Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to the specified products. That NPRM published in the Federal Register on January 18, 2011 (76 FR 2846). That NPRM proposed to require installing foreign object debris (FOD) rubber shields over the primary and secondary external power connectors for certain airplanes, and wrapping fire-resistant silicone tape around the hydraulic tube for certain other airplanes. \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and the FAA's response to each comment. \n\nSupport for the NPRM \n\n\n\tAmerican Airlines has accomplished the modifications on the majority of its fleet, and has no objection to the actions and compliance times in the NPRM (76 FR 2846, January 18, 2011). The National Transportation Safety Board supports the NPRM. \n\nRequest To Use Latest Production Hydraulic Tube \n\n\n\tJapan Airlines (JAL), Continental Airlines, and All Nippon Airways (ANA) asked that operators be allowed to use the latest production hydraulic tube having part number (P/N) 272W4190-192, which already has the silicone tape pre-wrapped, in lieu of modifying the existing hydraulic tube assembly by installing the silicone tape in accordance with Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007. JAL also noted a concern about procuring the hydraulic tube. \n\tWe do not agree with the request to use the latest production hydraulic tube as an acceptable alternative to installing the silicone tape. Based on the latest information received from Boeing engineering, the following applies to any possible hydraulic tube replacement: Any hydraulic tube having P/N 272W4190-192 (as specified in Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007), cannot be a direct replacement for the existing part. Hydraulic tubes having P/Ns 272W4190-93, -168, and -192 for production installation require the use of permaswage fittings on either side of the tube. Removal of the tube for its replacement requires that the tube be physically cut past the permaswage fitting, thus making it longer than the original production part. We have made no change to the AD in this regard. \n\nRequest To Include Instructions for Continued Airworthiness \n\n\n\tContinental and ANA also noted that the service information does not contain proper instructions for continued airworthiness (ICAs) to install the tape on the new line, or inclusion of the equivalent production part number in the Boeing 777 illustrated parts catalog (IPC). Continental added that a pre- and post-service bulletin configuration should be included to provide instructions to use a newer part or to accomplish the actions specified in the service information again. \n\tWe acknowledge the commenters' concern, but we do not agree. The Boeing ICAs do include a statement indicating that the production tubes are reworked by using the procedures in Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007. Since there is not direct replacement with a production tube, we are working with Boeing to identify additional information necessary in support of replacing the hydraulic tube. We have made no change to the AD in this regard. \n\nRequest To Include Information Notices \n\n\n\tUnited Airlines asked that we revise the NPRM (76 FR 2846, January 18, 2011) to refer to Boeing Service Bulletin Information Notices 777- 29-0032 IN 01, dated November 29, 2007, and 777-29-0032 IN 02, dated December 11, 2008, which include clarifications to the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007. \n\tWe acknowledge that these information notices may be useful to operators to clarify certain instructions specified in Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007. However, Boeing has provided these notices to operators. We do not reference information notices in ADs because those documents are not FAA- reviewed. In addition, the information notices do not contain technical information and are not necessary to accomplish the actions required by the AD. We have made no change to the AD in this regard. \n\nRequest To Change the Applicability \n\n\n\tBoeing requested that the applicability section in the NPRM (76 FR 2846, January 18, 2011) be changed. Boeing stated that the applicability should be limited to the airplanes identified in the referenced service information, which include only those airplanes on which the modifications required by the AD have not been accomplished in production. \n\n((Page 63165)) \n\n\n\tWe agree with the commenter for the reason provided and have limited the applicability section in this AD accordingly, in lieu of specifying "all'' airplanes of the affected model. \n\nRequest To Clarify Tape Qualities \n\n\n\tBoeing asked that we delete the term "fire-resistant,'' which describes "silicone tape,'' as specified in the Summary section, Relevant Service Information section, and paragraph (g)(2) of the NPRM (76 FR 2846, January 18, 2011). Boeing stated that the product data sheet identifies the tape as "high temperature arc- and track- resistant tape,'' but not "fire-resistant.'' \n\tWe agree with the commenter for the reason provided. However, the term "fire-resistant'' was used in the NPRM (76 FR 2846, January 18, 2011) because it is specified as such in the referenced service information. We have removed it from the Summary section and paragraph (g)(2) of this AD. The Relevant Service Information section of the preamble does not reappear in the final rule. \n\nRequest To Clarify Terminology of Tape Dimensions \n\n\n\tBoeing asked that we change the language in the "Exception to Service Information'' section in paragraph (h) of the NPRM (76 FR 2846, January 18, 2011) as follows: "Figure 1 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007, does not identify the units of the dimensions of the silicone tape installed on the hydraulic tube; those dimensions are identified in inches.'' Boeing noted that the dimensions of the tape are identified, but the units of the dimensions are missing. Boeing added that, although the tape can be used as "electrical'' tape, for this application it is more appropriate to identify it as "silicone'' tape. \n\tWe agree with the commenter for the reasons provided. The word "electrical'' was used in the NPRM (76 FR 2846, January 18, 2011) because it is specified as such in the referenced service information. We have changed paragraph (h) of this AD to reiterate the commenter's suggested language. \n\nRequest To Provide Additional Credit \n\n\n\tBoeing asked that the service information specified in paragraph (i) of the NPRM (76 FR 2846, January 18, 2011) under "Credit for Actions Accomplished in Accordance with Previous Service Information'' be changed to include Boeing Special Attention Service Bulletin 777-29- 0032, dated August 9, 2007 (referred to in the NPRM as the service information to use for installing the silicone tape). Boeing stated that the modification accomplished by this service bulletin before the effective date of the AD is identical to the modification accomplished by this service bulletin after the effective date of the AD. \n\tWe do not agree that the subject service bulletin should be added to paragraph (i) of this AD. Operators are already given credit for previously accomplished actions as allowed by the phrase in paragraph (f) of this AD which states the following: "Comply with this AD within the compliance times specified, unless already done.'' We have made no change to the AD in this regard. \n\nRequest To Exclude Certain Proposed Actions \n\n\n\tDelta Airlines asked that Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007, be excluded from the NPRM (76 FR 2846, January 18, 2011). Delta stated that since the root cause of the external power connector fires and overheating was related to foreign object debris (FOD) shorting out the external power connector inside the airplane, once the FOD shields are installed per Boeing Service Bulletin 777-24-0102, Revision 1, dated June 17, 2010, the protective tape identified in Boeing Special Attention Service Bulletin 777-29- 0032, dated August 9, 2007, serves no purpose. Delta added that if damage to the hydraulic tubing is still a concern even after accomplishment of this service bulletin, a routing change to the hydraulic tubing would be a better solution to protecting the tubing from a fire/overheat condition. Delta noted that the tape being installed is not fireproof, only fire-resistant. Delta also stated that the instructions for installing the tape specified in Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007, would be difficult to comply with. Subsequent inspections of the tape installation to ensure compliance with the NPRM would also be difficult when judging the overlap and number of tape wraps, since the tape installation is based on the amount of stretch and a percentage of overlap. \n\tWe do not agree to remove Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007, from this AD. Installation of the FOD shields is not the only action necessary to address the identified unsafe condition. FOD shields alone do not resolve the potential for overheating and arcing of the electrical connectors. Based on our evaluation, we have determined that the connector design, lack of proper connector maintenance actions, and the proximity of the hydraulic tubing to the connectors can result in a fire; therefore, accomplishing the actions required by this AD will minimize the threat of fire on the airplane. \n\tAdditionally, although the silicone tape is not fireproof, installing the tape provides an acceptable level of protection to the hydraulic tubing in the event of overheating or arcing of the connectors. The procedures for installing the tape are not difficult for compliance and include easy access and liberal application of the tape; several operators have already done this modification and did not encounter any problems. Further, it is the responsibility of operators to maintain the AD-mandated configuration, and this can be done using the procedures specified in Boeing Special Attention Service Bulletin 777-29-0032, dated August 9, 2007. In light of these factors, we have made no change to the AD. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCostsof Compliance \n\n\n\tWe estimate that this AD will affect 126 airplanes of U.S. registry. We estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tNumber of \n\tAction Labor cost Parts cost Cost per airplanes Fleet cost \n\tproduct affected ---------------------------------------------------------------------------------------------------------------- Install FOD rubber shields.......... 6 work-hour x $85 per $134 $644 124 $79,856 \n\thour = $510. \n\n((Page 63166)) \n\n\n\nWrap silicone tape.................. 2 work-hour x $85 per 0 170 126 21,420 \n\thour = $170. ---------------------------------------------------------------------------------------------------------------- \n\nAuthority for This Rulemaking \n\n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. \n\tWe are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701: "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\n\tThis AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a "significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a "significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), \n\t(3) Will not affect intrastate aviation in Alaska, and \n\t(4) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.