SIDEWALL INSULATION - APPROVED REPAIRS
1. General
A.  Extensively damaged insulation blankets must be replaced with locally fabricated new ones using damaged blankets as patterns.
B.  The following information is applicable to the repair of sidewall and ceiling insulation blankets located in the passenger compartment.
2.  Equipment and Materials
A.  Thermal-Acoustical Fiberglass Insulation - BMS 8-48, Type III, Class III (used in passenger cabin area.)
B.  Insulation Covering, Self-Extinguishing - BMS 8-142, Type XI, Class I Inbd, Class III Outbd (This material is used as the inboard and outboard covering for insulation blankets installed throughout the passenger cabin.) (AMM 20-30-51/201)
C.  Fabric, Lead Coated - BMS 8-47, Types I, III, and IV (This material is used inside blankets between layers of fiberglass in some areas of the passenger cabin.)
D.  4-Cord Cotton Thread - Federal Specification V-T-276, Type 1B3, Ticket Nos. 16 and 24 
E.  Cement Low Odor Synthetic Rubber - BMS 5-30.
F.  Adhesive - Churchill 3C-90 (AMM 20-30-11/201).
G.  Solvent - General Cleaning of Solvent - Resistant Organic Coatings (Series 82)
(AMM/SOPM 20-30-82).

H.  Tape, patch - OT-5, OT-6, OT-7 Orcon Corp (AMM 20-30-51/201).
I.  Tape - Permacel 621 (AMM 20-30-51/201).
J.  Fabric - BMS 8-115 (AMM 20-30-51/201).
3.  Repair Blankets or Covers
A.  Clean damaged area with solvent, Series 82 (AMM/SOPM 20-30-82).
May 01/00 25-21-339 Page 801 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

B. Cut piece of similar fabric to patch punctured blanket or cover. All patches to extend 0.75 or
1.50 inches beyond tear in all directions. All corners must be rounded.
NOTE:  If area to be repaired is greater than 25% total blanket area, blanket should be replaced.
C.  Apply adhesive 3C-90 or cement BMS 5-30 to faying surfaces of damaged area and patch. For an alternate approach, a patch of OT-5, OT-6, or OT-7 Orcon tape may be used to repair damaged BMS 8-142 cover material for blanket and capstrip assemblies.
D.  Firmly press patch into damaged area to ensure complete bond.
E.  Apply adhesive to any Velcro tapes not properly secured.
4.  Replacement of Extensively Damaged Insulation Blanket
A.  Remove Damaged Insulation Blanket
(1)  
For removal of sidewall insulation blanket, refer to 25-21-339 R/I.

(2)  
For removal of ceiling insulation blanket, refer to 25-21-349 R/I.

B.  Prepare New Insulation Blanket
(1)  
Make paper template using damaged blanket as pattern.

(2)  
Cut thermal-acoustical fiberglass insulation to same shape as template.

(3)  
Place fiberglass insulation layers between the inboard and outboard fabric covering. When using a fabric covering which has different surfaces, position the covering to have the same surface toward fiberglass as in the damaged blanket.

(4)  
If damaged blanket contained lead coated fabric, insert a sheet of this material between insulation layers same as damaged blanket.

NOTE:  The lead coated fabric must be equipped with 0.25-inch diameter air vent holes. Insulation blankets less than 12 inches wide require one vent hole through the lead coated fabric for each 10-inch length. Blankets more than 12 inches wide require two vent holes for each 10-inch length. 

(5)  
Trim fabric covering and lead coated fabric, if installed.

(6)  
The edges of the blanket may be stapled as required to facilitate stitching and handling of blanket. The staples must be located between the stitching and the outer edge of the blanket and must not be visible on the completed blanket.

(7)  
Bind all edges and cutouts of the blanket with fabric strips. On edges where flaps are required, make flaps the same width as on damaged blanket.

(a)  
On edges where full thickness of blanket is maintained, cement nylon binding with synthetic rubber cement.

(b)  
On edges where binding is to be sewn, use 4-cord cotton thread and space stitches four to the inch minimum and six to the inch maximum (minimum spacing is recommended).

(c)  
Install nylon fabric grommets through holes in blanket and bond to blanket with synthetic rubber cement.

(8)  
On passenger cabin ceiling blankets, seal stitching on outboard side of blanket with a continuous bead of synthetic rubber cement.

NOTE: Use same quantity and thickness of layers as used in damaged blanket.
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25-21-339 Page 802  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Oct 20/87 
　
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