36-11-01
ALL ú ú 01 Page 802 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
S 288-029
(2)
The surface roughness of the repaired area must not be more than 40 microinches (arithmetical average).
S 228-022
(3)
The slope of the repaired area must not be more than 10%.
S 228-023
(4)
The inner and the outer radius of the repaired area must not be more than 0.12 inch.
S 228-024
(5)
The damage must not be found less than 0.25 inch from a primary welded joint.
S 228-020
(6)
You must replace the duct if it cannot be repaired to these conditions.
TASK 36-11-01-308-013
5. Temporary Repair of Cracked Ducts (Fig. 801)
_________________________________
A. General
(1) You can temporarily repair ducts that have a crack along the longitudinal axis.
NOTE: This repair procedure is only permitted for ducts that
____ have a crack along the longitudinal axis. Replace ducts that have a crack along the circumference or have multiple cracks.
(2)
The repair is temporary and you must replace the duct as soon as possible.
(3)
A duct with a longitudinal crack that is less than three inches from the flange or pullout; a circumferential crack; or multiple cracks cannot be repaired by this procedure. It must be repaired in accordance to Overhaul Manual or be replaced.
B.
Consumable Materials
(1)
Silicone rubber sheet - BMS 1-57GR50A - 0.10 to 0.15 inch thick
(2)
Stainless steel sheet - 0.010 inch thick
(3)
Adjustable stainless steel clamps - BACC10B
C.
Repair the duct with the crack.
S 328-018
(1) Stopdrill the cracks, size of drilled hole to be 3/16-1/4 inch diameter.
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36-11-01
ALL ú ú 01 Page 803 ú Oct 10/95
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
S 358-015
(2) Put a silicone rubber sheet on the crack and extend it three inches beyond the ends of the crack to ensure that there is sufficient seal and support.
NOTE: The edge of the crack must not be less than three inches
____ from the flange and not interfere with the flange coupling when the duct is installed on the airplane.
S 358-016
(3)
Put the stainless steel sheet on the rubber sheet.
S 358-017
(4)
Put the clamps on the duct every 1 to 1 1/2 inches and tighten the clamps.
TASK 36-11-01-308-015
6. Duct Flange Repair
__________________
A. Equipment
(1)
Flange Reforming Tool, Adams Flange Spider
Adams-Bird, Inc.
5296 Pebbletree Way
San Jose, CA 95111
U.
S. A.
B. References
(1) AMM 36-11-01/401, Pneumatic Manifold
C. Procedure
S 018-012
(1)
Get access to the duct flange that you will repair.
S 328-013
(2)
Use the flange reforming tool and repair the duct flange.
S 028-014
(3)
If you cannot repair the duct flange while the duct flange is installed, remove the duct to get access to the damaged flange (AMM 36-11-01/401).
(4)
Repair the duct flange with the flange reforming tool.
(5)
Install the duct (AMM 36-11-01/401).
S 358-019
S 428-016
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