B.  Equipment and Materials
(1)  
An air pressure source with two individually regulated outlets, the pressure of which can be accurately set at pressures between 25.00 and 100.00 inches of mercury absolute. All pressures are to be monitored by pressure gages with an accuracy of + 0.5%. Shutoff valves must be provided on the source side of all gages (Fig. 501).

(2)  
Gage - Pressure, Model C, 0 - 50 or 0 - 100 inch HgA, 0.1% Full Scale, Hiese

(3)  
Shutoff Valve (4), A311 - 1/8" ID, Dwyer Instr.

(4)  
T-Fitting (4), A343-1 - 1/8" ID, Dwyer Instr.

(5)  
Fitting (2), A339 - 1/8" ID, Dwyer Instr.

(6)  
Tubing 30 feet, A225 - 1/8" ID, Dwyer Instr.

(7)  
Wheatstone Bridge, Shallcross 638-R, Shalltronix

C.  Prepare for Test
(1)  
Obtain access to inlet pressure line test "TEE" by removing cowl panels on engine(s) to be tested (Ref Chapter 71, Power Plant).

(2)  
Observe the following precautions for maintenance in engine exhaust section.

(a)  
Pull applicable engine START circuit breaker on circuit breaker panel P6-2, and placard circuit breaker with DO NOT CLOSE.

(b)  
Placard thrust reverser controls with DO NOT OPERATE.

(c)
Open ENGINE-1 and ENGINE-2 EPR circuit breakers on circuit breaker panel P6.

(3)  
Obtain access to exhaust pressure line connection on engine(s) by opening cowl panel on engine(s) (Ref Chapter 71, Power Plant).

(4)  
Disconnect exhaust pressure line from exhaust pressure manifold outlet elbow on engine(s) (Fig. 501).

WARNING:  SERIOUS INJURY CAN OCCUR IF ENGINE IS STARTED AND/OR IF THRUST REVERSER IS OPERATED.
563 
Oct 20/85  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  77-11-0 Page 501 

D.  Test Engine Pressure Ratio Indicating System
CAUTION:  DO NOT EXCEED 42 INCHES OF MERCURY ABSOLUTE (20.63 PSIA) ON INLET PRESSURE LINE, OR 80 INCHES OF MERCURY ABSOLUTE ON EXHAUST PRESSURE LINE WHILE LINES ARE CONNECTED TO TRANSMITTER. MAXIMUM PRESSURE DIFFERENTIAL SHALL NOT EXCEED 51 INCHES OF MERCURY (25.05 PSIA) DURING THESE TESTS TO PREVENT PERMANENT DAMAGE TO THE TRANSMITTER.
(1)  
Test Inlet Pressure Line Leakage

(a)  
Connect test hose from test apparatus to inlet pressure line Pt2 test "TEE" on bottom of engine aft of cowl flange (Fig. 501). Do not connect test hose to exhaust pressure line at this time.

(b)  
On airplanes with digital readout indicators, mask off pressure inlet coupler on accessory drive housing and connect test apparatus to inlet pressure test "TEE" on the bottom of the engine, aft of the cowl flange (Fig. 501). Do not connect test hose to exhaust pressure line at this time.

(c)  
Slowly apply pressure of 42 inches of mercury absolute (20.63 psia) to inlet pressure line, then close valve to pressure source.

NOTE:  Absolute pressure is the sum of gage pressure and barometric pressure. For example, if barometric pressure is 30.1 inches of mercury (14.79 psia), gage pressure required is 42 minus 30.1 or 11.9 inches of mercury (5.85 psia).

(d)  
Check that pressure leakage does not exceed 0.25 inches of mercury during a 5-minute period.

(e)  
Relieve pressure slowly through test apparatus vent valve.

(2)  
Test Exhaust Pressure Line Leakage

(a)  
With inlet pressure test line still connected, connect test hose from test apparatus to exhaust pressure line.

(b)  
Slowly apply pressure of 32 inches of mercury absolute (15.71 psia) to inlet pressure line.

(c)  
Slowly apply pressure of 70 inches of mercury absolute (34.38 psia) to exhaust pressure line, then close valve to pressure source.

(d)  
Check that pressure leakage does not exceed 0.25 inches of mercury in exhaust pressure line during a 5-minute period.

(e)  
Reduce pressure in both lines through test apparatus vent valves.

Engine Pressure Ratio Indicating System Test Connections  563 
77-11-0  Figure 501 (Sheet 1)  Oct 20/85 
Page 502 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

563  Engine Pressure Ratio Indicating System Test Connections 
Feb 15/80  Figure 501 (Sheet 2)  77-11-0 
Page 503 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

CAUTION:  REDUCE EXHAUST LINE PRESSURE BELOW 50 INCHES OF MERCURY ABSOLUTE (24.56 PSIA) BEFORE REDUCING INLET PRESSURE TO PREVENT DAMAGE TO TRANSMITTER.
　
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