AD/DHC-8/133 Amdt 2 Main Landing Gear System (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-8/133 Amdt 1 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-8/133 Amdt 2 Main Landing Gear System 4/2009 DM

Applicability:

Bombardier Inc. DHC-8 aircraft, Models 400, 401 and 402, serial numbers 4001, 4003, 4004, 4006, and 4008 through 4208.

Requirement:

1.    General Visual Inspection of the Main Landing Gear System - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4182.

Perform a general visual inspection of the left hand and right hand main landing gear system in accordance with Bombardier DHC-8 Series 400 Maintenance Requirements Manual (PSM 1-84-7), Part 1 (Maintenance Review Board Report), tasks Z700-03E (left hand) and Z700-04E (right hand) and rectify any discrepancy found.

2.    General Visual Inspection of the Main Landing Gear Retract Actuator Jam Nut - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4208.

a.     Perform a general visual inspection of the left hand and right hand main landing gear retract actuator jam nut to ensure the wire lock is in place and the nut is secured.  If the wire lock is not in place or the jam nut is not secured, accomplish Bombardier Repair Drawing (RD) 8/4-32-059 Issue 5 or later approved revision.

b.    Repeat the actions detailed in Requirement 2.a. of this AD.

3.    Detailed Visual Inspection of the Main Landing Gear Retract Actuator - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4182.

a.     Perform a detailed visual inspection and any required action(s) in accordance with Bombardier RD 8/4-32-059 Issue 5 or later approved revision.

b.    Repeat the actions detailed in Requirement 3.a. of this AD.

Respective inspections performed in accordance with earlier issues of RD 8/4-32-059 satisfy the actions detailed in Requirements 2 and 3 of this AD.

If the visual inspection of the piston (p/n 46570-1/-3) threads and thread relief area for evidence of corrosion in accordance with RD 8/4-32-059 Rev. NC was performed without using borescope or 10X magnification mirror, a one time deferral for up to 500 landings is permissible to complete the inspection of the piston using borescope or 10X magnification mirror.

4.    Reporting Requirement - Applicable to DHC Models 400, 401 and 402, serial numbers 4001, 4003, 4004, 4006, and 4008 through 4208.

Report any discrepancies found during any of the above inspections to the Bombardier Technical Help Desk.

5.    Modification of Main Landing Gear Retract Actuator - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4182.

Incorporate Bombardier Modsum 4-901603 to replace the affected retract actuator with a new design retract actuator, p/n 46550-13. Bombardier Service Bulletin (SB) 84-32-55, Revision A, dated 10 March 2008, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating Modsum 4-901603.

Terminating Action 1.

Incorporation of Modsum 4-901603 provides terminating action to the visual inspections detailed in Requirement 3 of this AD.

Note 1:  Incorporation of Modsum 4-901603 in accordance with Revision NC of Bombardier SB 84-32-55, dated 14 January 2008, meets Requirement 5 of this AD.

Note 2:  Incorporation of Modsum 4-901610 to replace the affected retract actuator with a new design retract actuator, p/n 46550-15, also satisfies Requirement 5 of this AD.

6.    Maintenance Requirement - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4208.

Amend the Transport Canada approved maintenance schedule by incorporating task numbers 320100-211 (Detailed Inspection of the Retraction Actuator Rod End Jam Nut, Gland Nut and Actuator Attachment Pins for Condition, Security of Installation and Corrosion) and 320100-212 (Restoration of the Retraction Actuator for Complete Overhaul) as introduced by the Temporary Revision (TR) MRB–35 of the DHC-8 Series 400 Maintenance Requirements Manual, PSM
1-84-7.

Terminating Action 2.

Incorporation of maintenance task numbers 320100-211 and 320100-212 provides terminating action to the general visual inspections detailed in Requirement 2 of this AD.

Ferry Flight:  Applicable to DHC-8 Aircraft, Models 400, 401, and 402, Serial Numbers 4001, 4003, 4004, 4006, 4008 through 4208.

To permit the ferry of an aircraft to a location where the inspection requirements of this directive can be accomplished, adhere to the following procedures and limitations:

Flight Crew Limitations and Procedures:

A.   Ferry Flight with gear extended and pinned.

B.    Landing to be conducted at a minimum descent rate.

C.   Minimize braking on landing.

D.   Flight to be conducted per Aircraft Operating Manual (AOM) Section 4.8.

E.    Essential crew only on board.

F.    Flight in known or forecast icing condition is prohibited.

Maintenance Procedures:

(i)    Inspect the left hand and right hand main landing gear retract actuator jam nut to ensure the wire lock is in place and the nut is secure.

(ii)   Perform the general visual inspections as defined in accordance with Bombardier All Operators Message No. 236 Rev A or later revisions.

(iii)  If items 1 and 2 results are satisfactory, insert main landing gear ground lock pins and lockwire in place.

(iv)  Ensure the nose landing gear ground lock is engaged.

Note 3:  Transport Canada AD CF-2007-20 R2 dated 6 February 2009 refers.

Compliance:

For Requirement 1 - Remains unchanged as detailed in the original issue of this AD as:

Before further flight after 14 September 2007 (the effective date of the original issue of this AD), unless previously accomplished.

For Requirement 2a - Remains unchanged as detailed in the original issue of this AD as:

Before further flight after 14 September 2007, unless previously accomplished.

For Requirement 2b - At intervals not to exceed 250 landings or one month from the previous inspection, whichever occurs first.

For Requirement 3a - Remains unchanged as detailed in the original issue of this AD as:

For aircraft main landing gear retract actuator (p/n 46550-7 or 46550-9) that have accumulated 8,000 or more landings or in service for more than 4 years since new, whichever occurs first at 14 September 2007 - before further flight after
14 September 2007.

For aircraft main landing gear retract actuator (p/n 46550-7 or 46550-9) that have accumulated between 4,000 to 7,999 landings or in service between 2 to 4 years since new at 14 September 2007 - Within 500 flight hours or 3 months after the effective date of this AD, whichever occurs first.

For aircraft main landing gear retract actuator (p/n 46550-7 or 46550-9) that have accumulated less than 4,000 landings or less than 2 years service in service since new, at 14 September 2007 - Prior to reaching 4,500 landings or 27 months in service new, whichever occurs first.

For aircraft main landing gear retract actuator (p/n 46550-11) - Prior to reaching 4,500 landings or 27 months in service new, whichever occurs first.

For Requirement 3b - At intervals not to exceed 2,000 landings or one calendar year from the previous inspection, whichever occurs first.

For Requirement 4 - Within 7 days after each inspection.

For Requirement 5

For aircraft main landing gear retract actuators (p/n 46550-7 or 46550-9 or 46550-11) that have accumulated 7,500 or more landings or more than 4 years in service since new at the effective date of this AD - Within 500 landings or 3 months from the effective date of this AD, whichever occurs first.

For aircraft main landing gear retract actuators (p/n 46550-7 or 46550-9 or 46550-11) that have accumulated less than 7,500 landings, and 4 years or less in service since new at the effective date of this directive - Prior to reaching 8,000 landings or 51 months in service since new, whichever occurs first.

For Requirement 6 - Within 30 days after the effective date of this AD.

This Amendment becomes effective on 9 March 2009.

Background:

The original issue of this AD was in response to two reported cases of main landing gear collapse.  Main landing gear collapse may result in an unsafe landing of the aircraft.

Amendment 1 changed the compliance time by introducing calendar periods and repetitive inspections until such time that a terminating action becomes available.

Amendment 2 amends the detailed visual inspection requirement and adds a requirement to mandate the incorporation of main landing gear actuator part number 46550-13 and adds additional maintenance requirements.

The original issue of this AD became effective on 14 September 2007.

Amendment 1 of this AD became effective on 2 November 2007.

James Coyne
Delegate of the Civil Aviation Safety Authority

19 February 2009