2021-13133. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

The FAA is withdrawing a notice of proposed rulemaking (NPRM) that proposed to adopt a new airworthiness directive (AD). That NPRM would have applied to certain The Boeing Company Model 737-700, -800, and -900ER series airplanes. The NPRM was prompted by a report of unshimmed gaps at a certain frame inner chord. The NPRM would have required a general visual inspection for repairs of a certain frame inner chord, a detailed inspection for unshimmed gaps of the frame inner chord, and applicable on-condition actions. Since issuance of the NPRM, the FAA determined that the proposed AD is inadequate to address the unsafe condition. The FAA intends to propose new rulemaking to incorporate changes to the proposed requirements and add airplanes that are also subject to the unsafe condition. Accordingly, the NPRM is withdrawn.

DATES:

The FAA is withdrawing the proposed rule published on February 4, 2020 (85 FR 6107), as of June 24, 2021.

ADDRESSES:

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. FAA-2020-0089; 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 AD action, any comments received, and other information. The street address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:

Greg Rutar, Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Background

The FAA issued an NPRM that proposed to amend 14 CFR part 39 by adding an AD that would apply to certain Boeing Model 737-700, -800, and -900ER series airplanes. The NPRM was published in the Federal Register on February 4, 2020 (85 FR 6107). The NPRM was prompted by a report of unshimmed gaps at a certain frame inner chord.

The NPRM proposed to require a general visual inspection for repairs of a certain frame inner chord, a detailed inspection for unshimmed gaps of the frame inner chord, and applicable on-condition actions. The proposed actions were intended to address gaps at a frame inner chord, which may initiate early cracking in fatigue critical baseline structure (FCBS) and result in the inability of a principal structural element (PSE) to sustain limit load and adversely affect the structural integrity of the airplane.

Actions Since the NPRM Was Issued

Since issuance of the NPRM, the FAA determined that the proposed actions are inadequate to address the unsafe condition. In addition to identifying missing shims, Boeing has found a wrong type of shims, shanked fasteners, fastener head gaps, and incorrect fastener hole sizes. The unsafe condition and location of the problem are the same as those described in the NPRM. The FAA has identified additional Model 737-700, -800, and -900ER airplanes as well as additional airplane models that are subject to the unsafe condition. The FAA has also determined that additional actions must be accomplished to address the unsafe condition on the affected airplanes. In light of these changes, the FAA intends to propose further rulemaking.

Withdrawal of the NPRM constitutes only such action. The withdrawal does not preclude the FAA from further rulemaking on this issue or commit the FAA to any course of action in the future.

Comments

The FAA received comments on the NPRM from four commenters, including Aviation Partners Boeing, Boeing, Delta Air Lines, and United Airlines. Although the FAA is withdrawing the NPRM because of new findings and not as a result of any of these comments, the following presents a brief discussion of the comments.

United Airlines concurred with the NPRM.

Aviation Partners Boeing and Delta Air Lines stated that the incorporation of supplemental type certificate (STC) ST00830SE for installation of blended or split scimitar winglets does not affect compliance with the proposed actions, so a “change in product” alternative method of compliance (AMOC) would not be necessary. The FAA agrees with the commenters' assertions, but because the FAA is withdrawing the NPRM, the request is no longer necessary.

Delta Air Lines noted that the service information recommended removing sealant squeeze-out that inhibits inserting the feeler gauge between the mating surfaces. The commenter was concerned that removing the sealant squeeze-out could damage the structure if a metallic tool is used. The FAA disagrees with the request; however, because the NPRM is being withdrawn, the commenter's requested change is unnecessary.

Boeing requested several changes to the Discussion and Related Service Information Under 1 CFR part 51 sections and the description of the unsafe condition in the NPRM. The FAA disagrees with Boeing's requested changes. However, because the NPRM is being withdrawn, the commenter's requested changes are unnecessary.

FAA's Conclusions

Upon further consideration, the FAA has determined that the NPRM does not adequately address the identified unsafe condition. Accordingly, the FAA is withdrawing the NPRM.

Regulatory Findings

Since this action only withdraws an NPRM, it is neither a proposed nor a final rule. This action therefore is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Withdrawal

Accordingly, the notice of proposed rulemaking (Docket No. FAA 2020-0089), which was published in the Federal Register on February 4, 2020 (85 FR 6107), is withdrawn.

Issued on June 15, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.