2021-01100. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (SNPRM); reopening of comment period.

SUMMARY:

The FAA is revising an earlier proposal for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This action revises the notice of proposed rulemaking (NPRM) by reducing the compliance time for certain airplanes. The FAA is proposing this airworthiness directive (AD) to address the unsafe condition on these products. Since these actions would impose an additional burden over that in the NPRM, the FAA is reopening the comment period to allow the public the chance to comment on these changes.

DATES:

The comment period for the NPRM published in the Federal Register on July 28, 2020 (85 FR 45355), is reopened.

The FAA must receive comments on this SNPRM by March 8, 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: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 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 Boeing service information identified in this SNPRM, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone [phone]; internet https://www.myboeingfleet.com.

For Aviation Partners Boeing service information identified in this SNPRM, contact Aviation Partners Boeing, 2811 South 102nd St., Suite 200, Seattle, WA 98168; phone: [phone]; fax: [phone]; email: [e-mail]; internet: http://www.aviationpartnersboeing.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 206-231-3195. Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, is also available on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-0587.

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-2020-0587; 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 SNPRM, any comments received, and other information. The street address for Docket Operations is listed above. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Wayne Ha, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [e-mail].

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. FAA-2020-0587; Product Identifier 2020-NM-086-AD” 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 we receive, 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 we receive about this proposed AD.

Confidential Business Information

CBI is commercial or financial information that is both customarily and 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 SNPRM 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 SNPRM, 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 SNPRM. Submissions containing CBI should be sent to Wayne Ha, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [e-mail]. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

Discussion

The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that would apply to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The NPRM published in the Federal Register on July 28, 2020 (85 FR 45355). The NPRM was prompted by crack indications found in the lower aft wing skin bolt holes where the flap tracks attach to the track support fitting. The NPRM proposed to require repetitive inspections for cracking of the left and right wing, lower aft wing skin aft edge, at certain flap track locations, and applicable on-condition actions.

Actions Since the NPRM Was Issued

Since the FAA issued the NPRM, the FAA determined that the compliance time should be reduced for airplanes on which Aviation Partners Boeing (APB) blended winglets have been installed using supplemental type certificate (STC) ST01219SE.

Comments

The FAA gave the public the opportunity to comment on the NPRM. The following presents the comments received on the NPRM and the FAA's response to each comment.

Support for the NPRM

One commenter, Jesse Smith, agreed with the intent of the NPRM.

Request To Reduce Compliance Time for Certain Airplanes

APB asked that the FAA revise this AD to reduce the compliance times required for accomplishing the specified actions for airplanes that have incorporated STC ST01219SE. APB stated that it issued APB Alert Service Bulletin AP737C-57-003, dated July 28, 2020, (which contains the same actions as those specified in Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, which is the source of service information for the actions specified in this proposed AD), with reduced compliance times for those airplanes, and, if approved by the FAA, could be added to paragraphs (g) and (h) of the proposed AD.

The FAA agrees with the commenter's request, and has reviewed Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020. The FAA revised paragraph (g) of this proposed AD, including adding paragraphs (g)(1) and (2) of this proposed AD. Paragraph (g)(2) of this proposed AD specifies, for airplanes on which winglets are installed using STC ST01219SE, doing the required actions in Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, at the compliance times in Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020. The FAA has also added paragraphs (h)(4) and (5) of this proposed AD to provide exceptions to Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020.

Request To Clarify Discussion Section

Boeing asked that the Discussion section of the NPRM be clarified by removing “This condition, if not addressed” from the description of the unsafe condition, and instead starting the sentence with “undetected cracking in the lower wing skin could result. . . .” Boeing stated that the term “this condition,” is not clearly defined and may lead to confusion. Boeing added that Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, describes inspections for cracking, and removing that language will more specifically indicate the unsafe condition being addressed in the referenced service information. Boeing noted that the suggested language is also consistent with the language for the unsafe condition specified in paragraph (e) of the proposed AD.

The FAA acknowledges the commenter's request. However, the sentence in question is not carried over to this SNPRM. The FAA has not changed this AD regarding this issue.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, and Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020. The service information describes procedures for repetitive high frequency eddy current (HFEC) inspections for cracking of the left and right wing, lower aft wing skin aft edge, at flap track numbers 1, 2, 3, 6, 7, and 8 attachment location and applicable on-condition actions. On-condition actions include repairing any cracking found. These documents are distinct since they apply to different airplane models in different configurations.

This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

FAA's Determination

The FAA is proposing this AD because the agency evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. Certain changes described above expand the scope of the NPRM. As a result, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this SNPRM.

Proposed Requirements of This SNPRM

This SNPRM would require accomplishing the actions specified in the service information described previously. For information on the procedures and compliance times, see Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, and Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020, at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-0587.

Costs of Compliance

The FAA estimates that this proposed AD affects 141 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

Estimated Costs for Required Actions

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
HFEC inspections	7 work-hours × $85 per hour = $595 per inspection cycle	$0	$595 per inspection cycle	$83,895 per inspection cycle.

The FAA has received no definitive data that would enable the FAA to provide cost estimates for the on-condition actions specified in this proposed AD.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs” describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect 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.

For the reasons discussed above, I certify this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Will not affect intrastate aviation in Alaska, and

(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

The Boeing Company: Docket No. FAA-2020-0587; Product Identifier 2020-NM-086-AD.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by March 8, 2021.

(b) Affected ADs

None.

(c) Applicability

This AD applies to all The Boeing Company Model 737-100, -200, 200C, -300, -400, and -500 series airplanes, certificated in any category.

(d) Subject

Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

This AD was prompted by crack indications found in the lower aft wing skin bolt holes where the flap tracks attach to the track support fitting. The FAA is issuing this AD to address undetected cracking in the lower wing skin, which could result in the inability of the structure to carry limit load, and adversely affect the structural integrity of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Required Actions

(1) For all airplanes except those identified in paragraph (g)(2) of this AD, except as specified in paragraph (h) of this AD, at the applicable times specified in the “Compliance” paragraph in Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020.

Note 1 to paragraphs (g)(1) and (2): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 737-57A1349, dated April 14, 2020, which is referred to in Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020.

(2) For airplanes on which Aviation Partners Boeing blended winglets are installed using supplemental type certificate (STC) ST01219SE: Except as specified in paragraph (h) of this AD, at the applicable time in the “Compliance” paragraph in Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020.

(h) Exceptions to Service Information Specifications

(1) Where Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, uses the phrase “the original issue date of Requirements Bulletin 737-57A1349 RB,” this AD requires using “the effective date of this AD.”

(2) Where Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020, specifies contacting Boeing for repair instructions: This AD requires doing the repair and applicable on-condition actions before further flight using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(3) For airplanes identified as Group 1 in Boeing Alert Requirements Bulletin 737-57A1349 RB, dated April 14, 2020: Within 120 days after the effective date of this AD, do actions to correct the unsafe condition using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(4) Where Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020, uses the phrase “the original issue date of this service bulletin,” this AD requires using “the effective date of this AD.”

(5) Where Aviation Partners Boeing Alert Service Bulletin AP737C-57-003, dated July 28, 2020, specifies contacting Boeing for repair instructions: This AD requires doing the repair and applicable on-condition actions before further flight using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(i) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Los Angeles ACO Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (j)(1) of this AD. Information may be emailed to: [e-mail].

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair, modification, or alteration required by this AD if it is approved by The Boeing Company Organization Designation Authorization (ODA) that has been authorized by the Manager, Los Angeles ACO Branch, FAA, to make those findings. To be approved, the repair method, modification deviation, or alteration deviation must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(j) Related Information

(1) For more information about this AD, contact Wayne Ha, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For Boeing service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone [phone]; internet https://www.myboeingfleet.com.

(3) For Aviation Partners Boeing service information identified in this AD, contact Aviation Partners Boeing, 2811 South 102nd St., Suite 200, Seattle, WA 98168; phone: [phone]; fax: [phone]; email: [e-mail]; internet: http://www.aviationpartnersboeing.com.

(4) You may view this referenced 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 206-231-3195.

Issued on December 30, 2020.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.