(b)
Remove the lower shroud.
S 946-001
CAUTION: PERMIT THE TEMPERATURE OF THE APU ENGINE TO DECREASE TO A
_______ SATISFACTORY LEVEL BEFORE YOU EXAMINE THE APU ENGINE. THE MAXIMUM ALLOWABLE TEMPERATURE IS 150°F (66°C). TOO MUCH HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.
(4)
Prepare the borescope equipment to examine the internal parts of the APU.
S 296-002
(5)
Do a borescope inspection of the lining assembly in the combustion chamber:
(a)
Remove the combustor unit (AMM 49-31-42/401).
(b)
Examine the combustor unit:
1) Replace the combuster unit if the cracks, erosion, deformation, or other damage are greater than the limits in Fig. 601.
S 296-003
(6) Examine the turbine section of the compressor and turbine assembly:
(a)
Replace the APU if the cracks, erosion, deformation, or other damage are greater than the limits given in Fig. 601.
(b)
Put the borescope through the turbine torus assembly.
(c)
Visually examine the part of the turbine torus assembly you can get access to for cracks, erosion, deformation and worn areas.
(d)
Visually examine the welds and the adjacent material in the
turbine plenum assembly for cracks.
(e)
Examine the turbine plenum gasket for signs of deterioration
and leakage.
(f)
Look at the guide vanes of the turbine nozzle for these
problems:
1) Erosion damage with a depth more than 0.125 inch on the
leading edge of the guide vane is not permitted. 2) Feather type damage with a depth more than 0.125 inch on the trailing edge of the guide vane is not permitted. 3) Erosion damage with a depth more than 0.050 inch or longer than 3.0 inches on the guide vane is not permitted.
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49-21-00
ALL ú ú 02 Page 608 ú Jul 12/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
(g) Look at the blades of the turbine wheel and the trailing edge of the turbine exducer for these problems:
NOTE: Axial movement of the turbine wheel and the turbine
____ exducer is permitted. The axial movement is cause by the clearance between the journal bearing, bearing spacer and sleeve of the bearing housing assembly.
1) Cracks in the turbine wheel are not permitted unless the crack is found on the blade tips. 2) Cracks longer than 0.200 inch and above the blade root on the trailing edge of the turbine exducer are not permitted. 3) Cracks longer than 0.400 inch in the hub area between the turbine exducer blades are not permitted.
(h)
Visually examine the part of the housing assembly for the
second stage diffuser that you can get access to for cracks.
(i)
Remove the borescope from the turbine torus assembly.
S 946-005
(7)
Disassemble the borescope equipment.
S 426-007
(8)
Install the combuster unit (AMM 49-31-42/401).
S 416-017
CAUTION: KEEP A MINIMUM CLEARANCE OF 0.18 INCHES (5 MM) BETWEEN THE
_______ ENGINE, FIRE DETECTOR, CLAMPS AND LOWER SHROUD.
BE CAREFUL WHEN YOU MOVE THE LOWER SHROUD. DAMAGE TO THE SHROUD DRAIN LINES CAN OCCUR.
(9) Install the lower shroud:
(a)
Hold the lower shroud against the upper shroud.
(b)
Close the shroud latches.
S 416-018
(10) Close the APU cowl door:
(a)
Disconnect the door support rods.
(b)
Put the support rods in the clips on the APU cowl door.
(c)
Close the APU cowl door.
(d)
Close the latches for the APU cowl door.
S 866-019
(11) Set the circuit breaker and the switch:
(a)
Remove the DO-NOT-CLOSE tag and close this circuit breaker:
1) E3-3 Electrical Shelf, APU Control Unit
(b)
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