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) 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 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), 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-1990-06R1

Issue Date 

07 January 2008 

Number: CF-1990-06R1 

Subject: Tail Rotor Pitch Change Chain 

Effective: 24 January 2008 

Revision: Supersedes Airworthiness Directive CF-90-06. 

Replacement: Supersedes FAA Airworthiness Directive 76-12-07 for Model 204B. 

Applicability: Bell Helicopter Textron Inc., (BHT) Model 204B helicopters equipped with tail rotor 

pitch change chain (silent chain) P/N 204-001-739-003, 204-001-739-105 and 

205-001-721-001. 

Compliance: As indicated unless already accomplished. 

Background: There have been two accidents attributed to the in-flight failure of the tail rotor pitch change 

chain. In both cases, cracks originated at the center of a link within the pitch change chain. 

An in-situ check of the chain has shown not to be reliable in detecting cracking of the chain. 

This revision extends applicability to chains of newer part numbers. 

Corrective 

Actions: 

Part A 

At every 100-hour scheduled inspection: 

1. Remove and clean the chain in accordance with instructions provided in 

BHT-204B-M&O-1, Maintenance and Overhaul Instructions, Revision 3 dated 

7 April 2006. 

2. Inspect for cracks in the link segments using a 10-power or higher magnifying glass and 

a bright light. Particular attention should be placed to the links of the chain that travel 

over the sprocket and six inches each side of this portion. 

Remove from service chains with cracked or broken links or segments before further 

flight. Install airworthy chains in accordance with the applicable maintenance manual; 

lubricate and rig the controls as specified in the applicable maintenance manual. 

Part B 

At every 25 hours, not coinciding with Part A inspections: 

1. Remove the cover from the chain assembly. 
No.

 N° CF-1990-06R1 2/2 

2. Inspect for cracks in the link segments using a 10-power or higher magnifying glass and 

a bright light. Particular attention should be placed to the links of the chain that travel 

over the sprocket and six inches each side of this portion. 

Remove from service chains with cracked or broken links or segments before further 

flight. Install airworthy chains in accordance with the applicable maintenance manual; 

lubricate and rig the controls as specified in the applicable maintenance manual. 

Authorization: For Minister of Transport, Infrastructure and Communities 

P. Tang 

Acting Chief, Continuing Airworthiness 

Contact: Mr. Bogdan Gajewski, Continuing Airworthiness, Ottawa, telephone 613-952-4450, facsimile 

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