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A 747-400 MAINTENANCE MANUAL
Open these circuit breakers and attach DO-NOT-CLOSE tags: 1) P6-2 Main Power Distribution Panel a) 6K18, APU ALTN CONT 2) P83 Aft APU Equipment Control and Circuit Breaker Panel a) APU PRIME CONT Remove the four nuts and four bolts from each side of the damaged gasket area and containment shield segment. NOTE: It may be necessary to remove more bolts and nuts to get ____ access to the damaged gasket. You can remove a maximum of 19 bolts and 19 nuts from the damaged gasket area. Remove the front and rear containment shields from the damaged gasket area. Remove the piece of damaged gasket. Open the duct flange and clean the surfaces with isopropyl alcohol.
NOTE: You can use option A or option B to repair the damaged
____ gasket area. Option A: 1) To fabricate a shim, install a piece of stainless sheet metal (0.027-0.037 inch) (0.07-0.09 mm) thick into the flange opening and mark the outer edge and hole pattern on the sheet metal. 2) Using the mark on the sheet metal, cut the sheet metal (shim) to the outer edge. 3) Using the mark(s) on the sheet metal, drill the bolt hole(s). 4) Clean the shim and surfaces of the duct flange with isopropyl alcohol. CAUTION: BEFORE YOU INSTALL THE SHIM, LET THE SEALANT ON THE _______ DUCT FLANGE BECOME TACKY. 5) Apply the silicone adhesive sealant to each side of the damaged gasket area. 6) Apply the silicone adhesive sealant to the top and bottom sides of the shim. EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú 49-21-00 ALL ú ú 02 Page 629 ú Oct 18/01 BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. (h) (i)
A 747-400 MAINTENANCE MANUAL
CAUTION:_______ MAKE SURE YOU HAVE SUFFICIENT SPACE BETWEEN THE DUCT FLANGES. IF YOU DO NOT HAVE SUFFICIENT SPACE BETWEEN THE DUCT FLANGES, YOU WILL REMOVE THE SEALANT WHEN
YOU INSTALL THE SHIM. 7) Install the shim and two (front and rear) containment shields with the four bolts and four nuts. NOTE: If you removed a maximum of 19 bolts and 19 nuts ____ during the removal of the two containment shields, install these bolts and nuts. 8) Tighten the nuts until the silicone adhesive sealant comes out of the duct flange. 9) Let the silicone adhesive sealant cure for 24 hours. 10) Tighten the nuts to 25-28 inch-pounds (2.8-3.2 newton-meters). 11) Remove the silicone adhesive sealant from the duct flange.Option B: 1) Cut a piece (section) of a new gasket (P/N 3912087-01) to the same size as the damaged part of the gasket that you will replace. 2) Clean the gasket and surface of the duct flange with isopropyl alcohol. 3) Apply the silicone adhesive sealant to the two ends of the gasket. 4) Install the gasket and two (front and rear) containment shields with the four bolts and four nuts. NOTE: If you removed a maximum of 19 bolts and 19 nuts ____ during the removal of the two containment shields, install these bolts and nuts. 5) Tighten the nuts until the silicone adhesive sealant comes out of the duct flange. 6) Let the silicone adhesive sealant cure for 24 hours. 7) Tighten the nuts to 25-28 inch-pounds (2.8-3.2 newton-meters). 8) Remove the silicone adhesive sealant from the duct flange.Remove the DO-NOT-CLOSE tags and close these circuit breakers: 1) P6-2 Main Power Distribution Panel a) 6K18, APU ALTN CONT 2) P83 Aft APU Equipment Control and Circuit Breaker Panel a) APU PRIME CONTRemove the DO-NOT-OPERATE tag from the APU control switch on the P5 overhead panel.Do a check for air leakages around the load compressor diffuser duct flange: 1) Do this task: APU Starting and Operation (AMM 49-11-00/201). EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú 49-21-00 ALL ú ú 02 Page 630 ú Oct 18/01 BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. A 747-400 MAINTENANCE MANUAL 2) Operate the APU for a minimum of five minutes. 3) During the APU operation, examine the flange of the load www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 机载辅助动力 2
