DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0161; Project Identifier MCAI-2022-01434-T;
Amendment 39-22331; AD 2023-03-06]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Bombardier, Inc., Model BD-700-1A10 and BD-700-1A11 airplanes. This AD
was prompted by the determination that radio altimeters cannot be
relied upon to perform their intended function if they experience
interference from wireless broadband operations in the 3.7-3.98 GHz
frequency band (5G C-Band), and a recent determination that this
interference can result in unavailable or misleading radio altimeter
information, adversely affecting the performance of the automatic
flight control system (AFCS) and resulting in increased flightcrew
workload during takeoff, approach, and landing below 400 feet above
ground level (AGL). This AD requires revising the existing airplane
flight manual (AFM) with new limitations to mitigate identified hazards
due to 5G C-Band interference as identified by Notices to Air Missions
(NOTAMs). The FAA is issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective March 13, 2023.
The FAA must receive comments on this AD by April 10, 2023.

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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2023-0161; 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 mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Steven Dzierzynski, Aerospace
Engineer, Avionics and Electrical Systems Section, FAA, New York ACO
Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone
516-228-7367; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this final rule. Send your comments to an address
listed under ADDRESSES. Include ``Docket No. FAA-2023-0161; Project
Identifier MCAI-2022-01434-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 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
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 Steven
Dzierzynski, Aerospace Engineer, Avionics and Electrical Systems
Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; telephone 516-228-7367; email 9-avs-nyaco-cos@faa.gov.
Any commentary that the FAA receives which is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.

Background

The FAA issued AD 2021-23-12, Amendment 39-21810 (86 FR 69984,
December 9, 2021) (AD 2021-23-12), to address the effect of
interference from wireless broadband operations in the 3.7-3.98 GHz
frequency band (5G C-Band) on all transport and commuter category
airplanes equipped with a radio (also known as radar) altimeter. AD
2021-23-12 was prompted by a determination that radio altimeters cannot
be relied upon to perform their intended function if they experience
interference from wireless broadband operations in the 5G C-Band. AD
2021-23-12 requires revising the limitations section of the existing
AFM to incorporate limitations prohibiting certain operations, which
require radio altimeter data to land in low visibility conditions, when
in the presence of 5G C-Band interference as identified by NOTAMs.
Transport Canada, which is the aviation authority for Canada, issued
corresponding AD CF-2021-52, dated December 24, 2021, to prohibit
certain flight operations requiring radio altimeter data in U.S.
airspace affected by 5G C-Band wireless signals.
Since Transport Canada issued AD CF-2021-52, Transport Canada
evaluated whether additional 5G-related hazards exist in certain
Bombardier model airplanes. Bombardier has determined that 5G C-Band
interference can result in unavailable or misleading radio altimeter
information, adversely affecting the performance of the AFCS as
follows:
Erroneous radio altimeter information has the potential to
cause incorrect gains on approach, flight guidance oscillation, and
crew over-correction. The flight director uses the glideslope to
linearize the angular deviation and if the radio altimeter erroneously
changes to an incorrect value, the resulting pitch command may be
inadequate, resulting in flight path oscillations.
Misleading radio altimeter information can adversely
impact the autothrottle function, resulting in early or late activation
of the retard mode, leading to an inappropriate level of thrust. This
may result in a low energy state or longer landing distance. This
malfunction will increase pilot workload as the crew disconnects the
autothrottle and overrides the throttle levers.
In the event of a weight-on-wheels (WOW) signal failure in
combination with a related Master Minimum Equipment List (MMEL)
dispatch, interference may result in the radio altimeter deploying the
two pairs of ground spoilers at heights above 7 feet AGL.
These effects may lead to increased flightcrew workload and
adversely affect the safe operation of the airplane during takeoff,
approach, and landing below 400 feet AGL. Accordingly, Transport Canada
determined that additional actions are necessary to address the unsafe
condition and issued AD CF-2022-60, dated November 4, 2022 (Transport
Canada AD CF-2022-60) (referred to after this as ``the MCAI''), on all
Bombardier, Inc., Model BD-700-1A10 and BD-700-1A11 airplanes.
Transport Canada AD CF-2022-60 prohibits dispatch under MMEL item ``WOW
FAULT (ADVISORY)'' and requires revising the AFM with new limitations
to prohibit autopilot and autothrottle operation below 400 feet AGL
when in the presence of 5G C-Band interference as identified by NOTAMs.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2023-0161.

FAA's Determination

This product has been approved by the aviation authority of another
country and is approved for operation in the United States. Pursuant to
the FAA's bilateral agreement with this State of Design Authority, it
has notified the FAA of the unsafe condition described in the MCAI
described above. The FAA is issuing this AD after determining that the
unsafe condition described previously is likely to exist or develop on
other products of the same type design.

AD Requirements

This AD requires revising the existing AFM with new limitations to
prohibit dispatch under MMEL Section 2, CAS Messages, item ``WOW FAULT
(ADVISORY)'' and to prohibit autopilot and autothrottle operation below
400 feet AGL when in the presence of 5G C-Band interference as
identified by NOTAMs.

Interim Action

The FAA considers this AD interim action. If final action is later
identified, the FAA might consider further rulemaking then.

Justification for Immediate Adoption and Determination of the Effective
Date

Section 553(b)(3)(B) 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 553(d) of the APA
authorizes agencies to make rules effective in less than thirty days,
upon a finding of good cause.
An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies forgoing notice and comment prior to adoption of this rule
because radio altimeters cannot be relied upon to perform their
intended function if they experience interference from wireless
broadband operations in the 5G C-Band. Further, this interference can
result in unavailable or misleading radio altimeter information,
adversely affecting the performance of the AFCS, which could lead to
increased flightcrew workload and adversely affect the safe operation
of the airplane during takeoff, approach, and landing. The required
actions to address the unsafe condition must be accomplished within 30
days, which is shorter than the time necessary to allow for public
comment and for the FAA to publish a final rule. Accordingly, notice
and opportunity for prior public comment are impracticable and contrary
to the public interest pursuant to 5 U.S.C. 553(b)(3)(B).
In addition, the FAA finds that good cause exists pursuant to 5
U.S.C. 553(d) for making this amendment effective in less than 30 days,
for the same reasons the FAA found good cause to forgo notice and
comment.

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 prior notice and
comment, RFA analysis is not required.

Costs of Compliance

The FAA estimates that this AD affects 165 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for AFM Revisions

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

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

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

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.

Sec. 39.13 [Amended

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