The FAA has received a report of failure of an override and jettison fuel pump on a Boeing Model 767 series airplane. Investigation revealed that the screws that attach the inlet diffuser assembly to the pumping unit housing became loose and were ingested into the fuel pump assembly. Loose screws caused the diffuser ring to become loose and contact the impeller, which damaged the impeller and pumping unit housing and caused the fuel pump to seize. During dry fuel pump operation, a loose diffuser ring also could cause metal-to-metal contact. This condition, if not corrected, could result in the generation of sparks and a potential ignition source inside the fuel tank. \n\nOther Relevant Rulemaking \n\n\tThe conditions described previously were addressed in AD 94-11-05, amendment 39-8921 (59 FR 27970, May 31, 1994), which is applicable to Boeing Model 767-200 and 767-300 series airplanes. That AD requires repetitive inspections of the pumping unit assembly on the override and jettison fuel boost pump assemblies to detect looseness of the screws that attach the inlet diffuser assembly to the pumping unit housing, and repair or replacement of the pumping unit assembly with a serviceable assembly, if necessary. For certain airplanes, that AD also provides for deactivation of the center wing fuel tank as an alternative to the repetitive inspections. The actions specified by that AD are intended to prevent the generation of sparks and a potential ignition source inside the fuel tank caused by metal-to-metal contact during dry fuel pump operation. \n\nFAA's Findings \n\n\tSince the issuance of AD 94-11-05, an alternative method of compliance was granted that entailed fuel pump modifications, which alleviated the need for repetitive inspections of the fuel pump. However, the previously described report of failure of an override fuel pump occurred on a unit that had incorporated those modifications. The FAA has determined that, even if theoverride fuel pump fails, operation of the center tank fuel pumps with no less than 1,000 pounds of fuel will prevent ignition of fuel vapors due to the generation of sparks inside the fuel tank due to metal-to-metal contact. Therefore, the FAA has determined that a revision to the FAA-approved Airplane Flight Manual (AFM) for Model 767 series airplanes is necessary to ensure that the center tank fuel pumps are not operated with less than 1,000 pounds of fuel in the center tank.\n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 767 series airplanes of the same type design, this AD is being issued to prevent the generation of sparks and a potential ignition source inside the fuel tank caused by metal-to-metal contact during dry fuel pump operation. This AD requires revising the AFM to include procedures that will ensure that the center tank fuel pumps are not operated with less than 1,000 pounds of fuel in the center tank. \n\nInterim Action\n \n\tThis is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \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 for comments, 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\t\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 thefollowing statement is made: "Comments to Docket Number 97-NM-239-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. \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\n PART 39 - AIRWORTHINESS DIRECTIVES \n\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: