(a) EFFECTIVE DATE

    This AD is effective November 27, 2019.

(b) AFFECTED ADS

    This  AD  replaces  AD  2011-18-15,  Amendment 39-16797  (76 FR 54093,
    August 31, 2011) ("AD 2011-18-15").

(c) APPLICABILITY

    This  AD  applies  to  De Havilland Aircraft of Canada  Limited  Model
    DHC-8-400, -401, and -402 airplanes,  certificated  in  any  category,
    serial numbers 4001 through 4437 inclusive.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 57, Wings.

(e) REASON

    This AD  was prompted  by in-service  reports of  cracked barrel  nuts
    found at the front  spar locations of the  wing-to-fuselage attachment
    joints, and  a loose  washer in  the barrel  nut assembly.  The FAA is
    issuing this AD to address cracked  barrel nuts and a loose washer  in
    the barrel nut assembly, which  could result in failure of  the barrel
    nuts, compromising  the structural  integrity of  the wing-to-fuselage
    attachments, and  possible separation  of the  wing from  the airplane
    during flight.

(f) COMPLIANCE

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

(g) RETAINED INITIAL AND REPETITIVE CHECKS AND INSPECTIONS,  WITH  REVISED
    SERVICE INFORMATION

    This paragraph restates the requirements of paragraph (g) of  AD 2011-
    18-15,  with  revised  service  information.  At  the  applicable time
    specified in paragraph (g)(1) or (2) of this AD: Do a torque check  to
    determine  if the  bolt preload  is correct,  and  if  the preload  is
    correct,  before  further flight,  do  a detailed  inspection  of each
    barrel  nut  and  cradle  for  cracking,  pitting  or  corrosion,   in
    accordance  with  paragraph  3.B.,  part  A,  of  the   Accomplishment
    Instructions  of Bombardier  Alert Service  Bulletin A84-57-25,  dated
    July 20, 2011; or  Bombardier Service Bulletin A84-57-25,  Revision A,
    dated  July 16, 2018.  After  the effective  date  of  this  AD,  only
    Bombardier  Service Bulletin A84-57-25,  Revision  A,  dated  July 16,
    2018, may  be used.  Repeat the  torque check  and, as applicable, the
    inspection thereafter at intervals not to exceed 2,000 flight hours or
    12 months, whichever occurs first.

(1) For airplanes that have accumulated 1,900  or  more total flight hours
    as of September 15, 2011 (the effective date of AD 2011-18-15), or for
    which it has been 12 months or more since the date of issuance of  the
    original Canadian airworthiness certificate or the date of issuance of
    the  original  Canadian  export  certificate  of  airworthiness  as of
    September 15, 2011: Within 100 flight hours or 10 days after September
    15, 2011, whichever occurs first.

(2) For airplanes that have accumulated less than 1,900 total flight hours
    as of September  15, 2011 (the  effective date of  AD 2011-18-15), and
    for which it has been less  than 12 months since the date  of issuance
    of  the original  Canadian airworthiness  certificate or  the date  of
    issuance of the original Canadian export certificate of  airworthiness
    as of  September 15,  2011: Prior  to the  accumulation of 2,000 total
    flight hours or  within 12 months  since the date  of issuance of  the
    original Canadian  standard airworthiness  certificate or  the date of
    issuance of the original Canadian export certificate of airworthiness,
    whichever occurs first.

(h) RETAINED CORRECTIVE ACTIONS FOR INCORRECT BOLT PRELOAD,  WITH  REVISED
    SERVICE INFORMATION

    This paragraph restates the requirements of paragraph (h) of  AD 2011-
    18-15, with revised service information. If any bolt preload is  found
    to be incorrect (i.e., the ring can be rotated during any torque check
    required by paragraph (g) of this AD), before further flight,  replace
    all hardware at that location (except the saddle washer and  retainer)
    in  accordance  with paragraph  3.B.,  part B,  of  the Accomplishment
    Instructions  of Bombardier  Alert Service  Bulletin A84-57-25,  dated
    July 20, 2011; or paragraph 3.B. of the Accomplishment Instructions of
    Bombardier Service Bulletin 84-57-26, Revision C, dated July 16, 2018.
    After the effective date of this AD,  only Bombardier Service Bulletin
    84-57-26, Revision C, dated July 16, 2018, may be used.

(i) RETAINED CORRECTIVE ACTIONS FOR BARREL NUT/CRADLE DISCREPANCIES,  WITH
    REVISED SERVICE INFORMATION

    This paragraph restates the requirements of paragraph (i) of  AD 2011-
    18-15, with  revised service  information. If  any crack,  pitting, or
    corrosion of the barrel nut  or cradle is found during  any inspection
    required by paragraph (g) of  this AD, before further flight,  replace
    all hardware at that location (except the saddle washer and  retainer)
    in  accordance  with paragraph  3.B.,  part B,  of  the Accomplishment
    Instructions  of Bombardier  Alert Service  Bulletin A84-57-25,  dated
    July 20, 2011; or paragraph 3.B. of the Accomplishment Instructions of
    Bombardier Service Bulletin 84-57-26, Revision C, dated July 16, 2018.
    After the effective date of this AD, only Bombardier Service  Bulletin
    84-57-26, Revision C, dated July 16, 2018, may be used.

(j) NEW REQUIREMENT OF THIS AD: REPLACEMENT AND VISUAL INSPECTION

    Within 12,000 flight  hours or 72  months after the  effective date of
    this AD, whichever occurs first: Do a visual inspection of the  saddle
    washer and retainer for any damage (cracks) or corrosion; and  replace
    the  wing  front  spar  barrel  nuts,  bolts,  and  preload indicating
    washers;  in  accordance  with paragraph  3.B.  of  the Accomplishment
    Instructions  of  Bombardier Service  Bulletin  84-57-26,  Revision C,
    dated July 16, 2018.

(k) NEW CORRECTIVE ACTIONS FOR DAMAGE (CRACKS) OR CORROSION

    If any damage (cracks) or corrosion is found during any inspection re-
    quired by paragraph (j) of this AD: Before further flight,  accomplish
    corrective  actions  in  accordance with  the procedures  specified in
    paragraph (p)(2) of this AD.

(l) NEW PROVISION OF THIS AD:  TERMINATING ACTIONS  FOR  REPETITIVE TORQUE
    CHECKS AND DETAILED INSPECTIONS

    Accomplishment of  the applicable  actions required  by paragraphs (j)
    and (k) of this AD, at  all four barrel nut locations, terminates  the
    repetitive torque checks and detailed inspections of paragraph (g)  of
    this AD.

(m) PARTS INSTALLATION PROHIBITION

    As of the effective date of this AD no person may install, on any air-
    plane, a barrel nut having part number DSC228-16.

(n) RETAINED  SPECIAL FLIGHT PERMIT PROVISIONS,  WITH  REVISED  COMPLIANCE
    LANGUAGE

    This paragraph restates the requirements of paragraph (k) of  AD 2011-
    18-15, with  revised compliance  language. Special  flight permits, as
    described in 14 CFR  21.197 and 21.199, may  be issued to operate  the
    airplane  to  a  location where  the requirements  of this  AD can  be
    accomplished, but  concurrence by  the Manager,  New York  ACO Branch,
    FAA, is required before issuance of the special flight permit.  Before
    using  any  approved  special flight  permits,  notify  your principal
    maintenance inspector (PMI) or principal avionics inspector (PAI),  as
    appropriate,  or  lacking  a principal  inspector,  your  local Flight
    Standards  District Office  (FSDO).  Operators  must request  a repair
    drawing  from Bombardier,  Inc., or  De Havilland  Aircraft of  Canada
    Limited, which provides recommendations for a one-time special  flight
    permit.  After  the  effective  date of  this  AD,  only  De Havilland
    Aircraft of Canada Limited may provide the repair drawing. The  repair
    drawing will be  applicable to the  operator’s aircraft serial  number
    only.  Special  flight  permits may  be  permitted  provided that  the
    conditions specified in paragraphs (n)(1)  through (5) of this AD  are
    met.

(1) Only one barrel nut out of four is cracked,  one cradle is cracked, or
    one washer is loose;  all other strut (wing front spar) bolt locations
    must be free of damage.

(2) The airplane must operate with reduced airspeed not to exceed 180 KIAS
    (knots indicated air speed). No passengers and no cargo are onboard.

(3) The airplane must not operate in known  or forecast turbulence,  other
    than light turbulence.

(4) The airplane descent rate on landing flare-out is not to exceed 5 feet
    per second.

(5) Heavy braking  or  hard turning of the airplane  upon landing is to be
    avoided if possible.

(o) CREDIT FOR PREVIOUS ACTIONS

(1) This paragraph  restates the provisions of paragraph (j)  of  AD 2011-
    18-15, with revised formatting  and updated service information.  This
    paragraph provides credit for torque checks, initial inspections,  and
    replacements required by paragraphs (g)  and (h) of this AD,  if those
    actions were performed before the effective date of this AD using  the
    service information specified in  paragraphs (o)(1)(i) through (v)  of
    this  AD,  which  is not  incorporated by  reference in  this AD.  The
    repetitive torque checks, and as applicable, the inspections  required
    by paragraph (g) of this AD must be continued at the time specified.

(i) Bombardier Alert Service Bulletin A84-57-19, dated February 1, 2008.

(ii) Bombardier  Alert  Service  Bulletin  A84-57-19,  Revision  A,  dated
     February 6, 2008.

(iii) Bombardier Alert Service Bulletin A84-57-19, Revision B, dated March
      6, 2008.

(iv) Bombardier Alert Service Bulletin A84-57-19, Revision C, dated August
     20, 2008.

(v) Bombardier Alert Service Bulletin A84-57-19, Revision D,  dated August
    12, 2011.

(2) This paragraph  provides credit for the actions required by paragraphs
    (h) through (k) of this AD, if those actions were performed before the
    effective date of this AD  using the service information specified  in
    paragraphs  (o)(2)(i)   through  (iii)   of  this   AD.  This  service
    information is not incorporated by reference in this AD.

(i) Bombardier Service Bulletin 84-57-26, dated March 21, 2013.

(ii) Bombardier Service Bulletin 84-57-26 Revision A, dated July 18, 2014.

(iii) Bombardier Service Bulletin 84-57-26, Revision B, dated February 26,
      2015.

(3) This paragraph provides credit for the actions required  by paragraphs
    (h) and (i) of this AD,  if  those  actions were performed  before the
    effective date of this AD  using the service information  specified in
    paragraphs (o)(3)(i) and (ii) of this AD.

(i) Bombardier Alert Service Bulletin A84-57-25 dated July 20, 2011, which
    was incorporated by reference in AD 2011-18-15.

(ii) Bombardier  Service Bulletin A84-57-25,  Revision A,  dated  July 16,
     2018, which is incorporated by reference in this AD.

(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 re-
    quested using the procedures found in 14 CFR 39.19. In accordance with
    14 CFR 39.19, send your  request to your principal inspector  or local
    Flight  Standards   District  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;
    phone:  516-228-7300;  fax: 516-794-5531.  Before  using any  approved
    AMOC,  notify  your  appropriate  principal  inspector,  or  lacking a
    principal  inspector,  the  manager  of  the  local  flight  standards
    district office/certificate holding district office.

(2) Contacting the Manufacturer:  For any requirement in this AD to obtain
    corrective  actions   from  a   manufacturer,  the   action  must   be
    accomplished 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 DAOauthorized signature.

(3) AMOCs approved previously  for AD 2011-18-15 are approved as AMOCs for
    the corresponding provisions of this AD.

(q) RELATED INFORMATION

(1) Refer   to   Mandatory  Continuing  Airworthiness  Information  (MCAI)
    Canadian AD CF-2011-24R1, dated January 21, 2019, for related informa-
    tion. This MCAI may be found in the AD docket on the Internet at http:
    //www.regulations.gov by searching  for  and  locating Docket No. FAA-
    2019-0493.

(2) For more information about this AD,  contact Andrea Jimenez, Aerospace
    Engineer, Airframe and Propulsion Section,  FAA,  New York ACO Branch,
    1600 Stewart Ave., Suite 410, Westbury, NY 11590; phone: 516-228-7330;
    fax: 516-794-5531; email: 9-avs-nyaco-cos@faa.gov.

(3) Service information  identified in this AD that is not incorporated by
    reference is available at the addresses specified in paragraphs (r)(4)
    and (5) of this AD.

(r) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference (IBR) of  the service information  listed in this  paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use  this service information as applicable to do the actions
    required by this AD, unless this AD specifies otherwise.

(3) The following service information was approved for IBR on November 27,
    2019.

(i) Bombardier Service Bulletin A84-57-25, Revision A, dated July 16, 2018

(ii) Bombardier Service Bulletin 84-57-26, Revision C, dated July 16, 2018

(4) For service information identified  in this AD,  contact  De Havilland
    Aircraft of Canada Ltd.,  Q-Series  Technical  Help  Desk, 123 Garratt
    Boulevard, Toronto, Ontario M3K 1Y5, Canada; phone: 416-375-4000; fax:
    416-375-4539; email thd@dehavilland.com; Internet https://dehavilland.
    com.

(5) You may view this service information at the FAA,  Transport Standards
    Branch,  2200 South 216th St., Des Moines, WA.  For information on the
    availability of this material at the FAA, call 206-231-3195.

(6) You  may  view  this  service  information  that  is  incorporated  by
    reference at the National Archives and Records Administration  (NARA).
    For information on the availability of this material  at  NARA,  email
    fedreg.legal@nara.gov,   or  go  to:  http://www.archives.gov/federal-
    register/cfr/ibr-locations.html.

Issued  in  Des Moines, Washington, on October 7, 2019.  Michael Kaszycki,
Acting Manager, System Oversight Division,  Aircraft Certification Service

FOR FURTHER INFORMATION CONTACT: Andrea Jimenez,  Aerospace Engineer, Air-
frame and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart Ave.,
Suite 410, Westbury, NY 11590;  phone: 516-228-7330; fax: 516-794-5531; e-
mail: 9-avs-nyaco-cos@faa.gov.