[Federal Register Volume 85, Number 38 (Wednesday, February 26, 2020)]
[Proposed Rules]
[Pages 11000-11003]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-03864]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0091; Product Identifier 2020-NM-012-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain The Boeing Company Model 737-8 and 737-9 airplanes. This 
proposed AD was prompted by a report that certain exterior fairing 
panels on the top of the engine nacelle and strut (the thumbnail 
fairing and mid strut fairing panels) may not have the quality of 
electrical bonding necessary to ensure adequate shielding of the 
underlying wiring from the electromagnetic effects of lightning strikes 
or high intensity radiated fields (HIRF), which could potentially lead 
to a dual engine power loss event from a critical lightning or HIRF 
exposure event. This proposed AD would require a detailed inspection of 
the thumbnail fairing panels and mid strut fairing panels for excessive 
rework of the metallic (aluminum foil) inner surface layer, replacement 
of any excessively reworked panels, and modification of the thumbnail 
fairing assembly to ensure adequate bonding. 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 March 27, 
2020.

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: 202-493-2251.
     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 service information identified in this NPRM, 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-2020-0091.

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-
0091; or in person at Docket Operations

[[Page 11001]]

between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this NPRM, the regulatory evaluation, 
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: Christopher Baker, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3552; email: 
[email protected].

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 the ADDRESSES section. Include ``Docket No. FAA-2020-0091; 
Product Identifier 2020-NM-012-AD'' at the beginning of your comments. 
The FAA specifically invites comments on the overall regulatory, 
economic, environmental, and energy aspects of this NPRM. The FAA will 
consider all comments received by the closing date and may amend this 
NPRM 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 FAA will also post a report summarizing each substantive 
verbal contact received about this NPRM.

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 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 
Christopher Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle 
ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 
206-231-3552; email: [email protected]. 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 has received a report from Boeing indicating that exterior 
fairing panels on the top of the engine nacelle and strut (the 
thumbnail fairing and mid strut fairing panels) may not have the 
quality of electrical bonding necessary to ensure adequate shielding of 
the underlying wiring from the electromagnetic effects of lightning 
strikes or HIRF. Excessive rework of the surface of the metallic 
(aluminum foil) inner layer of those panels can result in cuts to that 
layer. This metallic layer functions as part of the shielding for 
aircraft wiring, including wiring associated with the engine control 
systems. Cuts to the metallic layer, depending on their size and 
location, could create the potential for HIRF exposure or lightning 
attachment to induce spurious signals onto the underlying airplane 
wiring, including wiring associated with the engine control systems. 
Such spurious signals could cause a loss of engine thrust control. This 
loss of thrust control could simultaneously affect both engines in two 
different ways. The wiring for both engines could be independently 
exposed to the electromagnetic effects from the same HIRF or lightning 
event, or the signals induced on one engine's control system could be 
induced onto the other engine's wiring via common avionics system 
connections. This condition, if not addressed, could result in a forced 
off-airport landing or excessive flightcrew workload due to loss of 
thrust control on both engines.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Special Attention Service Bulletin 737-54-
1056, dated December 11, 2019. This service information describes 
procedures for a detailed inspection of the thumbnail fairing panels 
and mid strut fairing panels for excessive rework of the metallic 
(aluminum foil) inner surface layer (resulting in foil cuts), 
replacement of any excessively reworked panels, and modification of the 
thumbnail fairing assembly to ensure adequate bonding. Modification 
actions include doing a form-in-place gasket of the thumbnail land 
assemblies; preparing the mating surfaces between the thumbnail fairing 
panel and the left and right thumbnail land assemblies; and doing a 
bond check of the thumbnail fairing panel and the thumbnail land 
assemblies on the left and right side of the thumbnail fairing panel on 
both engines.
    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.

Proposed AD Requirements

    This proposed AD would require accomplishing the actions specified 
in the service information described previously, except as discussed 
under ``Differences Between this Proposed AD and the Service 
Information.'' For information on the procedures, see this service 
information at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2020-0091.

Differences Between This Proposed AD and the Service Information

    Boeing Special Attention Service Bulletin 737-54-1056, dated 
December 11, 2019, specifies a compliance time of 6 months to do the 
actions. However, for this proposed AD, the actions must be done before 
further flight. The proposed compliance time is based on the potential 
for a common-cause failure of both engines. The FAA has determined this 
compliance time is appropriate to address the identified unsafe 
condition.
    Additionally, the effectivity of Boeing Special Attention Service 
Bulletin 737-54-1056, dated December 11, 2019, lists certain line 
numbers of Model 737-8 and 737-9 airplanes. However, the FAA is not 
certain that the service bulletin lists all airplanes affected by the 
unsafe condition identified in this proposed AD. Thus, the 
applicability of this proposed AD is expanded to include all line 
numbers for Model 737-8 and 737-9 airplanes that may be affected by the 
identified unsafe condition. This will ensure that all potentially 
affected airplanes are subject to the proposed AD.

Costs of Compliance

    The FAA estimates that this proposed AD affects 128 airplanes of 
U.S. registry.

[[Page 11002]]

The FAA estimates the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                    Cost per       Cost on U.S.
              Action                        Labor cost            Parts cost        product         operators
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Inspection........................  5 work-hours x $85 per                 $0             $425          $54,400
                                     hour = $425.
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    The FAA estimates the following costs to do any necessary 
modifications that would be required based on the results of the 
proposed inspection. The FAA has no way of determining the number of 
aircraft that might need these modifications:

                                               On-Condition Costs
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                 Action                             Labor cost            Parts cost       Cost per product
----------------------------------------------------------------------------------------------------------------
Modification...........................  Up to 7 work-hours x $85 per           (*)   Up to $595 *.
                                          hour = Up to $595.
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* The FAA has received no definitive data that would enable the agency to provide parts cost estimates for the
  on-condition actions specified in this proposed AD.

    According to the manufacturer, all of the costs of this proposed AD 
will be covered under warranty, thereby reducing the cost impact on 
affected persons. The FAA does not control warranty coverage for 
affected persons. As a result, the FAA has included all known costs in 
the cost estimate.

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

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):

The Boeing Company: Docket No. FAA-2020-0091; Product Identifier 
2020-NM-012-AD.

(a) Comments Due Date

    The FAA must receive comments by March 27, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-8 and 737-9 
airplanes included in line numbers 5602 through 7901, certificated 
in any category.

(d) Subject

    Air Transport Association (ATA) of America Code 54, Nacelles/
pylons.

(e) Unsafe Condition

    This AD was prompted by a report that certain exterior fairing 
panels on the top of the engine nacelle and strut (the thumbnail 
fairing and mid strut fairing panels) may not have the quality of 
electrical bonding necessary to ensure adequate shielding of the 
underlying wiring from the electromagnetic effects of lightning 
strikes or high intensity radiated fields (HIRF), which could 
potentially lead to a dual engine power loss event from a critical 
lightning or HIRF exposure event. The FAA is issuing this AD to 
address this condition, which could result in a forced off-airport 
landing or excessive flightcrew workload due to loss of thrust 
control on both engines.

(f) Compliance

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

(g) Detailed Inspection and Modification

    Before further flight, do a detailed inspection of the thumbnail 
fairing panels and mid strut fairing panels for excessive rework of 
the metallic (aluminum foil) inner surface layer, and, before 
further flight, do the modification as applicable in accordance with 
Steps 4., 6. through 9., inclusive, 11., and 12. of the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-54-1056, dated December 11, 2019.

(h) Special Flight Permit

    Special flight permits, as described in 14 CFR 21.197 and 
21.199, may be issued to operate the airplane to a location where 
the requirements of this AD can be accomplished, but concurrence by 
the Manager, Seattle ACO Branch, FAA, is required before issuance of 
the special flight permit. Requests for a special flight permit

[[Page 11003]]

must be submitted to the FAA with a description of the 
electromagnetic field radiation sources (type, location, frequency, 
and power level) along the planned route. Send requests for a 
special flight permit to the person identified in paragraph (j)(1) 
of this AD.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle 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: [email protected].
    (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, Seattle 
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 Christopher 
Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 
206-231-3552; email: [email protected].
    (2) 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. 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.

    Issued on February 19, 2020.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2020-03864 Filed 2-25-20; 8:45 am]
BILLING CODE 4910-13-P