SUBTASK 72-00-00-296-194-G00
(11) Use the borescope to examine the rotor blades on the 1st-stage high pressure turbine (HPT)
(Figure 613).
NOTE: There are tip notches on the convex side of the four blades that are 90 degrees apart
on the first-stage rotor. The tip notches are for reference only and are not signs of
erosion.
If it is necessary, you can clean the blades with solvent, B00148 before the inspection.
(a) Examine all the areas of the rotor blades on the 1st-stage HPT for the conditions that
follow:
Condition Maximum Serviceable Limit
Codep coat that is gone Permitted with no quantity limit, if there are no holes or
cracks in the affected area.
Oxidation of the parent metal (green or black discoloration) Permitted with no quantity limit, if there are no holes or
cracks in the oxidized area.
Plugged cooling holes Permitted.
(b) Examine the leading edges of the rotor blades on the 1st-stage HPT for the conditions
that follow:
Condition Maximum Serviceable Limit
Material that is gone and tears in area 'A' Permitted, one blade in each set can have one sign of this
damage. The damage must have a diameter that is less than
the radial space between the leading edge holes (0.10 inch
(2.54 mm)). The damage must not extend past the gill holes.
Material that is gone from area 'B' Not permitted.
Dents and cracks from hits in area 'A' Permitted, if they do not extend past the gill holes.
Axial cracks (with no sign of a hit) in area 'A' Permitted, if the cracks do not extend past the gill holes.
Dents and radial cracks in area 'B' (not in the root radius) Permitted, if the damage has a length that is less than the
space between the leading edge holes (0.10 inch (2.54
mm)).
Dents and radial cracks in area 'B' (includes the root
radius)
Permitted, if there is no torn metal.
Axial cracks in area 'B' Not Permitted.
Radial cracks (with no sign of a hit) in area 'B' Permitted, if the crack does not connect two or more leading
edge holes.
Radial cracks (with no sign of a hit) in area 'A' Permitted.
(c) Examine the trailing edges of the rotor blades on the 1st-stage HPT for the conditions
that follow:
Condition Maximum Serviceable Limit
Cracks Not Permitted.
Dents Permitted, if the dent diameter is less than the span between
four trailing edge holes or 0.140 inch (3.56 mm). No trailing
edge holes can be closed by the dent.
(d) Examine the concave surfaces of the rotor blades on the stage 1 HPT for the conditions
that follow:
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-00-00
NoC
Page 694
D633T1B7 Aug 22/2017
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ABX 001-007, 011, 012, 016-019, 021, 022, 025, 101,
109, 114, 115, 314-999
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