Airworthiness Directive · Amendment 39-14131 · Bombardier Model DHC-8-400 Series Airplanes
Bombardier Model DHC-8-400 Series Airplanes
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.
The FAA is adopting a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This AD requires revising the Airworthiness Limitation section of the Instructions for Continued Airworthiness of the Dash 8 400 Series (Bombardier) Maintenance Requirements Manual to reduce the life limits of the main landing gear (MLG) orifice support tube, upper bearing, and piston plug; and to reduce the threshold for initiating repetitive detailed inspections for cracking of the engine isolator brackets. This AD is 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 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 the 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.
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 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.
