AD/DHC-8/120 Amdt 1 - Power Transfer Unit Overspeed (Cth)

AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/DHC-8/120 and issues the following AD under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes AD/DHC-8/120 Amdt 1 Power Transfer Unit Overspeed 12/2009

Applicability: Bombardier Inc. Models DHC-8-400, DHC-8-401 and DHC-8-402, Serial Numbers (S/N) 4001, 4003, 4004, 4006 and 4008 through 4184. Requirement: 1. Amend the Aeroplane Flight Manual (AFM), PSM 1-84-IA, by inserting Temporary Amendment (TA) No. 13, dated 14 July 2005, or later approved changes to this AFM temporary amendment.

2. Advise all flight crew of the changes introduced by the AFM temporary amendment.

Note 1: Aircraft S/N 4185 and subsequent have been removed from the applicability of this AD since an equivalent PTU control logic modification (consisting of both (a) Modsum 4-126354 and (b) Modsum 4-901472 or Modsum 4-901473) has been installed in production. As a result, it is permissible to amend AFM PSM 1-84-1A by removing TA No.13 for these specific aircraft S/Ns.

3. Modify/rework the PTU control logic by incorporating Modsum 4-126425. Bombardier Service Bulletin (SB) 84-29-22, Revision A, dated 24 February 2009, or later revisions approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada, provides approved instruction for incorporating Modsum 4-126425.