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51-10-00
ALL ú ú 01 Page 617 ú Feb 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
DOOR AND HATCH LEAK CHECK - INSPECTION/CHECK
____________________________________________
1. General_______
A. This procedure has this task:
(1) Doors and Hatches Leak Check
TASK 51-11-00-286-011
2. Doors and Hatches Leak Check____________________________
A. General
(1) This task is for the door and hatch leak check.
B. Equipment
(1)
ST6760A-1, Ultrasonic Leak Probe Tool
(2)
ST9999-VBA-201, Vacuum Generator (No. 2 window, door and hatch)
(3)
ST9999-VB, Door and Hatch Vacuum Blanket
C. Procedure
S 846-012
(1) Do the steps that follow to prepare the vacuum blanket:
(a)
Calibrate the ultrasonic leak detector as follows:
1) Use the white noise generator to set the PASS/FAIL indication to 40dB.
(b)
Connect the vacuum generator to the vacuum blanket.
(c)
Connect the vacuum generator to a compressed air source.
S 486-013
(2) Install the vacuum blanket over the exterior of the door or hatch.
(a)
Make sure the vacuum blanket covers the entire exterior of the door or hatch and the gap between the door or hatch and the fuselage.
(b)
Remove all bubbles and creases.
(c)
Make sure the vacuum gauge indicates 18 to 20 inches (HG) of vacuum when the blanket is attached to the door or hatch.
S 276-014
(3) Do a check of the noise levels around the interior of the door or hatch that you test as follows:
(a)
Hold the ultrasonic leak detector approximately 2 inches from the door or hatch.
(b)
Move the ultrasonic leak detector around the edge of the door or hatch.
(c)
Use the headphones and watch the noise meter on the ultrasonic leak detector.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
S 816-015
(4) If the noise levels are more than ed 40dB do the steps that follow:
(a)
Determine the exact location of the noise with a stethoscope.
(b)
Remove the vacuum blanket from the door or hatch.
(c)
Make sure the door seal or hatch seal is clean and in good condition; free from wrinkles, kinks, cracks, rips, tears, etc. 1) If you find wrinkles, kinks, cracks, rips, tears, or other
types of damage, do the applicable replacement.
(d)
Install the vacuum blanket again and check for leaks.
NOTE: You will have to repeat the installation of the vaccum
____ blanket and do a check for leaks to make sure all the leaks have been corrected.
(e)
If the seal does not need to be replaced do the applicable door or hatch adjustments.
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