DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1151; Project Identifier MCAI-2020-01603-T;
Amendment 39-22303; AD 2023-01-09]
RIN 2120-AA64

Airworthiness Directives; De Havilland Aircraft of Canada Limited
(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
certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series
airplanes. This AD was prompted by a report that electrical bonding
jumpers had been installed on fuel scavenge lines even after the
removal was required by previous AD rulemaking and that electrical
bonding jumpers may have been installed in production or in service at
other locations. This AD requires an inspection for electrical bonding
jumpers and brackets on the fuel scavenge and vent lines at specific
wing locations, and if installed, removal or modification of those
jumpers and brackets. This AD also requires a records check to
determine if certain maintenance tasks were performed and removal,
modification, or rework if those tasks were performed. This AD also
prohibits the use of earlier versions of certain maintenance tasks. The
FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective March 13, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 13,
2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-1151; 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:
For service information identified in this final rule,
contact De Havilland Aircraft of Canada Limited, Dash 8 Series Customer
Response Centre, 5800 Explorer Drive, Mississauga, Ontario, L4W 5K9,
Canada; telephone North America (toll-free): 855-310-1013, Direct: 647-
277-5820; email thd@dehavilland.com; website dehavilland.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 at
regulations.gov under Docket No. FAA-2022-1151.

FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; email 9-avs-nyaco-cos@faa.gov.

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 De Havilland
Aircraft of Canada Limited Model DHC-8-400, -401, and -402 airplanes.
The NPRM published in the Federal Register on September 9, 2022 (87 FR
55322). The NPRM was prompted by AD CF-2020-01, dated January 14, 2020,
issued by Transport Canada, which is the aviation authority for Canada
(referred to after this as the MCAI). The MCAI states it was reported
that electrical bonding jumpers had been installed on fuel scavenge
lines even after the removal was required by Transport Canada AD CF-
2010-31, dated September 3, 2010 (which corresponds to FAA AD 2011-13-
06, Amendment 39-16729 (76 FR 37258, June 27, 2011) (AD 2011-13-06)).
Subsequent investigation showed that electrical bonding jumpers may
have been installed in production or in service at other locations on
the fuel scavenge and vent lines. If installed, these electrical
bonding jumpers could affect the integrity of the fuel scavenge and
vent lines' electrical bonding paths, which may lead to lightning
strike induced fuel tank ignition.
In the NPRM, the FAA proposed to require an inspection for
electrical bonding jumpers and brackets on the fuel scavenge and vent
lines at specific wing locations, and if installed, removal or
modification of those jumpers and brackets. The FAA also proposed to
require a records check to determine if certain maintenance tasks were
performed and removal, modification, or rework if those tasks were
performed. The FAA also proposed to prohibit the use of earlier
versions of certain maintenance tasks. The FAA is issuing this AD to
address altered electrical bonding paths, which may lead to lightning
strike-induced ignition of the fuel tank.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2022-1151.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from the Air Line Pilots Association,
International (ALPA) who supported the NPRM without change.
The FAA received additional comments from Horizon Air. The
following presents the comments received on the NPRM and the FAA's
response to each comment.

Request To Remove Job Access and Close-up Requirements

Horizon Air requested revising paragraphs (h)(1) and (2) of the
proposed AD to remove the Job Set-up and Close-Out sections of the
Accomplishment Instructions of Bombardier Service Bulletins 84-28-29
and 84-28-30, both dated October 17, 2018, from the requirements of the
proposed AD. Horizon Air asserted that incorporating the Job Set-up and
Close Out sections of the Accomplishment Instructions do not address
the unsafe condition and also restrict an operator's ability to perform
other maintenance in conjunction with the incorporation of the service
bulletins.
In this case, the FAA agrees with the commenter's request to
exclude the ``Job Set-up'' and ``Close Out'' sections of Bombardier
Service Bulletin 84-28-29; and 84-28-30; both dated October 17, 2018.
The FAA has revised paragraphs (h)(1) and (2) of this AD to require
accomplishment of paragraph 3.B., ``Procedure,'' of the Accomplishment
Instructions of Bombardier Service Bulletins 84-28-29; or 84-28-30;
both dated October 17, 2018; as applicable.

Request To Correct Typographical Errors

Horizon Air requested correction of some typographical errors it
found in paragraphs (h)(1) and (2) of the proposed AD. Horizon Air
noted that the dates provided for the referenced service bulletins was
published in the NPRM as October 1 instead of October 17 in two places.
Horizon Air also pointed out that in paragraph (h)(2) of the proposed
AD, the first reference to a service bulletin seems to be in error and
should be 84-28-30 instead of 84-28-29.
The FAA acknowledges the typographical errors and agrees to the
request. Paragraphs (h)(1) and (2) of this AD have been revised as
requested.

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
comments 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, this AD is adopted as proposed in the NPRM. None of the
changes will increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

De Havilland Aircraft of Canada Limited has issued Bombardier
Service Bulletins 84-28-29; and 84-28-30; both dated October 17, 2018;
which describe procedures for an inspection of certain wing stations in
the left and right wings for the presence of brackets and electrical
bonding jumpers on the fuel scavenge and vent lines, and if installed,
removal or modification of those electrical bonding jumpers and
brackets. These documents are distinct because they apply to different
airplane configurations.
De Havilland Aircraft of Canada Limited has also issued the
following Bombardier service information, which describes fuel system
limitations, critical design configuration control limitations
(CDCCLs), or airworthiness limitations for fuel tank systems. These
documents are distinct because they
apply to different airplane configurations.
(Bombardier) Q400 Dash 8 Aircraft Maintenance Manual (AMM)
Temporary Revision (TR) 28-170, dated November 2, 2018.
(Bombardier) Q400 Dash 8 AMM TR 28-171, dated November 2,
2018.
(Bombardier) Q400 Dash 8 AMM TR 28-166, dated November 2,
2018.
(Bombardier) Q400 Dash 8 AMM TR 28-167, dated November 2,
2018.
(Bombardier) Q400 Dash 8 AMM TR 28-168, dated November 2,
2018.
(Bombardier) Q400 Dash 8 AMM TR 28-169 dated November 2,
2018.
(Bombardier) Q400 Dash 8 AMM TR 28-163, dated August 1,
2018.
(Bombardier) Q400 Dash 8 Maintenance Task Card Manual
(MTCM) Maintenance Task Card 000-28-520-704 (Config A01), Detailed
Inspection of the Teflon Sleeve on the Fuel Tank Vent Line (LH),
Revision 43, Amendment 0001, dated August 1, 2018.
(Bombardier) Q400 Dash 8 MTCM Maintenance Task Card 000-
28-620-704 (Config A01), Detailed Inspection of the Teflon Sleeve on
the Fuel Tank Vent Line (RH), Revision 43, Amendment 0001, dated August
1, 2018.
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 will affect 53 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions

Estimated Costs of On-Condition Actions

The FAA has received no definitive data on which to base the cost
estimates for the on-condition rework specified in this AD.

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.

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: