AIRWORTHINESS DIRECTIVE

CAA-AD-T-004/1999R4

Supersedes CAA-AD-T-004/1999R3

Date of issue: March 08, 2001

HELICOPTER - TAILBOOM SKIN - INSPECTION

Applicability: Applies to the following Bell Helicopter Textron Canada (BHTC) Model 206L series helicopters: 

(i) 206L            S/N 45004 through 45049, 45051 through 45153, and 46601 through 46617;

  (ii) 206L-1        S/N 45154 through 45790;

  (iii) 206L-3       S/N 51001 through 51612;

  (iv) 206L-4       S/N 52001 through 52163, 52165 through 522l2, and 52214 through 52216.
  (v) 206L-4T     ALL S/N.

Effective date: Upon receipt.

Compliance : Required as indicated in TC AD CF-1998-42R4.

Remarks:. The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel: 420 2 33320922, fax: 420 2 20562270

Ing. Pavel MATOUŠEK
Director of Airworthiness Division
CAA CZ

CF-1998-42R3 BELL

Subject: Bell 206L-Cracked Tail Boom Skin

Effective: 31 March 1999 (the effective date of Airworthiness Directives (AD) CF-98-42R1/R2 and CF-1998-42R3).

Revision: Supersedes AD CF-1998-42R3 issued 17 February 2000.

Applicability: the following Bell Helicopter Textron Canada (BHTC) Model 206L helicopters:

  (i) 206L            S/N 45004 through 45049, 45051 through 45153, and 46601 through 46617;

  (ii) 206L-1        S/N 45154 through 45790;

  (iii) 206L-3       S/N 51001 through 51612;

  (iv) 206L-4       S/N 52001 through 52163, 52165 through 522l2, and 52214 through 52216.

Compliance: When indicated, unless already accomplished.

Background: There have been at least seven reports of cracks to the tail boom skin in the area of the horizontal stabilizer. The cracks were found by normal visual inspection. The average time accumulated on the tail booms was more than 2000 hours; however, cracks could develop at any time. A review of crack growth rates after Airworthiness Directive (AD) CF-98-42 was issued indicated a need to detect cracks earlier. This necessitated the use of non destructive inspections of the tail boom skin under the support plates. As an interim measure, these inspections were mandated by CF-9842R1.   CF-98-42R2mandated Alert Service Bulletin (ASB) 206L-99-115 Revision A, which introduced the reinforcement of the tail boom skin around the left horizontal stabilizer cutout, together with instructions for improved installation of the horizontal stabilizer and its supports. Accomplishment of ASB 206L-99-115 Revision A constituted terminating action to ASB 206L-98-114 as mandated by CF-98-42R1. CF-1998-42R3 clarified the applicability of Model 206L serial numbers and extended the compliance time for paragraph 6 to December 2000.

This revision extends the compliance time for paragraph 6 to 31 March 2001, or later compliance date specified in subsequent Transport Canada approved revisions of ASB 206L-99-115.

Corrective Actions:

1.  Initially, before the next flight after the effective date of this directive, perform a visual inspection of the tail

boom in accordance with Bell Helicopter Textron (BHT) Alert Service Bulletin (ASB) 206L-98-114, or its Revision A dated 31 January 2000 or later revisions approved by the Director, Aircraft Certification, Transport Canada.

2. Within 50 hours air time after the effective date of this directive:

  (a) Remove the upper and lower supports of the horizontal stabilizer in accordance with the applicable sections of the Maintenance Manual.

  (b) In accordance with section 6.2 of Standard Practices Manual BHT-ALL-SPM, perform a one-time fluorescent penetrant inspection of the tail boom skin in the area at least 0.75 inch around the edges of the horizontal stabilizer openings.

3.  Subsequently, before the first flight of each day perform a visual inspection of the tail boom in accordance with the above noted ASB 206L-98-114 Revision A.

 

Note: While away from technical support, this visual check may be done by pilots as part of the Preflight Check. To exercise this option, pilots must first be trained by a technician on the requirements of ASB 206L-98-114 Revision A, Figure l.

 

4.  Within every l00 hours air time, remove the support plates and visually inspect for cracks the entire edge of the horizontal stabilizer opening on both sides of the tail boom, using a 10X magnifying glass.

5.  If a crack is found on the tail boom skin as a result of one of the above inspections, replace the tail boom before the next flight. Report findings to Transport Canada, Continuing Airworthiness Division (AARDG) at facsimile (613) 996-9178 by use of a Service Difficulty Report form, and to Bell Helicopter Textron Canada - Product Support Engineering at facsimile (450) 433-0272.

6. No later than 31 March 2001, modify the tail boom in accordance with Parts I, II and III of BHT ASB 206L-99-1l5 Revision E, dated 19 December 2000, or later Transport Canada approved revisions. If a compliance date other than 31 March 2001 is specified in subsequent approved revisions to BHCT ASB 206L-99-115, that date shall supersede the 31 March 2001 date specified in this AD. Installation of the doubler terminates all actions required by paragraphs 1 through 5 of this directive.

Authorisation: For Minister of Transport

B. Goyaniuk

Chief, Continuing Airworthiness

Contact: Mr. Luc Deniger, Continuing Airworthiness, Ottawa, telephone (613) 952-5385, facsimile (613) 996-9l78 or e-mail denigel@tc.gc.ca or any Transport Canada Centre.