B. Access
(1) Location Zone
311 Area Aft of Pressure Bulkhead
C. Procedure
S 865-229
(1) Seal the left visco jet drain with vinyl adhesive tape.
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747-400 MAINTENANCE MANUAL
S 865-231
(2) Connect the pneumatic test set to the left dedicated static system.
(a)
Connect the static (vacuum) source in the pneumatic test unit through the static control valve to the static cutoff valve.
(b)
Connect the static port test adapter to the static cutoff valve through the static system test gage and flow restrictor.
(c)
Connect the test adapter to the left dedicated static pressure port.
(d)
Open the static cutoff valve.
S 795-290
(3) Do a leak test of the left dedicated static system.
CAUTION: MAKE SURE THAT THE PITOT LINE PRESSURE IS EQUIVALENT OR
_______ MORE THAN THE STATIC LINE PRESSURE. KEEP THE STATIC PRESSURE CHANGES LESS THAN 5000 FEET FOR EACH MINUTE. MAKE SURE THAT THE DIFFERENTIAL PRESSURE STAYS BETWEEN 0 AND 5.0 INCHES OF MERCURY. YOU CAN CAUSE DAMAGE TO THE PITOT-STATIC SYSTEM.
(a)
Apply vacuum to the left dedicated static system equivalent to 5,000 feet of altitude above field elevation (ambient pressure minus 4.55 |0.16 in. Hg).
VACUUM.
(b)
Close the static cutoff valve to the system when the instrument shows the necessary altitude.
(c)
Stop for 2 to 3 minutes to permit the system to become stable.
(d)
Write the altitude.
(e)
Stop for 1 minute and read the altitude again.
(f)
Make sure that the altitude does not go down by more than 80 feet (0.07 in. Hg).
CAUTION:_______ HOLD THE VACUUM, AS AN ALTERNATIVE, BEHIND THE CUTOFF
VALVE DURING THE CUTOFF TIME. YOU CAN CAUSE DAMAGE TO THE
EQUIPMENT WHEN YOU OPEN THE CUTOFF VALVE WITHOUT THE
S 845-233
CAUTION: MAKE SURE THAT THE PITOT LINE PRESSURE IS EQUIVALENT OR MORE
_______ THAN THE STATIC LINE PRESSURE. KEEP THE STATIC PRESSURE CHANGES LESS THAN 5000 FEET FOR EACH MINUTE. MAKE SURE THAT THE DIFFERENTIAL PRESSURE STAYS BETWEEN 0 AND 5.0 INCHES OF MERCURY. YOU CAN CAUSE DAMAGE TO THE PITOT-STATIC SYSTEM.
(4)
Open the static cutoff valve.
S 865-291
(5)
Put the left dedicated static system to ambient pressure.
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747-400 MAINTENANCE MANUAL
NOTE: You must release the vacuum from the cutoff valves slowly.
____
S 845-234
CAUTION: DO NOT DISCONNECT THE PNEUMATIC TEST SET WHEN THE PITOT-STATIC
_______ SYSTEM IS NOT AT AMBIENT PRESSURE. YOU CAN CAUSE DAMAGE TO THE EQUIPMENT.
(6)
Remove the static port test adapter from the left dedicated static pressure port.
S 845-235
(7)
Examine the left dedicated static pressure port for unwanted materials and rough locations on the inner and outer surfaces.
S 865-461
(8)
Remove the vinyl adhesive tape from the left visco jet drain.
TASK 34-11-00-795-240
13. The Right Dedicated Static System Leak Test
___________________________________________
A. Standard Tools and Equipment
(1)
Adapters
(a) Static port test adapter - NAVAIDS, P/N 33410LH-125-4 (1 required)
(2)
Pneumatic Test Set
(a) Vaccum source, 0 to 30 inches of mercury (absolute)
(3)
Gages
(a) Static system test gage - required to indicate 0 to 30 inches of mercury (absolute) with accuracy of |0.1 (readable to |0.01) inch of mercury or |200 (readable to |20) feet.
(4)
Flow restrictors, control valves, and cutoff valves as required.
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