A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 98-25-52, amendment 39-10957 (63 FR 71214, December 24, 1998), which is applicable to all Boeing Model 747 series airplanes, was published in the Federal Register on November 20, 2000 (65 FR 69718). The action proposed to require, for certain airplanes, installation of improved fuel pumps, which would terminate the requirements of the existing AD. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nClarify Intent of Paragraph (b) \n\n\tOne commenter requests that the FAA revise paragraph (b) of the proposed rule to clarify that compliance with the requirements of that paragraph terminates the requirements of paragraph (a) of the proposed rule. The commenter points out that, while paragraph (b) states that no further action is requiredif it is determined that the correct thrust washer is installed under the guidelines in paragraphs (b)(1), (b)(2), and (b)(3) of the proposed rule, paragraph (b) does not state that the operational limitations in paragraph (a) are no longer necessary. \n\n\tThe FAA concurs with the commenter's request, and has revised paragraph (b) of this AD to state that accomplishment of that paragraph terminates the requirements of paragraph (a) of this AD. \n\nRevise Paragraph (b) to Reference Acceptable Parts \n\n\tOne commenter requests that the FAA revise paragraph (b) to refer to the acceptable replacement parts identified in paragraph (c) of the proposed rule. The commenter states that Crane Hydro-Aire fuel pumps having thrust washers, part number 60-06561, with a date code of 9848 or higher etched on the outside diameter of the thrust washer, are acceptable. If such pumps are installed, no further action is required by this AD; thus, this guideline should be included with the others under paragraph (b). The commenter notes that this change will make the proposed rule easier to follow. \n\n\tThe FAA concurs, and has added a new paragraph (b)(4) to this final rule. \n\nRevise Cost Impact \n\n\tOne commenter, the parts manufacturer, requests that the FAA revise the "Cost Impact" section of the proposed rule to remove the statement "Required parts would be provided by the manufacturer at no cost to the operators." The commenter states that there are certain restrictions on the cost of parts to the operators, based on the date of overhaul or repair of the pumps. The commenter suggests including a new statement such as, "Modification of the fuel pump by CRANE Hydro-Aire or required parts for modification by the operator will be provided by the manufacturer at no cost to the operator in accordance with the "Repair Options" and "Warranty" sections of the applicable CRANE Hydro-Aire Service Bulletin." \n\n\tThe FAA concurs with the intent of the commenter's request. The FAA has revisedthe "Cost Impact" section of this final rule to include the following statement, which is more general than the statement suggested by the commenter: "The parts manufacturer has committed previously to its customers that it may bear the cost of replacement parts with certain restrictions, based on the date of overhaul or repair of the pumps." \n\nLimit Applicability \n\n\tOne commenter, the airplane manufacturer, requests that the FAA revise the proposed rule to limit the applicability to airplanes up to and including line number 1188. The commenter states that airplanes after line number 1188 have the correct thrust washers installed and, therefore, are not subject to the actions in the proposed rule. The commenter further notes that in-service pump replacements on airplanes after line number 1188 will be maintained by normal operator practices for parts control. \n\n\tThe FAA does not concur with the commenter's request to limit the applicability. Though only certain airplanes were produced with the incorrect thrust washer, the pump with the subject washer may easily be removed from one airplane and installed on another airplane. Thus, airplanes such as those with line numbers 1188 and subsequent, which were delivered with the correct thrust washer, may subsequently have had a pump with a discrepant thrust washer installed. No change to the final rule is necessary in this regard. \n\nRequest To Clarify Compliance Tracking \n\n\tOne commenter requests that paragraph (b) of the proposed rule be revised to specifically reference the accomplishment instructions of Boeing Service Bulletin 747-28-2225, dated December 3, 1998. Paragraph (b) defines conditions under which no action is required per this AD. The commenter states that including a reference to Boeing Service Bulletin 747-28-2225 would make it easier for operators to track compliance for the purposes of this proposed rule. \n\n\tThe FAA does not concur with the commenter's request. The FAA finds that compliance may be tracked by the part number of the override or override/jettison pump, or by review of maintenance records, methods which are allowed by paragraph (b) of this AD. The FAA finds that revising paragraph (b) of this AD in the manner suggested by the commenter would provide no improvement in the clarity of the AD. However, the original issue of Boeing Service Bulletin 747-28-2225, as well as Revision 3, dated March 3, 1999, were previously approved as alternative methods of compliance (AMOCs) for AD 98-25-52. Accordingly, paragraph (d)(2) of this AD, states that (with one exception) AMOCs approved previously in accordance with AD 98-25-52, amendment 39-10957, are approved as alternative methods of compliance with paragraph (a) of this AD. Airplanes on which the intent of paragraph (a) of this AD has been accomplished are not subject to paragraph (b) of this AD. Thus, no change to the final rule is necessary in this regard. \n\nComment on Implied Life Limit of Thrust Washer \n\n\tOne commenter notes that the following statement, made in the "Actions Since Issuance of Previous Rule" section of the proposed rule, indicates that the life of the thrust washer on the improved pumps has been extended from 500 hours to "more than 15,000 hours." The commenter expresses concern that, while this may be a significant improvement in life limit, failure of the pump, whether at 15,000 hours or 500 hours, would still be catastrophic and, thus, is an unacceptable risk. The commenter states that, if the failure mode is still present in the improved pump, the commenter would not support the removal of the fuel quantity restrictions from the Airplane Flight Manual as allowed by the proposed rule. \n\n\tThe FAA infers that the commenter is requesting that the FAA remove the terminating action provided by paragraph (c) of this AD. The FAA does not concur with the commenter's request. The statement noted by the commenter was intended as a reference, not to indicate that the life of the thrust washer was 15,000 hours. Service experience has shown that the aluminum oxide coating applied to the thrust washer using a D-gun spray method lasts at least as long as the currently expected service life of the pump between overhauls. While no specific limit on the overhaul interval for the pump exists, the FAA has determined that an acceptable level of safety will be provided with respect to failure of the thrust bearing without continuing to require the AFM procedures for early pump shutoff. However, the FAA recognizes and agrees with the commenter's concern regarding the possible failure modes of fuel pumps and the current design practice of routinely allowing fuel pumps in auxiliary fuel tanks (including built-in auxiliary tanks such as the center wing tank and the horizontal stabilizer tank on Model 747-400 series airplanes) to run until the inlets are uncovered. The FAA is examining this issue and is considering issuing additional rulemaking to address fuel pump installationsthat are not fail-safe on existing transport airplane designs. No change to the final rule is necessary in this regard. \n\nConclusion \n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 1,100 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 250 airplanes of U.S. registry will be affected by this AD. \n\n\tThe AFM revisions that are currently required by AD 98-25-52 take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $15,000, or $60 perairplane. \n\n\tThe replacements required for certain airplanes by this new AD will take approximately 25 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. The parts manufacturer has committed previously to its customers that it may bear the cost of replacement parts with certain restrictions, based on the date of overhaul or repair of the pumps. Based on these figures, the cost impact of the requirements of this AD on U.S. operators is estimated to be $375,000, or $1,500 per airplane. \n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the timerequired to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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. A final evaluation has been prepared for this action and it is contained in theRules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-10957 (63 FR 71214, December 24, 1998), and by adding a new airworthiness directive (AD), amendment 39-12277, to read as follows: