Features Advantages and Potential Benefits
A particular requirement of aviation greases is the need to resist high temperature stresses, while providing excellent starting and low torque at low-temperature. To meet this combination of needs, specific synthetic base oils are used in Mobilgrease 27 because of their exeptional thermal/oxidative resistance potential, and superb low-temperature capability.
Mobilgrease 27 meets the requirements of key military and commercial aviation specifications and has built up a superb reputation for performance and reliability among users around the world.
- High viscosity index base stock with no wax content.
- Very wide operating temperature range - outstanding high and low temperature performance
- Excellent film protection at high temperatures
- Minimum resistance to start-up at extremely low temperatures
- Good storage stability Low separation
- Excellent protection against wear and corrosion
- Provides excellent bearing protection
- Extreme-pressure characteristics
- Prevents excessive wear, even under shock load
- High resistance to water washout
- Maintains excellent grease performance in adverse weather and other water-exposure conditions
Application
Mobilgrease 27 is a true multipurpose aviation grease intended for use in highly loaded gears and actuators as well as instruments, high speed bearings (though not recommended for wheel bearings), and general airframe lubrication over temperatures from –100?F to 250?F. Mobilgrease 27 is also an excellent choice for applications where a smooth, low noise, wide temperature range lubricating grease is required, such as in miniature precision bearings. Mobilgrease 27 contains a synthetic ester and should not be used in contact with incompatible seal materials. It may soften natural rubber, neoprene, certain electrical insulation materials and paints.
Mobilgrease 27 meets the requirements and is approved against U.S. Military Specification MIL-PRF-23827, Grease, Aircraft and Instrument, Gear and Actuator Screw, Type I (Grease thickened with metallic soap). It is listed in the QPL-23827 Qualified Products List. In addition, Mobilgrease 27 may be used in all applications where MIL-G-3278, MIL-G-7118, MIL-G-7421, MIL-G-15793 and MIL-G-23827 are specified, subject to approval by the aircraft manufacturer. It is a NATO Code Number G-354 grease.
Typical Properties
|
Test Method |
Mobilgrease 27 |
MIL-PRF-23827 Limits |
| NLGI Grade | | 1 1/2 | |
| Thickener Type | | Lithium | |
| Color | Visual | Light Tan | |
| Structure | Visual | Smooth | |
| Dropping Point, ºC (ºF) | ASTM D 2265 | 200 (392) | 165 (329) min |
| Viscosity of Base Oil, cSt | ASTM D 445 | | |
| at 40ºC | | 9.2 | |
| at 100ºC | | 2.7 | |
| Low Temp. Torque at -100ºF, Nm | ASTM D 1478 | | |
| Starting | | 0.40 | 1.0 max |
| Running, after 1 Hr | | 0.04 | 0.10 max |
| Penetration at 25 C (77 F), mm/10 | ASTM D 217 | | |
| Unworked | | 275 | 200 min |
| 60 Stoke Worked | | 290 | 270-310 |
| Extended Worked Penetration Stability, 100,000 Strokes, mm/10 | FTM 313 | 325 | 270-375 |
| Oil Separation, 30 Hrs at 100ºC, wt % | ASTM D 6184 | 2.3 | 5.0 max |
| Evaporation Loss, 22 Hrs at 100ºC, wt % | ASTM D 2595 | 1.2 | 2.0 max |
| Copper Strip Corrosion, 24 Hrs at 100ºC | ASTM D 4048 | Pass | 1b max |
| Load Wear Index, kgf | ASTM D 2596 | 33 | 30 min |
| Rust Protection, 48 Hrs at 125ºF, > 1mm dia Corrosion Spots | ASTM D 1743 | Pass | 0 in 2 out of 3 bearings |
| Water Washout, 1 Hr at 38 ºC (100 ºF), wt % | ASTM D 1264 | 13 | 20 max |
| High Temperature Performance, Hrs at 121ºC | ASTM D 3336 | Pass | 1,000 min |
| Oxidation Stability, pressure drop in kPa | ASTM D 942 | | |
| 100 Hrs at 99ºC | | Pass | 70 max |
| 500 Hrs at 99ºC | | Pass | 105 max |
| Gear Wear | FTM 335 | Pass | Pass |
| Storage Stability, 6 months at 40ºC | FTM 3467 | Pass | Pass |
| Dirt Count, Particles/mL | FTM 3005 | | |
| 25-74 Micron Size | | 0 | 1000 max |
| 75 Micron or Larger | | 0 | 0 |
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