On December 3, 1998, the FAA issued telegraphic AD T98-25-52, which is applicable to all Boeing Model 747 series airplanes. That action was prompted by a report indicating that an operator of Boeing Model 747 series airplanes removed seven override/jettison fuel pumps from center wing tanks on several airplanes because the circuit breakers for the override/jettison fuel pumps were tripped, or low pump output pressure was indicated. Seven more pumps of the same design had been removed from the main tank override/jettison positions for the same reason on several airplanes. The pumps were found to have severe wear of the pump shaft carbon thrust bearing after only 200 hours of pump operation. \n\n\tA priming stage paddle wheel is mounted on the pump shaft, and this steel paddle wheel is positioned between two steel end plates. Severe wear of the carbon thrust bearing allows the pump shaft to shift axially, which causes contact of the rotating steel paddlewheel and the stationary steel end plates. Boeing reported that, on one pump, 0.10 inch of the steel paddle wheel had worn away during 200 hours of pump operation. The cause of such severe wear is still under investigation. (Such wear conditions were not found on the center wing fuel tank override/jettison pumps that were recovered from a Model 747-100 series airplane involved in an accident, in which the airplane broke up shortly after takeoff from John F. Kennedy International Airport in Jamaica, New York, on July 17, 1996. In addition, those pumps are not believed to have been operating on the accident airplane during that flight because mission fuel had not been loaded into the center tank.) \n\n\tContact between the rotating paddle wheel and the stationary end plates within a center wing tank override/jettison fuel pump due to excessive wear of the pump shaft carbon thrust bearing can cause sparks and/or a hot surface condition. This condition, if not corrected, could ignite fuel vapor in the center wing tank during dry pump operation (no fuel flowing). \n\n\tThe pumps of the center wing fuel tank on Model 747 series airplanes are normally operated until the fuel in the tank is exhausted and the pump inlet is uncovered, exposing the fuel pump to dry or partially dry operation for a period of time during each flight when the center wing tank is used. The horizontal stabilizer tank on Model 747-400 series airplanes uses the same pumps and also is run dry each time it is used. \n\nExplanation of the Requirements of the Rule \n\n\tSince the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued telegraphic AD T98-25-52 to require revising the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include procedures to prevent dry operation of the center wing fuel tank override/jettison pumps and, for Model 747-400 series airplanes, to prohibit operation of the horizontal stabilizer tanktransfer pumps in flight. \n\n\tThe AFM revision provides for two options for accomplishment: \n\n\t Option 1 minimizes the effects of the limitations on available airplane payload due to maximum zero fuel weight limitations. This option ensures that the forward (right) and aft (left) center wing tank override/jettison pumps remain covered during rapid acceleration and high nose attitudes during takeoff and departure. \n\t Option 2 minimizes the unusable fuel retained on some Boeing Model 747-400 series airplanes, or airplanes with inoperative scavenge systems of the center wing tank. This option also ensures that the forward (right) and aft (left) center wing tank override/jettison pumps remain covered during rapid acceleration and high nose attitudes during takeoff and departure, and ensures that the shutoff of the center wing tank override/jettison pumps will not normally be required until the cruise phase of flight. \n\n\tThis AD is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking. \n\n\tIt should be noted that this AD does not require any interim action related to the main tank override/jettison pumps because those pumps are selected off well before the inlets are uncovered (no dry operation). \n\n\tSince it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual telegrams issued on December 3, 1998, to all known U. S. owners and operators of all Boeing 747 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and,thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date forcomments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-NM-360-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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. \nAdoption of the Amendment \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 part39) as follows: PART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: