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Federal Register / Vol. 86, No. 34 / Tuesday, February 23, 2021 / Rules and Regulations The FAA is adopting a new airworthiness directive AD for certain The Boeing Company Model 737600, 700, 700C, 800, and 900 series airplanes. This AD was prompted by reports of cracks in the bear strap from station STA 290 to STA 296, and between stringers S8R and S9R, sometimes common to fasteners in the gap cover and emanating from rough sanding marks found on the surface of the bear strap. This AD requires inspections of the fuselage skin and bear strap at the forward galley door between certain stations for cracks, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective March 30, 2021.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD
as of March 30, 2021.
ADDRESSES: For service information identified in this final rule, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services C&DS, 2600 Westminster Blvd., MC
110SK57, Seal Beach, CA 907405600;
phone: 5627971717; internet: https
www.myboeingfleet.com. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 2062313195.
It is also available on the internet at https www.regulations.gov by searching for and locating Docket No.
FAA20190705.
SUMMARY:

Examining the AD Docket You may examine the AD docket on the internet at https
www.regulations.gov by searching for and locating Docket No. FAA2019
0705; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
Michael Bumbaugh, Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 2062313522; email:
michael.bumbaugh@faa.gov.
SUPPLEMENTARY INFORMATION:

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Discussion The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 by adding an AD that would apply to certain The Boeing Company Model 737600, 700, 700C, 800, and 900 series airplanes. The NPRM
published in the Federal Register on October 1, 2019 84 FR 52047. The NPRM was prompted by reports of cracks in the bear strap between certain stations, sometimes common to fasteners in the gap cover and emanating from rough sanding marks found on the surface of the bear strap.
The NPRM proposed to require inspections of the fuselage skin and bear strap at the forward galley door between certain stations for cracks, and applicable on-condition actions.
The FAA issued a supplemental NPRM SNPRM to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 737600, 700, 700C, 800, and 900
series airplanes. The SNPRM published in the Federal Register on May 1, 2020
85 FR 25348. The FAA issued the SNPRM to revise certain inspections to provide the correct thickness callouts for the fuselage skin and bear strap.
The FAA is issuing this AD to address cracking of the bear strap, which could result in severing of the bear strap, possibly leading to uncontrolled decompression and loss of structural integrity of the airplane.
Comments The FAA gave the public the opportunity to participate in developing this final rule. The following presents the comments received on the SNPRM
and the FAAs response to each comment.
Support for the SNPRM
United Airlines stated that it has no technical objection to the SNPRM and that it concurs with the proposed rulemaking.
Request for an Alternative Method of Compliance for a Certain Repair Southwest Airlines SWA requested that the Boeing 737700/-800 Structural Repair Manual SRM 531001, Repair 6, be approved as an alternative method of compliance AMOC to certain corrective actions specified in Boeing Alert Requirements Bulletin 737
53A1383 RB, Revision 1, dated February 19, 2020. SWA contended that this repair covers the affected inspection zone, and that this SRM repair should be a terminating action to the inspections specified in Boeing Alert Requirements Bulletin 73753A1383
RB, Revision 1, dated February 19, 2020,
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because the entire inspection area covered is common to the repair given in Boeing 737700/-800 SRM 531001, Repair 6. SWA asserted that operators should be able to accomplish this SRM
repair without contacting Boeing, provided there are no deviations and that the findings meet the criteria listed in the Boeing 737700/-800 SRM 53
1001, Repair 6. SWA also noted that the SRM was published after Boeing Alert Requirements Bulletin 737
53A1383 RB, Revision 1, dated February 19, 2020, so there was no way to reference the SRM repair within it.
The FAA disagrees with the request because the referenced SRM repair has not yet been approved for the specified conditions. However, under the provisions of paragraph j of this AD, the FAA will consider requests for approval of an AMOC if a proposal is submitted that is supported by technical data indicating that the proposed repair will provide an acceptable level of safety. If the referenced SRM repair is determined to be acceptable to address the specified conditions, the FAA may approve, and Boeing may issue, a global AMOC for the SRM repair. The FAA has not changed this AD as a result of this comment.
Request for an Altered Compliance Time for Condition 1, Action 1, of the Service Information Southwest Airlines requested that where table 1 of paragraph 1.E., Compliance, of Boeing Alert Requirements Bulletin 73753A1383
RB, Revision 1, dated February 19, 2020, states a compliance time of Before further flight for certain on-condition actions, the proposed AD should specify this compliance time as Before 15,000
total flight cycles or within 6,000 flight cycles after the original issue of the AD, whichever occurs later. Southwest Airlines also requested that the FAA
clarify the requirement of Condition 1, Action 1, and Condition 3 and Condition 4.1.1, within Boeing Alert Requirements Bulletin 73753A1383
RB, Revision 1, dated February 19, 2020, paragraph 1.E., Compliance, in Tables 1 and 2, to do the alternative inspections and applicable on-condition actions before further flight. SWA
asserted that there is an equivalent level of safety between an airplane without a repair reaching the compliance time threshold to perform the Boeing service bulletin inspection and an airplane with a repair reaching the compliance time threshold before an action is required.
Therefore, the compliance times for obtaining the alternative inspections for the existing repairs should align with the compliance times allowed for
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