DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2023-2001; Project Identifier MCAI-2023-00666-T]
Airworthiness Directives; Bombardier, Inc., Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to supersede Airworthiness Directive
2021-20-13, which applies to certain Bombardier, Inc., Model CL-600-
2B16 (604 Variant) airplanes. AD 2021-20-13 requires repetitive
lubrication and repetitive detailed visual inspections (DVI) and non-
destructive test (NDT) inspections of the main landing gear (MLG) shock
strut lower pins, and replacement if necessary. Since the FAA issued AD
2021-20-13, Bombardier, Inc. developed a new design solution for this
potential failure. This proposed AD would continue to require the
lubrication and inspections specified in AD 2021-20-13 until the MLG
shock strut assembly is modified by replacing the trailing arm bushing
and installing new dynamic joint components. 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 December
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
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-2023-2001; 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 NPRM, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
For service information identified in this NPRM, contact
Bombardier, Inc., 200 Cote-Vertu Road West, Dorval, Quebec
H4S 2A3, Canada; North America toll-free telephone 1-866-538-1247 or
direct-dial telephone 1-514-855-2999; email firstname.lastname@example.org;
You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 2200 South
216th Street, Des Moines, WA. For information on the availability of
this material at the FAA, call 206-231-3195.
FOR FURTHER INFORMATION CONTACT: Gabriel Kim, Aviation Safety Engineer,
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-
228-7300; email email@example.com.
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2023-2001; Project Identifier
MCAI-2023-00666-T'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, 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
the proposal 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 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
Gabriel Kim, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite
410, Westbury, NY 11590; telephone 516-228-7300; 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
The FAA issued AD 2021-20-13, Amendment 39-21751 (86 FR 57033,
October 14, 2021) (AD 2021-20-13), for certain Bombardier, Inc., CL-
600-2B16 (604 Variant) airplanes. AD 2021-20-13 was prompted by an MCAI
originated by Transport Canada, which is the aviation authority for
Canada. Transport Canada issued AD CF-2020-54R1, dated December 23,
2020 (Transport Canada AD CF-2020-54R1), to correct an unsafe condition
identified as cracking of the MLG shock strut lower pin part number
19146-3. Transport Canada AD CF-2020-54R1 states that friction torque,
when the shock strut is under compression loading, causes the pin anti-
rotation tangs to become loaded beyond their load carrying capability.
According to Transport Canada, this overload condition can result in
pin fracture originating at the base of the pin anti-rotation tang and
is aggravated by inadequate lubrication.
AD 2021-20-13 requires repetitively lubricating, repetitively
inspecting (DVI and NDT inspections for cracking and damage, including
fracture of the MLG shock strut lower pin at the pin rotation tang
location), and replacing the MLG shock strut lower pin if there is any
cracking or damage as a result of the inspections. The FAA issued AD
2021-20-13 to address cracking of the MLG shock strut lower pin. If not
addressed, this condition could result in structural failure of one or
Actions Since AD 2021-20-13 Was Issued
Since the FAA issued AD 2021-20-13, Transport Canada superseded
Transport Canada AD CF-2020-54R1 and issued Transport Canada AD CF-
2023-32, dated May 9, 2023 (referred to after this as ``the MCAI'').
The MCAI states there is a new design solution for this potential
failure of the shock strut lower pin, which involves replacing the
training arm bushings at the attachment and reassembly of the MLG shock
strut assembly to training arm assembly joint with new dynamic joint
components. As a result, the MCAI requires this new design as
terminating action for the requirements of Transport Canada AD CF-2020-
Bombardier, Inc. also reduced the range of one group of applicable
aircraft from serial numbers 6050 through 6999 to 6050 through 6188.
Bombardier, Inc. advises that subsequent aircraft are scheduled to have
the new design completed in production. Therefore, the FAA has revised
the applicability of this proposed AD accordingly.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2023-2001.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Bombardier, Inc., service information:
Service Bulletin 604-32-031, dated December 29, 2022.
Service Bulletin 605-32-008, dated December 29, 2022.
Service Bulletin 650-32-005, dated December 29, 2022.
This service information contains procedures for disassembling the
left- and right-hand MLG shock strut and trailing arm joint, replacing
the trailing arm bushings at the attachment, and re-assembling the
joint with new dynamic joint components. These documents are distinct
since they apply to different airplane configurations.
This proposed AD would also require the following Bombardier, Inc.,
service information, which the Director of the Federal Register
approved for incorporation by reference as of November 18, 2021 (86 FR
57033, October 14, 2021):
Service Bulletin 604-32-030, dated June 30, 2020.
Service Bulletin 605-32-007, dated June 30, 2020.
Service Bulletin 650-32-004, dated June 30, 2020.
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.
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 and
service information referenced above. The FAA is issuing this NPRM
after determining that unsafe condition described previously is likely
to exist or develop on other products of the same type design.
Proposed AD Requirements in This NPRM
This proposed AD would retain all of the requirements of AD 2021-
20-13 until the MLG shock strut assembly to trailing arm assembly joint
is modified by accomplishing the actions specified in the service
information described previously.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 433 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
Estimated Costs for Required Actions
||Cost per product
||Cost on U.S. operators
|Lubrication and inspections (retained
actions from AD 2021-20-13)
||7 work-hours x $85
per hour = $595
||$595 per cycle
||$257,635 per cycle
|Modification and testing (new
||9 work-hours x $85 per
hour = $765
The FAA estimates the following costs
to do any necessary on-
condition replacement that would be required based on the results of
the repetitive inspections. The FAA has no way of determining the
number of aircraft that might need this on-condition action:
Estimated Costs of On-Condition Replacement
|6 work-hours x $85 per 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.
The FAA has 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
For the reasons discussed above, I certify this proposed
(1) Is not a ``significant regulatory action'' under Executive
(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
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
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:
a. Removing Airworthiness Directive 2021-20-13, Amendment 39-21751 (86
FR 57033, October 14, 2021); and
b. Adding the following new Airworthiness Directive: