2018-19185. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD was prompted by reports of cracking in certain flanges, and the adjacent web, of the wing outboard flap track at certain positions, and a determination that new inspections of certain flap track flanges and webs forward of the rear spar attachment are necessary. This AD requires an inspection to determine the part number of the wing outboard flap track assembly; repetitive inspections of each affected wing outboard flap track for discrepancies, and applicable on-condition actions; and repetitive overhaul of each wing outboard flap track. We are issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective October 18, 2018.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of October 18, 2018.

ADDRESSES:

For service information identified in this final rule, 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. You may view this referenced service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0112.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0112; 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, the regulatory evaluation, any comments received, and other information. The address for Docket Operations (phone: [phone]) is Docket Operations, 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:

Payman Soltani, 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:

Discussion

We issued a notice of proposed rulemaking (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 February 21, 2018 (83 FR 7425). The NPRM was prompted by reports of cracking in certain flanges, and the adjacent web, of the wing outboard flap track at certain positions, and a determination that new inspections of certain flap track flanges and webs forward of the rear spar attachment are necessary. The NPRM proposed to require an inspection to determine the part number of the wing outboard flap track assembly; repetitive inspections of each affected wing outboard flap track for discrepancies, and applicable on-condition actions; and repetitive overhaul of each wing outboard flap track.

We are issuing this AD to detect and correct cracking of the wing outboard flap tracks. Cracking in the area between the forward and rear spar attachments of the wing outboard flap tracks could lead to the inability of a principal structural element to sustain required flight loads, and result in loss of the outboard trailing edge flap and consequent reduced controllability of the airplane.

Comments

We gave the public the opportunity to participate in developing this final rule. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Extend the Compliance Time

All Nippon Airways (ANA) and Utair Aviation requested that paragraph (h) of the proposed AD be revised to extend the compliance time from 6 months to 18 months after the effective date of the final rule. The commenters are concerned that there are not enough spare flap track parts available. The commenters indicated that overhaul of the removed flap tracks takes significant time, and if the final rule is released without a sufficient number of spare flap tracks available, there could be a long-term aircraft on ground (AOG) situation if the proposed compliance times are used.

Furthermore, Utair Aviation stated that a review of maintenance records on 38 airplanes for flap tracks at positions 1 and 8 did not find any records of inspections or overhaul, and it would not be able to replace the subject flap tracks within the compliance time specified in the proposed AD. Utair Aviation also noted that it took 60 days, including shipping, to replace the outboard flap tracks for similar requirements specified in AD 2013-09-02, Amendment 39-17443 (78 FR 27010, May 9, 2013).

We do not agree with the commenters' requests. The 6-month compliance time for inspection and overhaul is applicable only to flap tracks that have unknown maintenance records and flap tracks that were last overhauled several years ago. Airplanes with flap tracks that have known maintenance records generally have later compliance times, depending on how long it has been since the flap tracks were overhauled. The NPRM was issued to address findings of stress corrosion cracking in the flap tracks. Stress corrosion cracking is more likely to occur in flap tracks that have been in operation for a longer time. Flap tracks with unknown maintenance records and flap tracks that were last overhauled several years ago are more susceptible to the unsafe condition. The probability of the existence of stress corrosion cracking on flap tracks with unknown maintenance history is higher and warrants the shorter compliance time. We have verified that spare flap tracks are available on the parts surplus market; however, since we do not know how many flap tracks have unknown maintenance records, it is difficult to estimate how many spare flap tracks will be necessary to meet the demand. If there is a critical shortage of parts, operators may contact the FAA and request an adjustment to the compliance time using the procedures specified in paragraph (l) of this AD. We might approve a longer compliance time if additional data are presented that would justify an extension to the compliance time while still maintaining an adequate level of safety.

We urge operators to seek out maintenance records for their flap tracks in order to justify use of the extended compliance times specified in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017. We cannot justify extending the compliance times for flap tracks without maintenance records to 18 months. We have not changed this AD in regard to this issue.

Request To Omit Inspection 1 in the Service Information

Utair Aviation stated that it is inadvisable to require operators to do the inspections included in “INSPECTION 1,” as defined in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017. The commenter noted that “ACTION 1” in Table 1 and Table 2 of paragraph 3, “Compliance,” of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, states that operators need to do INSPECTION 1. The commenter suggested that “ACTION 2,” overhaul of each affected flap track, would already include all of the inspections included in INSPECTION 1.

We infer that the commenter is requesting that the proposed requirement to do the inspections included in INSPECTION 1 of the specified service bulletin be removed from the proposed AD. We do not agree with the commenter's request. ACTION 1 and ACTION 2 have different purposes. The inspections included in ACTION 1 are intended to detect specific existing damage on the flap track, including cracks, nicks, corrosion, galling, broken pieces, and stop drills. The intention of ACTION 2, overhaul of each affected flap track, is a visual examination for defects. The intent of this visual examination during overhaul is to identify additional discrepancies, such as excessive wear or degraded surface finish, that might not be noted during INSPECTION 1. It is important to detect these additional discrepancies since they can be early indicators of stress corrosion cracking. Since the inspections to detect specific existing damage on the flap track are not included in the overhaul instructions, it is necessary to require both ACTION 1 and ACTION 2 in this AD. We have not changed this AD in regard to this issue.

Request for Alternative To Overhaul

ANA requested that an alternative to overhaul of the flap tracks be provided that does not involve removing the flap tracks from the wing. The commenter suggested that an on-wing inspection could be used instead of the overhaul. The commenter is concerned that there is not a sufficient supply of spare flap track parts.

We do not agree with the commenter's request. There is no on-wing inspection method available that can detect the additional discrepancies that overhaul of the flap tracks is designed to address. The concern regarding availability of spare flap track parts was addressed in the response to an earlier comment. We have not changed this AD in regard to this issue.

Request To Revise Parts Installation Limitation Paragraph

Boeing requested that the Parts Installation Limitation Paragraph, paragraph (k) in the proposed AD, be revised to allow flap tracks to be installed and inspected at the time of installation. Boeing noted that paragraph (k) states “. . . no person may install a flap track unless the flap track is inspected prior to installation.” Boeing pointed out that there are several inspections that pertain to the track-to-wing joint, which cannot be accomplished until after the flap track is installed.

We agree with the commenter's request for the reasons provided by the commenter. We have revised paragraph (k) of this AD to state “As of the effective date of this AD, no person may install, on any airplane, a wing outboard flap track having a part number listed in paragraph 1.B. of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, unless the inspections . . . are accomplished prior to or concurrently with the part's installation on the airplane.”

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that accomplishing the installation of winglets using Supplemental Type Certificate (STC) ST01219SE does not affect compliance with the actions proposed in the NPRM.

We concur with the commenter. We have redesignated paragraph (c) of the proposed AD as paragraph (c)(1) of this AD and added paragraph (c)(2) to this AD to state that installation of STC ST01219SE does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a “change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.

Additional Change to This AD

The proposed AD included Note 1 to paragraph (h), which stated that guidance for accomplishing the proposed actions could be found in Boeing Alert Service Bulletin 737-57A1338, dated September 25, 2017, which is referred to in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017. Since the proposed AD was published, Boeing has issued Boeing Information Notice 737-57A1338 IN 01, dated October 16, 2017; Boeing Information Notice 737-57A1338 IN 02, dated March 16, 2018; and Boeing Information Notice 737-57A1338 IN 03, dated March 20, 2018. These information notices provide additional guidance material related to Boeing Alert Service Bulletin 737-57A1338, dated September 25, 2017, including clarification of compliance times for spares (not AD compliance times), inspection figures, and the relationship between flap track part numbers and airplanes groups. We have revised Note 1 to paragraph (h) in this AD to include these information notices.

Conclusion

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the changes described previously and minor editorial changes. We have determined that these minor changes:

• Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and
• Do not add any additional burden upon the public than was already proposed in the NPRM.

We also determined that these changes will not increase the economic burden on any operator or increase the scope of this final rule.

Related Service Information Under 1 CFR Part 51

We reviewed Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017. This service information describes procedures for repetitive inspections and repetitive overhaul of the wing outboard flap tracks, and applicable on-condition actions including repair and replacement of the wing outboard flap tracks. 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.

Costs of Compliance

We estimate that this AD affects 160 airplanes of U.S. registry. We estimate the following costs to comply with this AD:

Estimated Costs for Required Actions

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Inspection (positions 1 and 8; Group 2 and Group 3, configuration 1)	78 work-hours × $85 per hour = $6,630 per cycle	$0	$6,630 per cycle	$1,060,800 per cycle.
Inspection (positions 1 and 8; Group 3, configuration 2)	89 work-hours × $85 per hour = $7,565 per cycle	0	7,565 per cycle	1,210,400 per cycle.
Inspection (positions 2 and 7; Group 2 and Group 3, configuration 1)	83 work-hours × $85 per hour = $7,055 per cycle	0	7,055 per cycle	1,128,800 per cycle.
Inspection (positions 2 and 7; Group 3, configuration 2)	86 work-hours × $85 per hour = $7,310 per cycle	0	7,310 per cycle	1,169,600 per cycle.

We have received no definitive data that will enable us to provide cost estimates for the actions for Group 1 airplanes, the repetitive overhaul, or the on-condition actions specified in this 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.

We are 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.

This AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to the Director of the System Oversight Division.

Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD will 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 that this AD:

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

(2) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

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

(4) 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

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 (AD):

2018-18-13 The Boeing Company: Amendment 39-19392; Docket No. FAA-2018-0112; Product Identifier 2017-NM-161-AD.

(a) Effective Date

This AD is effective October 18, 2018.

(b) Affected ADs

This AD affects AD 2013-09-02, Amendment 39-17443 (78 FR 27010, May 9, 2013) (“AD 2013-09-02”).

(c) Applicability

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

(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgstc.nsf/​0/​ebd1cec7b301293e86257cb30045557a/​$FILE/​ST01219SE.pdf) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a “change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.

(d) Subject

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

(e) Unsafe Condition

This AD was prompted by reports of cracking in certain flanges, and the adjacent web, of the wing outboard flap track at certain positions, and a determination that new inspections of certain flap track flanges and webs forward of the rear spar attachment are necessary. We are issuing this AD to detect and correct cracking of the wing outboard flap tracks. Cracking in the area between the forward and rear spar attachments of the wing outboard flap tracks could lead to the inability of a principal structural element to sustain required flight loads, and result in loss of the outboard trailing edge flap and consequent reduced controllability of the airplane.

(f) Compliance

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

(g) Required Actions for Group 1 Airplanes

For airplanes identified as Group 1 in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017: 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 (l) of this AD.

(h) Required Actions

For airplanes not specified in paragraph (g) of this AD: Except as required by paragraph (i) of this AD, at the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017.

Note 1 to paragraph (h) of this AD:

Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 737-57A1338, dated September 25, 2017, which is referred to in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017. Additional guidance can be found in Boeing Information Notice 737-57A1338 IN 01, dated October 16, 2017; Boeing Information Notice 737-57A1338 IN 02, dated March 16, 2018; and Boeing Information Notice 737-57A1338 IN 03, dated March 20, 2018.

(i) Exceptions to Service Information Specifications

For purposes of determining compliance with the requirements of this AD: Where Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, uses the phrase “the original issue date of Requirements Bulletin 737-57A1338 RB,” this AD requires using “the effective date of this AD.”

(j) Terminating Action for Requirements of AD 2013-09-02

Accomplishment of the requirements specified in paragraph (h) of this AD terminates all requirements of AD 2013-09-02.

(k) Parts Installation Limitation

As of the effective date of this AD, no person may install, on any airplane, a wing outboard flap track having a part number listed in paragraph 1.B. of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, unless the inspections and corrective actions specified in the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, are accomplished prior to or concurrently with the part's installation on the airplane.

(l) 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 (m)(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 local flight standards district office/certificate holding district 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 Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Los Angeles ACO Branch, 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.

(m) Related Information

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

(2) Service information identified in this AD that is not incorporated by reference is available at the addresses specified in paragraphs (n)(3) and (n)(4) of this AD.

(n) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise.

(i) Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 2017.

(ii) Reserved.

(3) For 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.

(4) You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.

(5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/​federal-register/​cfr/​ibr-locations.html.

Issued in Des Moines, Washington, on August 24, 2018.

James Cashdollar,

Acting Director, System Oversight Division, Aircraft Certification Service.