FAA APPROVED AIRPLANE MAINTENANCE MANUAL SUPPLEMENT. Eyebrow Window Replacement

Transcription

1 FAA APPROVED AIRPLANE MAINTENANCE MANUAL SUPPLEMENT AIRPLANE MAKE: Boeing AIRPLANE MODEL: , -200, -200C, -300, -400, -500, -600, -700, -700C, -800, -900 TO BE ADDED TO AMM CHAPTER XX This document describes the maintenance procedures for the Cascade Aviation Services installed eyebrow window blanks when they have been installed in accordance with Supplemental Type Certificate _ST01630SE_. The information contained herein supplements or supersedes the basic Airplane Maintenance Manual only in those areas listed herein. For limitations, procedures, and performance information not contained in this document, consult the basic Airplane Maintenance Manual. Page 1 of 11

2 LOG OF REVISIONS REV NO DESCRIPTION REVISED PAGES PREPARED BY APPROVED BY DATE New Initial Release All E.Graudins P.Kingswell 9/8/05 A Clarified inspections in section , 2, 4 E.Graudins E.Graudins 5/4/06 B Revised inspection intervals defined in section , 4 E.Graudins B.Norman 11/22/06 C Added eddy current inspection to section , 4 E.Graudins B.Norman 2/21/07 D Added alternate install kit and optional insulation upgrade. Added alternate gasket p/n s in section , 4, 5 E.Graudins P. Vallins 6/25/07 E Added section 4.0 and figures 2 and 3. All E.Graudins B.Norman 10/10/07 F Section 3.2: updated inspection intervals to match current ICA. Revised wording in 3.5. Added new section 3.6. Added section 5.0. Added Figure 4. 2, 3, 4, 5, 7, 11 E.Graudins E.Graudins 10/16/12 Page 2 of 11

3 Table of Contents Section Page 1.0 GENERAL DESCRIPTION ROUTINE MAINTENANCE REMOVAL AND INSTALLATION SPECIAL PROCDURES...7 Page 3 of 11

4 1.0 GENERAL The following document outlines the procedures for performing common maintenance tasks on the 737 window blanks manufactured by Cascade Aviation Services (CAS). For removal and installation procedures see Section DESCRIPTION The metallic window blanks replaced the high-maintenance eyebrow windows. The blanks consist of a machined aluminum plug, a layer of aircraft insulation, and a thin decorative cover plate. They install the same as the OEM windows. Unlike the OEM eyebrow windows, the window blanks do not have a de-icing heating element. 3.0 ROUTINE MAINTENANCE 3.1 Remove and install window blanks per the Section 4.0 and standard Boeing Maintenance Manual procedures (ref ). 3.2 Perform a general visual inspection (GVI) of the window blanks and their attachment within every 4,500 flight cycles. Perform a detailed inspection (DET) within every 30,000 flight cycles General visual inspection may be performed without removing or disassembling the window blank In addition to inspecting the exterior of the window blank assembly, detailed inspection includes disassembling the window blank by removing the cover plate and insulation blanket(s), and inspecting the inner surface of the window blank for cracks, corrosion, or other possible damage Disassembly of window blank assemblies that have integral insulation and cover plates require removal of inspection placards (p/n 05CAS ). After inspection, reassemble window blank assembly and install new inspection placards to original locations. Allowable to leave window blank in place if inside surface of blank can be inspected without removal of window blank from window frame. 3.3 Corrosion and minor nicks & scratches up to deep may be blended out as follows: 1) Blend out defect with a minimum 1.0 blend out radius. Ensure a minimum 10:1 length to depth blend ratio. 2) Smooth blend out area to 63 RMS or better surface finish. 3) Eddy Current inspect for cracks in and around the repaired area per standard Boeing NDT Manual procedures. 4) Apply chemical conversion coating per BAC5719 and two coats of epoxy primer, BMS10-11 type 1 per BAC ) Apply top coat to match surrounding finish. Page 4 of 11

5 3.4 Dents on the cover plate of the interior face are acceptable providing that it is not cracked and the insulation is not exposed. 3.5 If a crack is detected on the surface of the window blank a detailed inspection should be performed at the earliest possible time. Both surfaces of the window blank should be inspected at the crack location to determine the extent of the cracking and whether it is a through crack (this inspection may require removing the window blank from the window frame). All cracking of the window blank requires replacement of the blank within the cycle allowances noted in the following table. Crack Description Surface crack less than 0.20 long Surface crack between 0.20 and 0.34, or any through crack less than 0.34 Surface or through crack longer than 0.34 Replacement time Within 4,500 cycles Within 800 cycles Within 100 cycles 3.6 Larger dents that are outside of the blend-out limits of Section 3.3 require replacement of the window blank. If the window blank is dented or deformed such that it can no longer hold aircraft pressure, replace window blank immediately. If the flanges of the window blank are not noticeably deformed and can still hold aircraft pressure, replace the damaged window blank within 200 cycles. If the damaged window blank is also cracked, see section 3.5 for crack assessment. 3.7 Window gaskets 05CAS (or -101A) and 05CAS (or -101A) are preinstalled on the window blanks. If a gasket is damaged such that it may not hold aircraft pressure, replace the gasket. Attach new gasket with RTV108 silicone adhesive, 3M 80# spray adhesive, or equivalent. 4.0 REMOVAL AND INSTALLATION 4.1 Remove window blanks per the standard Maintenance Manual procedures (ref ) and the following instructions Remove ceiling panels and other equipment as required to access cockpit windows #4 and # If 05CAS XX insulated covers are installed, remove insulated covers to access window blanks (ref Figure 3) For Classic 737s, remove bolts, nuts, and washers that retain window blanks (ref Figure 2). For Next-Gen 737s, remove bolts, nut-plate strips, and o-ring strips that retain window blanks (ref Figure 1). Page 5 of 11

6 4.1.4 Remove window blanks from airframe. CAUTION: Once bolts are removed, the spacers will be loose and may fall out of the window blank assembly. 4.2 Reinstall window blanks per the standard Maintenance Manual procedures (ref ) and the following instructions Ensure clean mating surface on airframe. As required, replace leveling compound per standard Boeing AMM procedures Locate window blank in appropriate airframe position For Classic 737 s, install bolts, nuts, and washers (ref Figure 2). For Next- Gen 737s, install bolts, nut-plate strips, and o-ring strips (ref Figure 1). Torque bolts of window #4 to in-lbs, and torque bolts of window #5 to in-lbs. NOTE: Apply the corrosion preventative compound, MIL-C class III, to the bolt shanks immediately before installation (ref AMM ). CAUTION: Only after all the bolts are installed loosely should any of the bolts be tightened. Tightening some of the bolts before all of them are installed may pull the remaining holes out of alignment and prevent bolts from being installed. Keeping the bolts loose will allow for adjustment of the window blank positioning. Also note that salvaged spacers will be loose when installed in the new window blanks before bolts are tightened. This is to allow for easier adjustment of window blank positioning Perform electrical bonding check between the window blank and the surrounding airframe per BAC Ensure resistance is ohm max. On window blank, contact the spot of bare metal on lower fwd corner (window #4) or lower aft corner (window #5) for bonding check (spot may still be covered with paint to protect it during shipping) Reinstall insulated covers to their original positions (ref Figure 3). As required, replace the Velcro and double-sided tape Reinstall ceiling panels and other equipment that was removed Install aerodynamic sealer per standard Boeing AMM procedures (ref AMM ). 4.3 Ref Cascade Engineering Drawing 05CAS or 05CAS for original installation. Page 6 of 11

7 5.0 SPECIAL PROCDURES 5.1 The replacement #1 window frame installed by Boeing Service Bulletin SB may interfere slightly with the aft edge of the #4 window blank. To eliminate this interference an operator may do either of the following: Operator may replace the #4 window blank assembly (p/n 05CAS , -2, -3, -4, -5, or -6) with a new window blank assembly manufactured after 10/16/ Operator may modify the window blank assembly as follows. 1) Remove and disassemble the #4 window blank assembly as needed (see section 4.0 for removal instructions). 2) Chamfer the aft, inboard edge of the #4 window blank (see Figure 4) to a maximum chamfer size of 0.15 x0.15. The chamfered edge should have a surface finish of 63 micro-inches or better. Ensure there are no cracks by accomplishing an eddy current inspection of the trimmed edge per standard 737 NDT manual procedures. 3) The exposed material should be protected with a chemical conversion coating (Alodine) and primer (BMS Type I or MIL-PRF Type I). 4) As needed, trim up to 0.10 from one side of the retainer strip of the nutplate strip for the row of bolts adjacent to the chamfered edge. Ensure that the nutplates themselves are not damaged when trimming the retainer stip. 5) If installed, trim the aft edge of the 05CAS * metallic cover plate to match the chamfered edge. 6) Reinstall window blank assembly as normal (ref section 4.0). Window blank assemblies purchased after 10/16/12 should already have this chamfered feature and would not need to be modified to clear the strengthened #1 window frame. Page 7 of 11

8 Metallic Window Blank Bolt. Spacer Insulation Blanket Nutplate Cover Plate Fig 1: Typical Window Blank Installation (Next-Gen 737), window #4 (LH) Window blank assembly of 05CAS (or -3) kit normally in one piece, shown exploded for clarity. Page 8 of 11

9 Metallic Window Blank Bolt. Spacer Nut Washer O-ring Cover Plate Insulation Blanket Fig 2: Typical Window Blank Installation (Classic 737), window #4 (LH) Window blank assembly of 05CAS (or -3) kit normally in one piece, shown exploded for clarity. Page 9 of 11

10 LH #5 Window Blank Assembly (ref) LH #4 Window Blank Assembly (ref) Insulated Covers Fig 3: Insulation Upgrade (LH windows shown, RH is opposite) Page 10 of 11

11 AFT EDGE 05CAS (LH) WINDOW BLANK (PART OF 05CAS , -3, -5 WINDOW BLANK ASSEMBLIES) CHAMFER SECTION A-A Fig 4: Chamfer Modification (LH window blank shown, RH is opposite) Page 11 of 11