Top Quality MIL PRF 83282 Hydraulic Fluids: Specifications & Benefits

We’ve talked about a couple of different turbine engine oils, but what about the rest of the aircraft? Modern aircraft operate with massive systems that control flight controls, landing gear, flaps, and other components. The system that drives these is the hydraulic system. These rely on large quantities of hydraulic fluid to operate, and the fluid commonly used is MIL-PRF-83282.

Greenwood Aerospace supplies several popular and common types of hydraulic fluid, including Royco 782 MIL-PRF-83282D Fire-Resistant Hydraulic Fluid in one-quart cans. But first, what exactly is it? Let’s find out. 

What is MIL PRF 83282 Hydraulic Fluid?

Hydraulic fluid is one of the most critical fluids on an airplane; without it or with the wrong one, you are looking at a fairly bad day. MIL PRF 83282 hydraulic fluid is a fire-resistant synthetic hydraulic fluid used in aircraft hydraulic systems. Every aircraft in the inventory, except for a handful of smaller, specialized-use aircraft, utilizes a hydraulic system. Some hold a few gallons, while others, like the B-1B, have hundreds of gallons of hydraulic fluid. 

Speaking of B-1s, there have been a couple of incidents involving these aircraft that highlight the importance of fire-resistant hydraulic fluid. One of the more noteworthy events occurred at Andersen AFB, Guam, when a hydraulic leak caught fire, ignited by sparks from the brake assembly. 

Back to MIL PRF 83282. MIL PRF  is a performance specification that defines the functional requirements for the item and is used on all lubricants for military use. Several commercial options meet MIL-PRF-83282 standards, manufactured by prominent petroleum companies. We stock Royco 782 MIL-PRF-83282D Fire-Resistant Hydraulic Fluid, which you can easily procure by filling out our online quote feature, or you can email us or call us. 

This fluid is identified by NATO Code Number H-537 and is used in a temperature range of -40 °C to +205°C.

Specifications and Approvals

Hydraulic systems are also exposed to some of the harshest conditions, so the enhanced fire resistance provides peace of mind regarding the performance specifications. 

Our hydraulic fluid:

  • Meets the requirements of MIL-PRF-83282D, Amendment 1. This revision is the most current, meaning it is acceptable for all applications that require any revision of MIL-PRF-83282 hydraulic fluid. 
  • Identified by NATO Code Number H-537.

Here are the key specifications and approvals (specifications are from the Royco 782 TDS):

Property

Test Method

ROYCO® 782

Kinematic Viscosity, cSt @ 205°C

ASTM D445

1.08

Kinematic Viscosity, cSt @ 100°C

ASTM D445

3.51

Kinematic Viscosity, cSt @ 40°C

ASTM D445

14.2

Kinematic Viscosity, cSt @ -40°C

ASTM D445

2027

Low Temperature Stability, -40°C, 72 hours

FTM 3458

Pass

Flash Point, °C (°F)

ASTM D92

218 (424)

Fire Point, °C (°F)

ASTM D92

251 (483)

Pour Point, °C (°F)

ASTM D97-61

-77

Neutralization Number, mg KOH/g

ASTM D664

0.03

Barium Content, ICP-AES, ppm

ASTM D5185

0

Specific Gravity (15.6°C)

ASTM D1298

0.852

Gravimetric Filtration, mg

ASTM D4898

0.1

Water Content, ppm

ASTM D6304

65

Evaporation, 205°C, 6.5 hours, % loss

FTM 350

10.5

Lubricity, 4-Ball Wear, scar diameter, mm - 1 Kg, 1200 RPM, 1 hr, 75°C

ASTM D4172

0.14

Lubricity, 4-Ball Wear - 10 Kg, 1200 RPM, 1 hr, 75°C

ASTM D4172

0.21

Lubricity, 4-Ball Wear - 40 Kg, 1200 RPM, 1 hr, 75°C

ASTM D4172

0.44

Solid Particle Contamination - Filtration time, min

FTM 3009

722

Solid Particle Contamination - 5–15 μm

FTM 3009

95

Solid Particle Contamination - 16–25 μm

FTM 3009

27

Solid Particle Contamination - 26–50 μm

FTM 3009

4

Solid Particle Contamination - 100+ μm

FTM 3009

0

Foam Characteristics, 25°C, ml (5 min / 10 min)

ASTM D892

4 / 0

Applications and Uses

MIL-PRF-83282D and its identical civilian counterpart are used in all types of aircraft, primarily in military and civilian aircraft hydraulic systems, where fire resistance is crucial. Heavy aircraft rely on hydraulics for landing gear, flaps, and stabilizer movement, so they operate large systems with a significant amount of fluid. 

It is also suitable for use in automatic pilots, shock absorbers, hydraulic struts, brakes, flight control systems, and other systems that utilize synthetic elastomer seals. These are typical applications across most large aircraft. It can be used in air compressor gearboxes, flap control mechanisms, and other hydraulic systems, provided that the technical guidance approves MIL-PRF-83282.

Finally, it is recommended for use in temperatures from -40°C to +205°C.

Handling and Maintenance

Hydraulic fluid must be stored in a clean, dry environment. The components in hydraulic systems are susceptible to dirt, grime, and other forms of buildup. Even a small amount of grit can damage a seal on a landing gear strut, potentially draining the entire strut, which is a serious issue. Here are some best practices: 

  • Should be stored in a clean, dry, and temperature-controlled environment. HAZMAT lockers are ideal.
  • It should be stored away from direct sunlight and heat sources.
  • Proper storage helps prevent contamination, degradation, or separation of components.
  • Refer to the Safety Data Sheet (SDS) for specific safety information and handling procedures, and ensure that you keep your SDS updated with any new revisions you have received. 

Final Thoughts from Greenwood Aerospace

We currently offer Royco 782 Fire-Resistant Hydraulic Fluid in single-quart cans, but depending on your demand, we can source different sizes. We can also make bulk purchases to meet your large fleet demands. 

We also offer a wide range of lubricants, sealants, and solvents. Please start your quote here to see how we can assist you with all your POL needs.