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737-300/400/500MAINTENANCE MANUAL
(j) If the test is to be run again, do a 20 minute cool-down time.
1) Do this with the equipment cooling fans operatiing at zero differential pressure.
NOTE: This will make sure the fans will not overheat.
____
S 722-013
(8) Do the leakage rate analysis.
(a) Get the correction factor from Figure 201 and correct the time data for each data point.
NOTE: You want to use the correction factors with the bleed
____ down time data when the ambient pressure does not equal
14.7 psi and/or the cabin temperature does not equal 70 degress F.
(b)
Plot each time-pressure data point onto the chart shown in Figure 202.
(c)
Draw a best fit straight line through the data points plotted in Figure 202.
(d)
If the plotted line is in the upper zone in Figure 202, the pressure leakage rate is satisfactory.
E. Areas of Possible Leakage
S 712-019
(1)
Do a the forward outflow valve test (AMM 21-43-11/401).
S 792-020
(2)
Do a check of the areas that follow for excessive leakage:
NOTE: Do this while the airplane is pressurized between 3 psid and
____
4 psid.
(a) Make sure the EE cooling automatic flow control valve is closed correctly.
NOTE: Valves with P/N 10-60704-1 thru 10-60704-6 should
____ close at differential pressures of 2.0 to 2.8 psi.
Valves with the P/N 10-60704-7 should close at differential pressures of 0.7 to 1.1 psi.
(b) Make sure the bilge drains which are found along the bottom center line of the airplane are correctly closed.
NOTE: The bilge drain valves close at approximately 2.0 psid.
____
(c)
Make a check of all door and hatch seals for leakage.
(d)
Make a check of all flight deck windows for leakage.
(e)
Make a check of the forward outflow valve for leakage.
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(f)
Make a check of the cabin pressure outflow valve seal for leakage.
(g)
Make a check of the cabin pressure safety relief valves for leakage.
(h)
Make a check of the cabin pressure negative relief valve seal for leakage.
(i)
Make a check of the water service panel seals for leakage.
(j)
Make a check of all air conditioning and APU duct seals at the pressure bulkhead penetrations (these are found in the A/C bay, aft pressure dome, right rear wheel well and forward pack bays) for leakage.
(k)
Make a check of the control cable seals in the pressure bulkhead penetrations for excessive leakage.
S 792-021
(3) Do a check of the areas which are difficult to access because they can also have leaks.
(a) Structure hidden by the wing-to-body fairing and the APU bulkhead area should be checked for potenntial structure and seal leaks.
F. Put the Airplane Back to its Initial Condition
S 792-009
(1)
Do a check of the Pitot Static system for leaks and correct
operation if it is necessary (AMM 34-11-00).
(2)
Open the equipment cooling flow control valve.
S 862-022
(3)
If the equipment cooling fans were selected from NORMAL to ALTERNATE, the switches must be returned to the NORMAL position.
S 862-010
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