[Federal Register Volume 89, Number 195 (Tuesday, October 8, 2024)]
[Rules and Regulations]
[Pages 81333-81335]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-23115]


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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; 
Amendment 39-22838; AD 2024-18-04]
RIN 2120-AA64


Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Bombardier, Inc., Model BD-700-2A12 airplanes. This 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 AD requires replacement of the 
existing TRU Number 2 with a new part number that incorporates a 
correction to the fan and the monitoring circuit. This AD also 
prohibits the installation of affected parts. The FAA is issuing this 
AD to address the unsafe condition on these products.

DATES: This AD is effective November 12, 2024.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of November 12, 
2024.

ADDRESSES: 
    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 final rule, the mandatory continuing airworthiness 
information (MCAI), 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.
    Material Incorporated by Reference:
    <bullet> For Bombardier material 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 <a href="/cdn-cgi/l/email-protection#6504064b1c1009250400170a4b5904450d17000358" http: bombardier.com">bombardier.com</a>">ac.yul@aero.bombardier.com</a>; website bombardier.com.
    <bullet> You may view this material 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 at regulations.gov under 
Docket No. FAA-2024-0227.

FOR FURTHER INFORMATION CONTACT: William Reisenauer, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
telephone 516-228-7300; email <a href="/cdn-cgi/l/email-protection#7a43571b0c095714031b1915571915093a1c1b1b541d150c"><span class="__cf_email__" data-cfemail="20190d4156530d4e5941434f0d434f53604641410e474f56">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain Bombardier, 
Inc., Model BD-700-2A12 airplanes. The NPRM published in the Federal 
Register on February 14, 2024 (89 FR 11228). The

[[Page 81334]]

NPRM was prompted by AD CF-2023-53, dated July 14, 2023, issued by 
Transport Canada, which is the aviation authority for Canada (referred 
to after this as the MCAI). 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 the NPRM, the FAA proposed to require replacement of the 
existing TRU Number 2 with a new part number that incorporates a 
correction to the fan and the monitoring circuit. The NPRM also 
proposed to prohibit the installation of affected parts. 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.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2024-0227.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from NetJets Inc. The following presents 
the comments received on the NPRM and the FAA's response to the 
comments.

Request To Update the Service Bulletin to the Latest Revision

    NetJets requested that paragraphs (g) and (i) of the proposed AD be 
revised to change Bombardier Service Bulletin 700-24-7507, Revision 1, 
dated May 19, 2023, to Bombardier Service Bulletin 700-24-7507, 
Revision 2, dated October 16, 2023.
    The FAA agrees with the request. For airplanes on which the actions 
of Revision 1 of the service bulletin have already been done, no more 
work is required by Revision 2. The FAA clarified with Bombardier that 
credit can be given for the accomplishment of actions specified in 
Bombardier Service Bulletin 700-24-7507, Revision 1, dated May 19, 
2023. The FAA has therefore revised this AD to require Revision 2 and 
to add credit in paragraph (i) of this AD for accomplishment of the 
actions specified in Bombardier Service Bulletin 700-24-7507, Revision 
1, dated May 19, 2023, if completed before the effective date of this 
AD.

Request for Allowance To Install Part Number G02404521-001 for TRU 
Number 1 and Number 3

    NetJets noted that the Bombardier Service Bulletin 700-24-7507, 
Revision 2, dated October 16, 2023, limits the installation of TRU part 
number (P/N) G02404521-001 to the Number 2 position. NetJets requested 
that an exception be added to paragraph (h) of the proposed AD to also 
allow the installation of TRU P/N G02404521-001 for TRU Number 1 and 
TRU Number 3.
    The FAA does not agree to allow installation of TRU P/N G02404521-
001 for TRU Number 1 or Number 3. The TRU P/N G02404521-001 design 
fails to detect a fan failure. Bombardier Service Bulletin 700-24-7507, 
Revision 2, dated October 16, 2023, replaces only TRU Number 2 position 
because it has a higher electrical load and is more susceptible to the 
fan inoperative condition. TRU P/N G02404521-001 is no longer 
manufactured. The new production airplanes are all installed with TRU 
P/N G02404521-003. All TRUs that are removed from service (e.g., for 
repair) are upgraded to TRU P/N G02404521-003. Therefore, this AD has 
not been changed regarding this request.

Conclusion

    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 
referenced above. The FAA reviewed the relevant data, considered the 
comment received, and determined that air safety requires adopting this 
AD as proposed. Accordingly, the FAA is issuing this AD to address the 
unsafe condition on this product. Except for minor editorial changes, 
and any other changes described previously, this AD is adopted as 
proposed in the NPRM. None of the changes will increase the economic 
burden on any operator.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Bombardier Service Bulletin 700-24-7507, Revision 
2, dated October 16, 2023. This material specifies procedures for 
replacing the existing TRU Number 2 P/N G02404521-001 with new P/N 
G02404521-003, including removal of the secondary layer of insulation 
blanket ENM386519113C or P/N ENM386519113D in front of the TRU Number 2 
fan air inlet, reidentifying the blanket installation by ink stamp, 
checking the electrical bond resistance for TRU Number 2, and 
performing the operational test.
    This material 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 56 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
              Labor cost                      Parts cost            Cost per product      Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all the costs of this 
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

[[Page 81335]]

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.

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

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:

2024-18-04 Bombardier, Inc.: Amendment 39-22838; Docket No. FAA-
2024-0227; Project Identifier MCAI-2023-00886-T.

(a) Effective Date

    This airworthiness directive (AD) is effective November 12, 
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 2, dated October 16, 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 Bombardier Service Bulletin 700-24-7507, dated 
March 31, 2023, or Bombardier Service Bulletin 700-24-7507, Revision 
1, dated May 19, 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 and only essential crew are on board, and day visual 
flight rules are used.

(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. 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-
<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="beffe8ed93f0e7fffdf193fdf1edfed8dfdf90d9d1c8">[email protected]</a>. 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) 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 <a href="/cdn-cgi/l/email-protection#d9e0f4b8afaaf4b7a0b8bab6f4bab6aa99bfb8b8f7beb6af"><span class="__cf_email__" data-cfemail="1a23377b6c693774637b7975377975695a7c7b7b347d756c">[email protected]</span></a>.
    (2) Material identified in this AD that is not incorporated by 
reference is available at the addresses specified in paragraph 
(m)(3) of this AD.

(m) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference of the material listed in this paragraph 
under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this material as applicable to do the actions 
required by this AD, unless this AD specifies otherwise.
    (i) Bombardier Service Bulletin 700-24-7507, Revision 2, dated 
October 16, 2023.
    (ii) [Reserved]
    (3) For Bombardier material 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 <a href="/cdn-cgi/l/email-protection#f29391dc8b879eb29397809ddcce93d29a809794cf" http: bombardier.com">bombardier.com</a>">ac.yul@aero.bombardier.com</a>; website 
bombardier.com.
    (4) You may view this material 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 <a href="/cdn-cgi/l/email-protection#d8beaaf6b1b6aba8bdbbacb1b7b698b6b9aab9f6bfb7ae"><span class="__cf_email__" data-cfemail="a9cfdb87c0c7dad9cccaddc0c6c7e9c7c8dbc887cec6df">[email protected]</span></a>.

    Issued on September 4, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-23115 Filed 10-7-24; 8:45 am]
BILLING CODE 4910-13-P


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