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PROPOSED AD DE HAVILLAND AIRCRAFT OF CANADA LIMITED (TYPE CERTIFICATE PREVIOUSLY HELD BY BOMBARDIER, INC.): Docket No. FAA-2022-0287; Project Identifier MCAI-2020-01602-T.
(a) COMMENTS DUE DATE

    The FAA must receive comments  on this airworthiness directive (AD) by
    May 9, 2022.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This AD applies to De Havilland Aircraft of Canada Limited  (type cer-
    tificate previously held by Bombardier, Inc.)  Model  DHC-8-400, -401,
    and -402 airplanes,  certificated  in  any  category,  serial  numbers
    (S/Ns) 4001, 4003, and subsequent.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 28,  Fuel System;  and
    05, Time Limits/Maintenance Checks.

(e) UNSAFE CONDITION

    This AD  was prompted  by reports  of broken  P-clamps on the pressure
    relief  line  and  the motive  flow  line  in the  fuel  tanks,  and a
    subsequent  determination  that  certain  service  information  lacked
    instructions  for  maintaining appropriate  clearance  between certain
    fuel  tubes and  their support  brackets,  and  may also  have led  to
    incorrect installation of certain Teflon™ sleeves.  The FAA is issuing
    this AD to address adverse impacts on the integrity of the  electrical
    bonding paths  throughout the  fuel line,  which could  lead to arcing
    between the  vent line  and airplane  structure, and  could result  in
    possible 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) DEFINITION

    For the  purposes of  this AD,  "prohibited tasks"  are defined as any
    task identified in paragraph (l) of this AD and any procedure or  task
    that  specifies  fuel  tank  access  using   non-manufacturer-approved
    procedures.

(h) MODIFICATIONS

(1) For airplanes  having S/N 4001 and 4003 through 4525 inclusive: Within
    6,000 flight hours or 36 months  after the effective date of this  AD,
    whichever occurs first, increase the  hole size in the collector  tank
    partition wall, inspect the motive  flow line for damage, and  replace
    the  associated  grommet  and motive  flow  line,  in accordance  with
    paragraph  3.B.  of  the  Accomplishment  Instructions  of  Bombardier
    Service Bulletin 84-28-18, Revision B, dated April 20, 2017.

(2) For  airplanes  having  S/N  4001 and 4003 through 4533 inclusive,  on
    which Bombardier Service Bulletin 84-28-19,  dated August 16, 2016; or
    Revision A,  dated November 4, 2016,  has not been done:  Within 6,000
    flight hours or 36 months after the effective date of this AD,  which-
    ever occurs first,  replace the affected single nut plate brackets and
    standoffs  at  the  affected  left-hand (LH)  and right-hand (RH) wing
    stations on the motive flow line and pressure relief line,  in accord-
    ance with paragraphs 3.B. and 3.C.  of Bombardier Service Bulletin 84-
    28-19, Revision D, dated February 16, 2018.

(3) Accomplishing  Bombardier Repair Drawing  8/4-28-018,  Issue 1,  dated
    October 30, 2017;  Issue 2, dated June 12, 2018;  Issue 3,  dated June
    21, 2018; or Issue 04,  dated July 27, 2018,  is an alternative method
    of compliance (AMOC)  only for the replacement  of the affected single
    nut plate brackets and standoffs on the motive flow line and vent line
    at LH and RH wing stations Yw ± 209.019  and  Yw ± 317.019 required by
    paragraph (h)(2) of this AD.

(4) Accomplishing  Bombardier Repair Drawing  8/4-28-018,  Issue 1,  dated
    October 30, 2017; Issue  2, dated June 12,  2018; Issue 3, dated  June
    21, 2018; or  Issue 04, dated  July 27, 2018,  prior to the  effective
    date of this AD, along with the replacement of the affected single nut
    plate  brackets and  standoffs  on  the motive  flow line,  vent line,
    pressure relief line, and scavenge line at LH and RH wing stations  Yw
    ± 209.019, Yw ± 317.019, and Yw ± 371.019, is an acceptable method  of
    compliance for the actions required by paragraph (h)(2) of this AD.

(5) For  airplanes  having  S/N  4001 and 4003 through 4533 inclusive,  on
    which Bombardier Service Bulletin 84-28-19, dated August 16, 2016;  or
    Revision A, dated November 4, 2016, has been done: Within 6,000 flight
    hours or  36 months  after the  effective date  of this  AD, whichever
    occurs  first, inspect  the motive  flow line  and vent  line at  wing
    stations  -371.019  and  371.019  in   the  LH  and  RH  fuel   tanks,
    respectively,  to  ensure  that   these  fuel  tubes  are   adequately
    supported, and inspect  the fuel tubes  to verify that  an appropriate
    clearance has been maintained between the fuel tubes and their support
    brackets, in accordance with paragraph 3.B., step (13), and  paragraph
    3.C.,  of  Bombardier  Service Bulletin  84-28-19,  Revision  D, dated
    February 16, 2018.

(6) For airplanes having S/N 4001 and 4003 through 4572 inclusive:  Within
    8,000 flight hours or 48 months  after the effective date of this  AD,
    whichever occurs first,  install Teflon™ sleeves  on the vent  line at
    wing stations  Yw ±  209.019 and  Yw ±  371.019 in  the LH and RH fuel
    tanks, inspect  the Teflon™  sleeve installation  on the  vent line at
    wing stations Yw  ± 317.019 in  the LH and  RH fuel tanks,  and if any
    sleeve is incorrectly installed, reposition the Teflon™ sleeves before
    further flight,  in accordance  with paragraphs  3.B. and  3.C. of the
    Accomplishment Instructions of  Bombardier Service Bulletin  84-28-24,
    dated November 27, 2017.

(7) Prior to accomplishment of the actions required by paragraph (h)(6) of
    this AD, the applicable actions  specified in paragraph (h)(2) or  (5)
    of this  AD must  be done.  Accomplishment of  Bombardier Modification
    Summary (ModSum) 4Q113904 on an  airplane prior to the effective  date
    of this AD is acceptable for compliance with this paragraph.

(8) For airplanes  having S/N 4001 and 4003 through 4575 inclusive: Within
    8,000 flight hours or 48 months  after the effective date of this  AD,
    whichever occurs first, inspect the Teflon™ sleeve installation on the
    vent line in  the LH and  RH fuel tanks  for correct installation  and
    damage, and  if the  sleeves are  incorrectly installed  or damage  is
    found,  before  further  flight, replace  and  reposition  the Teflon™
    sleeves, as applicable, in accordance with paragraphs 3.B. and 3.C. of
    the Accomplishment Instructions  of Bombardier Service  Bulletin 84-28
    -25, dated November 27, 2017.

(9) Prior to accomplishment of the actions required by paragraph (h)(8) of
    this AD, the applicable actions  specified in paragraph (h)(2) or  (5)
    of this AD must be done. Accomplishment of Bombardier ModSum  4Q113904
    on an airplane prior  to the effective date  of this AD is  acceptable
    for compliance with this paragraph.

(i) VERIFICATION AND REWORK FOR EXISTING MAINTENANCE PROGRAM

(1) For  airplanes  having  S/N  4001 and 4003 through 4575 inclusive,  on
    which the actions required by paragraph (h)(6) or (8) of this AD  have
    been done before the effective date of this AD, or that have  complied
    with paragraph (m)(4) of this  AD: Within 60 days after  the effective
    date of this AD, review the airplane maintenance records to confirm if
    any of the prohibited tasks (defined in paragraph (g) of this AD) were
    accomplished during or after  compliance with paragraph (h)(6)  or (8)
    of this AD or paragraph (m)(4) of this AD.

(i) If any of the prohibited tasks were accomplished  during or after com-
    pliance with paragraph (h)(6) or (m)(4) of this AD, or if it cannot be
    conclusively confirmed that they were not accomplished during or after
    compliance  with  paragraph (h)(6)  or  paragraph (m)(4)  of  this AD:
    Within 8,000  flight hours  or 48  months after  the effective date of
    this AD, whichever occurs first, do the actions required by  paragraph
    (h)(6) of this AD and, as applicable, comply with the requirements  of
    paragraph (h)(7) of this AD.

(ii) If any of the prohibited tasks were accomplished during or after com-
     pliance  with  paragraph  (h)(8)  of this  AD,  or  if  it cannot  be
     conclusively  confirmed  that  they were  not accomplished  during or
     after  compliance  with paragraph  (h)(8)  of this  AD:  Within 8,000
     flight  hours  or  48 months  after the  effective date  of this  AD,
     whichever occurs first, do  the actions required by  paragraph (h)(8)
     of  this  AD and,  as  applicable, comply  with  the requirements  of
     paragraph (h)(9) of this AD.

(2) For airplanes having S/N 4573 and subsequent, with an airplane date of
    manufacture,  as  identified  on  the  identification  plate  of   the
    airplane, dated before the effective  date of this AD: Within  60 days
    after the effective date of  this AD, review the airplane  maintenance
    records  to  confirm  if  any  of  the  prohibited  tasks  (defined in
    paragraph (g) of this AD)  were accomplished on or after  the airplane
    date of manufacture. If any of the prohibited tasks were  accomplished
    on or  after the  airplane date  of manufacture,  or if  it cannot  be
    conclusively confirmed that they were not accomplished on or after the
    airplane date of manufacture, within  8,000 flight hours or 48  months
    after the effective  date of this  AD, whichever occurs  first, obtain
    and follow  instructions for  rework using  a method  approved by  the
    Manager, New York ACO Branch, FAA; or Transport Canada Civil  Aviation
    (TCCA);  or  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.

(j) MAINTENANCE OR INSPECTION PROGRAM REVISION

    For all airplanes: Within 30 days after the effective date of this AD,
    revise the existing maintenance or inspection program, as  applicable,
    to incorporate the information  specified in (Bombardier) Q400  Dash 8
    Temporary Revision (TR) ALI-0192 and TR ALI-0193, both dated April 24,
    2018,  into  Section  4-28 Fuel  System  Limitation,  or Section  5-00
    Critical Design Configuration  Control Limitations, as  applicable, of
    Part 2, of the Bombardier Q400 Dash 8 Maintenance Requirements Manual,
    PSM  1-84-7.  The  initial  compliance time  for  doing  the  tasks in
    (Bombardier) Q400 Dash 8 TR ALI-0192, dated April 24, 2018, is at  the
    applicable  time specified  in  paragraph  (j)(1) or  (2) of  this AD,
    whichever occurs later:

(1) Prior to the accumulation of 18,000 total flight cycles  or within 108
    months since  issuance of  the original  airworthiness certificate  or
    original export certificate of airworthiness, whichever occurs first.

(2) Within 90 days after the effective date of this AD.

(k) NO ALTERNATIVE ACTIONS,  INTERVALS,  OR  CRITICAL DESIGN CONFIGURATION
    CONTROL LIMITATIONS (CDCCLS)

    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 AMOC in accordance  with the
    procedures specified in paragraph (n)(1) of this AD.

(l) MAINTENANCE TASK PROHIBITIONS

    For all airplanes: As  of the effective date  of this AD, comply  with
    the prohibitions specified in paragraphs (l)(1) and (2) of this AD.

(1) It is prohibited to use the  Bombardier  airplane  maintenance  manual
    (AMM) tasks identified in paragraphs (l)(1)(i) through (v) of this AD,
    which are  specified in  the Bombardier  Q400 Dash  8 AMM, PSM 1-84-2,
    Revision  59  dated  October 5, 2017,  or  earlier revisions  of these
    tasks. TRs  including these  AMM tasks,  dated  November 27, 2017,  or
    earlier, are also prohibited for use except as specified in  paragraph
    (l)(1)(i) through (v) of this AD.

(i) Task 28-10-00-280-806 Detailed Inspection of the Teflon™ Sleeve on the
    Fuel Tank Vent Line, LH and RH (FSL#284000-406), with the exception of
    (Bombardier) Q400 Dash 8 AMM TR 28-145, dated November 21, 2017.

(ii) Task 28-12-06-000-801 Removal of the Outboard Vent Line, with the ex-
     ception of (Bombardier) Q400 Dash 8 AMM TR 28-146, dated November 21,
     2017.

(iii) Task 28-12-06-400-801  Installation of the Outboard Vent Line,  with
      the  exception  of  (Bombardier)  Q400  Dash 8 AMM TR 28-147,  dated
      November 21, 2017.

(iv) Task 28-12-01-000-801 Removal of the Inboard Vent Line,  with the ex-
     ception of (Bombardier) Q400 Dash 8 AMM TR 28-148, dated November 24,
     2017.

(v) Task 28-12-01-400-801 Installation of the Inboard Vent Line,  with the
    exception of (Bombardier)  Q400 Dash 8 AMM TR 28-149,  dated  November
    27, 2017.

(2) It is prohibited  to  use  the Bombardier Q400 Dash 8 Maintenance Task
    Card Manual (MTCM)  task cards identified  in paragraphs (l)(2)(i) and
    (ii) of this AD that are specified in the Bombardier Q400 Dash 8 MTCM,
    PSM 1-84-7TC, Revision 42 dated November 5, 2017, or earlier revisions
    or amendments of these task cards.  MTCM task card revisions or amend-
    ments dated November 21, 2017 or earlier, are also prohibited for use,
    except as specified in paragraphs (l)(2)(i) and (ii) of this AD.

(i) Bombardier Q400 Dash 8 MTCM Maintenance Task Card 000-28-520-704 (Con-
    fig A01),  Detailed Inspection of the Teflon™ Sleeve  on the Fuel Tank
    Vent Line (LH),  with  the  exception of (Bombardier) Q400 Dash 8 MTCM
    Maintenance Task Card 000-28-520-704 (Config A01), Detailed Inspection
    of the Teflon™ Sleeve  on the Fuel Tank Vent Line  (LH),  Revision 42,
    Amendment 0002, dated November 21, 2017.

(ii) 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),  with the exception of (Bombardier)  Q400 Dash 8
     MTCM Maintenance Task Card 000-28-620-704 (Config A01),  Detailed In-
     spection  of  the  Teflon™ Sleeve  on  the  Fuel Tank Vent Line (RH),
     Revision 42, Amendment 0002, dated November 21, 2017.

(m) CREDIT FOR PREVIOUS ACTIONS

(1) This paragraph provides credit  for  actions required by paragraph (h)
    (1) of this AD,  if those actions were performed  before the effective
    date  of  this  AD  using Bombardier Service Bulletin 84-28-18,  dated
    April 20, 2016; or Revision A, dated November 14, 2016.

(2) This paragraph provides credit  for actions required  by paragraph (h)
    (2) of this AD,  if those actions were performed  before the effective
    date of this AD using Bombardier Service Bulletin 84-28-19, Revision B
    dated July 28, 2017, or Revision C, dated September 1, 2017.

(3) This paragraph provides credit  for actions required  by paragraph (h)
    (5) of this AD,  if those actions were performed  before the effective
    date of this AD using paragraphs 3.A. and 3.C and paragraph 3.B., step
    (13) of Bombardier Service Bulletin 84-28-19,  Revision B,  dated July
    28, 2017, or Revision C, dated September 1, 2017

(4) This paragraph provides credit  for  actions required by paragraph (h)
    (6) of this AD, if, before the effective date of this AD,  the ModSums
    identified in paragraph (m)(4)(i), (ii), or (iii)  of this AD were in-
    corporated and provided the conditions identified in figure 1 to para-
    graph (m)(4) of this AD have been met.

         FIGURE 1 TO PARAGRAPH (M)(4) – CONDITIONS FOR MODSUM CREDIT      
    ______________________________________________________________________
                   It can be conclusively confirmed that none of the pro-
                   hibited tasks (defined in paragraph (g) of this AD)
    Condition 1    were performed during or after the incorporation of
                   any of the applicable modsums identified in paragraphs
                   (m)(4)(i) through (iii) of this AD.

                   It can be conclusively confirmed that Bombardier
                   Service Bulletin 84-28-19 or Bombardier ModSum 4Q113904
    Condition 2    (any revision) was incorporated prior to the incorpor-
                   ation of any of the applicable modsums identified in
                   paragraphs (m)(4)(i) through (iii) of this AD.

                   It can be conclusively confirmed that Bombardier ModSum
                   IS4Q2800023 (Revisions A, B, C, D, E, F, G, H, and J),
                   Bombardier ModSum IS4Q2800030 (Revisions A and B), Bom-
    Condition 3    bardier ModSum IS4Q2800025 (Revisions A, B, C, D and E)
                   and Bombardier ModSum IS4Q2800027 (Revisions A and B)
                   were not incorporated during or after the actions re-
                   quired by paragraph (h)(8) of this AD.
    ______________________________________________________________________

(i) Incorporation of both a modsum identified in paragraph (m)(4)(i)(A) of
    this AD and a modsum identified in paragraph (m)(4)(i) (B) of this AD.

(A) One of the modsums  identified  in  paragraphs (m)(4)(i)(A)(1) through
    (9) of this AD.

(1) Bombardier ModSum IS4Q2800023, Revision A, dated February 7, 2017.

(2) Bombardier ModSum IS4Q2800023, Revision B, dated April 11, 2017.

(3) Bombardier ModSum IS4Q2800023, Revision C, dated August 30, 2017.

(4) Bombardier ModSum IS4Q2800023, Revision D, dated October 11, 2017.

(5) Bombardier ModSum IS4Q2800023, Revision E, dated October 19, 2017.

(6) Bombardier ModSum IS4Q2800023, Revision F, dated October 20, 2017.

(7) Bombardier ModSum IS4Q2800023, Revision G, dated November 24, 2017.

(8) Bombardier ModSum IS4Q2800023, Revision H, dated November 29, 2017.

(9) Bombardier ModSum IS4Q2800023, Revision J, dated December 12, 2017.

(B) One of the modsums  identified  in  paragraphs (m)(4)(i)(B)(1) through
    (5) of this AD.

(1) Bombardier ModSum IS4Q2800025, Revision A, dated October 20, 2017.

(2) Bombardier ModSum IS4Q2800025, Revision B, dated November 3, 2017.

(3) Bombardier ModSum IS4Q2800025, Revision C, dated November 21, 2017.

(4) Bombardier ModSum IS4Q2800025, Revision D, dated November 23, 2017.

(5) Bombardier ModSum IS4Q2800025, Revision E, dated November 29, 2017.

(ii) Incorporation of both  a modsum identified in paragraph (m)(4)(ii)(A)
     of this AD and a modsum identified in paragraph (m)(4)(ii)(B) of this
     AD.

(A) Bombardier ModSum IS4Q2800030, Revision A,  dated November 3, 2017; or
    Bombardier ModSum IS4Q2800030, Revision B, dated November 21, 2017.

(B) One of the modsums  identified  in paragraphs (m)(4)(ii)(B)(1) through
    (5) of this AD.

(1) Bombardier ModSum IS4Q2800025, Revision A, dated October 20, 2017.

(2) Bombardier ModSum IS4Q2800025, Revision B, dated November 3, 2017.

(3) Bombardier ModSum IS4Q2800025, Revision C, dated November 21, 2017.

(4) Bombardier ModSum IS4Q2800025, Revision D, dated November 23, 2017,

(5) Bombardier ModSum IS4Q2800025, Revision E, dated November 29, 2017.

(iii) Incorporation of a modsum  identified  in  paragraphs (m)(4)(iii)(A)
      through (C) of this AD.

(A) Bombardier ModSum IS4Q2800027, Revision A, dated October 27, 2017.

(B) Bombardier ModSum IS4Q2800027, Revision B, dated November 9, 2017.

(C) Bombardier ModSum IS4Q2800027, Revision C, dated November 15, 2017.

(n) OTHER FAA AD PROVISIONS

    The following provisions also apply to this AD:

(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 TCCA;  or 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.

(o) RELATED INFORMATION

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) TCCA AD
    CF-2017-05R2, dated September 20, 2019, 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-
    0287.

(2) For more information about this AD,  contact  Joseph Catanzaro,  Aero-
    space 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.

(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  thd@dehavilland.com;   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 March 15, 2022. Lance T. Gant, Director, Compliance & Airworthi-
ness Division, Aircraft Certification Service.

DATES: The FAA must receive comments on this proposed AD by May 9, 2022.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


14 CFR Part 39

[Docket No. FAA-2022-0287; Project Identifier MCAI-2020-01602-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 adopt a new airworthiness directive (AD)
for certain De Havilland Aircraft of Canada Limited Model DHC-8-400
series airplanes. This proposed AD was prompted by reports of broken P-
clamps on the pressure relief line and the motive flow line in the fuel
tanks, and a subsequent determination that certain service information
lacked instructions for maintaining appropriate clearance between
certain fuel tubes and their support brackets, and may also have led to
incorrect installation of certain Teflon™ sleeves. This
proposed AD was also prompted by a determination that new or more
restrictive airworthiness limitations are necessary. This proposed AD
would require inspecting the motive flow line, vent line, and related
parts, and adding support or additional clearance if necessary. This
proposed AD would also require inspection, and replacement or
relocation if necessary, of affected Teflon™ sleeves on the
vent line, and installation of Teflon™ sleeves on the vent
line at additional wing stations. This proposed AD would also require
revising the existing maintenance or inspection program, as applicable,
to incorporate new or more restrictive airworthiness limitations. 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 May 9,
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 thd@dehavilland.com; 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 at https://www.regulations.gov by
searching for and locating Docket No. FAA-2022-0287; 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,
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:

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-2022-0287; Project Identifier
MCAI-2020-01602-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 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
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. 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 Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued TCCA AD CF-2017-05R2, dated September
20, 2019 (CF-2017-05R2) (also referred to after this 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, -401, and -402 airplanes. You may examine the MCAI in
the AD docket at https://www.regulations.gov by searching for and
locating Docket No. FAA-2022-0287.
This proposed AD was prompted by reports of broken P-clamps on the
pressure relief line and the motive fuel line in the fuel tanks, as
well as fouling conditions between the motive flow line and the
collector tank partition wall in both fuel tanks. Later, certain
service information designed to mitigate these issues was found to not
contain instructions to support the motive flow line and vent line at
wing stations -371.019 and 371.019 in the fuel tanks or to maintain
appropriate clearance between the fuel tubes and their support brackets
at wing stations -371.019 and -209.109 in the left-hand fuel tank and
wing stations 371.019 and 209.019 in the right-hand fuel tank.
Bombardier issued Modification Summaries (ModSums) to provide
instructions for addressing the initial reports of inadequate
clearance. Bombardier later issued revised service information to
address this inadequate support and clearance on all affected
airplanes. Subsequently, the manufacturer determined that certain
service information was missing instructions to relocate certain
Teflon™ sleeves and certain other service information may
have caused Teflon™ sleeves to be incorrectly installed on
the vent line. The FAA is proposing this AD to address adverse impacts
on the integrity of the electrical bonding paths throughout the fuel
line, which could lead to arcing between the vent line and airplane
structure, and could result in possible 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

De Havilland Aircraft of Canada Limited has issued the following
Bombardier service information.
Bombardier Service Bulletin 84-28-18, Revision B, dated
April 20, 2017, which describes procedures for increasing the hole size
in the collector tank partition wall, inspecting the motive flow line
for damage, and replacing the associated grommet and motive flow line.
Bombardier Service Bulletin 84-28-19, Revision D, dated
February 16, 2018, which describes procedures for replacing the
affected single nut plate brackets and standoffs at the affected left-
hand (LH) and right-hand (RH) wing stations on the motive flow line and
pressure relief line; inspecting the motive flow line and vent line at
certain wing stations in the fuel tanks to ensure that these fuel tubes
are adequately supported; and inspecting the fuel tubes to verify that
an appropriate clearance has been maintained between the fuel tubes and
their support brackets.
Bombardier Service Bulletin 84-28-24, dated November 27,
2017, which describes procedures for installing Teflon™
sleeves on the vent line at the specified wing stations in the LH and
RH fuel tanks, inspecting the Teflon™ sleeve installation
on the vent line at those wing stations in the LH and RH fuel tanks,
and repositioning the Teflon™ sleeves.
Bombardier Service Bulletin 84-28-25, dated November 27,
2017, which describes procedures for inspecting the Teflon™
sleeve installation on the vent line in the LH and RH fuel tanks for
correct installation and damage, and replacing and repositioning the
Teflon™ sleeves.
De Havilland Aircraft of Canada Limited has also issued the
following Bombardier service information, which describes procedures
for replacing the affected single nut plate brackets and standoffs on
the motive flow line and vent line at LH and RH wing stations. These
documents are distinct since they apply to different airplane
configurations.
Bombardier Repair Drawing 8/4-28-018, Issue 1, dated
October 30, 2017.
Bombardier Repair Drawing 8/4-28-018, Issue 2, dated June
12, 2018.
Bombardier Repair Drawing 8/4-28-018, Issue 3, dated June
21, 2018.
Bombardier Repair Drawing 8/4-28-018, Issue 4, dated July
27, 2018.
De Havilland Aircraft of Canada Limited has also issued the
following Bombardier service information, which describes fuel systems
limitations. These documents are distinct because they apply to
different airplane configurations.
(Bombardier) Q400 Dash 8 Temporary Revision (TR) ALI-0192,
dated April 24, 2018, to Section 4--28 Fuel System Limitation, of Part
2, of the Bombardier Q400 Dash 8 Maintenance Requirements Manual (MRM),
PSM 1-84-7.
(Bombardier) Q400 Dash 8 TR ALI-0193, dated April 24,
2018, to Section 5--00 Critical Design Configuration Control
Limitations, of the Bombardier Q400 Dash 8 MRM, PSM 1-84-7.
De Havilland Aircraft of Canada Limited has also issued the
following Bombardier service information, which describes new or more
restrictive airworthiness limitations for fuel tank systems. These
documents are distinct because they apply to different airplane
configurations.
(Bombardier) Q400 Dash 8 Airplane Maintenance Manual (AMM)
TR 28-145, dated November 21, 2017.
(Bombardier) Q400 Dash 8 AMM TR 28-146, dated November 21,
2017.
(Bombardier) Q400 Dash 8 AMM TR 28-147, dated November 21,
2017.
(Bombardier) Q400 Dash 8 AMM TR 28-148, dated November 24,
2017.
(Bombardier) Q400 Dash 8 AMM TR 28-149, dated November 27,
2017.
(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 42, Amendment 0002, dated November 21, 2017.
(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 42, Amendment 0002,
dated November 21, 2017.
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 AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in the service information already described. This proposed AD would
allow using Bombardier Repair Drawing 8/4-28-018 as a method of
compliance for the actions required by paragraph (h)(2) of this
proposed AD, provided the replacement of the affected single nut plate
brackets and standoffs on the motive flow line, vent line, pressure
relief line, and scavenge line at LH and RH wing stations Yw ± 209.019,
Yw ± 317.019, and Yw ± 371.019, is also done.
This proposed AD would also require revising the existing
maintenance or inspection program, as applicable, to incorporate new or
more restrictive airworthiness limitations for fuel tank systems.
This proposed AD would require revisions to certain operator
maintenance documents to include new actions (e.g., inspections) and
Critical Design Configuration Control Limitations (CDCCLs). Compliance
with these actions and CDCCLs is required by 14 CFR 91.403(c). For
airplanes that have been previously modified, altered, or repaired in
the areas addressed by this proposed AD, the operator may not be able
to accomplish the actions described in the revisions. In this
situation, to comply with 14 CFR 91.403(c), the operator must request
approval for an alternative method of compliance according to paragraph
(n)(1) of this proposed AD.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 52 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
Up to 93 work-hours x $85 per hour = Up to $7,905 Up to $7,862 Up to $15,767 Up to $819,884

* Table does not include estimated costs for revising the maintenance or
inspection program.

The FAA has determined that revising the 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).
The FAA has received no definitive data on which to base the cost
estimates for the on-condition actions specified in this proposed 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

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

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: