British Airways

BAB has reviewed the NPRM, including the Summary, which states "This proposed AD will also require installing a fiberglass reinforcement overcoat to the top surface of the aft MEC drip shield gutters". The NPRM later states, in section (g)(2), “Install a fiberglass reinforcement overcoat to the top surface of the aft MEC drip shield gutters, and install a cargo liner support.” This appears to be in contradiction to the SB 747-25A3613 requirements. BAB note that the SB 747-25A3613 Figure 4 Sheet 2 and 3 shows the fibreglass cloth being installed from underneath the aft MEC dripshield gutter. Figure 4 Step 3 Note (c) states “Install the prepared BMS 9-3 fibreglass impregnated fabric to the underside of the bonded seams.” BAB believes that the Boeing SB 747-25A3613 gives the correct interpretation of the location of the installed fiberglass. BAB therefore requests that the referenced section of the Summary of the NPRM be revised to state: "This proposed AD will also require installing a fiberglass reinforcement overcoat to the underside surface of the aft MEC drip shield gutters", and that the section (g)(2) should be revised to state “Install a fiberglass reinforcement overcoat to the underside surface of the aft MEC drip shield gutters, and install a cargo liner support.” An alternative wording that clarifies the intent of the SB 747-25A3613 is to install the fibreglass to the underside of the dripshield gutter is also acceptable.