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75-31-03
ALL ú ú C01 Page 404 ú Nov 15/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / /
CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
S 434-021-C00
(9) Install the four D- head bolts and nuts.
NOTE:____The bolthead must be on the aft side for the IGV. It must be on the forward side for stages 1, 2 and 3.
S 434-020-C00
(10)
Tighten the nuts to 105-115 pound-inches (12-13 Newton meters).
S 434-016-C00
(11)
Install the VSV actuator (AMM 75-31-01/401).
S 434-017-C00
(12)
If the left bellcrank assembly is to be installed, attach the VSV feedback cable to the bellcrank lever arm.
(a) ON ROD-END BEARINGS WITH DROP-IN UNIBALLS
(WITH CFMI SB 72-667),
lubricate the uniballs on the rod end bearing.
1) Lubricate the two sides of the uniballs on the rod end
bearing with LPS-1 penetrating oil.
a) Let the uniballs soak in the oil for 2-3 minutes.
2) Turn the uniballs back and forth in the two directions fully three times, until there is a smooth operation of the uniballs. a) If more oil is necessary for smooth operation, do the
above steps again. 3) Wipe off all unwanted oil with a lint free cloth.
(b)
ON ROD-END BEARINGS WITH UNIBALLS STAKED IN WITH TEFLON SLEEVES (WITHOUT CFMI SB 72-667), put the rod end bearing into position on the lever arm.
(c)
Install the washer and bolt (the bolthead must be away from the compressor case).
(d)
Install the slotted nut.
(e)
Tighten the nut to 20-40 pound-inches (2.3-4.5 Newton meters) while you align the nut slot with the cotter pin hole.
NOTE: Replace the nut if you cannot get the minimum torque
____ value or if you go above the maximum torque value.
(f) Install the cotter pin.
NOTE: Bend the ends around the nut flats.
____
S 414-018-C00
(13) Close the fan thrust reverser half (AMM 78-31-00/201).
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
75-31-03
ALL ú ú C01 Page 405 ú Mar 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / /
CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
VARIABLE BLEED VALVE SYSTEM - DESCRIPTION AND OPERATION
_______________________________________________________
1. General (Fig. 1 and 2)
_______
A. The variable bleed valve (VBV) system controls the amount of air that flows through the high pressure compressor (HPC).
B. The engines have 12 bleed valves installed around the fan frame mid box structure. When the bleed valves are open, a portion of the primary air flow from the booster (low pressure compressor) is permitted to go through the mid box and into the secondary (fan) air flow.
C. The bleed valves open during low and transient operations to increase the booster mass flow and to improve booster and HPC matching. The bleed valves open fully during rapid decelerations or thrust reverser operation. A hydromechanical computer, integral within the main engine control (MEC), determines the bleed schedule as a function of the angular setting of the variable compressor stator vanes at steady-state operation and during accelerations or as modified by the VBV feedback reset system. For additional information on the VBV feedback system, refer to the description of the Fuel Control System (AMM 73-21-00/001). The VBV system includes the following:
(1)
A power unit consisting of a fuel powered hydraulic gear motor. Fuel is supplied from the high pressure pump as scheduled by an external signal.
(2)
A mechanical transmission system that consists of:
(a)
A bleed valve stop mechanism.
(b)
A bleed valve and master ballscrew actuator unit consisting of a speed reduction gearbox and a ballscrew actuator linked to a bleed valve door.
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