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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Rules and Regulations
Background The FAA has received reports indicating that several of the fittings that provide attachment between the radome and fuselage were cracked to the point of failure. The radome to fuselage fittings were part of the ViaSat In-Flight Connectivity IFC System Antenna Provisions installed in accordance with FAA STC ST04096CH on Model 737
800 and 900ER series airplanes. This failure of the attachment fittings, if not addressed, could result in loss of the radome and antennae, and consequent damage to the tail and damage to the fuselage in the vicinity of the radome, which could reduce the ability of the flightcrew to maintain safe flight and landing of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.
FAAs Determination The FAA is issuing this AD because the agency has determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

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Related Service Information Under 1
CFR Part 51
The FAA reviewed Astronics Armstrong Aerospace Engineering Order, ViaSat In-Flight Connectivity IFC System DEMOD Boeing 737800/
900ER Series Aircraft, Document No.
EO23964202, Revision B, dated April 25, 2016. This service information specifies procedures for demodification of the STC installation by removing the external equipment including radome, antenna, and associated structure that was installed in accordance with FAA
STC ST04096CH, and installing doubler and fasteners de-mod kit, and system deactivation by pulling and collaring associated circuit breakers.
The FAA also reviewed Astronics Connectivity Systems and Certification Service Bulletin SB44964201, dated July 8, 2021. This service information specifies procedures for inspecting the external and feed-through doublers, intercostals, skin, and frames in the area around the removed external equipment for cracking. The inspections include an external low frequency eddy current LFEC inspection of the skin at the alteration installation area, doubler fastener holes in the first two rows of attachments between the doubler and fuselage skin, fastener and connector hole locations, the external doublers between fasteners at the area common to the stringers, and at the area common to the frame tees; an internal high frequency eddy current HFEC
inspection of the intercostal at the
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fastener locations and the frames in the area of added frame segments; an internal detailed visual inspection of the frames between stringers 3L and 3R; an open hole HFEC rotating hole inspections of the stringer fastener holes where the doublers cover the stringer; a HFEC open-hole inspection of the 4X
fitting base holes common to the external doublers at the 8X AR240
194901 side fitting assembly locations;
and an external HFEC inspection of the skin at the stringer fasteners, including all stringer fasteners which may be covered beneath the radome and adapter ring.
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.
AD Requirements This AD requires accomplishing the actions specified in the service information already described. This AD
also requires repairing any crack found during the inspections.
Justification for Immediate Adoption and Determination of the Effective Date Section 553b3B of the Administrative Procedure Act APA 5
U.S.C. 551 et seq. authorizes agencies to dispense with notice and comment procedures for rules when the agency, for good cause, finds that those procedures are impracticable, unnecessary, or contrary to the public interest. Under this section, an agency, upon finding good cause, may issue a final rule without providing notice and seeking comment prior to issuance.
Further, section 553d of the APA
authorizes agencies to make rules effective in less than thirty days, upon a finding of good cause.
There are currently no U.S.-registered airplanes affected by this AD.
Accordingly, notice and opportunity for prior public comment are unnecessary, pursuant to 5 U.S.C. 553b3. In addition, for the foregoing reasons, the FAA finds that good cause exists pursuant to 5 U.S.C. 553d for making this amendment effective in less than 30
days.
Comments Invited The FAA invites you to send any written data, views, or arguments about this final rule. Send your comments to an address listed under ADDRESSES.
Include Docket No. FAA20210670
and Project Identifier AD202100849
T at the beginning of your comments.
The most helpful comments reference a specific portion of the final rule, explain the reason for any recommended
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change, and include supporting data.
The FAA will consider all comments received by the closing date and may amend this final rule 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 agency will also post a report summarizing each substantive verbal contact received about this final rule.
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 AD 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 AD, 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 AD. Submissions containing CBI
should be sent to Surinder Sangha, Aerospace Engineer, Propulsion &
Program Management Section, FAA, Chicago ACO Branch, Room 107, 2300
East Devon Avenue, Des Plaines, IL
60018; telephone 8472947010; fax 8472947834; email: surinder.sangha@
faa.gov. Any commentary that the FAA
receives that is not specifically designated as CBI will be placed in the public docket for this rulemaking.
Regulatory Flexibility Act The requirements of the Regulatory Flexibility Act RFA do not apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt a rule without prior notice and comment. Because the FAA has determined that it has good cause to adopt this rule without notice and comment, RFA analysis is not required.
Costs of Compliance Currently, there are no affected U.S.registered airplanes. For any affected airplane that is imported and placed on the U.S. Register in the future, the FAA
provides the following cost estimates to comply with this AD:

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