AD 98-16-19

This amendment adopts a new airworthiness directive (AD) that is applicable to all Boeing Model 747 series airplanes. This action requires, for certain airplanes, revising the Airplane Flight Manual (AFM) to advise the flightcrew of limitations on dry (no fuel) operation of the override/jettison pumps of the center wing fuel tank. This action also requires repetitive inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps, and replacement of the check valves and pumps with new or serviceable parts, if necessary. Such replacement terminates the AFM revision. This amendment is prompted by a report that inlet adapters of override/jettison pumps were found to be worn excessively, which allowed contact to occur between the inlet check valve and the inducer. The actions specified in this AD are intended to ensure that the flightcrew is advised of the hazards of dry operation of the override/jettison pumps of the center wing fuel tank, and to detect and correct wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps; such conditions, if not corrected, could result in a fire or explosion in the fuel tank during dry operation.

Final rule; request for comments

98-16-19 BOEING: Amendment 39-10695. Docket 98-NM-180-AD. \n\n\tApplicability: All Model 747 series airplanes, certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo ensure that the flightcrew is advised of the hazards of dry (no fuel) operation of the override/jettison pumps of the center wing fuel tank, and to detect and correct wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps, which, if not corrected, could result in a fire or explosion in the fuel tank during dry operation; accomplish the following: \n\n\t(a)\tFor airplanes that have accumulated 20,000 total hours time-in-service or more as of the effective date of this AD: Within 14 days after the effective date of this AD, revise the Limitations section of the FAA-approved Airplane Flight Manual (AFM) to include the following procedures. This may be accomplished by inserting a copy of this AD into the AFM. \n\n\t"If the center tank override/jettison fuel pumps are to be used, there must be at least\n\t17,000 pounds (7,720 kilograms) of fuel in the center tank prior to engine start. \n\n\tDo not operate the center tank override/jettison fuel pumps with less than 7,000 \t\tpounds \t(3,200 kilograms) of fuel in the center tank. For airplanes with an inoperative \tcenter tank scavenge system, this 7,000 pounds of center tank fuel must be \t\tconsidered unusable. \n\n\tIf the center tank override/jettison fuel pumps circuit breakers are tripped, do not \t\treset." \n\n\t(b)\tPrior to the accumulation of 10,000 total hours time-in-service, or within 90 days after the effective date of this AD, whichever occurs later, accomplish the requirements of paragraphs (b)(1) and (b)(2) of this AD, in accordance with the Accomplishment Instructions specified in Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998. \n\t\t(1)\tPerform a detailed visual inspection for wear or damage of the inlet check valve of the left and right override/jettison pumps of the center wing fuel tank. \n\n\t\t\t(i)\tIf the inlet check valve passes all wear and damage criteria, as specified in Figure 3 of the alert service bulletin, accomplish the actions specified in paragraph (b)(1)(i)(A), (b)(1)(i)(B), or (b)(1)(i)(C) of this AD, as applicable. \n\n\t\t\t\t(A)\tIf the wear to the stainless steel disk is less than or equal to 0.70 inch, and does not penetrate the disk, repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection. \n\n\t\t\t\t(B)\tIf the wear to the stainless steel disk is greater than 0.70 inch, and does not penetrate the disk, repeat the inspection thereafter at intervals not to exceed 1,000 hours time-in-service after the last inspection. \n\n\t\t\t\t(C)\tIf the wear penetrates the stainless steel disk of the inlet check valve, prior to further flight, accomplish the actions specified in paragraph (b)(1)(ii) of this AD. \n\n\t\t\t(ii)\tIf the inlet check valve fails any wear or damage criteria, as specified in Figure 3 of the alert service bulletin, prior to further flight, replace the existing check valve with a new or serviceable check valve, in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection. \n\n\t\t(2)\tPerform a detailed visual inspection for wear or damage of the inlet adapter of the left and right override/jettison pumps of the center wing fuel tank. \n\n\t\t\t(i)\tIf the wear to the inlet adapter is less than or equal to 0.50 inch, prior to further flight, reinstall the existing override/jettison pump, in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection. \n\n\t\t\t(ii)\tIf the wear to the inlet adapter is greater than 0.50 inch, but less than 0.60 inch, prior to further flight, accomplish the actions required by either paragraph (b)(2)(ii)(A) or (b)(2)(ii)(B), in accordance with the alert service bulletin. \n\n\t\t\t\t(A)\tInstall a new or serviceable override/jettison pump, and repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection. Or(B)\tReinstall the existing override/jettison pump, and repeat the inspection thereafter at intervals not to exceed 1,000 hours time-in-service after the last inspection. \n\n\t\t\t(iii)\tIf the wear to the inlet adapter is greater than or equal to 0.60 inch, prior to further flight, install a new or serviceable override/jettison pump, in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 10,000 hours time-in-service after the last inspection. \n\n\tNOTE 2: Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, includes figures that illustrate specific areas to inspect for wear and damage. \n\n\tNOTE 3: Accomplishment of the actions specified in paragraph (b) of this AD prior to the effective date of this AD in accordance with Revision 1 of Boeing Alert Service Bulletin 747-28A2212, dated April 23, 1998, is considered acceptable for compliance with paragraph (b) of this AD. \n\n\t(c)\tAccomplishment of the actions specified by paragraph (b) of this AD constitutes terminating action for the requirements of paragraph (a) of this AD. Following accomplishment of those actions, the AFM revision may be removed from the AFM. \n\n\t(d)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(e)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements ofthis AD can be accomplished. \n\n\t(f)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(g)\tThis amendment becomes effective on August 24, 1998.

The FAA has received a report indicating that, during an inspection of the fuel system on a Boeing Model 747-400 series airplane, inlet adapters of the override/jettison pumps of the center wing fuel tank were found to be worn. Two of the inlet adapters had worn down enough to cause damage to the rotating blades of the inducer. The inlet check valves also had significant damage. Another operator reported damage to the inlet adapter that was so severe that contact had occurred between the steel disk of the inlet check valve and the steel screw that holds the inducer in place. (Such wear conditions were not found on the override/jettison pumps of the center wing fuel tank that were recovered from a Model 747-400 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 onthe accident airplane during that flight because mission fuel had not been loaded into the center tank.) \n\n\tWear to the inlet adapters has been attributed to contact between the inlet check valve and the adapter. Vibration, possibly due to oscillations of the fuel flow, causes wear to both the stainless steel disk of the inlet check valve and the inlet adapter. The wear to the inlet adapter is accelerated by the steel disk of the check valve chafing against the edge of the adapter. Such excessive wear of the inlet adapter can lead to contact between the inlet check valve and inducer, which could result in pieces of the check valve being ingested into the inducer and damaging the inducer and impellers. Contact between the steel disk of the inlet check valve and the steel rotating inducer screw can cause sparks. Also, during dry (no fuel) operation of the fuel pump, excessive temperatures at the contact point between the inlet check valve and the inducer could create an ignition source for fuel vapors. Wear and damage to the inlet check valves and inlet adapters of the override/jettison pumps of the center wing fuel tank, if not corrected, could result in a fire or explosion in the fuel tank during dry operation of the pumps. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998. This alert service bulletin describes procedures for repetitive detailed visual inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps of the center wing fuel tank; and replacement of the check valves and override/jettison pumps with new or serviceable parts, if necessary. The inspections involve defueling the center wing tank; removing the override/jettison pumps; examining the seals, hinge pins, and springs of the inlet check valves for wear or damage; and measuring the amount of wear to the stainless steel disks of the inlet check valves and to the inlet adapters. \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 airplanes of the same type design, this AD is being issued to ensure that the flightcrew is advised of the hazards of dry operation of the override/jettison pumps of the center wing fuel tank; and to detect and correct wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps, which could result in a fire or explosion in the fuel tank during dry operation. This AD requires, for certain airplanes, a revision to the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to provide the flightcrew with restrictions on operating the override/jettison pumps with less than a certain amount of fuel in the center wing fuel tank. This AD also requires, for all airplanes, repetitive detailed visual inspections for wear or damage of the inlet check valves and inlet adapters of the override/jettison pumps of the center wing fuel tank, and replacement of the check valves and override/jettison pumps with new or serviceable parts, if necessary. Accomplishment of the inspections terminates the AFM revision. \n\nDetermination of Threshold for AFM Revision \n\n\tThis AD requires that the AFM be revised for airplanes that have accumulated 20,000 total hours time-in-service. The 20,000-hour threshold was established based on reports from the manufacturer that all of the airplanes on which wear or damage to the inlet check valves and inlet adapters of the override/jettison pumps was detected had accumulated more than 40,000 total hours time-in-service. The FAA finds that a threshold of 20,000 total hours time-in-service for requiring the accomplishment of the AFM revision is warranted. \n\nDifferences Between Rule and Alert Service Bulletin\n \n\tOperators should note that Boeing Alert Service Bulletin 747-28A2212, Revision 2, dated May 14, 1998, recommendsthat the accomplishment of the initial inspections be completed within 120 days (from the date of receipt of the service bulletin). While the FAA agrees that 120 days is an appropriate time interval in which the initial inspections can be accomplished and an adequate level of safety maintained, this AD specifies a compliance time of 90 days for the accomplishment of the initial inspections. This 90-day compliance time was developed by taking into account the manufacturer's recommended 120-day compliance time from May 14, 1998 (the service bulletin issue date), as well as the number of work hours required to accomplish the specified actions and the size of the affected U.S.-registered fleet. In consideration of these factors, the FAA finds that a compliance time of 90 days is appropriate in order to address the identified unsafe condition in a timely manner without compromising safety. \n\nInterim Action \n\n\tThis is considered to be interim action. The manufacturer has advised thatit currently is developing a modification that will positively address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, the FAA may consider additional 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\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-180-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 FR11034, 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, Incorporation by reference, 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: