2) 2nd-stage turbine disk transmits energy to 1st-stage disk. An aft flange supports aft
pressure balance seal and integral coupling nut and pressure tube.
3) Turbine blades are used in both stages and are cooled by compressor discharge air
which flows through blade shank into airfoil. 1st-stage blade cooling is a
combination of internal convection, leading edge internal impingement, and external
film cooling. Convection cooling of mid-chord region is accomplished through
serpentine passages. Leading edge circuit provides internal convection cooling by
impingement of air against inside surface, and by flow through leading edge and gill
holes. Convection cooling of the trailing edge is provided by air flowing over pinned
fins and finally through trailing edge exit holes. 2nd-stage blades are entirely cooled
by convection, with all of cooling air discharged at blade tip.
4) Turbine rotor spacer is a cone which serves as structural support between turbine
disks and transmits torque from 2nd-stage. Radial integral vanes on spacer
increase pressure of cooling air supply on its way to 1st-stage turbine blades.
5) Catenary shaped thermal shield contains turbine rotor cooling air and provides
rotating portion of interstage seal. Shield is rabbeted and bolted to rotor disk
structure and transmits part of torque from 2nd-stage disk. Forward and aft grooves
are used to trap a ring seal wire for preventing parasitic leakage of blade cooling air.
6) Blade retainers serve two primary functions: they prevent blades from translating
axially under gas loads, and they seal forward face of 1st-stage rim and blade
dovetail, and aft face of 2nd-stage rim and blade. An additional function is to cover
rotor bolt ends at rotor rim thus preventing drag loss.
7) Nut portion of coupling nut/pressure tube secures rotor assembly to high pressure
compressor rear shaft. Pressure tube serves to separate internal cooling air from
engine sump pressure region.
8) Pressure balance seal provides a sealing cavity for directing cooling air to diffuser.
Rotating integral diffuser vanes are spiralled and used to accelerate and direct
compressor discharge cooling air into rotor cavity. Air is used to cool rotor and 1st
and 2nd-stage blades.
B. Low Pressure Turbine Rotor and Stators
(1) Low pressure turbine rotor and stator consists of 1st-stage low pressure turbine nozzle, low
pressure turbine stator, and low pressure turbine rotor.
(2) 1st-Stage Low Pressure Turbine Nozzle (Figure 1)
(a) 1st-stage low pressure turbine nozzle consists of eleven segments each containing five
hollow vanes. Segments are supported by rails in low pressure turbine forward case.
Hollow vanes are used to carry 7th-stage compressor bleed air into pressure balance
seal attached to 1st-stage nozzle. The forward case provides flanges to bolt to HPT stator
case and to LPT aft stator case for support. Ports are provided in case for attachment of
7th stage bleed air tubing, thermocouple and pressure probes, and for borescope
inspections.
(3) Low Pressure Turbine Stator (Figure 2)
(a) Low pressure turbine stator consists of casing, nozzle segments for stages 2 through 4
and four stages of turbine shrouds.
1) The Casing serves as load carrying structure between the low pressure turbine
forward case and turbine rear frame. The casing retains turbine shrouds and nozzle
segments, and may be either a one-piece, 360° design or a 2-piece, 180° split type.
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-50-00
NoC
Page 6
D633T1B7 Dec 22/2016
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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