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Federal Register / Vol. 86, No. 123 / Wednesday, June 30, 2021 / Proposed Rules
Issued on June 6, 2021.
Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service.
FR Doc. 202113932 Filed 62921; 8:45 am BILLING CODE 491013P

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 39
Docket No. FAA20210503; Project Identifier AD202100163T
RIN 2120AA64

Airworthiness Directives; The Boeing Company Airplanes Federal Aviation Administration FAA, DOT.
ACTION: Notice of proposed rulemaking NPRM.
AGENCY:

The FAA proposes to supersede Airworthiness Directive AD
20050518, which applies to certain The Boeing Company Model 737600, 700, 700C, 800, and 900 series airplanes. AD 20050518 requires repetitive inspections for cracking of the webs of the aft pressure bulkhead at a certain body station, and corrective action if necessary. Since the FAA
issued AD 20050518, cracking was found in that inspection area on airplanes not identified in the applicability of AD 20050518. This proposed AD would retain the requirements of AD 20050518, revise the applicability to include additional airplanes, and add an inspection for existing repairs on the newly added airplanes. The FAA is proposing this AD to address the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by August 16, 2021.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https www.regulations.gov. Follow the instructions for submitting comments.
Fax: 2024932251.
Mail: U.S. Department of Transportation, Docket Operations, M30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9 a.m. and 5
p.m., Monday through Friday, except Federal holidays.
For service information identified in this NPRM, contact Boeing Commercial
jbell on DSKJLSW7X2PROD with PROPOSALS

SUMMARY:

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Airplanes, Attention: Contractual & Data Services C&DS, 2600 Westminster Blvd., MC 110SK57, Seal Beach, CA
907405600; telephone 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 at https
www.regulations.gov by searching for and locating Docket No. FAA2021
0503.
Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210503; 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 NPRM, any comments received, and other information. The street address for Docket Operations is listed above.
FOR FURTHER INFORMATION CONTACT:
Wayne Lockett, Aerospace Engineer, Airframe Section, FAA, Seattle ACO
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206
2313524; email: wayne.lockett@
faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES. Include Docket No.
FAA20210503; Project Identifier AD
202100163T at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend the proposal because of those comments.
Except for Confidential Business Information CBI as described in the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to https
www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this proposed AD.
Confidential Business Information CBI is commercial or financial information that is both customarily and
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actually treated as private by its owner.
Under the Freedom of Information Act FOIA 5 U.S.C. 552, CBI is exempt from public disclosure. If your comments responsive to this NPRM
contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI
as PROPIN. The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI
should be sent to Wayne Lockett, Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198;
phone and fax: 2062313524; email:
wayne.lockett@faa.gov. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
Background The FAA issued AD 20050518, Amendment 3914007 70 FR 12410, March 14, 2005 AD 20050518, for certain The Boeing Company Model 737600, 700, 700C, 800, and 900
series airplanes. AD 20050518 was prompted by a report of cracks found, during fatigue testing, at several of the fastener rows in the web lap splices at the dome apex of the aft pressure bulkhead. AD 20050518 requires repetitive detailed, low frequency eddy current LFEC, and high frequency eddy current HFEC inspections for cracking of the webs of the aft pressure bulkhead at body station BS 1016, and corrective action if necessary. The FAA
issued AD 20050518 to detect and correct fatigue cracks in the webs of the aft pressure bulkhead, which could result in rapid decompression of the airplane.
Actions Since AD 20050518 Was Issued Since the FAA issued AD 200505
18, cracking has been found at apex webs on airplanes outside the applicability of AD 20050518, which includes line numbers 1 through 1166
inclusive. Line numbers 1167 through 1755 inclusive, which are included in this proposed AD, use a revised fastener pattern in the 0.032-inch webs that was intended to correct the cracking addressed by AD 20050518. During the assembly process on line numbers 1167 through 1755, the fasteners in the apex dome region are subjected to
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