blade leading edge are not permitted.
c) Nicks or dents less than 0.250 inch (6.35 mm) on the blade leading edge are permitted if you do a borescope inspection at 300 APU hours.
NOTE: Subsequent inspections are required at 3000 APU
____ hour intervals, if the damage does not change and no cracks have developed at this inspection.
d) Damage to the hub fillet radii is not permitted. e) Unusual bends or damage to the leading edge of the impeller blades are not permitted.
(j)
When you complete the inspection, carefully remove the borescope and the guide tube from the inspection port.
(k)
Install the borescope inspection cover on the accessory drive adapter with the two washers and the nuts. 1) Tighten the nuts to 36-40 pound-inches (4.0-4.5 N.m).
(l)
If the high turbine inspection is not to be done at this time, install the crank cover on the accessory gearbox: 1) Install the new packing lubricated with engine oil, on the
crank cover. 2) Install the crank cover on the accessory gearbox housing with the two washers and the nuts. 3) Tighten the nuts to 36-40 pound-inches (4.0-4.5 N.m).
S 296-007
(7)
Do the borescope inspection of the high turbine (Fig. 605):
(a)
Do this task for the two igniter plugs: "Igniter Plug Removal" (Ref 49-41-04/401).
CAUTION:_______DO NOT USE FORCE TO INSTALL THE GUIDE TUBE. THE GUIDE TUBE MUST EASILY INSTALL IN THE PORT. DAMAGE TO THE GUIDE TUBE CAN OCCUR.
(b)
Install the PWC 41492 guide tube in one of the igniter plug ports. 1) Attach the guide tube to the boss.
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MAINTENANCE MANUAL
GAS GENERATOR CASE
SEAL COVER
GASKET
A
IGNITER PLUG
HIGH TURBINE-RIGHT
(LEFT SIDE EQUIVALENT)
A SEE A
IGNITION EXAMPLE - BOTH SIDES CABLE
A
HIGH PRESSURE ROTOR
GUIDE TUBE
INSPECTION AREA A-A High Pressure Turbine Blades and Vane Ring Borescope Inspection Figure 605
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CAUTION:_______BE VERY CAREFUL WITH THE BORESCOPE DEVICE. THIS DEVICE CAN BE EASILY DAMAGED. DO NOT TWIST OR HOLD THE DEVICE TIGHTLY. DO NOT LET THE BORESCOPE DEVICE FALL TO THE GROUND. DAMAGE TO THE BORESCOPE CAN OCCUR.
(c) Connect the fiberscope cable to the light source.
1) Adjust the light intensity to make the light brighter if it is necessary.
CAUTION: MAKE SURE THE ACTUATOR LEVER FOR THE DISTAL TIP IS IN THE
_______ NEUTRAL POSITION WHEN YOU INSTALL OR REMOVE THE BORESCOPE. THIS WILL PERMIT THE TIP TO MOVE FREELY IN THE GUIDE TUBE.
CAUTION: MAKE SURE YOU LET 40 MINUTES GO BY AFTER AN ENGINE
_______ SHUTDOWN BEFORE YOU DO THE INSPECTION. DAMAGE TO THE FIBERSCOPE CAN OCCUR IF THE APU IS TOO HOT.
(d)
Slowly install the borescope tip in the guide tube while you look through the eyepiece. 1) Stop the installation when you can see the high turbine
blades.
(e)
Loosen the knurled knob on the PWC 41393 fixture.
(f)
Align the distal tip and slowly turn the eyepiece to examine the tip, the root, and the airfoil sections of the high turbine blade.
(g)
If it is installed, remove the crank cover from the rear of the accessory gearbox: 1) Remove the two nuts and the washers that attach the crank
cover to the accessory gearbox. 2) Remove the crank cover from the accessory gearbox with the PWC 41325-001 puller. 3) Remove and discard the packing.
(h)
Attach a wrench to the square end socket of the gear shaft.
CAUTION: MAKE SURE THE BORESCOPE DISTAL TIP DOES NOT ENGAGE THE
_______ HIGH TURBINE BLADES. DAMAGE TO THE BLADES AND THE BORESCOPE CAN OCCUR WHEN YOU TURN THE LOAD SECTION.
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