TB 1-1520-240-20-108
(1) Examine fillet seal around window for cracks, cuts, and unbonding. If any of these conditions
exist, reseal locally with proseal 890.
(2) If water appears to enter around rivnut locations, remove attaching screw and washer.
Remove old sealant from screw and washer. Apply sealant between each screw and washer and between
each washer and window. Reinstall screw and torque to 10-14 inch pounds.
(3) After sealant has fully cured, perform a leak check in accordance with paragraph 8d above.
(4) After locally testing for leaks, if there is still water intrusion, it may be necessary to remove
the window and replace sealant tape under window. Remove window and inspect sealant tape for tears,
cracks and unbonding from aircraft structure. If any of these conditions exist, replace tape and install window
in accordance with TM 55-1520-240-23 or TM 1-1520-252-23. Again perform leak check in accordance
f.
For leaks around pilot, copilot or center windshields.
NOTE
Most leaks occur from improper sealing of the window, or
improper installation of attachment screws.
(1) Examine fillet seal around window for cracks, cuts, and unbonding. If any of these conditions
exist, reseal locally with proseal.
(2) After sealant has fully cured, perform a leak check in accordance with paragraph 8d above.
(3) After locally testing for leaks, if there is still water intrusion, remove window and inspect rubber
strip for tears, cracks and unbonding from aircraft structure in accordance with TM 55-1520-240-23 or TM
1-1520-252-23.
(4) If any of these conditions exist, replace rubber strip and install window in accordance with TM
55-1520-240-23 or TM 1-1520-252-23. Perform a leak check in accordance with paragraph 8d above.
g.
For leaks from the area above the overhead console.
(1) Remove the forward transmission forward faking in accordance with TM 55-1520-240-23
or TM 1-1520-252-23.
(2) Inspect the sealant in the area forward of the forward transmission to ensure that it has been
applied uniformly.
(3) If the sealant appears to have been applied improperly or not uniformly, remove all sealant,
clean structure and reapply proseal to all seams In the skin.
(4) For leaks around fasteners (rivets), apply sealant to all of the fasteners in the area. After
sealant has fully cured, perform a leak check In accordance with paragraph 8d above.
h.
For water/moisture from above the cockpit dome lights.
(1) Open the forward transmission work platforms. Pour a small amount of water in the area of
the forward transmission mounts (left and right sides) between the transmission mounts and the work
platform hinge.
(2) Check the cockpit for leaks. If any leak is detected, reseal with proseal. After sealant is fully
cured, perform a leak check.
For water/moisture due to a plugged drain hole.
i.
(1) Inspect drain hole just above and aft of the pilots and w-pilots crown windows at sta. 84.20,
WL +55.25, BL 20.48. It is located at the bottom of the vertical row of rivets at this location.
(2) If drain hole is filled with sealant, remove sealant.
10. Supply/Parts and Disposition.
a. Parts Required. N/A.
3