F89342
Typical Duct Section Installation 501
36-19-11 Figure 401 May 01/75
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
(2) Position V-band clamps and tighten.
(a)
Do not apply any lubricant to the clamping area or clamp bolt.
(b)
Tighten all clamps in work evenly so as to load each joint equally.
(c)
Tighten clamp nuts. Tap clamps with a soft mallet while tightening.
NOTE: If V-band clamps are being installed in areas adjacent to control cables, align clamp in a position so that the clamp tee bolt is a minimum of 30 degrees circumferentially from the control cable (Fig. 401, Detail B). Test the clearance by physically deflecting the cable towards the clamp to check that cable slack will not interfere under any flight conditions.
D. Tighten duct support clamps. If duct support clamps were removed to obtain alignment for V-band clamp alignment, deflect the assembled tubing sufficiently to engage the support clamps in a manner that will not physically damage tubing. Do not loosen V-band clamps in order to align support clamps.
NOTE: Installation torque range for 0.016 inch titanium ducts on TAI system support clamps shall be 10 to 15 pound-inches or 10 pound-inches over the nut threading torque, whichever is greater.
E. Pressurize system as required and check for leakage at all joints involved in the repair.
F. Install access panels.
501
May 01/75 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 36-19-11 Page 403
TITANIUM DUCTS - INSPECTION/CHECK
1. Ducts Inspection
A. Titanium Ducts Inspection
(1) General
(a)
At normal ambient temperatures fire resistant hydraulic fluid is compatible with titanium. Above 170oF, however, the fluid becomes acidic and attacks titanium causing it to corrode and become brittle.
(b)
Titanium ducts are found in the air condition equipment bay area, wing leading edge TAI system, and on the pneumatic system aft of the APU check valve.
(c)
When it is suspected that titanium ducts have been contaminated with fire resistant hydraulic fluid an inspection of the applicable ducts should be accomplished. Refer to Chapter 5, Hydraulic Fluid Reaction with Titanium - Conditional Inspection, for duct inspection and check.
500
Dec 15/70 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 36-19-11 Page 601
TITANIUM DUCTS - CLEANING/PAINTING
1. General
A. Titanium ducts in some airplanes may not be painted with preservative and even those that are painted may corrode and become brittle if they come in contact with fire resistant hydraulic fluid at temperature above 270oF. On either painted or unpainted ducts, contamination is evidenced by a bright glossy brown film, dull black residue, or a bare surface on painted ducts.
B. Contamination can be removed by cleaning, either removing the ducts or as installed, provided caution is exercised to avoid cleaning solution coming in contact with other airplane components or structure.
2. Duct Cleaning
A. References
(1) OHM 20-30-03, Standard Overhaul Practices Manual, General Cleaning Procedures OHM 20-41-01, Standard Overhaul Practices Manual, Application of Corrosion Preventives to Interior of Closed End Tubes OHM 20-44-01, Standard Overhaul Practices Manual, Application of Special Purpose Coating and Finishes
B. Clean the Ducts
(1)
If the ducts are touched with the fire-resistant hydraulic fluid, clean the ducts (Ref Standard Overhaul Practices Manual 20-30-03, Section 8, Manual Cleaning).
(2)
Titanium ducts that require the removal of hydraulic fluid contamination while installed on the airplane may be cleaned as follows:
(a)
Clean the duct with the use solvents such as cold alkaline, solvent emulsion, and foam cleaners (Ref SOPM 20-30-03, Section 8, Manual Cleaning).
(b)
Soak ducts with thick hydraulic fluid residues with alkaline solvent for 20 to 40 minutes, then scrape it off the duct with a soft piece of wood (tongue depressor).
NOTE: Do not remove hydraulic fluid residues on titanium ducts with power wire brush or abrasive air blast materials. Aluminized steel wool or scotch brite pads may be used. The ducts may be stained as many times as you want after it has been cleaned and provided that all the hydraulic fluid residues has been removed and the surface of the duct is smooth.
(3) After you clean the ducts, you can paint them with BMS 10-82 low emissitivity gold coating (Ref SOPM 20-44-01) or B-2000 high temperature coating (Ref SOPM 20-41-01, SRF-14.87) to provide a protective coating for the duct.
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