Airworthiness Directive · Amendment 39-17215 · Landing gear
Bombardier, Inc. Airplanes
This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category, having serial numbers 4001 through 4247 inclusive.
We are superseding an existing airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400 series airplanes. That AD currently requires a modification to trim the edge of the bumper plate, including performing an inspection for damage or cracks of the bumper plate and base fitting, and replacing any damaged or cracked part. That AD also currently requires, for certain airplanes, reidentifying the bumper plate. This new AD requires, for airplanes on which the reidentification is done, an operational check of the alternate extension system of the main landing gear (MLG), and repair if necessary. This AD was prompted by the determination that an operational check must be done after reidentifying the bumper plate to ensure the identified unsafe condition is addressed. We are issuing this AD to detect and correct failure of the MLG to extend and lock, which could adversely affect the safe landing of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 2,000 flight hours after September 19, 2011 (the effective date of AD 2011-17-04, Amendment 39-16768 (76 FR 50403, August 15, 2011)): Incorporate Bombardier Modsum 4-113645, including performing a detailed visual inspection for damage or cracks of the bumper plate and base fitting and replacing any damaged or cracked part, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-32-74, Revision A, dated May 17, 2010. Do all applicable replacements before further flight.
Note 1 to paragraphs (g) and (h) of this AD: Bombardier Service Bulletin 84-32-74, Revision A, dated May 17, 2010, includes an operational check of the alternate extension system of the MLG. If the operational check fails, guidance on doing corrective actions can be found in the Bombardier Q400 Dash 8 Aircraft Maintenance Manual.
For airplanes on which a bumper plate having part number 85424082-101 or 85424082-103 is installed on which the rework specified in Bombardier Repair Drawing 8/4-54-553 has been done: Within 1,000 flight hours after September 19, 2011 (the effective date of AD 2011-17-04, Amendment 39-16768 (76 FR 50403, August 15, 2011)), reidentify the bumper plate, in accordance with paragraph 3.B., step (8) of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-74, Revision A, dated May 17, 2010.
This paragraph provides credit for the modification required by paragraph (h) of this AD by incorporation of Bombardier Modsum 4-113645 if the modification was performed before September 19, 2011 (the effective date of AD 2011-17-04, Amendment 39-16768 (76 FR 50403, August 15, 2011)), using Bombardier Service Bulletin 84-32-74, dated December 23, 2009 (which is not incorporated by reference in this AD); and provided the modification is done within the compliance time specified in paragraph (h) of this AD.
Concurrently with doing the actions required by paragraph (h) of this AD, or within 30 days after the effective date of this AD, whichever occurs later: Perform an operational check of the alternate extension system of the MLG, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-32-74, Revision A, dated May 17, 2010. If the operational check fails, before further flight, repair in accordance with a method approved by either the Manager, New York Aircraft Certification Office (ACO), FAA; or the Transport Canada Civil Aviation (TCCA) (or its delegated agent).
Note 2 to paragraph (j) of this AD: If the operational check fails, guidance on doing the repair can be found in the Bombardier Q400 Dash 8 Aircraft Maintenance Manual.
This paragraph provides credit for actions required by paragraph (g) of this AD, if those actions were performed before the effective date of this AD, provided the operational check specified in paragraph (j) of this AD is done within the compliance time specified in paragraph (g) of this AD, or within 30 days after the effective date of this AD, whichever occurs later, using Bombardier Service Bulletin 84-32-74, dated December 23, 2009 (which is not incorporated by reference in this AD).
