MIL-PRF-27601C
3.3.7 Lubricity. When tested in accordance with 4.4.2, wear values for hydraulic fluid shall be as specified in
table IV.
TABLE IV. Wear values.
Load (kg)
Scar diameter mm (max)
1
0.21
10
0.30
40
0.65
3.3.8 Storage stability. The fully blended product shall show no separation of ingredients nor evidence of
crystallization, shall be clear and transparent when examined visually and shall conform to the requirements of
section 3 after 12 months storage as specified in 4.4.2.
3.3.9 Compatibility. The hydraulic fluid shall be compatible in all concentrations with each of the fluids approved
under this specification when tested as specified in 4.4.3 from -40°C to 290°C in that no formation of resinous
gums, sludges, or insoluble materials will occur.
3.3.10 Thermal Stability. When tested in accordance with 4.4.5, the change in fluid viscosity at 40°C shall not
exceed 25 percent. The neutralization number of the fluid shall not increase more than 0.4 and there shall be no
formation of precipitate or insoluble material.
3.3.11 Low temperature stability. When tested as specified in 4.4.2 for 72 hours at a temperature of -40°C ±
1°C, the fluid shall show no evidence of gelling, clouding, crystallization, or separation of ingredients.
3.3.12 Swelling of synthetic rubber. When tested as specified in 4.4.2, the volume increase of the standard
synthetic rubber FKM (as referenced in AMS 3217/4) by the fluid shall be within the range of 0.0 to 10.0 percent.
Shrinkage of the rubber is not allowed.
4. VERIFICATION
4.1 Classification of inspection.
a. Qualification inspection (see 4.2).
b. Quality conformance inspection (see 4.3).
4.2 Qualification inspection.
4.2.1 Qualification inspection sample. The qualification sample shall consist of two one-gallon containers of the
finished fluid, one quart of the base stock(s) without additives, one ounce of the anti-wear additive, one ounce of
the oxidation inhibitor and one ounce each of any additional additives used in the finished fluid. In the event that
additives are supplied as concentrated solution, an equivalent quantity of the solution shall be furnished.
4.2.2 Qualification tests. Qualification sample(s) shall be subjected to all the tests specified in table V.
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