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 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.

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 Communications 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)

1/2 No.

CF-2012-02R1

Issue Date 

 12 October 2012 

Number: CF-2012-02R1 

Subject: Rudder Control System – Seizure of the Rudder Feel Trim Unit 

Revision: 

Effective: 

Supersedes Airworthiness Directive CF-2012-02, dated 23 January 2012 

26 October 2012 

Applicability: Bombardier Inc. DHC-8 aeroplanes models 400, 401 and 402, serial numbers (S/N)

4001, 4003 and subsequent, equipped with Rudder Feel Trim Unit (RFTU) part 

number (P/N) 399500-1007, serial numbers 0008 through 0509, including serial 

numbers with the suffix “A”. 

Compliance: As indicated below, unless already accomplished. 

Background: There have been several reported incidents on DHC-8 Series 400 aeroplanes where the 

movement of the rudder pedals have been impeded. An investigation showed that the 

Rudder Feel Trim Unit (RFTU) trunnion shaft was corroded. The root cause of the 

corrosion was a quality escape where cadmium plating on the trunnion bushing was not 

removed. Corrosion in the trunnion bushing seized the trunnion and caused difficulties in 

controlling the rudder movement. 

This condition, if not corrected, could cause a rudder control jam or a large and rapid 

alternating rudder input leading to a structural failure of the vertical fin. 

This AD is issued to replace the affected RFTUs to limit the possibility of binding and 

replace the affected RFTUs with units that have been reworked with conformal bushings 

to terminate the lubrication requirements. 

This AD was revised to expand the applicability and revise compliance times. 

Corrective 

Actions: 

A. Within 200 hours air time or 2 months, whichever occurs first, from the effective date 

of this AD, inspect the S/N of the RFTU in accordance with the Accomplishment 

Instructions of Bombardier Aerospace Service Bulletin (SB) 84-27-60, dated 

12 July 2012, or later revisions approved by the Chief, Continuing Airworthiness, 

Transport Canada. 

1. If the RFTU’s S/N is not in the range from 0008 thru 0509 or if the S/N has a 

suffix “B”, no further action is required. 

Note: Inspection of the RFTU serial number may be conducted visually on the 

aeroplane or by checking the maintenance records. 

2. If the RFTU’s S/N is in the range from 0008 thru 0509, including those with a 

suffix “A”, perform an operational check of the RFTU for any sign of rough 
No.

N° CF-2012-02R1 2/2 

movement or seizure of the trunnion and centre shaft in accordance with the 

Accomplishment Instructions, Paragraph 3.B, Part A of the above mentioned SB.

a. If rough movement or seizure of the RFTU trunnion and centre shaft is found, 

before further flight, replace the RFTU in accordance with the 

Accomplishment Instructions, Paragraph 3.B, Part B, of the above mentioned 

SB. 

b. If no rough movement or seizure of the RFTU trunnion and centre shaft is 

found, lubricate the RFTU in accordance with the Accomplishment 

Instructions, Paragraph 3.B, Part C of the above mentioned SB. Repeat the 

lubrication of the RFTU at intervals not to exceed 600 hours air time, or 3 

months, whichever occurs first until the RFTU is replaced with a unit that has 

a S/N outside of the affected range or a S/N with the suffix “B”. 

B. Within 5000 hours air time or 3 years, whichever occurs first, from the effective date 

of this AD, replace all affected RFTUs with units that have a S/N outside of the 

affected range or a S/N with the suffix “B” in accordance with the Accomplishment 

Instructions, Paragraph 3.B, Part B of the above mentioned SB. 

C. As of the effective date of this AD, no person shall install a RFTU P/N 399500-1007 

with S/N from 0008 thru 0509, including S/N with suffix “A” on an aeroplane. 

Authorization: For the Minister of Transport, Infrastructure and Communities 

ORIGINAL SIGNED BY

Robin Lau 

Acting Chief, Continuing Airworthiness 

Contact: Gordanko Jeremic, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 

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