United Airlines

United Airlines has the following comments: 1. United noted in the NPRM that the proposed effectivity differs from SB 737-29-1113, dated March 23, 2011, by incorporation of Information Notice (IN) 737-29-1113 IN 01. The effectivity in the NPRM contains excluded aircraft by L/N but these are not shown in the SB original release nor shown in the IN. Where did the NPRM effectivity come from if not in the subject S/B or the IN? 2. The NPRM Applicability paragraph (c) references aircraft "line numbers (L/Ns) 1060 through 3347, excluding L/Ns 3138... 3290 to 3293 inclusive, and 3295 to 3347 inclusive ". United suggests deleting "...3295 to 3347 inclusive." and simply adding up front "...(L/Ns) 1065 through 3294...". 3. S/B 737-29-1113, dated 3/23/2011, Par. 1.A. Effectivity, provides a small configuration table. In the Description column for Group 1 aircraft, it states "... line numbers 1060 through 3447 (typo), without insufficient separation between hydraulic tubing, P/N 272A4451-136/-137, and wire bundles W6128, ...". This wording contradicts the steps provided in the S/B, because it implies a conditional effectivity based on if there is sufficient separation or not, Operators may elect to NOT install new clamps if they find sufficient separation between the wire bundle and tubing. 4. United found at least one aircraft with clamps installed at the location. Boeing agreed to add a statement for the operator to first look for clamps, and if found, check the P/N of the subject clamp. If it is not the P/N listed in the referenced S/B, the clamp is to be replaced. United revised it's work instructions to include the clamp P/N check. As of this date, no Rev. to the S/B exists, only the original release. Thus, United may not be in full compliance with the proposed AD. United has learned that release of S/B 737-29-1113, Rev 1, is imminent and likely to address the concerns above. The final AD should be written per the revised S/B, not Rev. 0.