DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0911; Product Identifier 2020-NM-075-AD; Amendment
39-21497; AD 2021-08-03]
RIN 2120-AA64

Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate
Previously Held by Bombardier, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 &
702) airplanes; Model CL-600-2C11 (Regional Jet Series 550) airplanes;
Model CL-600-2D15 (Regional Jet Series 705) airplanes; Model CL-600-
2D24 (Regional Jet Series 900) airplanes; and Model CL-600-2E25
(Regional Jet Series 1000) airplanes. This AD was prompted by a
determination that a new or more restrictive airworthiness limitation
is necessary. This AD requires revising the existing maintenance or
inspection program, as applicable, to incorporate a new or more
restrictive airworthiness limitation. The FAA is issuing this AD to
address the unsafe condition on these products.

DATES: This AD is effective May 25, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 25,
2021.

ADDRESSES: For service information identified in this final rule,
contact MHI RJ Aviation ULC, 12655 Henri-Fabre Blvd., Mirabel,
Quebec J7N 1E1, Canada; Widebody Customer Response Center North
America toll-free telephone +1 844 272 2720 or direct-dial telephone +1
514 855 8500; fax +1-514 855-8501; email thd.crj@mhirj.com; internet
https://mhirj.com. You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety 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-2020-0911.

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-
0911; 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, 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: Siddeeq Bacchus, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 516-228-7362; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2020-08, dated April 6,
2020 (also referred to as the Mandatory Continuing Airworthiness
Information, or the MCAI), to correct an unsafe condition for all MHI
RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702)
airplanes; Model CL-600-2C11 (Regional Jet Series 550) airplanes; Model
CL-600-2D15 (Regional Jet Series 705) airplanes; Model CL-600-2D24
(Regional Jet Series 900) airplanes; and Model CL-600-2E25 (Regional
Jet Series 1000) airplanes. You may examine the MCAI in the AD docket
on the internet at https://www.regulations.gov by searching for and
locating Docket No. FAA-2020-0911.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all MHI RJ Aviation ULC
Model CL-600-2C10 (Regional Jet Series 700, 701 & 702) airplanes; Model
CL-600-2C11 (Regional Jet Series 550) airplanes; Model CL-600-2D15
(Regional Jet Series 705) airplanes; Model CL-600-2D24 (Regional Jet
Series 900) airplanes; and Model CL-600-2E25 (Regional Jet Series 1000)
airplanes. The NPRM published in the Federal Register on October 13,
2020 (85 FR 64417). The NPRM was prompted by a determination that a new
or more restrictive airworthiness limitation is necessary. The NPRM
proposed to require revising the existing maintenance or inspection
program, as applicable, to incorporate a new or more restrictive
airworthiness limitation. The FAA is issuing this AD to address failed
telescopic ducts in the wing anti-ice system, which could result in
loss of the wing anti-ice system function, slat skew, slat jam,
structural damage to the slat panel, and loss of the slat panel,
possibly resulting in reduced control of the airplane. See the MCAI for
additional background information.

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.

Support for the NPRM

An anonymous commenter and Endeavor Air indicated support for the
NPRM.

Request To Extend the 60-Day Compliance Time for Initial Actions

Endeavor Air requested a revision to the initial compliance times
proposed in the NPRM for accomplishing the tasks. Endeavor Air
suggested removing the phrase ``or within 60 days after the effective
date of the AD, whichever is later'' and replacing it with ``for
aircraft with more than 15,200 FH [flight hours], phase in within 8,800
FH from the effective date of the AD.'' Endeavor Air reasoned that the
change would allow the work to be scheduled during C-check maintenance,
and align with the original intent.
The FAA disagrees with replacing the 60-day grace period with the
compliance time suggested by the commenter. The FAA reviewed the
compliance times, typical fleet usage, and the TCCA AD, and found that
the compliance time specified in paragraph (g) of this AD adequately
addresses the unsafe condition. Most airplanes average 8.5 flight hours
per day and will not reach another 8,800 flight hours for 32 months;
therefore, an extension is not warranted. However, under the provisions of
paragraph (i)(1) of this AD, the FAA will consider requests for approval of an
extension of the compliance time if sufficient data are submitted to substantiate
that the extension would provide an acceptable level of safety. The FAA
has not changed this AD in this regard.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this AD as proposed, except for minor editorial
changes. The FAA has 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.

Related Service Information Under 1 CFR Part 51

Bombardier has issued CRJ700/900/1000 Series Regional Jet Temporary
Revision ALI-0721, dated December 20, 2019. This service information
describes safe life limitation task 30-11-10-701, Telescopic Duct, that
specifies the life limitation for the telescopic duct. 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 577 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD.
The FAA has determined that revising the maintenance or inspection
program takes an average of 90 work-hours per operator, although the
agency recognizes that this number may vary from operator to operator.
Since operators incorporate maintenance or inspection program changes
for their affected fleet(s), the FAA has determined that a per-operator
estimate is more accurate than a per-airplane estimate. Therefore, the
agency estimates the average total cost per operator to be $7,650 (90
work-hours x $85 per work-hour).

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,
(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

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: