AD 97-25-15 SUPERSEDED

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 727 series airplanes. This action requires repetitive inspections to detect cracking of the rear spar web or fuel leakage of the wing center section, and repair, if necessary. This amendment also provides for an optional modification of the rear spar web that constitutes terminating action for the repetitive inspections. This amendment is prompted by several reports of fuel leakage due to cracking of the rear spar web of the wing center section. The actions specified in this AD are intended to detect and correct such cracking of the rear spar web, which could permit fuel leakage into the airflow multiplier, and could result in an electrical short that could cause a fire.

Final rule; request for comments

97-25-15 BOEING: Amendment 39-10239. Docket 97-NM-282-AD. \n\n\tApplicability: Model 727 series airplanes having line numbers 858 through 864 inclusive, 867 through 869 inclusive, 872 through 883 inclusive, and 885 through 1832 inclusive; 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 otherwise 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 (e) 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 proposedactions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo detect and correct cracking of the rear spar web, which could permit fuel leakage into the airflow multiplier, and could result in an electrical short that could cause a fire, accomplish the following: \n\n\t(a)\tPrior to the accumulation of 15,000 total flight cycles, or within 300 flight cycles after the effective date of this AD, whichever occurs later: Accomplish the inspections specified in either paragraph (a)(1) or (a)(2) of this AD, in accordance with Boeing Alert Service Bulletin 727-57A0182, dated September 18, 1997. For purposes of this AD, the access panels specified in the alert service bulletin need not be removed; the access panels need only be opened. \n\n\tNOTE 2: The fuel tank of the wing center section may be filled with fuel to assist in detecting cracking or fuel leakage during the accomplishment of the visual inspections required by this AD. \n\n\t\t(1)\tPerform avisual inspection using a borescope or mirror to detect cracking of the rear spar web and/or fuel leakage of the wing center section between Right Body Buttock Line (BBL) 40 and Left BBL 40, in accordance with Part I of the Accomplishment Instructions of the alert service bulletin. Thereafter, repeat this inspection at intervals not to exceed 300 flight cycles. Or \n\n\t\t(2)\tPerform an ultrasonic and high frequency eddy current (HFEC) inspection to detect cracking of the rear spar web of the wing center section between Right BBL 40 and Left BBL 40, in accordance with Part II of the Accomplishment Instructions of the alert service bulletin. Thereafter, repeat this inspection at intervals not to exceed 3,000 flight cycles.\n\n\t(b)\tIf any cracking of the rear spar web and/or fuel leakage of the wing center section is detected between Right BBL 40 and Left BBL 40 near the upper machined land radius, prior to further flight, repair in accordance with Part III of the Accomplishment Instructions in Boeing Alert Service Bulletin 727-57A0182, dated September 18, 1997. Accomplishment of this repair constitutes terminating action for the repetitive inspection requirements of this AD. \n\n\t(c)\tIf any cracking of the rear spar web and/or fuel leakage of the wing center section is detected that is outside the area specified in paragraph (b) of this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t(d)\tAccomplishment of paragraphs (d)(1) and either (d)(2) or (d)(3) of this AD, as applicable, constitute terminating action for the repetitive inspection requirements of this AD.\n\n\t\t(1)\tAccomplish an ultrasonic and HFEC inspection in accordance with the requirements of paragraph (a)(2) of this AD. And, \n\n\t\t(2)\tIf no cracking is detected, prior to further flight, modify the rear spar web of the center section of the fuel tank between Right BBL 40 and LeftBBL 40, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 727-57A0182, dated September 18, 1997. \n\n\t\t(3)\tIf any cracking is detected, prior to further flight, repair in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 727-57A0182, dated September 18, 1997. \n\n\t(e)\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 ACO. 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\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, Seattle ACO. \n\n\t(f)\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 operatethe airplane to a location where the requirements of this AD can be accomplished, provided the limitations specified in paragraphs (f)(1) through (f)(6) of this AD are included in the special flight permit:\n\n\t\t"(1)\tRequired trip and reserve fuel must be carried in the No. 1 and No. 3 \t\t\touter wing tanks. \n\t\t(2)\tWing center tank No. 2 must be empty of fuel. \n\t\t(3)\tThe fuel system must be checked for normal operation prior to flight by verifying that all boost pumps are operational; configuring the fuel system by turning on all boost pumps in the No.'s 1 and 3 outer wing tanks and by opening all crossfeed valve selectors; and by confirming that fuel is not bypassing tank No. 2 check valves by observing that there is no leakage into tank No. 2. \n\t\t(4)\tMaintain a minimum of 5,300 pounds of fuel in tanks No. 1 and No. 3 to prevent uncovering the fuel bypass valve.\n \t\t(5)\tThe fuel quantity indication system must be operational in all three tanks.\n\t\t(6)\tThe effects of loading fuel onlyin the wing tanks on the airplane weight and balance must be considered and accounted for." \n\n\t(g)\tExcept as provided by paragraph (c) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 727-57A0182, dated September 18, 1997. 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(h)\tThis amendment becomes effective on December 29, 1997.

The FAA has received reports indicating that fuel leakage of the wing center section has occurred on several Boeing Model 727 series airplanes due to cracking of the rear spar web of the wing center section. The cracking initiates on the forward side of the spar and propagates through the web at the upper machined land radius between Left Body Buttock Line (BBL) 40 and Right BBL 40. In two instances, cracking was reported on airplanes that had accumulated less than 25,000 total flight cycles. In another case, fuel leakage resulted in fuel odors being emitted into the cabin area. Investigation revealed that fuel was leaking into the airflow multiplier. Fuel leakage into the airflow multiplier due to cracking of the rear spar web of the wing center section, if not detected and corrected, could result in an electrical short that could cause a fire. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert ServiceBulletin 727-57A0182, dated September 18, 1997. This alert service bulletin describes procedures for removing the access panels of the wing center section to perform repetitive visual inspections using a borescope, or ultrasonic with high frequency eddy current inspections, to detect cracking of the rear spar web or fuel leakage of the wing center section, and repair, if necessary. \n\n\tIn addition, the alert service bulletin describes procedures for modification of the rear spar web of the wing center section to prevent cracking of the rear spar web, which eliminates the need for the repetitive inspections. The modification involves stop drilling any cracking, and repairing the rear spar web. \n\n\tThe alert service bulletin references Boeing Drawing 65C37620 as an additional source of service information for accomplishment of the repair and modification. \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 727 series airplanes of the same type design, this AD is being issued to detect and correct cracking of the rear spar web, which could permit fuel leakage into the airflow multiplier and resultant electrical shorting and fire. This AD requires repetitive inspections (either visual inspections using a borescope or a mirror, or ultrasonic and high frequency eddy current (HFEC) inspections) to detect cracking of the rear spar web or fuel leakage of the wing center section, and repair, if necessary. This AD also provides for an optional modification of the rear spar web of the wing center section, which constitutes terminating action for the repetitive inspection requirements of this AD. The inspections, certain repairs, and the modification are required to be accomplished in accordance with the alert service bulletin described previously. Certain repairs are required to be accomplished in accordance with a method approved by the FAA. \n\nDifferences Betweenthe AD and the Service Information \n\n\tOperators should note the following differences between this AD and the Boeing alert service bulletin: \n\n\t* Although the alert service bulletin recommends an initial inspection threshold of within 500 flight cycles for airplanes that have accumulated between 15,000 and 25,000 total flight cycles, and an initial inspection threshold of within 300 flight cycles for airplanes that have accumulated 25,000 or more total flight cycles, this AD specifies an initial compliance time of "prior to the accumulation of 15,000 total flight cycles, or within 300 flight cycles after the effective date of this AD, whichever occurs later." The FAA finds that, in view of the reports of cracking of the rear spar web on two airplanes that had accumulated less than 25,000 total flight cycles, the initial compliance time specified in this AD is appropriate. Further, the FAA finds that adequate justification for permitting an inspection threshold of 500 flight cycles for airplanes that have accumulated over 15,000 total flight cycles, but under 25,000 total flight cycles, has not been presented. Therefore, an initial inspection is required to be accomplished on all airplanes within 300 flight cycles after the effective date of this AD. \n\n\t* This AD requires that, for any cracking or fuel leakage detected that is outside the areas specified in the alert service bulletin, repair must be accomplished in accordance with a method approved by the FAA. \n\n\t* This AD requires that the access panel only be opened in order to perform the inspections, rather than removed, as described in the Boeing alert service bulletin. The manufacturer has advised the FAA that procedures to remove the access panels were inadvertently included in the alert service bulletin and will be removed at the next revision of the alert service bulletin. \n\n\t* Although the alert service bulletin describes procedures for performing the visual inspection using a borescope, the manufacturer has advised the FAA that the option of performing the visual inspection using a mirror was inadvertently omitted from the alert service bulletin. Moreover, Figure 1 of the Accomplishment Instructions of the alert service bulletin specifies that the subject area can be examined with a borescope or mirror. Therefore, the FAA has included the option of using a mirror as an acceptable method of compliance with the visual inspection requirements of this AD. \n\nInterim Action \n\n\tThis is considered to be interim action. The FAA is currently considering requiring the modification of the rear spar web of the wing center section, which will constitute terminating action for the repetitive inspections required by this AD. However, the planned compliance time for the installation of the modification is sufficiently long so that notice and opportunity for prior public comment will be practicable. \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 97-NM-282-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 atthe 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:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 97-NM-282-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.\n\n\tThe service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined 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.

Walter Sippel, Aerospace Engineer, Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2774; fax (425) 227-1181.