and sealing fixtures, grit-blast the part, and then re-coat the part. Ignore light green or brown areas.
NOTE:
Dark green areas indicate that the coating is too wet or too thick, and that it may flake during final baking.
F.Bake the part at 600-750°F (316-399°C) for a minimum 15 minutes, cool to a room temperature.
G.Make sure that the coating is sufficiently cured by quickly rubbing a small area with a swab soaked in water. If the coating does not change color, it is cured; if the coating color becomes green, repeat Step 5.E. until the coating is cured.
H.Use the same procedure to apply additional coats as required to get the specified thickness. Cure each coat separately before you apply the next.
I.Visually check the final coating to make sure that it is free from cracks, pin-holes, runs, sags, inclusions of foreign material, or other defects.
6 . Quality Tests.
Subtask 70-43-05-380-055
A.Adhesion bend testing is intended to verify that the equipment and processing parameters are well adapted to the application and reproduction of these coatings. Bend tests must be performed prior to processing parts in any of the following situations and as required by local quality organization:
(1)The surface preparation and/or coating system is newly installed.
(2)The surface preparation and/or coating system has not been utilized within a twelve month period.
(3)The surface preparation and/or coating system equipment is dismantled and repositioned.
(4)The surface preparation and/or coating system equipment receives a major overhaul or replacement of a major component.
(5)Equipment settings are modified.
B.Panel configurations and tests are recommended as follows:
(1)Test panels shall be approximately 3 X 4 X 0.063 inches (76.2 X 101.6 X 1.6 mm) in size with a 63 microinches (1.6 micrometers) maximum surface finish, they shall have smooth edges and rounded corners, and they shall be annealed. The panels shall be of the same material as the parts or made from AISI 4130 alloy steel.
(2)Test panels should be coated in the same manner and with the parts.
(3)Bend the coated test panels through an angle of 90° ± 5° , around a 0.125 ± 0.005 inch (3.18 ± 0.13 mm) bend radius. Spring-back to less than 90° is permitted.
(4)Inspect the test panels. No less than 90% of the coating along the axial lines on the convex panel surface shall be free from chipping or peeling. If the panels do not agree with this requirement, strip and refinish the engine parts that they represent.
7 . Touch-up Procedure.
Subtask 70-43-05-380-056
A.Defective areas may be touched up with inorganic bonded aluminum paint C03-039  , full strength from the can. Keep the can tightly covered when not in use. Refer to Subtask 70-43-05-380-052, Materials.
NOTE:
Not more than 5% of total coated area may be touched up. This touch-up procedure does not give the same corrosion protection as the original coating.
(1)Clean and prepare the alloy surface by grit-blasting the area to be touched up. Refer to TASK 70-21-04-120-001, Cleaning Method No. 4 - Dry Abrasive Blast Cleaning. An alternative method is to expose only clean metal by sanding the surface with 180 grit aluminum oxide abrasive cloth or paper.
(2)Remove the remaining grit particles by air-blasting the area with clean, dry shop air. Make sure all organic solvents are removed from the surface.
(3)Wipe the cleaned area with a clean, lint-free cloth.
(4)Brush or spray the touch-up coating onto the prepared area. Shake the container thoroughly before use to keep the material from collecting rapidly at the bottom.
(5)Let the touched-up part dry for 8 hours at room temperature to cure fully.
(6)Check the bond and cure of the touch-up coating as follows:
(a)Flush the repaired and cured surface by immersing it in room-temperature water, or by flowing water over the repaired surface, for one minute. If the surface is not removed or softened, it is satisfactory.
(b)Rub the touched-up areas with a rag soaked with Jet-B fuel or lubricating oil (MIL-PRF-7808) for one minute. If the repaired surface is not removed or softened, it is satisfactory.
NOTE:
The surface is also resistant to steam cleaning. The touch-up coating may not be an exact color match for the original coating, but the color is very close to that of the original coating after it cures.