EFFECTIVITY
ALL CFM56 ENGINES
CFMI PROPRIETARY INFORMATION
CFM56-ALL TRAINING MANUAL
HIGH PRESSURE
COMPRESSOR
BORESCOPE
INSPECTION
Page 94
Sep 03
N2 ROTOR INDEXING
(ALL) :
Stage 4 of the High Pressure Compressor is the rst
stage where the blades are retained in position with blade
locks. These locks can be used to determine a reference
point.
The following procedure enables the reference point for
the N2 rotor to be obtained. Refer to the AMM for more
information.
1. Open the VSV system. (AMM section 75-31-00).
2. Insert probe No 3 (green) into borescope port S4,
and look rearward at the compressor stage 4 rotor
blades.
3. Rotate the core (manually, or with a tool) in the
CW direction so that blades convex side comes
into view. Continue turning until the rst blade lock
appears in the eld of view.
4. Continue rotating the core until the second blade
lock appears. This lock is located 2 blades past the
rst blade lock.
5. The next blade is blade No 1. Position the leading
edge of blade No 1 in line with the leading edge of
the stage 4 stator vane.
6. If using a rotation tool, position the pointer on the
protractor to the 0 alignment mark.
If turning the core manually through the
handcranking pad, position the wrench to the top
vertical position.
The N2 rotor is now in the zero reference position.
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