### Transport Transports

Canada Canada TP 7245E



# AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your na me. ADs are issued pursuant to Canadian Aviation Regulation (CAR) 593 . Pursuant to CAR 605.84 and the further details of CAR Standard 625, Appendix H , the continuing airworthiness of a Canadian registered aircraft is contingent upon compliance with all applicable ADs. Failure to comply with the requirements of an AD may invalidat e the flight authorization of the aircraft. Alternative means of compliance shall be applied for in accordance with CAR 605.84 and the above-referenced Standard

. This AD has been issued by the Continuing Airworthiness Division (AARDG), Aircraft Certification Branch, Transport Canada, Otta wa, telephone 613 952-4357.

Pursuant to CAR 202.51 the registered owner of a Canadian aircraft shall, within seven days, notify the Minister in writing of any change of his or her name or address.

To request a change of address, contact the Civil Aviation Communica tions Centre (AARC)

at Place de Ville, Ottawa, Ontario K1A 0N8 , or 1-800-305-2059

, or www.tc.gc.ca/civilaviation/communications/centre/ address.asp

24-0022 (01-2005) 

### 1/3 No

. 

### CF-2007-20R2

Issue Date 

### 6 February 2009

Number: CF-2007-20R2

Subject: Failure of Main Landing Gear Retract Actuator

Effective: 

### 9 March 2009

Revision: 

### Supersedes Airworthiness Directiv e CF-2007-20R1 issued on 11 October 2007.

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

Compliance: When indicated, unless already accomplished.

Background: Two cases of main landing gear collapse had been reported. Main landing gear collapse may result in unsafe landing of the aircraft.

Revision 1 of this directive amended the time co mpliance in paragraph C.2 (3 months in addition to 500 hours air time), to add new paragraph C.3 to cater for retract actuator which has accumulated less than 4,000 landings or 2 y ears since new and to add new paragraphs B.2 and C.4 to require that the respective inspecti ons be repetitively perform ed until terminating action

becomes available.

Revision 2 of this directive am ends the detailed visual inspecti on requirement in paragraph C.3 to include the main landinggear retract actuator , part number 46550-11, and to add new paragraph F to mandate the incorporation of main landing gear retract actuator part number, 46550-13 as the terminating action and to add new paragraph G for the maintenance requirement.

Corrective

Actions: A. 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

For all aircraft, before further flight after the effect ive date of the original issue of this directive (12 September 2007), perform a general visual inspection of the left hand and right hand main landing gear system in accordance wi th 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). Rectify any discrepancy found prior to further flight.

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

1. For all aircraft, before further flight after t he effective date of the or iginal issue of this directive (12 September 2007), perform a gener al 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, prior to further flight, accomplish Bombardier R epair Drawing (RD) 8/4- 32-059, Issue 5, or later approved revision.

2. Subsequently, at intervals not to exceed 250 landings, or one month from the previous inspection, whichever occurs first, repeat the 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 lo ck is not in place or the jam nut is not secured, prior to further flight, re-torque the jam nut and safety lockwire in accordance with Bombardier RD 8/4-32-059, Issue 5, or later approved revision.No.

N ° 

### CF-2007-20R2 2/3

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



### 1. F or aircraft main landing gear retract ac tuator (p/n 46550-7 or 46550-9) that have accumulated 8,000 or more landings, or more than 4 years in service since new, at the effective date of the origi nal issue of this directiv e (12 September 2007), perform a detailed visual inspection and any required ac tion(s) in accordance with Bombardier RD 8/4-32-059, Issue 5, or later approved revision, before further flight after the effective date of the original issue of th is directive (12 September 2007).



### 2. F or aircraft main landing gear retract ac tuator (p/n 46550-7 or 46550-9) that have accumulated between 4,000 to 7,999 landings, or between 2 to 4 years in service since new, at the effective date of the original issue of this directive (12 September 2007), perform a detailed visual inspection and any required action(s) in accordance with Bombardier RD 8/4-32-059, Iss ue 5 or later approved revision within 500 hours air time, or 3 months, whichever occurs first, after the effective date of the or iginal issue of this directive (12 September 2007).



### 3. F or aircraft main landing gear retract ac tuator (p/n 46550-7 or 46550-9) that have accumulated less than 4,000 landings, or less t han 2 years in service since new, at the effective date of the original issue of this directive ( 12 September 2007), and for aircraft main landing gear retract actuator (p/n 46550- 11), prior to retract actuator reaching 4,500 landings or 27 months in service si nce new, whichever occurs first, perform a detailed visual inspection and any required acti on(s) in accordance with Bombardier RD 8/4-32-059, Issue 5 or later approved revision.



### 4. S ubsequently, at intervals not to exceed 2, 000 landings, or one calendar year from the previous inspection, whichever occurs fi rst, repeat the detailed visual inspection and any required action(s) in accordance with Bombardier RD 8/4-32-059, Issue 5 or later approved revision.

Note : 1) Respective inspections performed in accordance with earlier issues of Bombardier RD 8/4-32-059 satisfy the requirements of this directive, paragraphs B and C.

2) If the visual inspection of the pist on (p/n 46570-1/-3) threads and thread relief

area for evidence of corrosion in acco rdance with Bombardier 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 bor escope or 10X magnification mirror.

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

Within 7 days after each inspection, report any discrepancies found dur ing any of the above inspections to Bombardier Technical Help Desk.

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

To permit the ferry of an aircraft to a loca tion where the inspection requirements of this directive can be accomplished, adhere to the following procedur es and limitations:

Flight Crew Limitations and Procedures:

1. Ferry Flight with gear extended and pinned. 2. Landing to be conducted at a minimum descent rate. 3. Minimize braking on landing. 4. Flight to be conducted per Aircraft Operating Manual (A OM) Section 4.8. 5. Essential crew only on board. 6. Flight in known or forecast icing condition is prohibited.

Maintenance Procedures:

1. Inspect the left hand and right hand main landi ng gear retract actuator jam nut to ensure the wire lock is in place and the nut is secure. 2. Perform the general visual inspections as defined in accordance with Bombardier All Operators Message No. 236 Rev A or later revisions. 3. If items 1 and 2 results are satisfactory , insert main landing gear ground lock pins and lockwire in place. 4. Ensure the nose landing gear ground lock is engaged.No.

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### CF-2007-20R2 3/3

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

1. 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 directive:

Within 500 landings or 3 months from the e ffective date of this directive, whichever occurs first, incorporate Bombardier Mods um 4-901603 to replace the affected retract actuator with a new design retract actuat or, 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.

2. For aircraft main landing gear retract actuators (p/n 46550-7 or 46550-9 or 46550-11)

that have accumulated less t han 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, incorporate Bombardier Modsum 4-901603 to replace the affected retract actuator with a new design retract actuator, p/n 46550-13. Bombardier SB 84-32-55, Revision A, dated 10 March 2008, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructi ons for incorporating Modsum 4-901603.

3. Incorporation of Modsum 4-901603 provides terminating action to the detailed visual inspection requirements of par agraph C of this directive.

Note : 1) Incorporation of Modsum 4- 901603 in accordance with Revision NC of Bombardier SB 84-32-55, dated 14 Januar y 2008, meets the requirements of paragraph F of this directive.

2) Incorporation of Modsum 4-901610 to replace the affected retract actuator with a new design retract actuator , p/n 46550-15, also satisfies the requirements of paragraph F of this directive.

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

1. Within 30 days after the effective date of this directive, amend the Transport Canada approved maintenance schedule by incor porating task numbers 320100-211 (Detailed Inspection of the Retracti on Actuator Rod End Jam Nut, Gland Nut and Actuator Attachment Pins for Condition, Securi ty of Installation and Corrosion) and 320100-212 (Restoration of the Retraction Actuator fo r Complete Overhaul) as introduced by the Temporary Revision (TR) MRB–35 of the DHC-8 Series 400 Maintenance Requirements Manual, PSM 1-84-7.

2. Incorporation of maintenance task numbers 320100-211 and 320100-212 provides terminating action to the general visual ins pection requirements of paragraph B of this

directive.

Authorization: For Minister of Transport, Infrastructure and Communities

D. Ferguson A/Chief, Continuing Airworthiness

Contact: Mr. Anthony Wan, Continuing Airworthine ss, Ottawa, telephone 613-952-4410, facsimile 613-996- 9178 or e-mail wana@tc.gc.ca or any Transport Canada Centre.