AD 2005-12-15 Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

Models named: DHC-8-400 series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Bombardier Model DHC-8-400 series airplanes, certificated in any category; serial numbers 4001, and 4003 through 4094 inclusive. Note 1: This AD requires revision to a certain operator maintenance document to include a new replacement time. Compliance with this replacement time is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this replacement time, the operator may not be able to accomplish the replacement described in the revision. 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 (g) of this AD. The request should include a description of changes to the required replacement time that will ensure the continued damage tolerance of the affected structure. The FAA has provided guidance for this determination in Advisory Circular (AC) 25-1529.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Revisions to Airworthiness Limitation (AWL) Section (f) Within 30 days after the effective date of this AD, revise the AWL section of the Instructions for Continued Airworthiness of the Dash 8 400 Series (Bombardier) Maintenance Requirements Manual, PSM 1-84-7, by doing the actions specified in paragraphs (f)(1) and (f)(2) of this AD. (1) Reduce the life limits of the MLG orifice support tube having part number (P/N) 46117-1, upper bearing having P/N 46114-1, and piston plug having P/N 46137-1, by inserting Dash 8 400 Series (Bombardier) Temporary Revision ALI-28, dated December 11, 2003, into the AWL section. Thereafter, except as provided in paragraph (g) of this AD, no alternative life limits may be approved for the MLG orifice support tube, upper bearing, or piston plug. (2) Incorporate structural inspection tasks 712001F102 and 712003F102 to reduce the threshold for initiating repetitive detailed inspections for cracking of the engine isolator brackets by inserting Dash 8 400 Series (Bombardier) Temporary Revision ALI-37, dated March 30, 2004, into the AWL section. Thereafter, except as provided in paragraph (g) of this AD, no alternative structural inspection threshold may be approved. Alternative Methods of Compliance (AMOCs) (g) The Manager, New York Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. Related Information (h) Canadian airworthiness directive CF-2004-19, dated September 21, 2004, also addresses the subject of this AD. Material Incorporated by Reference (i) You must use Dash 8 400 Series (Bombardier) Temporary Revision ALI-28, dated December 11, 2003; and Dash 8 400 Series (Bombardier) Temporary Revision ALI-37, dated March 30, 2004; to the Dash 8 400 Series (Bombardier) Maintenance Requirements Manual, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approves the incorporation by reference of these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. To get copies of the service information, contact Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. To view the AD docket, go to the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, Nassif Building, Washington, DC. To review copies of the service information, go to the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. Issued in Renton, Washington, on June 7, 2005. Michael J. Kaszycki, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 05-11695 Filed 6-14-05; 8:45 am] BILLING CODE 4910-13-P

This AD was prompted by the discovery of fatigue failures, during type certification fatigue testing, at the engine isolator bracket and at the orifice support tube, upper bearing, and piston plug in the shock strut assembly of the main landing gear (MLG), which are principal structural elements. We are issuing this AD to prevent the development of cracks in these principal structural elements, which could reduce the structural integrity of the engine installation and MLG. Reduced structural integrity of the engine installation could result in separation of the engine from the airplane, and reduced structural integrity of the MLG could result in collapse of the MLG.