# AD 97-20-01: Airworthiness Directives; Boeing Model 747 Series Airplanes - Type: Airworthiness directive - Effective: October 7, 1997 - Published: September 22, 1997, 62 FR 49431–49433 - Issued as: Final rule; request for comments - Superseded by: Nothing supersedes this AD - Amendment: 39-10139 - Docket: 97-NM-237-AD - Official PDF: https://openairdocs.org/files/sha256/2e/08/2e087cf41c24ad8d26f44fe2e3c83bca1eb9d53eba35510a92e387129e510805 (from https://www.govinfo.gov/content/pkg/FR-1997-09-22/pdf/97-25042.pdf) - Federal Register: https://www.federalregister.gov/documents/1997/09/22/97-25042/airworthiness-directives-boeing-model-747-series-airplanes - Page: https://openairdocs.org/ad/97-20-01 ## Summary This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This action requires repetitive inspections to detect cracks, corrosion, or damage of the lower spar fitting body and lug, and corrective actions, if necessary. This AD also provides for optional terminating action for the repetitive inspection requirements. This amendment is prompted by reports that fatigue cracking was found in the lower spar fitting lug on the number 3 pylon and in the lower spar fitting body. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could result in failure of the strut and separation of the engine from the airplane. ## The airworthiness directive ### PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. ### Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: 97-20-01 Boeing: Amendment 39-10139. Docket 97-NM-237-AD. Applicability: Model 747 series airplanes, having line numbers 1 through 500 inclusive, equipped with Pratt & Whitney Model JT9D-3, -7, or -7Q engines, or having line numbers 202, 204, 232, or 257, equipped with General Electric Model CF6 series engines; certificated in any category; and on which the strut/wing modification has not been accomplished in accordance with either of the following Boeing service bulletins: Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994, or Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994. Note 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 (c) 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. Compliance: Required as indicated, unless accomplished previously. To detect and correct fatigue cracking in the lower spar fitting lug or the lower spar fitting body, which could result in failure of the strut and separation of the engine from the airplane, accomplish the following: ### (a) (a) Within 90 days after the effective date of this AD, perform a detailed visual inspection and an ultrasonic inspection to detect cracks, corrosion, or damage of the lower spar fitting body and lug, as applicable, in accordance with Figures 9 and 10 of Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997. Note 2: This AD does not require an inspection of the inboard strut-to-diagonal brace attach fitting as described in Figure 1 of Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997. However, this inspection is required to be accomplished as part of AD 95-20-05, amendment 39-9383 (60 FR 51705, October 10, 1995). (1) If no crack, corrosion, or damage is detected, repeat the detailed visual and ultrasonic inspections thereafter at intervals not to exceed 400 landings. (2) If any crack, corrosion, or damage is detected, prior to further flight, accomplish either paragraph (a)(2)(i) or (a)(2)(ii) of this AD. (i) Replace the lower spar fitting with a new steel lower spar fitting, in accordance with Part II of the Accomplishment Instructions of the service bulletin. Or (ii) Modify the nacelle strut and wing structure in accordance with Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994, or Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994. ### (b) (b) Replacement of the lower spar fitting with a new steel lower spar fitting, in accordance with Part II of the Accomplishment Instructions of Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997; or modification of the nacelle strut and wing structure in accordance with Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994, or Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994; constitutes terminating action for the repetitive inspection requirements of this AD. ### (c) (c) An 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. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. ### (d) (d) Special 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 of this AD can be accomplished. ### (e) (e) The inspections and replacement shall be done in accordance with Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997. The modification, if accomplished, shall be done in accordance with Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994, or Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994. (1) The incorporation by reference of Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. (2) The incorporation by reference of Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51 as of July 28, 1995 (60 FR 33336, June 28, 1995). (3) The incorporation by reference of Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51 as of June 21, 1995 (60 FR 27008, May 22, 1995). (4) 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. ### (f) (f) This amendment becomes effective on October 7, 1997. Issued in Renton, Washington, on September 15, 1997. S.R. Miller, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. ## Rule preamble ### Dates Effective October 7, 1997. The incorporation by reference of Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997, as listed in the regulations, is approved by the Director of the Federal Register as of October 7, 1997. The incorporation by reference of Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of July 28, 1995 (60 FR 33336, June 28, 1995). The incorporation by reference of Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of June 21, 1995 (60 FR 27008, May 22, 1995). Comments for inclusion in the rules docket must be received on or before November 21, 1997. ### Addresses Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 97-NM-237-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. The 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. ### For further information contact Tamara L. Dow, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2771; fax (425) 227-1181. ### Supplementary information On September 21, 1995, the FAA issued AD 95-20-05, amendment 39-9383 (60 FR 51704, October 3, 1995), applicable to certain Boeing Model 747 series airplanes, to require repetitive inspections for cracking in the inboard strut-to-diagonal brace attach fittings, and repair or replacement, if necessary. That AD also provides for an optional terminating modification for the required inspections. The requirements of that AD are intended to prevent failure of the strut and separation of an engine from the airplane due to cracking of the inboard strut-to-diagonal brace attach fittings. Since issuance of that AD, the FAA has received reports of fatigue cracking in the lower spar fitting lug on the number 3 pylon and in the lower spar fitting body on Boeing Model 747 series airplanes. This cracking area is beyond the inspection area specified in AD 95-20-05. The airplane on which the lower spar fitting lug was cracked had accumulated 12,734 total flight cycles with 64,537 total flight hours. The lower spar fitting with the cracked lug had accumulated 1,078 flight cycles from the previous inspection required by AD 95-20-05. The lower spar fitting with the cracked body had accumulated less than 1,000 flight cycles from the previous inspection required by AD 95-20-05. Fatigue cracking in the lower spar fitting lug or the lower spar fitting body, if not detected and corrected in a timely manner, could result in failure of the strut and separation of the engine from the airplane. ### Explanation of Relevant Service Information Subsequent to the finding of this new cracking, the manufacturer issued, and the FAA reviewed and approved Boeing Service Bulletin 747-54-2062, Revision 8, dated August 21, 1997. The service bulletin describes procedures for repetitive detailed visual and ultrasonic inspections to detect cracks, corrosion, or damage of the lower spar fitting body and lug, as applicable, and replacement, if necessary. The service bulletin also describes procedures for replacement of the lower spar fitting with a new steel lower spar fitting, which eliminates the need for the repetitive inspections. ### Explanation of the Requirements of the Rule Since an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 747 series airplanes of the same type design, this AD is being issued to detect and correct fatigue cracking in the lower spar fitting lug or the lower spar fitting body, which could result in failure of the strut and separation of the engine from the airplane. This AD requires repetitive detailed visual and ultrasonic inspections to detect cracks, corrosion, or damage of the lower spar fitting body and lug, as applicable, and replacement, if necessary. This AD also provides for an optional replacement of the lower spar fitting with a new steel lower spar fitting, which constitutes terminating action for the repetitive inspection requirements. The actions are required to be accomplished in accordance with the service bulletin described previously. In lieu of accomplishing the subject replacement or repetitive inspections, this AD provides for an optional terminating modification of the nacelle strut and wing structure. (This modification is part of the ``Boeing Model 747 Strut and Wing Structural Modification Program,'' described in Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994, and Boeing Alert Service Bulletin 747-54A2158, dated November 30, 1994.) ### Determination of Rule's Effective Date Since 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. ### Comments Invited Although 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. Comments 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. Commenters 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-237-AD.'' The postcard will be date stamped and returned to the commenter. ### Regulatory Impact The 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. The 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. ### List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. ### Adoption of the Amendment Accordingly, 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: No proposed rule in this release led to it. Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.