[Federal Register Volume 89, Number 31 (Wednesday, February 14, 2024)]
[Proposed Rules]
[Pages 11228-11231]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-02948]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0227; Project Identifier MCAI-2023-00886-T]
RIN 2120-AA64


Airworthiness Directives; Bombardier, Inc., 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 Bombardier, Inc., Model BD-700-2A12 airplanes. This 
proposed AD was prompted by a report indicating that the fan in a 
transformer rectifier unit (TRU) can become inoperative in a manner 
that is not detectable by the fan monitoring circuit. This proposed AD 
would require replacement of the existing TRU Number 2 with a new part 
number that incorporates a correction to the fan and the monitoring 
circuit. This proposed AD would also prohibit the installation of 
affected parts. 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 April 1, 
2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:

[[Page 11229]]

     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-2024-0227; 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 Business Aircraft Customer Response Center, 400 C[ocirc]te-
Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada; telephone 514-
855-2999; email bombardier.com">ac.yul@aero.bombardier.com; website bombardier.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.

FOR FURTHER INFORMATION CONTACT: William Reisenauer, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
telephone 516-228-7300; 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 ADDRESSES. Include ``Docket No. FAA-2024-0227; Project Identifier 
MCAI-2023-00886-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 
William Reisenauer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, 
Suite 410, Westbury, NY 11590; telephone 516-228-7300; 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.

Background

    Transport Canada, which is the aviation authority for Canada, has 
issued Transport Canada AD CF-2023-53, dated July 14, 2023 (Transport 
Canada AD CF-2023-53) (also referred to after this as the MCAI), to 
correct an unsafe condition on certain Bombardier, Inc., Model BD-700-
2A12 airplanes. The MCAI states that the fan in a TRU can become 
inoperative in a manner that is not detectable by the fan monitoring 
circuit. An inoperative fan leads to higher TRU operating temperatures, 
which can trigger the activation of the load shed function to reduce 
the electrical load and temperature in the TRU. If the TRU temperature 
continues to rise and exceeds the maximum temperature threshold, the 
TRU will automatically disconnect. The shed electrical load will be 
transferred to the remaining two TRUs, which could lead to overheating 
and cascading failures on the remaining TRUs.
    In addition, a design issue was uncovered where the fan power-up 
built-in test (PBIT) and continuous built-in-test (CBIT) are not 
adequate to detect fan failure. The fan PBIT is a test that is 
automatically performed once the airplane is powered up. The fan PBIT 
initiates the fan to turn on regardless of the TRU temperature to test 
the fan's functionality. The fan CBIT detects fan failure during 
airplane operation. Therefore, if FAN PBIT and/or CBIT are not reliable 
to detect a fan failure, inoperative fan conditions will remain 
dormant.
    It was also identified that an insulation blanket located close to 
the TRU 2 fan air inlet may be leading to an eventual reduction of TRU 
2 cooling efficiency.
    The FAA is proposing this AD to address the inability of a TRU to 
detect the fan failure. The unsafe condition, if not addressed, could 
lead to overheating and failures on the remaining TRUs, which could 
contribute to additional pilot workload and adversely affect the safe 
operation of the airplane.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2024-0227.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Bombardier Service Bulletin 700-24-7507, Revision 
1, dated May 19, 2023. This service information specifies procedures 
for replacing the existing transformer rectifier unit (TRU) Number 2 
part number (P/N) G02404521-001 with new P/N G02404521-003, including 
removal of the secondary layer of insulation blanket P/N ENM386519113D 
in front of the TRU Number 2 fan air inlet, re-identifying the blanket 
installation by ink stamp, checking the electrical bond resistance for 
TRU Number 2, and performing the operational test.
    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

    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 the unsafe condition described previously is 
likely to exist or develop on other products of the same type design.

[[Page 11230]]

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the service information already described, except as discussed under 
``Difference Between this NPRM and the Service Information.'' This 
proposed AD would also prohibit the installation of affected parts.

Difference Between This NPRM and Service Information

    This AD does not require replacing the existing essential TRU P/N 
G02404521-001 with new P/N G02404521-003, as specified in Bombardier 
Service Bulletin 700-24-7507, Revision 1, dated May 19, 2023. TRU 
Number 2 has a higher electrical load than the essential TRU and, 
therefore, is more susceptible to the fan inoperative condition. 
Replacement of TRU Number 2, as specified in this proposed AD, will 
adequately address the safety concern.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 56 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
              Labor cost                      Parts cost            Cost per product      Cost on U.S. operators
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Up to 5 work-hours x $85 per hour =    Up to $34,754..........  Up to $35,179..........  Up to $1,970,024.
 Up to $425.
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    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all the costs of this 
proposed AD may be covered under warranty, thereby reducing the cost 
impact on affected operators.

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) Would not affect intrastate aviation in Alaska, and
    (3) Would 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:

Bombardier, Inc.: Docket No. FAA-2024-0227; Project Identifier MCAI-
2023-00886-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by April 1, 2024.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Bombardier, Inc., Model BD-700-2A12 
airplanes, certificated in any category, serial numbers 70006 
through 70166 inclusive.

(d) Subject

    Air Transport Association (ATA) of America Code 24, Electrical 
power.

(e) Unsafe Condition

    This AD was prompted by a report that the fan in a transformer 
rectifier unit (TRU) can become inoperative in a manner that is not 
detectable by the fan monitoring circuit. The FAA is issuing this AD 
to address the inability of a TRU to detect the fan failure. The 
unsafe condition, if not addressed, could lead to overheating and 
failures on the remaining TRUs, which could contribute to additional 
pilot workload and adversely affect the safe operation of the 
airplane.

(f) Compliance

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

(g) Transformer Rectifier Unit (TRU) Number 2 Replacement

    Within 1,500 flight hours or 3 years, whichever occurs first 
after the effective date of this AD, replace TRU Number 2 part 
number (P/N) G02404521-001 with P/N G02404521-003, in accordance 
with the Accomplishment Instructions of Bombardier Service Bulletin 
700-24-7507, Revision 1, dated May 19, 2023.

(h) Parts Installation Prohibition

    As of the effective date of this AD, no person may install, on 
any airplane, a TRU part number G02404521-001.

(i) Credit for Previous Actions

    This paragraph provides credit for actions required by paragraph 
(g) of this AD, if those actions were performed before the effective 
date of this AD using in accordance with Bombardier Service Bulletin 
700-24-7507, dated March 31, 2023.

(j) Special Flight Permits

    Special flight permits may be issued in accordance with 14 CFR 
21.197 and 21.199 to operate the airplane to a location where the 
actions required by this AD can be accomplished, provided no 
passengers are on board, only essential crew, and day visual flight 
rules.

(k) Additional AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, 
International Validation Branch, FAA, has the authority to approve 
AMOCs for this AD, if requested using the procedures found in 14 CFR 
39.19.

[[Page 11231]]

In accordance with 14 CFR 39.19, send your request to your principal 
inspector or responsible Flight Standards Office, as appropriate. If 
sending information directly to the manager of the International 
Validation Branch, mail it to the address identified in paragraph 
(l)(2) of this AD. Information may be emailed to: 9-AVS-NYACO-
[email protected]. Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the responsible Flight Standards Office.
    (2) Contacting the Manufacturer: For any requirement in this AD 
to obtain instructions from a manufacturer, the instructions must be 
accomplished using a method approved by the Manager, International 
Validation Branch, FAA; or Transport Canada or Bombardier, Inc.'s 
Transport Canada Design Approval Organization (DAO). If approved by 
the DAO, the approval must include the DAO-authorized signature.

(l) Additional Information

    (1) Refer to Transport Canada AD CF-2023-53, dated July 14, 
2023, for related information. This Transport Canada AD may be found 
in the AD docket at regulations.gov under Docket No. FAA-2024-0227.
    (2) For more information about this AD, contact William 
Reisenauer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, 
Suite 410, Westbury, NY 11590; telephone 516-228-7300; email [email protected].
    (3) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (m)(3) and (4) of this AD.

(m) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless this AD specifies otherwise.
    (i) Bombardier Service Bulletin 700-24-7507, Revision 1, dated 
May 19, 2023.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact 
Bombardier Business Aircraft Customer Response Center, 400 
C[ocirc]te-Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada; 
telephone 514-855-2999; email bombardier.com">ac.yul@aero.bombardier.com; website 
bombardier.com.
    (4) 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.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations, or email [email protected].

    Issued on February 7, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-02948 Filed 2-13-24; 8:45 am]
BILLING CODE 4910-13-P