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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757 MAINTENANCE MANUAL
AIRPLANE SERVICING (LUBRICATION) - DESCRIPTION AND OPERATION
____________________________________________________________
1. General
_______
A. Lubrication (Fig. 1)
(1) Certain bearings and bushings used throughout the airplane have teflon surfaces and do not require additional lubrication.
CAUTION: ONLY LUBRICATE BEARINGS AND BUSHINGS THAT HAVE LUBRICATION
_______ FITTINGS. LUBRICATION OF BEARINGS AND BUSHINGS WITH TEFLON SURFACES WILL CAUSE DETERIORATION OF THE TEFLON AND REDUCE BEARING LIFE.
(2)
The subjects of this section contain information about airplane lubrication (items to be lubricated, lubricant to be used and method of application).
(3)
Lubrication equipment, such as grease guns, brushes and oil cans must be clean and free of everything but the lubricant to be used.
NOTE: Some incompatibility may exist between MIL-PRF-23827 and
____ MIL-G-21164 greases that are thickened with clay and those thickened with lithium soap. Therefore, intermixing of brand name greases that employ different thickening systems should be avoided. Whenever changing a brand name grease, flush out old grease to minimize intermixing.
FILL TO LEVEL PAINT BRUSH OF FILLER PORT GREASE GUN HAND GREASE GUN OIL CAN
(SAMPLE SYMBOLS)
Lubrication Symbols
Figure 1
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ú 01 Page 1
ú Jan 28/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
(4)
On the illustrations, lubrication blocks are used to locate the component or unit to be lubricated. Each block is divided into two sections. One section calls out the method of application, and the other section calls out the type of lubricant.
(5)
Lubrication of sealed ball and roller bearings having lubrication provisions requires care to prevent seal blow-out during lubrication. A restrictor type adapter used on the grease gun will aid in preventing seal blow-out by limiting the rate of grease flow. An Alemite Midget flush adapter No. 314150 is recommended for flush type grease fittings. Lincoln/St. Louis Medium Pressure Control Valve, which limits pressure to less than 2500 psi, is recommended with a ZERK Type 1728B lubrication fitting. The flow of grease should be discontinued at the first evidence of seal deformation or grease seeping from the bearing.
(6)
Lubrication pressures from 100-200 psi should normally be sufficient for the joint to accept grease. However, higher pressures may be required in some cases. Lubrication pressures in excess of 2500 psi may cause the lubrication fitting to come loose (blow out) from the joint.
(a) If a fitting "blow out" occurs 1) Check the lubrication path of the joint for obstruction or
foreign material. 2) Install a new fitting (Ref 20-10-29).
B. BMS 3-33 is a general purpose grease that provides improved corrosion and wear protection. BMS 3-33 grease is a preferred alternative to MIL-G-23827, BMS 3-24 and where MIL-G-21164 is listed as an option to MIL-G-23827 for all Boeing models. One exception is the 757 Trailing Edge Flap Torque Limiter which will continue to require MIL-G-23827.
NOTE:____Avoid intermixing different greases. If changing grease, force the old grease out by replacing with new until only the new grease is seen exiting the fitting.
2. Referenced Procedures_____________________
A. AMM 20-10-29/401 - Lubrication Fittings
(1) General Purpose Lubricants
(a) MIL-G-21164 and MIL-G-23827 are referred to as general purpose airplane lubricants. MIL-G-21164 is equivalent to MIL-G-23827 but it has 5% molybdenum disulfied. This makes the MIL-G-21164 black or very dark. The MIL-G-21164 grease can cause stains which are difficult to remove. Each operator can make the decision of which grease to use. The data that follows can help you make your decision. 1) MIL-G-23827 is usually better for:
a) Instrument bearings.
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