[Federal Register Volume 87, Number 111 (Thursday, June 9, 2022)]
[Proposed Rules]
[Pages 35128-35132]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-12265]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0672; Project Identifier MCAI-2020-01606-T]
RIN 2120-AA64


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 supersede Airworthiness Directive (AD) 
2020-04-20, which applies to certain De Havilland Aircraft of Canada 
Limited Model DHC-8-400 series airplanes. AD 2020-04-20 requires 
repetitive inspections of certain parts for discrepancies that meet 
specified criteria, and replacement as necessary; repetitive 
inspections of certain parts for damage and wear, and rework of parts; 
and electrical bonding checks of certain couplings. AD 2020-04-20 also 
requires revising the existing maintenance or inspection program, as 
applicable, to incorporate new or more restrictive airworthiness 
limitations. For certain airplanes, AD 2020-04-20 allows a modification 
that would terminate the repetitive inspections. Since the FAA issued 
AD 2020-04-20, the FAA has determined that a more robust lightning 
ignition protection design is necessary and that additional airplanes 
are affected by the unsafe condition. This proposed AD would continue 
to require the actions in AD 2020-04-20, revise the applicability by 
adding airplanes, and require, for certain airplanes, the previously 
optional rework and retrofit of certain parts of the fuel system. Doing 
the rework and retrofit would terminate the retained initial and 
repetitive inspections in this AD. 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 July 25, 
2022.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.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.
    For service information identified in this NPRM, contact De 
Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk, 123 
Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone 416-375-
4000; fax 416-375-4539; email [email protected]; internet https://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.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2022-
0672; 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, any comments received, and other information. The street 
address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aerospace Engineer,

[[Page 35129]]

Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart 
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; 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-2022-0672; Project Identifier 
MCAI-2020-01606-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 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this proposed AD.

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 
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 [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.

Discussion

    The FAA issued AD 2020-04-20, Amendment 39-19857 (61 FR 17473, 
March 30, 2020) (AD 2020-04-20), for certain De Havilland Aircraft of 
Canada Limited Model DHC-8-400 series airplanes. AD 2020-04-20 requires 
repetitive inspections of certain parts for discrepancies that meet 
specified criteria, and replacement as necessary; repetitive 
inspections of certain parts for damage and wear, and rework of parts; 
and electrical bonding checks of certain couplings. AD 2020-04-20 also 
requires revising the existing maintenance or inspection program, as 
applicable, to incorporate new or more restrictive airworthiness 
limitations. For certain airplanes, AD 2020-04-20 allows a modification 
that would terminate the repetitive inspections. AD 2020-04-20 resulted 
from reports of wear on fuel couplings, bonding springs, and sleeves as 
well as fuel tube end ferrules and fuel component end ferrules. The FAA 
issued AD 2020-04-20 to address wear on fuel couplings, bonding 
springs, and sleeves as well as fuel tube end ferrules and fuel 
component end ferrules, which could reduce the integrity of the 
electrical bonding paths through the fuel line and components, and 
ultimately lead to fuel tank ignition in the event of a lightning 
strike.

Actions Since AD 2020-04-20 Was Issued

    Since the FAA issued AD 2020-04-20, the FAA has determined that a 
more robust lightning ignition protection design is necessary, which 
will better mitigate the risk of lightning strike induced fuel tank 
ignition through the use of high resistance isolators, a new fuel 
coupling design, and improved structural support. Additional airplanes 
are also affected by the unsafe condition.
    Transport Canada Civil Aviation (TCCA), which is the aviation 
authority for Canada, has issued TCCA AD CF-2017-04R3, dated April 1, 
2020 (also referred to as the Mandatory Continuing Airworthiness 
Information, or ``the MCAI''), to correct an unsafe condition for 
certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series 
airplanes. You may examine the MCAI in the AD docket on the internet at 
https://www.regulations.gov by searching for and locating Docket No. 
FAA-2022-0672.
    This proposed AD was prompted by reports of wear on fuel couplings, 
bonding springs, and sleeves as well as fuel tube end ferrules and fuel 
component end ferrules, and that a more robust lightning ignition 
protection design is necessary. The FAA is proposing this AD to address 
wear on fuel couplings, bonding springs, and sleeves as well as fuel 
tube end ferrules and fuel component end ferrules, which could reduce 
the integrity of the electrical bonding paths through the fuel line and 
components, and ultimately lead to fuel tank ignition in the event of a 
lightning strike. See the MCAI for additional background information.

Related Service Information Under 1 CFR Part 51

    This proposed AD would require the following service information, 
which the Director of the Federal Register approved for incorporation 
by reference as of May 4, 2020 (61 FR 17473, March 30, 2020).
     Bombardier Service Bulletin 84-28-20, Revision D, dated 
November 23, 2018.
     Bombardier Service Bulletin 84-28-21, Revision C, dated 
July 13, 2018.
     Bombardier Service Bulletin 84-28-26, Revision A, dated 
November 29, 2018.
     Q400 Dash 8 (Bombardier) Temporary Revision ALI-0192, 
dated April 24, 2018.
     Q400 Dash 8 (Bombardier) Temporary Revision ALI-0193, 
dated April 24, 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.

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 the State of Design Authority, 
the FAA has been notified of the unsafe condition described in the MCAI 
and service information referenced above. The FAA is proposing this AD 
because the FAA evaluated all the relevant information and determined 
the unsafe condition described previously is likely to exist or develop 
on other products of the same type design.

Proposed Requirements of This NPRM

    This proposed AD would retain all of the requirements of AD 2020-
04-20. This proposed AD would also require revising the applicability 
by adding airplanes, and for certain airplanes, reworking and 
retrofitting certain parts of the fuel system. Doing the rework and 
retrofit would terminate the existing initial and repetitive 
inspections in this proposed AD.

[[Page 35130]]

Costs of Compliance

    The FAA estimates that this proposed AD affects 54 airplanes of 
U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                         Estimated Costs for Required Actions *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Action                          Labor cost           Parts cost            Cost per product                Cost on U.S. operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
Retained actions from AD 2020-04-20...  268 work-hours x $85 per               $0  $22,780........................  $1,230,120.
                                         hour = $22,780.
New proposed actions..................  Up to 1,747 work-hours x           87,385  Up to $235,880.................  Up to $12,737,520.
                                         $85 per hour = Up to
                                         $148,495.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Table does not include estimated costs for revising the existing maintenance or inspection program.

    The FAA has determined that revising the existing maintenance or 
inspection program takes an average of 90 work-hours per operator, 
although the FAA recognizes that this number may vary from operator to 
operator. In the past, the FAA has estimated that this action takes 1 
work-hour per airplane. Since operators incorporate maintenance or 
inspection program changes for their affected fleet(s), the FAA has 
determined that a per-operator estimate is more accurate than a per-
airplane estimate. Therefore, the FAA estimates the total cost per 
operator to be $7,650 (90 work-hours x $85 per work-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.

Regulatory Findings

    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 
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:
0
a. Removing Airworthiness Directive (AD) 2020-04-20, Amendment 39-19857 
(61 FR 17473, March 30, 2020); and
0
b. Adding the following new AD:

De Havilland Aircraft of Canada Limited (Type Certificate previously 
held by Bombardier, Inc.): Docket No. FAA-2022-0672; Project 
Identifier MCAI-2020-01606-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by July 25, 2022.

(b) Affected ADs

    This AD replaces AD 2020-04-20, Amendment 39-19857 (61 FR 17473, 
March 30, 2020) (AD 2020-04-20).

(c) Applicability

    This AD applies to De Havilland Aircraft of Canada Limited Model 
DHC-8-400, -401, and -402 airplanes, certificated in any category, 
manufacturer serial numbers 4001 and 4003 and subsequent.

(d) Subject

    Air Transport Association (ATA) of America Code 28, Fuel.

(e) Reason

    This AD was prompted by reports of wear on fuel couplings, 
bonding springs, and sleeves as well as fuel tube end ferrules and 
fuel component end ferrules, and that a more robust lightning 
ignition protection design is necessary. The FAA is issuing this AD 
to address such wear, which could reduce the integrity of the 
electrical bonding paths through the fuel line and components, and 
ultimately lead to fuel tank ignition in the event of a lightning 
strike.

(f) Compliance

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

(g) Retained Initial Inspection Compliance Times, With New Terminating 
Action

    This paragraph restates the requirements of paragraph (g) of AD 
2020-04-20, with new terminating action. For airplanes having serial 
numbers 4001 and 4003 through 4575 inclusive that, as of May 4, 2020 
(the effective date of AD 2020-04-20), have not done the actions 
specified in Bombardier Service Bulletin 84-28-21: At the applicable 
times specified in paragraph (g)(1) or (2) of this AD, do the 
actions specified in paragraphs (h)(1) and (2) of this AD. 
Accomplishing the terminating action required by paragraph (o) of 
this AD terminates the initial inspection required by this 
paragraph.
    (1) For all airplanes except those identified in paragraph 
(g)(2) of this AD: Within 6,000 flight hours or 36 months, whichever 
occurs first after May 4, 2020 (the effective date of AD 2020-04-
20).
    (2) For airplanes with an original airworthiness certificate or 
original export certificate of airworthiness issued on or after May 
4, 2020 (the effective date of AD 2020-04-20): Within 6,000 flight 
hours or 36 months, whichever occurs first after the date of 
issuance of the original airworthiness certificate or the date of 
issuance of the original export certificate of airworthiness.

[[Page 35131]]

(h) Retained Repetitive Inspections and Corrective Actions, With New 
Terminating Action

    This paragraph restates the requirements of paragraph (h) of AD 
2020-04-20, with new terminating action. For airplanes having serial 
numbers 4001 and 4003 through 4575 inclusive that, as of May 4, 2020 
(the effective date of AD 2020-04-20), have not done the actions 
specified in Bombardier Service Bulletin 84-28-21: At the applicable 
times specified in paragraph (g)(1) or (2) of this AD, do the 
actions specified in paragraphs (h)(1) and (2) of this AD. Repeat 
the actions thereafter at intervals not to exceed 6,000 flight hours 
or 36 months, whichever occurs first. Accomplishing the terminating 
action required by paragraph (o) of this AD terminates the 
repetitive inspections required by this paragraph.
    (1) Do a detailed inspection of the clamshell coupling bonding 
wires, fuel couplings, and associated sleeves for discrepancies that 
meet specified criteria, as identified in, and in accordance with, 
paragraph 3.B., ``Procedure,'' of the Accomplishment Instructions of 
Bombardier Service Bulletin 84-28-20, Revision D, dated November 23, 
2018. If any conditions are found meeting the criteria specified in 
Bombardier Service Bulletin 84-28-20, Revision D, dated November 23, 
2018, before further flight, replace affected parts with new 
couplings and sleeves of the same part number, in accordance with 
paragraph 3.B., ``Procedure,'' of the Accomplishment Instructions of 
Bombardier Bulletin 84-28-20, Revision D, dated November 23, 2018.
    (2) Do a detailed inspection of the fuel tube end ferrules, fuel 
component end ferrules, and ferrule O-ring flanges for damage and 
wear, and rework (repair, replace, or blend, as applicable) the 
parts, in accordance with paragraph 3.B., ``Procedure,'' of the 
Accomplishment Instructions of Bombardier Service Bulletin 84-28-20, 
Revision D, dated November 23, 2018.

(i) Retained Electrical Bonding Checks/Detailed Inspection, With No 
Changes

    This paragraph restates the requirements of paragraph (j) of AD 
2020-04-20, with no changes. For airplanes having serial numbers 
4001, 4003 through 4489 inclusive, and 4491 through 4575 inclusive 
that, as of May 4, 2020 (the effective date of AD 2020-04-20), have 
done the actions specified in Bombardier Service Bulletin 84-28-21, 
Revision A, dated September 29, 2017; and airplanes having serial 
numbers 4576 through 4581 inclusive: Within 6,000 flight hours or 36 
months after May 4, 2020, whichever occurs first, do the actions 
specified in paragraph (i)(1) or (2) of this AD.
    (1) Accomplish electrical bonding checks of all threaded 
couplings on the inboard vent lines in the left and right wings, in 
accordance with paragraph 3.B., ``Procedure,'' of the Accomplishment 
Instructions of Bombardier Service Bulletin 84-28-26, Revision A, 
dated November 29, 2018.
    (2) Do a detailed inspection of the fuel tube end ferrules, fuel 
component end ferrules, and ferrule O-ring flanges for damage and 
wear, and rework (repair, replace, or blend, as applicable) the 
parts; and a retrofit (structural rework) of the fuel couplings, 
isolators, and structural provisions; in accordance with paragraph 
3.B., ``Procedure,'' of the Accomplishment Instructions of 
Bombardier Service Bulletin 84-28-21, Revision C, dated July 13, 
2018.

(j) Retained Revision of the Existing Maintenance or Inspection 
Program, With No Changes

    This paragraph restates the requirements of paragraph (k) of AD 
2020-04-20, with no changes. Within 30 days after May 4, 2020 (the 
effective date of AD 2020-04-20), revise the existing maintenance or 
inspection program, as applicable, to incorporate the information 
specified in Q400 Dash 8 (Bombardier) Temporary Revision ALI-0192, 
dated April 24, 2018; and Q400 Dash 8 (Bombardier) Temporary 
Revision ALI-0193, dated April 24, 2018. Except as specified in 
paragraph (k) of this AD, the initial compliance time for doing the 
tasks in Q400 Dash 8 (Bombardier) Temporary Revision ALI-0192, dated 
April 24, 2018, is at the time specified in Q400 Dash 8 (Bombardier) 
Temporary Revision ALI-0192, dated April 24, 2018, or within 30 days 
after May 4, 2020, whichever occurs later.

(k) Retained Initial Compliance Time for Task 284000-419, With No 
Changes

    This paragraph restates the requirements of paragraph (l) of AD 
2020-04-20, with no changes. The initial compliance time for task 
284000-419 is at the time specified in paragraph (k)(1) or (2) of 
this AD, as applicable, or within 30 days after May 4, 2020 (the 
effective date of AD 2020-04-20), whichever occurs later.
    (1) For airplanes having serial numbers 4001 and 4003 through 
4575 inclusive: Within 18,000 flight hours or 108 months, whichever 
occurs first, after the earliest date of embodiment of Bombardier 
Service Bulletin 84-28-21 on the airplane.
    (2) For airplanes having serial numbers 4576 and subsequent: 
Within 18,000 flight hours or 108 months, whichever occurs first, 
from the date of issuance of the original airworthiness certificate 
or original export certificate of airworthiness.

(l) Retained No Alternative Actions, Intervals, or Critical Design 
Configuration Control Limitations (CDCCLs), With No Changes

    This paragraph restates the requirements of paragraph (m) of AD 
2020-04-20, with no changes. After the existing maintenance or 
inspection program has been revised as required by paragraph (j) of 
this AD, no alternative actions (e.g., inspections), intervals, or 
CDCCLs may be used unless the actions, intervals, and CDCCLs are 
approved as an alternative method of compliance (AMOC) in accordance 
with the procedures specified in paragraph (p)(1) of this AD.

(m) Retained No Reporting Provisions, With No Changes

    This paragraph restates the provisions of paragraph (n) of AD 
2020-04-20, with no changes. Although Bombardier Service Bulletin 
84-28-20, Revision D, dated November 23, 2018, specifies to submit 
certain information to the manufacturer, this AD does not include 
that requirement.

(n) Retained Credit for Previous Actions, With No Changes

    (1) This paragraph restates the requirements of paragraph (o) of 
AD 2020-04-20, with no changes. This paragraph provides credit for 
the actions required by paragraphs (h)(1) and (2) of this AD, if 
those actions were performed before May 4, 2020 (the effective date 
of AD 2020-04-20), using the service information specified in 
paragraph (n)(1)(i) through (iii) of this AD.
    (i) Bombardier Service Bulletin 84-28-20, Revision A, dated 
December 14, 2016.
    (ii) Bombardier Service Bulletin 84-28-20, Revision B, dated 
February 13, 2017.
    (iii) Bombardier Service Bulletin 84-28-20, Revision C, dated 
April 28, 2017.
    (2) For the airplane having serial number 4164, this paragraph 
provides credit for the initial inspections required by paragraphs 
(h)(1) and (2) of this AD, if those actions were performed before 
May 4, 2020 (the effective date of AD 2020-04-20), using Bombardier 
Service Bulletin 84-28-20, dated September 30, 2016.
    (3) This paragraph provides credit for the actions specified in 
paragraph (o) of this AD if those actions were performed before May 
4, 2020 (the effective date of AD 2020-04-20), using the service 
information specified in paragraph (n)(3)(i) through (v) of this AD.
    (i) Bombardier Service Bulletin 84-28-21, dated August 31, 2017.
    (ii) Bombardier Service Bulletin 84-28-21, Revision A, dated 
September 29, 2017, in combination with incorporating the 
information specified in Bombardier Modification Summary Package 
(ModSum) IS4Q2800032, Revision A, dated February 1, 2018.
    (iii) Bombardier Service Bulletin 84-28-21, Revision A, dated 
September 29, 2017, in combination with incorporating any of the 
applicable airworthiness limitation change request (ACR) specified 
in figure 1 to paragraph (n)(6)(ii) of this AD.
    (iv) Bombardier Service Bulletin 84-28-21, Revision B, dated 
June 8, 2018.
    (4) This paragraph provides credit for the actions required by 
paragraph (i)(1) of this AD if those actions were performed before 
May 4, 2020 (the effective date of AD 2020-04-20), using Bombardier 
Service Bulletin 84-28-26, dated August 14, 2018.
    (5) This paragraph provides credit for the actions required by 
paragraph (i)(2) of this AD if those actions were performed before 
May 4, 2020 (the effective date of AD 2020-04-20), using Bombardier 
Service Bulletin 84-28-21, Revision B, dated June 8, 2018.
    (6) For airplanes having serial numbers 4001, 4003 through 4489 
inclusive, and 4491 through 4575 inclusive, and that are post 
Bombardier Service Bulletin 84-28-21, Revision A, dated September 
29, 2017: This paragraph provides credit for the actions required by 
paragraph (i) of this AD if those actions were performed before May 
4, 2020 (the effective date of AD 2020-04-20), using the service 
information specified in paragraph (n)(6)(i) or (ii) of this AD.
    (i) Bombardier Modification Summary Package (ModSum) 
IS4Q2800032, dated February 1, 2018.

[[Page 35132]]

    (ii) Any ACR specified in figure 1 to paragraph (n)(6)(ii) of 
this AD.
[GRAPHIC] [TIFF OMITTED] TP09JN22.009

(o) Rework and Retrofit

    For airplanes having serial numbers 4001, 4003 through 4489 
inclusive, and 4491 through 4575 inclusive, that have accomplished 
the actions specified in Bombardier Service Bulletin 84-28-21, 
Revision A, dated September 29, 2017, but have not incorporated the 
information in Bombardier Modification Summary Package (ModSum) 
IS4Q2800032, Revision A, dated February 1, 2018, or have not 
incorporated any of the applicable ACR specified in figure 1 to 
paragraph (n)(6)(ii) of this AD: At the applicable time specified in 
paragraph (o)(1) or (2) of this AD, rework (repair, replace, or 
blend, as applicable) the parts (fuel tube end ferrules, fuel 
component end ferrules, and ferrule O-ring flanges); and do a 
retrofit (structural rework) of the fuel couplings, isolators, and 
structural provisions; in accordance with Part B of paragraph 3.B., 
``Procedure,'' of the Accomplishment Instructions of Bombardier 
Service Bulletin 84-28-21, Revision C, dated July 13, 2018. 
Accomplishing these actions terminates the initial and repetitive 
inspections required by paragraphs (g) and (h) of this AD.
    (1) For airplanes with greater than 20,000 total flight hours as 
of the effective date of this AD: Do the actions within 6,000 flight 
hours or 36 months after the effective date of this AD, whichever 
occurs first.
    (2) For airplanes with less than or equal to 20,000 total flight 
hours as of the effective date of this AD: Do the actions within 
8,000 flight hours or 48 months after the effective date of this AD, 
whichever occurs first.

(p) Other FAA AD Provisions

    (1) Alternative Methods of Compliance (AMOCs): The Manager, New 
York ACO 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 certification 
office, send it to ATTN: Program Manager, Continuing Operational 
Safety, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; telephone 516-228-7300. 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, New York ACO 
Branch, FAA; or Transport Canada Civil Aviation (TCCA); De Havilland 
Aircraft of Canada Limited's TCCA Design Approval Organization 
(DAO). If approved by the DAO, the approval must include the DAO-
authorized signature.

(q) Related Information

    (1) Refer to Mandatory Continuing Airworthiness Information 
(MCAI) TCCA AD CF-2017-04R3, issued April 1, 2020 for related 
information. This MCAI may be found in the AD docket on the internet 
at https://www.regulations.gov by searching for and locating Docket 
No. FAA-2022-0672.
    (2) For more information about this AD, 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 [email protected].
    (3) For service information identified in this AD, contact De 
Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk, 
123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone 
416-375-4000; fax 416-375-4539; email [email protected]; internet 
https://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.

    Issued on June 2, 2022.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2022-12265 Filed 6-8-22; 8:45 am]
BILLING CODE 4910-13-P


