Of 359 grease application points on a Boeing 737 – AeroShell Grease 33 lubricates all but 9 of them
Historically, aircraft maintenance operations had to carry several different greases for different lubrication needs. But then Shell developed AeroShell Grease 33 – a universal airframe grease. AeroShell Grease 33 is effective on virtually all airframe components. For those components where AeroShell Grease 33 is not suitable, AeroShell 22 will do the job. A complete grease range in two products.
Why use AeroShell Grease 33?
- replacing the number of greases used on the aircraft with a common grease prevents misapplication of the wrong grease and damage to the aircraft
- the much improved corrosion resistance and wear protection properties of ASG 33 help prevent expensive replacement of parts whilst also allowing lubrication intervals to be extended
- replacing a range of greases with just one, reduces stock inventory and cost.
For many years aircraft operators have been seeking to rationalise the greases used on aircraft and to reduce the number of different greases in their inventories. Recently Boeing began research on a new, general purpose, corrosion-inhibiting grease. The aim was for a non-clay based grease that would provide longer life for components and mechanisms and possess improved wear and corrosion resistance. This led to the introduction of the new Boeing Specification BMS 3-33.
Owing to the wide range of operating temperatures, loads and other environmental conditions required for various aircraft components, several different types of grease with different desirable properties are used during routine lubrication of aircraft components. Boeing, in developing their BMS 3-33 specification, took account of the properties of the different grease types used on aircraft and wrote a specification for a grease which would provide improved performance and which could be used in the widest possible range of grease applications.
Shell worked closely with Boeing during the development of BMS 3-33 and formulated AeroShellGrease 33 to meet the improved performance properties required by this specification. It was the first, and for several years the only, grease approved to BMS 3-33. AeroShell Grease 33 is also approved to the MIL-PRF-23827C specification.
AeroShell Grease 33 can be used for routine lubrication on Boeing aircraft for applications where MIL-PRF-23827C or BMS 3-24 is specified. AeroShell Grease 33 can also be used in some applications on Boeing aircraft which require use of MIL-G-21164D. Other applications on Boeing aircraft which require use of MIL-G-21164D and some other greases are being reviewed and in due course Boeing will issue details of the full range of applications.
AeroShell Grease 33 can be used for routine lubrication in applications where MIL-PRF-23827C is specified on aircraft manufactured by McDonnell Douglas, Airbus Industrie, BAe Regional Aircraft, Fokker and Gulfstream (except for wheel bearings, applications above 121°C and sliding applications requiring molybdenum disulphide).
Other aircraft manufacturers, such as Canadair, Saab and Lockheed are evaluating AeroShell Grease 33 with the aim of approving it for use on their aircraft. Operators should regularly check with these manufacturers for the latest status.
The following pictures illustrate the superior load-carrying and anti-corrosion properties of AeroShellGrease 33 (green) when compared with a competitive grease meeting the MIL-PRF-81322F specification (red):
Four-Ball EP test (ASTM D2596)
One test ball rotates on three fixed balls in a cup filled with grease
- Load: 160kg; Speed: 1770 rpm
- Duration: 10 seconds, or until weld occurs, whichever comes first
AeroShell Grease 33 – small wear scars
Competitor grease – lubrication failure and welding
Timken EP Test (ASTM D2509)
- Test cup rotates on test block under load while being continuously fed with fresh grease
- Load: 40lbs; Speed: 800rpm
- Duration: 10 minutes, or until noise and vibration indicate failure, whichever comes first.
- Wear scar measured on completion of test
AeroShell Grease 33 – small wear scar
Competitor grease – large wear scar
Corrosion Prevention (Modified ASTM D1743)
- Bearings: Timken cone and roller assembly
- Procedure: bearings packed with test grease and rotated under light load for 60 seconds, then submerged in 3% salt solution for one minute and then stored at 52ºC and 100% humidity for 12 hrs. Bearings disassembled and bearing races examined for rust.
AeroShell Grease 33 – no corrosion
Competitor grease – corrosion between rollers and race
AeroShell Grease 33 – taking airframe lubrication into the next millennium.