DISTRIBUTION MANIFOLD DUCT ASSEMBLY - REMOVAL/INSTALLATION
1. Equipment and Materials
A. Solvent - Aliphatic Naptha TT-N-95 (Ref 20-30-31)
B. Sealant - BMS 5-32 (Ref 20-30-11)
C. Sealant - BMS 5-126 (Ref 20-30-11)
D. Sealant - GE RTV 133 (Ref 20-30-11)
E. Tape - 3M 474 or Permacel-29 2-inch and 3-inch (Ref 20-30-51)
2. Remove Distribution Manifold Duct Assembly (Fig. 401)
A. Close forward lower cargo compartment door.
B. Remove right outboard ceiling panels from forward lower cargo compartment (Ref 25-52-121, 25-52-122 or 25-52-123, as applicable).
C. Remove pneumatic power (Ref 21-11-0 A/T).
D. Remove tape securing ducts to elbows on manifold duct assembly and slide the ducts off the elbows.
E. At aft end of duct assembly, remove fasteners securing the duct assembly to aft transition duct from distribution manifold.
F. Carefully separate duct assembly from aft transition duct with a thin bladed metal spatula or knife.
G. Support duct assembly and remove hardware securing duct assembly to structure.
H. Remove duct assembly from airplane.
3. Prepare for Duct Assembly Installation
A. Clean faying surface of aft transition duct with a wiper saturated with solvent.
NOTE: It is not necessary to remove all residual sealant from transition duct flange.
B. Prepare and apply a faying surface seal of GE RTV 133 to transition duct flange.
500
Feb 20/85 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 21-23-12 Page 401
Conditioned Air Distribution Duct Assembly 500
21-23-12 Figure 401 (Sheet 1) Feb 20/85
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500 Conditioned Air Distribution Duct Assembly
Feb 20/85 Figure 401 (Sheet 2) 21-23-12
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4. Install Distribution Manifold Duct Assembly (Fig. 401)
A. Loosely secure duct assembly to structure with fasteners.
B. Install and tighten fasteners securing aft end of duct assembly to transition duct.
C. Tighten hardware securing duct assembly to structure.
D. Clean faying surfaces of forward end of manifold duct assembly and transition duct with solvent.
E. Apply a layer of BMS 5-126 sealant to each faying surface.
F. Attach forward transition duct to distribution manifold duct assembly and secure transition duct to structure.
G. On airplanes with forward transition duct installed inside distribution manifold duct assembly, apply a fillet seal of BMS 5-32 at forward end of distribution manifold duct assembly.
H. On airplanes with forward transition duct installed over distribution manifold duct assembly, apply two wraps of two inch tape positioned equally over each duct.
I. Install ducts to elbows on distribution manifold duct assembly and forward transition duct.
J. Apply one wrap of two inch tape followed by two wraps of three inch tape over each flexible duct connection.
K. Provide electrical power (Ref 24-22-00 MP).
L. Start one air conditioning pack (Ref 21-51-0 A/T).
M. Check all areas for leakage. Diffused leakage permitted, jet blast leakage must be repaired.
N. Shut down air conditioning pack (Ref 21-51-0 A/T).
O. Install forward lower cargo compartment ceiling panels (Ref 25-52-121, 25-52-122 or 25-52-123, as applicable).
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FORWARD OVERHEAD DISTRIBUTION DUCT - MAINTENANCE PRACTICES
EFFECTIVITY
Standard Passenger Airplanes
1. General
A. Maintenance practices for the forward duct are the same as for the aft duct. Refer to 21-23-42.
530 Forward Overhead Distribution Duct and Valve Assembly
Nov 15/69 Figure 201 21-23-22
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AFT OVERHEAD DISTRIBUTION DUCT - REMOVAL/INSTALLATION
1. General
A. The aft overhead distribution duct is a duct section, made of polyurethane, which connects the overhead distribution duct to the light fixture. The following procedure describes removal/installation of the aft duct. Removal/installation for the forward duct may be accomplished by using the same procedure.
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