[Federal Register Volume 84, Number 245 (Friday, December 20, 2019)]
[Rules and Regulations]
[Pages 70000-70003]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-27465]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0406; Product Identifier 2019-NM-059-AD; Amendment 
39-21006; AD 2019-24-17]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
The Boeing Company Model MD-90-30 airplanes. This AD was prompted by 
reports indicating that certain center wing stringers and skins are 
potentially susceptible to cracking. This AD requires repetitive eddy 
current, low frequency (ETLF) inspections of the left and right side 
fastener holes for any crack; repetitive eddy current, high frequency 
(ETHF) inspections of the lower skin for any crack; and repair if any 
crack is found. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective January 24, 2020.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of January 24, 
2020.

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 562-797-1717; internet https://www.myboeingfleet.com. 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. It is also available on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2019-
0406.

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-2019-
0406; 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 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: David Truong, Aerospace Engineer, 
Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount 
Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5224; fax: 562-627-
5210; email: david.truong@faa.gov.

SUPPLEMENTARY INFORMATION: 

Discussion

    The FAA 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 MD-90-30 airplanes. The NPRM published in the Federal Register on 
June 21, 2019 (84 FR 29105). The NPRM was prompted by reports 
indicating that based on Model MD-80 airplane service experience, 
certain center wing stringers and skins are potentially susceptible to 
fatigue-related cracking on Model MD-90 airplanes. The Model MD-80 and 
Model MD-90 wings share the same basic design and experience similar 
stresses, but no such cracking has been found on Model MD-90 airplanes. 
Cracks on Model MD-80 airplanes were found in the center wing lower 
stringers, at the inboard end where they are joined to the airplane 
centerline by end fittings; in the lower stringer end fittings, at the 
outboard end where they attach to stringers; and in the lower forward 
and aft skins, underneath cracked stringers. If not addressed, this 
cracking could result in the inability of the structure to sustain 
limit loads, and adversely affect the structural integrity of the 
airplane. The NPRM proposed to require repetitive ETLF inspections of 
the left and right side fastener holes for any crack; repetitive ETHF 
inspections of the lower skin for any crack; and repair if any crack is 
found.

Comments

    The FAA 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 for Clarification of Other Relevant Rulemaking Section

    Boeing requested clarification regarding the number of cracking 
occurrences reported in areas outside of those addressed by AD 2016-07-
28, Amendment 39-18473 (81 FR 21253, April 11, 2016) (``AD 2016-07-
28''), or Boeing Alert Service Bulletin MD80-

[[Page 70001]]

57A244, dated March 3, 2016. Boeing noted that in the NPRM, the Other 
Relevant Rulemaking section stated that since AD 2016-07-28 was issued, 
cracking was found at fastener holes common to stringers (S) S-11 
through S-22, and around the external bracket angle at S-18 and S-19. 
Boeing emphasized that there was only one case of cracking, at S-13.
    In addition, Boeing requested that the Other Relevant Rulemaking 
section in the NPRM be revised to explain that the new service 
information that Boeing is developing for Model MD-80 airplanes is to 
address potential cracking in new stringer locations and is not in 
response to actual in-service reports of cracking.
    The FAA agrees with the commenter's assessment of crack findings. 
Of the cracks found since issuance of AD 2016-07-28, only one was found 
at S-13--the only area not addressed by AD 2016-07-28. All remaining 
crack findings were within the scope of the requirements of AD 2016-07-
28. As a result of these cracks, Boeing made the determination to 
expand the inspection to stringers S-11 through S-22. This AD addresses 
those stringers on Model MD-90-30 airplanes.
    The FAA acknowledges that the service information for the Model MD-
80 airplanes, Boeing Service Bulletin MD80-57A244, dated March 3, 2016, 
which is mandated by AD 2016-07-28, has been revised. Boeing Service 
Bulletin MD80-57A244, Revision 1, dated October 1, 2019, updates the 
inspection method and expands the inspection area. The FAA may consider 
further rulemaking in the future to mandate these changes for Model MD-
80 airplanes.
    Because the Other Relevant Rulemaking section in SUPPLEMENTARY 
INFORMATION is not retained in final rules, the FAA has not revised 
this final rule in regard to these issues.

Request To Revise Cost Information

    Delta Air Lines (DAL) requested clarification regarding the number 
of airplanes on the U.S. registry that would be affected by the NPRM. 
DAL stated that the Costs of Compliance paragraph indicated that an 
estimated 43 airplanes would be affected. However, DAL is the only U.S. 
operator of the affected airplanes, and DAL reports that there are 65 
airplanes in their operations specification.
    The FAA agrees with the commenter and has revised the Costs of 
Compliance paragraph in this final rule accordingly.

Request for Legible Service Information

    DAL requested that better quality copies of certain sheets of 
Boeing Drawing SN09570007 be provided to operators. The commenter 
stated that the poor quality of these sheets renders them useless in 
terms of doing inspections and is concerned about showing compliance 
with the requirements specified in the proposed AD.
    The FAA acknowledges the commenter's concern regarding the 
legibility of certain sheets of Boeing Drawing SN09570007. Since Boeing 
Alert Service Bulletin MD90-57A031, dated March 19, 2019, does not 
include Boeing Drawing SN09570007 in the ``Required for Compliance 
(RC)'' section, the drawing is not required to comply with this AD. The 
drawing is referenced in Paragraph 1.J.2., Planning Information, 
References, Data Supplied with the Service Bulletin, in Boeing Alert 
Service Bulletin MD90-57A031, dated March 19, 2019. Operators notified 
Boeing about the illegible drawing sheets, and in response, Boeing 
issued Boeing Multi Operator Message MOM-MOM-19-0549-01B, dated October 
4, 2019, which provides clearer images of Boeing Drawing SN09570007. 
The FAA recognizes that Boeing Drawing SN09570007 may provide helpful 
information to operators. Therefore, the FAA has added Note 1 to 
paragraph (g) of this AD to notify operators that if they have 
illegible pages of Boeing Drawing SN09570007, additional guidance can 
be found in Boeing Multi Operator Message MOM-MOM-19-0549-01B, dated 
October 4, 2019.

Conclusion

    The FAA 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. The FAA 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.
    The FAA also determined that these changes will not increase the 
economic burden on any operator (other than the estimated number of 
affected airplanes as explained under the ``Request to Revise Cost 
Information'' section of this final rule) or increase the scope of this 
final rule.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Service Bulletin MD90-57A031, dated 
March 19, 2019. This service information describes procedures for 
repetitive ETLF inspections of the left and right side fastener holes 
for any crack, repetitive ETHF inspections of the lower skin for any 
crack, and repair if any crack is found. 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

    The FAA estimates that this AD affects 65 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                Cost on U.S.
         Action                   Labor cost            Parts cost      Cost per product          operators
----------------------------------------------------------------------------------------------------------------
Inspection..............  30 work-hours x $85 per                $0   $2,550 per            $165,750 per
                           hour = $2,550 per                           inspection cycle.     inspection cycle.
                           inspection cycle.
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data that would enable the 
agency to provide cost estimates for 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.
    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

[[Page 70002]]

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) 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.

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

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2019-24-17 The Boeing Company: Amendment 39-21006; Docket No. FAA-
2019-0406; Product Identifier 2019-NM-059-AD.

(a) Effective Date

    This AD is effective January 24, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model MD-90-30 
airplanes, certificated in any category.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by reports indicating that certain center 
wing stringers and skins are potentially susceptible to cracking. 
The FAA is issuing this AD to address cracking of the center wing 
stringers and skins, which could result in the inability of the 
structure to sustain limit loads, 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

    Except as specified in paragraph (h) of this AD: At the 
applicable times specified in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019, do 
all applicable actions identified as ``RC'' (required for 
compliance) in, and in accordance with, the Accomplishment 
Instructions of Boeing Alert Service Bulletin MD90-57A031, dated 
March 19, 2019.

    Note 1 to paragraph (g) of this AD: Boeing Alert Service 
Bulletin MD90-57A031, dated March 19, 2019, refers to Boeing Drawing 
SN09570007, as data supplied with this service bulletin. If the 
pages of Boeing Drawing SN09570007 are illegible, guidance can be 
found in Boeing Multi Operator Message MOM-MOM-19-0549-01B, dated 
October 4, 2019.

(h) Exceptions to Service Information Specifications

    (1) For purposes of determining compliance with the requirements 
of this AD: Where Boeing Alert Service Bulletin MD90-57A031, dated 
March 19, 2019, uses the phrase ``the original issue date of this 
service bulletin,'' this AD requires using ``the effective date of 
this AD.''
    (2) Where Boeing Alert Service Bulletin MD90-57A031, dated March 
19, 2019, specifies contacting Boeing for repair instructions and 
doing the repair: This AD requires doing the repair 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 9-ANM-LAACO-AMOC-Requests@faa.gov.
    (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 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.
    (4) Except as specified by paragraph (h) of this AD: For service 
information that contains steps that are labeled as Required for 
Compliance (RC), the provisions of paragraphs (i)(4)(i) and (ii) of 
this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. If a step or substep is labeled ``RC Exempt,'' then the 
RC requirement is removed from that step or substep. An AMOC is 
required for any deviations to RC steps, including substeps and 
identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(j) Related Information

    (1) For more information about this AD, contact David Truong, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5224; fax: 562-627-5210; email: david.truong@faa.gov.
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (k)(3) and (4) of this AD.

(k) 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.

[[Page 70003]]

    (i) Boeing Alert Service Bulletin MD90-57A031, dated March 19, 
2019.
    (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 562-797-1717; 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, email fedreg.legal@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Des Moines, Washington, on December 4, 2019.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2019-27465 Filed 12-19-19; 8:45 am]
BILLING CODE 4910-13-P


