Airworthiness Directive · Amendment 39-18613 · Landing gear
Bombardier, Inc. Airplanes
This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category, serial numbers (S/Ns) 4001 through 4431 inclusive.
We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. This AD was prompted by reports of chafing damage due to insufficient clearance on the main landing gear (MLG) stabilizer brace, the nacelle A-frame structure, and the adjacent electrical wiring harnesses. An insufficient fillet radius may also exist on certain airplanes. This AD requires, depending on airplane configuration, an inspection of the nacelle A-frame structure for insufficient fillet radius; an inspection for cracking of affected structure, and rework or repair if necessary, and rework of the nacelle A-frame structure; repetitive inspections of the nacelle A-frame structure and the MLG stabilizer brace for insufficient clearance and damage, and repair if necessary, and rework of the nacelle A-frame structure, which would terminate the repetitive inspections; installation of new stop brackets and a shim on each MLG stabilizer brace assembly; and rework of the electrical wiring harnesses in the nacelle area. We are issuing this AD to detect and correct chafing damage and subsequent premature cracking and fracture of the nacelle A-frame structure, which could result in failure of the MLG stabilizer brace and loss of the MLG down-lock indication, which could adversely affect the safe landing of the airplane.
For airplanes having S/Ns 4001 through 4055 inclusive: Do the actions required by paragraphs (g)(1) and (g)(2) of this AD.
(1) Within 600 flight hours or 100 days after the effective date of this AD, whichever occurs first: Do a detailed inspection of the left-hand (LH) side and right-hand (RH) side nacelle A-frame structure for insufficient fillet radius, in accordance with “Part A—Inspection” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013. If an insufficient fillet radius exists, before further flight, do an eddy current or fluorescent dye penetrant inspection for cracking, in accordance with “Part A—Inspection” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013.
(i) If any cracking is found: Before further flight, repair using a method approved by the Manager, New York Aircraft Certification Office (ACO), ANE-170, FAA; or Transport Canada Civil Aviation (TCCA); or Bombardier, Inc.'s TCCA Design Approval Organization (DAO).
(ii) If no cracking is found: Before further flight, rework the structure, in accordance with “Part B—Rectification” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013.
(2) Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first: Rework the LH side and RH side nacelle A-frame structure, including doing a measurement of the clearance between the fasteners/A-frame structure and MLG stabilizer brace assembly and making sure no fouling condition exists, in accordance with paragraph 3.B., “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-21, dated May 9, 2013. If the clearance is found to be less than 0.100 inch (2.54 millimeters (mm)) between the fasteners/A-frame structure and MLG stabilizer brace assembly after the rework is done, or a fouling condition exists during the extension of the MLG after rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
For airplanes having S/Ns 4056 through 4426 inclusive: Within 600 flight hours or 100 days after the effective date of this AD, whichever occurs first, do a detailed inspection of the LH side and RH side nacelle A-frame structure and upper surface of the MLG stabilizer brace for insufficient clearance and damage (e.g., cracking), in accordance with “Part A—Inspection” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-20, Revision C, dated March 5, 2015. If no damage is found and clearance is sufficient: Repeat the inspection thereafter at intervals not to exceed 600 flight hours until the terminating action required by paragraph (i) of this AD has been done.
(1) If a clearance less than 0.100 inch (2.54 mm) exists between the A-frame structure and the MLG stabilizer brace assembly in the retracted position, after the rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
(2) If any damage is found: Before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
For airplanes having S/Ns 4056 through 4426 inclusive: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first, rework the LH side and RH side nacelle A-frame structure, including doing a measurement of the clearance between the A-frame structure and MLG stabilizer brace assembly and doing a fluorescent dye penetrant inspection or high frequency eddy current inspection for cracking, in accordance with “Part B—Rework” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-20, Revision C, dated March 5, 2015. Accomplishment of the actions required by this paragraph terminates the repetitive inspections required by paragraph (h) of this AD.
(1) If a clearance less than 0.100 inch (2.54 mm) exists between the A-frame structure and the MLG stabilizer brace assembly in the retracted position, after the rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
(2) If any cracking is found: Before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
For airplanes having S/Ns 4001 through 4431 inclusive with a MLG stabilizer brace assembly having part number (P/N) 46400-27 installed: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first, incorporate Bombardier ModSum 4-902416 by installing new stop brackets and a new shim on each MLG stabilizer brace assembly, in accordance with paragraph 3.B., “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-112, Revision C, dated April 2, 2015; and Goodrich Service Bulletin 46400-32-102 R2, Revision 2, dated February 17, 2015.
For airplanes having S/Ns 4001 through 4411 inclusive: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first, rework the LH and RH sides of the electrical wiring harnesses in the nacelle area adjacent to the A-frame structure, including doing the actions specified in paragraphs (k)(1) through (k)(4) of this AD, in accordance with “Part B—Procedure” of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-114, Revision B, dated February 3, 2015. If any damage is found on the A-frame structure or MLG stabilizer brace, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
(1) Doing a detailed inspection of the conduit assembly for the conditions specified in Bombardier Service Bulletin 84-32-114, Revision B, dated February 3, 2015, and, before further flight, repairing if any condition is found.
(2) Replacing damaged conduit.
(3) Measuring the clearance between the stabilizer brace and electrical harness on both LH and RH nacelles to make sure there is 0.100 inch (2.54 mm) minimum clearance between the MLG stabilizer brace.
(4) Checking for damage on the A-frame structure and MLG stabilizer brace.
(1) Installing specified fasteners on the MLG A-frame, in both LH and RH nacelles, in accordance with Bombardier ModSum IS4Q5450002, Revision B, dated June 22, 2012, is acceptable for compliance with the actions specified in paragraph (g)(2) of this AD, provided the actions specified in Bombardier ModSum IS4Q5450002 are done within the applicable compliance time specified in paragraph (g) of this AD, except where ModSum IS4Q5450002, Revision B, dated June 22, 2012, specifies to contact Bombardier for reduced clearances, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
(2) Trimming the horizontal and vertical stiffeners on the MLG A-frame in both LH and RH nacelles, in accordance with Bombardier ModSum IS4Q5450003, Revision C, dated November 29, 2012, is acceptable for compliance with the actions specified in paragraph (i) of this AD, provided the actions specified in Bombardier ModSum IS4Q5450003 are done within the compliance time specified in paragraph (i) of this AD, except where ModSum IS4Q5450003, Revision C, released November 29, 2012, specifies to contact Bombardier for reduced clearances, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
(3) Rerouting certain electrical harnesses and installing grommets, in accordance with Bombardier ModSum IS4Q2400028, Revision B, dated December 11, 2012 (for S/Ns 4001 through 4098 inclusive); or Bombardier ModSum IS4Q2400029, Revision A, dated July 6, 2012 (for S/Ns 4090 through 4411 inclusive); is acceptable for compliance with the actions specified in paragraph (k) of this AD, provided the actions specified in the applicable modsum are done within the compliance time specified in paragraph (k) of this AD, except where Bombardier ModSum IS4Q2400028, Revision B, dated December 11, 2012; and Bombardier ModSum IS4Q2400029, Revision A, dated July 6, 2012; specify to contact Bombardier to report stabilizer brace or structural damaged findings, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.
