DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-1653; Project Identifier MCAI-2022-01193-T]
Airworthiness Directives; De Havilland Aircraft of Canada Limited
(Type Certificate Previously Held by Bombardier, Inc.) Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400
series airplanes. This proposed AD was prompted by reports of flap
power unit (FPU) pressure switch failures resulting in flap inoperative
events. This proposed AD would require replacing the FPU pressure
switch or the FPU. 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 February
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.
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-2022-1653; 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
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 firstname.lastname@example.org; 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.
FOR FURTHER INFORMATION CONTACT: Gabriel Kim, Aerospace Engineer,
Mechanical Systems and Administrative Services Section, FAA, New York
ACO Branch, 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-2022-1653; Project Identifier
MCAI-2022-01193-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
this 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, Aerospace Engineer, Mechanical Systems and Administrative
Services Section, FAA, New York ACO Branch, 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
Transport Canada, which is the aviation authority for Canada, has
issued AD CF-2022-52, dated September 1, 2022 (Transport Canada AD CF-
2022-52) (also referred to as the MCAI), to correct an unsafe condition
for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and
-402 airplanes. The MCAI states there have been increasing reports of
FPU pressure switch failures, part number (P/N) 150135-1 or P/N 162660-
1, over the past year leading to a high number of flap inoperative
events in flight and on the ground. An investigation has determined the
root cause to be a deformation of the FPU pressure switch internal
mechanism due to hydraulic pressure spikes. If not corrected, a failed
FPU pressure switch could lead to a failure of the FPU resulting in
abnormal flap landings and increased landing distances, which could
require the use of emergency landing procedures and/or airfield
diversions. The improved pressure switch, P/N 162660-2, has a
restrictor insert in the pressure switch inlet.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2022-1653.
Related Service Information Under 1 CFR Part 51
The FAA reviewed De Havilland Aircraft of Canada Limited (DHC)
Service Bulletin (SB) 84-27-75, dated June 23, 2022 (SB 84-27-75). SB
84-27-75 is a combined service bulletin consisting of DHC SB 84-27-75
and Collins Aerospace SB 27-0029, Basic Issue, dated June 13, 2022.
This service information specifies procedures for replacing FPU P/N
C148656-1 or C148656-2 with a new FPU P/N C148656-3, or replacing FPU
pressure switch P/N 150135-1 or 162660-1 within the FPU with a new
pressure switch P/N 162660-2 and re-identifying the FPU as P/N C148656-
3. 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 ADDRESSES.
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 the State of Design Authority, it
has notified the FAA of the unsafe condition described in the MCAI
described above. The FAA is issuing this NPRM after determining that
the unsafe condition described previously is likely to exist or develop
in other products of the same type design.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in the service information already described. This proposed AD would
also prohibit the installation of affected parts.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 53 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
Estimated Costs for Required Actions
|Up to 6 work-hours x $85 per
hour = Up to $510
Up to $3,000
Up to $3,510
Up to $186,030
The FAA has included all known costs
in its cost estimate.
According to the manufacturer, however, some or all of 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.
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
(1) Is not a ``significant regulatory action'' under Executive
(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
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 adding the following new airworthiness