Product Description

Mobil HyJet IV-Aplus is a fire-resistant phosphate ester hydraulic fluid designed for use in commercial aircraft. It is the best-performing Type IV fluid and approaches to a great extent many of the performance capabilities of Type V fluids, including high temperature stability, long fluid life, density, and rust protection. It is superior to all other Type IV fluids in these respects. Mobil HyJet IV-A plus meets the specifications of all major aircraft manufacturers and SAE AS1241.

Features and Benefits

Mobil HyJet IV-A plus offers the following key features and benefits:

Features Advantages and Potential Benefits
Best in high temperature stability among Type IV fluids Longer fluid life.

Lesser need to replace fluid due to degradation.

Reduced hydraulic system maintenance costs

Lowest density Type IV fluid Reduced weight of the hydraulic fluid carried by aircraft.

Reduced aircraft fuel consumption, lower operating costs

Effective rust protection Reduced the risk of equipment damage in the event of major water contamination
Excellent low temperature flow (viscosity) properties Precise hydraulic system control and response even during extended range/polar flights.

Longer equipment life

Excellent deposit control Longer equipment life.

Reduced maintenance costs

Excellent protection against electro-chemical corrosion (erosion) Protection against servo valve and pump damage
Approved by all major aircraft manufacturers Use as fleet lubricant by airline operators
Fully compatible with all approved phosphate ester hydraulic fluids Flexibility in use by airline operators


Mobil HyJet IV-A plus fire-resistant aviation hydraulic fluid is used in commercial aircraft hydraulic systems where phosphate hydraulic fluids are recommended. It is compatible in all proportions with commercial Type IV and Type V phosphate ester aviation hydraulic fluids.

Mobil HyJet IV-A plus meets or exceeds the following industry and aircraft builder specifications. It is approved against all commercial aircraft manufacturer requirements and is included in their Qualified Products Lists.

Specifications and Approvals

This product has the following approvals:
AIRBUSNSA307110N – Type IV, Low Density
BOMBARDIERBAMS 564-003A – Type IV, Low Density
EMBRAERType IV, Low Density
FOKKERType IV, Low Density
GULFSTREAM1159SCH302J – Type IV, Low Density
LOCKHEEDC-34-1224C – Type IV, Low Density
ATRType IV, Low Density
BOEINGBMS 3-11P – Type V, Grade B and Grade C
BOEINGBMS 3-11P – Type IV, Low Density
Boeing-Long BeachDMS2014H – Type 4
BAE/AVROBAC.M.333C – Type IV, Low Density
This product meets or exceeds the requirements of:
SAEAS1241D, Type IV, Class 1 (low density)

Properties and Specifications

Acid Number, mgKOH/g, ASTM D974 0.04
Autoignition Temperature, F, ASTM D2155 800
Bulk Modulus, Isothermal secant at 100 F/3000 psi, psi, ASTM D6793 210000
Calcium, ppm, ICPES 103
Chlorine, ppm, XRF 10
Coefficient of Thermal Expansion, 25 to 100 C, per degree C, API MPMS 11.1 0.00086
Conductivity @ 20 C, MicS/cm, ASTM D2624 1.4
Density @ 60 F, lb/USg, ASTM D4052 8.35
Fire Point, Cleveland Open Cup, °F, ASTM D92 370
Flash Point, Cleveland Open Cup, °F, ASTM D92 349
Foam, Sequence I, Collapse Time, s, ASTM D892 15
Foam, Sequence II, Collapse Time, s, ASTM D892 13
Foam, Sequence III, Collapse Time, s, ASTM D892 16
Four-Ball Wear Test, Scar Diameter, 10 kg, 600 rpm, 1 h, 75 C, mm, ASTM D4172 (mod) 0.33
Four-Ball Wear Test, Scar Diameter, 4 kg, 600 rpm, 1 h, 75 C, mm, ASTM D4172 (mod) 0.22
Four-Ball Wear Test, Scar Diameter, 40 kg, 600 rpm, 1 h, 75 C, mm, ASTM D4172 (mod) 0.73
Kinematic Viscosity @ 100 F, mm2/s, ASTM D445 10.6
Kinematic Viscosity @ 127.6 C, mm2/s, ASTM D445 2.6
Kinematic Viscosity @ -15 F, mm2/s, ASTM D445 130
Kinematic Viscosity @ 210 F, mm2/s, ASTM D445 3.6
Kinematic Viscosity @ -65 F, mm2/s, ASTM D445 1320
Potassium, ppm, ICPES/AA 38
Shear Stability, % Kinematic Viscosity Loss, 40 C, %, ASTM D5621 22
Sodium, ppm, ICPES 1
Specific Gravity, 25 C/25 C, ASTM D4052 0.996
Specific Heat Capacity, cal/g-deg.C, Reference 0.41
Sulfur, ppm, ICPES/XRF 224
Thermal Conductivity at 40 C, cal/cm-sec-deg.C, Reference 0.00033
Viscosity Index, ASTM D2270 280
Water Content, mass%, ASTM D6304 0.1
Foam, Sequence I, Tendency, ml, ASTM D892 27
Foam, Sequence II, Tendency, ml, ASTM D892 23
Foam, Sequence III, Tendency, ml, ASTM D892 28
Pour Point, °F, ASTM D97 / ASTM D5950 -80
NAS 1638 Class, HIAC, ISO 11500 7

Health and safety

Health and Safety recommendations for this product can be found on the Material Safety Data Sheet (MSDS) @


It cannot be guaranteed that the product information given above is up to date. For the latest version of the Product Data Sheet we refer to the product library of ExxonMobil.