(2)
Loosen the thermostatic valve assembly mounting bolts.
B. Manually support the duct and loosely install the two clamps with the screws and nuts.
C. Install the duct forward connecting ring at the nose cowl.
D. Loosely install the duct forward coupling nut at the nose cowl.
E. Loosely install the duct aft coupling nut on the thermostatic valve.
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Feb 20/92 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 75-11-61 Page 401
F. Tighten the thermostatic valve assembly mounting bolts.
G. Tighten the duct forward coupling nut at the nose cowl.
H. Tighten the two duct clamps.
I. Tighten the duct aft coupling nut at the thermostatic valve.
J. Use washers to shim between the clamp and the support bracket at the location shown in Fig. 401 to prevent a preload on the thermal anti-ice duct.
NOTE: The maximum height of the washers is 0.30 inch.
K. Tighten all the thermal anti-icing duct clamps.
L. Make sure the clearance between the cowl frames and the air ducts is a minimum of 0.125 inch.
(1)
Place modeling clay on the cowl frames that are between the cowl frames and the air ducts.
(2)
Close the right side cowl panel.
(3)
Open the right side cowl panel.
(4)
Make sure that the compressed part of the modeling clay has a thickness of a minimum of
0.125 inch.
(5)
Adjust the air ducts if the clearance is not correct.
(6)
If the air ducts are moved, make sure there are no air leaks the next time you operate the engine.
M. Close the right side removable cowl panel.
500
75-11-61 Page 402 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 20/92
G42814
500 Nose Cowl Anti-Icing Duct Installation
Feb 20/92 Figure 401 75-11-61
Page 403
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
GENERATOR COOLING - DESCRIPTION AND OPERATION
1. General
A. The generator is a high speed unit that requires cooling whenever it is operating. To provide this cooling the generator is supplied with engine bleed air. A port on the outer fan case of the engine is connected by a large duct, to a fitting on the end of the generator. An exhaust duct, attached to the generator shroud, mates with the cooling air exhaust port in the engine cowl panel. (See figure 1.)
B. When an engine is operating, low pressure fan air is forced through the large duct into the generator. The air circulates around the inside of the generator then leaves through the screened openings around the forward end of the generator casing. After leaving the generator, the air enters the generator shroud, passes through the exhaust duct and is then exhausted overboard through the exhaust port in the engine cowl panel.
500
May 15/68 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 75-21-0 Page 1
Generator Cooling 500
75-21-0 Figure 1 May 15/68
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
COMPRESSOR BLEED SYSTEM - DESCRIPTION AND OPERATION
1. General (Fig. 1 through 3)
A. The compressor bleed air system is primarily designed to permit operational flexibility by allowing high compressor discharge air to bleed into the fan discharge duct.
B. In current JT8D engines this is accomplished by two basic arrangements of 8th and 13th stage bleed valves:
(1)
Prior to P&WA SB 5425: Two 13th stage bleed valves (at four and seven o'clock positions on annulus of diffuser case) bleed compressor discharge air (Ps4) into the fan stream. On current engines an additional, single 8th stage bleed valve on the rear compressor case (acting in unison with the 13th stage valves) bleeds 8th stage compressor air into the fan stream. Actuating air (Ps4) to the 8th and 13th stage bleed valves is interrupted by the pressure ratio bleed control.
(2)
Incorporating P&WA SB 5425: One 13th stage bleed valve (at four o'clock position on annulus of diffuser case) bleeds compressor discharge air (Ps4) into the fan stream. Three 8th stage bleed valves on the rear compressor case bleed 8th stage compressor air into the fan stream. Both the 13th stage bleed valve and the 8th stage bleed valves are actuated by Ps4 air; actuating air to the 13th stage bleed valve is interrupted by the start bleed control valve (Fig. 3), and actuating air to the 8th stage bleed valves is interrupted by the pressure ratio bleed control.
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