We have received a report of loss of DC power generation on a Boeing Model 767 airplane during flight. Investigation by Boeing revealed that the operator had incorporated Boeing Service Bulletin 767-24-0119, dated May 14, 1998, and/or Revision 1, dated December 16, 1999, without proper preparation of the bonding surface of the ground bracket and the airplane structure. The inadequate preparation caused the loss of an adequate electrical ground path between the bracket and frame used for the transformer rectifier units (TRU) and the main battery charger, which caused the subsequent loss of all DC power generation. When the operator inspected the rest of its Model 767 fleet, it found a number of brackets that were not properly grounded. This condition, if not corrected, could result in depletion of the main battery and consequent loss of all DC power, which could cause the loss of flight critical systems. \n\nRelevant Service Information \n\n\tWe have reviewed Boeing Alert Service Bulletin 767-24A0119, Revision 2, dated August 19, 2004. The service bulletin describes procedures for reworking the bonding surfaces of the ground stud brackets of the TRU and airplane structure, and measuring the resistance from the bracket to the structure and from the ground lug to bracket using a bonding meter. The reworking includes: \n\n\tRemoving the ground stud bracket of the TRU; \n\n\tCleaning the bracket mounting surface and airplane structure surface for a faying surface bond; \n\n\tInstalling the ground bracket assembly of the TRU to the surface using bolts; \n\n\tApplying fillet sealant to the bracket; \n\n\tApplying alodine to the prepared surfaces; \n\n\tAnd applying primer on bare metal surface. \n\n\tWe have also reviewed Boeing Information Notice 767-24A0119 IN 01, dated October 21, 2004. This information notice provides more detailed illustrations than those shown in Figure 1, Details A and B, of Boeing Alert Service Bulletin 767-24A0119, Revision 2, dated August 19, 2004. The information notice clarifies the Figure 1, Step 10, procedure of the Accomplishment Instructions in the service bulletin. \n\nFAA's Determination and Requirements of This AD \n\n\tThe unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. Therefore, we are issuing this AD to prevent depletion of the main battery and consequent loss of all DC power, which could cause the loss of flight critical systems. This AD requires accomplishing the actions specified in the service information described previously, except as discussed below in "Clarification of Error in the Service Bulletin." \n\nClarification of Error in the Service Bulletin \n\n\tBoeing has informed us of an inadvertent error in the service bulletin. In Step 4, Sheet 3, of Figure 1 of the Accomplishment Instructions, the service bulletin only specifies to install a collar with part number (P/N) BACC30M6. However, a second collar with P/N BACC30BL6, which is listed in paragraph 2.C., "Parts Necessary For Each Airplane," is also acceptable for installation. We have included paragraph (g) in this AD to allow the installation of P/N BACC30BL6 as an alternative method of compliance to the corresponding requirement of paragraph (f) of this AD (which references the service bulletin as the appropriate source of service information for accomplishing the required actions). \n\nInterim Action \n\n\tThis is considered to be interim action. The manufacturer has advised that it currently is developing a modification (to add a redundant TRU grounding bracket on all 767 airplanes) that will address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, we may consider additional rulemaking. \n\nFAA's Determination of the Effective Date \n\n\tAn unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days. \n\nComments Invited \n\n\tThis AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2004-19569; Directorate Identifier 2004-NM-179-AD" at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the AD in light of those comments. \n\n\tWe will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of our docket Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov. \n\n\tWe are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You can get more information about plain language at http://www/faa.gov/language and http://www.plainlanguage.gov.\n\nRegulatory Findings \n\n\tWe have determined that this 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\n\tFor the reasons discussed above, I certify that the regulation: \n\n\t1. Is not a "significant regulatory action" under Executive Order 12866; \n\n\t2. Is not a "significant rule" under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t3. 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\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:PART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):