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AD Number: CF-2014-45

Issue Date: 23 December 2014

AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your name. ADs are issued pursuant to Canadian Aviation 

Regulation (CAR) 521 Division X. 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 invalidate 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), National Aircraft Certification Branch, Transport Canada, Ottawa, telephone 613 952-4357.

Number: CF-2014-45 Effective Date: 7 January 2015

ATA: 54 Type Certificate: A-142

Subject: Nacelle – A-Frame Structure – Insufficient Fillet Radius and Fouling with Main Landing 

Gear Stabilizer Brace and the Electrical Wiring Harnesses

Applicability: Bombardier Inc. model DHC-8-400, -401 and -402 aeroplanes, serial numbers 4001 

through 4431.

Compliance: As indicated below, unless already accomplished.

Background: The aeroplane manufacturer has discovered that an insufficient fillet radius may exist on 

the flange of the nacelle A-frame structure on certain aeroplanes. There have also been 

several in-service reports of chafing damage on the main landing gear (MLG) stabilizer 

brace, the nacelle A-frame structure and its adjacent electrical wiring harnesses due to 

insufficient clearance.

An insufficient fillet radius and chafing damage on the nacelle A-frame structure and MLG 

stabilizer brace could lead to premature cracking. Fracture of the nacelle A-frame 

structure or failure of the MLG stabilizer brace could adversely affect the safe landing of 

the aeroplane. The damage to the electrical wiring harnesses could result in the loss of 

the MLG downlock indication.

This AD mandates the inspection and rework of the nacelle A-frame structure, and the 

rework of the forward MLG stabilizer brace assembly and the electrical harnesses in the 

nacelle area adjacent to the A-frame structure.

Corrective Actions:

Part I – Inspection, Rework, and Reversal of Fasteners on the Nacelle A-Frame 

Structure - Applicable to aeroplane serial numbers 4001 through 4055:

A. Within 600 hours air time or 100 days, whichever occurs first, from the effective date of 

this AD, inspect and rectify, as required, the left hand (LH) side and right hand (RH) 

side nacelle A-frame structure in accordance with the Accomplishment Instructions in 

Bombardier Service Bulletin (SB) 84-54-19, Initial Issue, dated 18 April 2013, or later 

revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

If any cracks are found, contact the Q-Series Technical Help Desk for an approved 

repair and incorporate the repair before further flight. The approved repair must 

specifically reference this AD.

B. Within 6000 hours air time or 36 months, whichever occurs first, from the effective 

date of this AD, rework the LH side and RH side nacelle A-frame structure in 

accordance with the Accomplishment Instructions in Bombardier SB 84-54-21, 

Initial Issue, dated 9 May 2013, or later revisions approved by the Chief, Continuing 

Airworthiness, Transport Canada.

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. 

For all changes to your mailing address, contact your TC Regional Aircraft Registration Office at 1-800-305-2059,

option 1 for English, 2 for Aircraft Registration and then select the appropriate region.

24-0022 (01-2005)
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If any of the following conditions are found, contact the Q Series Technical Help Desk 

for an approved disposition/repair and incorporate the disposition/repair, as required, 

before further flight:

1. A clearance of less than 2.54mm (0.100in) exists between the fasteners/A-frame 

structure and the MLG stabilizer brace assembly in the retracted position, after the 

rework is accomplished; or

2. A fouling condition exists during the extension of the MLG after the rework is 

accomplished.

The approved disposition/repair must specifically reference this AD.

Incorporation of Bombardier Modsum IS4Q5450002 also meets the requirements of 

Part I, paragraph B of this AD.

Part II – Inspection and Rework of the Nacelle A-Frame Structure - Applicable to 

aeroplane serial numbers 4056 through 4426:

A. Initial Inspection:

Within 600 hours air time or 100 days, whichever occurs first, from the effective date 

of this AD, perform a detailed visual inspection (DVI) of the LH side and RH side 

nacelle A-frame structure and upper surface of the MLG stabilizer brace lug in 

accordance with the Accomplishment Instructions in Part A of Bombardier 

SB 84-54-20, Revision B, dated 2 October 2014, or later revisions approved by the 

Chief, Continuing Airworthiness, Transport Canada.

1. If any damage is found, contact the Q Series Technical Help Desk for an 

approved disposition/repair and incorporate the disposition/repair, before further 

flight. The approved disposition/repair must specifically reference this AD.

2. If no damage is found, proceed to Part II, paragraph B of this AD.

B. Repetitive Inspections:

Subsequently, at intervals not to exceed 600 hours air time, repeat the DVI specified 

in Part II, paragraph A, of this AD until Part II, paragraph C of this AD is accomplished.

C. Terminating Action to the Inspections in Part II of this AD:

Within 6000 hours air time, or 36 months, whichever occurs first, from the effective 

date of this AD, rework the LH side and RH side nacelle A-frame structure in 

accordance with the Accomplishment Instructions in Part B of Bombardier 

SB 84-54-20, Revision B, dated 2 October 2014, or later revisions approved by the 

Chief, Continuing Airworthiness, Transport Canada.

If any of the following conditions are found, contact the Q Series Technical Help Desk

for an approved disposition/repair and incorporate the disposition/repair, as required, 

before further flight:

1. Any cracks found on the nacelle A-frame structure; or

2. A clearance of less than 2.54mm (0.100in) exists between the A-frame structure 

and the MLG stabilizer brace assembly in the retracted position, after the rework is 

accomplished.

The approved disposition/repair must specifically reference this AD.
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Rework of the LH side and RH side nacelle A-frame structure in accordance with the 

Initial Issue or Revision A of Bombardier SB 84-54-20, dated 25 April 2013 and 

9 April 2014, respectively, prior to the effective date of this AD, also meets the 

requirements of Part II, paragraph C of this AD.

Incorporation of Bombardier ModSum IS4Q5450003 also meets the requirements of 

Part II, paragraph C of this AD.

Rework of the LH side and RH side nacelle A-frame structure in accordance with Part II, 

paragraph C of this AD, constitutes terminating action to the inspections in Part II, 

paragraphs A and B of this AD.

Part III – Modification of the MLG Stabilizer Brace Assembly – Applicable to 

Aeroplane Serial Numbers 4001 through 4431 with MLG Stabilizer Brace Assembly 

Part Number 46400-27 installed:

Within 6000 hours air time, or 36 months, whichever occurs first, from the effective date of 

this AD, incorporate Bombardier Modsum 4-902416. Bombardier SB 84-32-112, 

Revision B, dated 12 September 2014, or later revisions approved by the Chief, 

Continuing Airworthiness, Transport Canada, provides approved instructions for 

incorporating Modsum 4-902416.

Incorporation of Modsum 4-902416 in accordance with the Initial Issue or Revision A of 

Bombardier SB 84-32-112, dated 20 December 2012, and 16 April 2014, respectively, 

prior to the effective date of this AD, also meets the requirements of Part III of this AD.

Part IV – Rework of the Electrical Wiring Harnesses in the Nacelle Area Adjacent to 

the A-Frame Structure – Applicable to Aeroplane Serial Numbers 4001 through 

4411:

Within 6000 hours air time, or 36 months, whichever occurs first, from the effective date of 

this AD, rework the LH side and RH side electrical wiring harnesses in accordance with

Bombardier SB 84-32-114, Revision A, dated 18 September 2013, or later revisions 

approved by the Chief, Continuing Airworthiness, Transport Canada.

If any damage is found on the A-frame structure or MLG stabilizer brace, contact the 

Q Series Technical Help Desk for an approved repair and incorporate the repair before 

further flight. The approved repair must specifically reference this AD.

Rework of the LH side and RH side electrical wiring harnesses in accordance with the 

Initial Issue of SB 84-32-114, dated 6 June 2013, prior to the effective date of this AD, 

also meets the requirements of Part IV of this AD.

Incorporation of Bombardier Modsums IS4Q2400028 or IS4Q2400029, as applicable, 

also meets the requirements of Part IV of this AD.

Authorization: For the Minister of Transport, 

ORIGINAL SIGNED BY

Derek Ferguson

Chief, Continuing Airworthiness

Contact: Robert Farinas, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 

613-996-9178 or e-mail AD-CN@tc.gc.ca or any Transport Canada Centre.