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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-SW-80-AD] 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Bell Helicopter Textron Canada (BHTC) Model 206L, L-1, L-3, and L-4 helicopters. That AD currently requires removing the horizontal stabilizer supports and inspecting the edges of the tailboom skins around the horizontal stabilizer openings for a crack. This action would require inspecting the tailboom skins for a crack, replacing a cracked tailboom with a modified tailboom before further flight, and implementing a recurring inspection of the modified tailboom. This proposal is prompted by several additional reports of cracks found during mandatory inspections. The actions specified by the proposed AD are intended to detect a crack in the tailboom and to prevent separation of the tailboom from the helicopter and subsequent loss of control of the helicopter. 

# DATES:

Comments must be received on or before June 19, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-80-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed rule may be obtained from Bell Helicopter Textron Canada, 12,800 Rue de l'Avenir, Mirabel, Quebec JON1LO, telephone (800) 463-3036, fax (514) 433-0272. This information may be examined at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. 

# FOR FURTHER INFORMATION CONTACT:

Sharon Miles, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Regulations Group, Fort Worth, Texas 76193-0111 telephone (817) 222-5122, fax (817) 222-5961. 

# SUPPLEMENTARY INFORMATION:

 

## Comments Invited 

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. 

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. 

                    Commenters wishing the FAA to acknowledge receipt of their comments                           ( print page 20928)                        submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 99-SW-80-AD.” The postcard will be date stamped and returned to the commenter.                 

## Availability of NPRMs 

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-80-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. 

## Discussion 

On June 16, 1999, the FAA issued AD 99-13-12, Amendment 39-11207 (64 FR 33747, June 24, 1999), to require at specified time intervals visually inspecting and preflight checking for cracks around the horizontal stabilizer opening. The AD also requires within 50 hours time-in-service (TIS) removing the horizontal stabilizer supports and visually inspecting the edges of the tailboom skins around the horizontal stabilizer openings for a crack using a fluorescent-penetrant inspection. That action was prompted by crack growth analysis that indicated the need to detect cracks before they propagate from underneath the horizontal stabilizer supports. The requirements of that AD are intended to detect a crack in the tailboom skin, prevent separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter. 

Since the issuance of that AD, several additional cracks in tailbooms were found during mandatory inspections. 

Since an unsafe condition has been identified that is likely to exist or develop on other BHTC Model 206L, L-1, L-3, and L-4 helicopters of the same type design, the proposed AD would supersede AD 99-13-12 to require the following: 
    - Inspecting the tailboom skins for a crack;
    - Replacing any cracked tailboom with an airworthy modified tailboom;
    - Modifying the tailboom within the next 300 hours time-in-service (TIS) by adding a doubler on the left side of the tailboom in the area of the left horizontal stabilizer, and
    - Inspecting the modified tailboom for a crack at intervals not to exceed 1200 hours TIS.

This proposal is prompted by several additional reports of cracks found during mandatory inspections. The actions specified by the proposed AD are intended to detect a crack in the tailboom and to prevent separation of the tailboom from the helicopter and subsequent loss of control of the helicopter. 

Transport Canada, which is the airworthiness authority for Canada, has notified the FAA that an unsafe condition may exist on BHTC Model 206L, L-1, L-3, and L-4 helicopters. Transport Canada advises that cracks were found on the tailboom skins in the area of the horizontal stabilizer. 

BHTC has issued Alert Service Bulletin 206L-99-115, Revision D, dated January 26, 2000 (ASB), which specifies modifying the tailboom by adding a doubler on the left side of the tailboom in the area of the left horizontal stabilizer and inspecting the modified tailboom for a crack at intervals not to exceed 1200 hours of operation. Transport Canada classified Revision A of this ASB as mandatory and issued AD CF-98-42R2, dated July 22, 1999. Transport Canada has subsequently issued AD CF-1998-42R3, dated February 17, 2000, which extended the compliance date. 

These helicopter models are manufactured in Canada and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, Transport Canada has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada, reviewed all available information, and determined that AD action is necessary for products of these type designs that are certificated for operation in the United States. 

The FAA estimates that 1546 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 52 work hours to inspect and replace the tailbooms, if necessary, and that the average labor rate is $60 per work hour. Required parts would cost approximately $22,954 per helicopter. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $40,310,404 if all tailbooms must be replaced. 

The regulations proposed herein would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132. 

                    For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption                     **ADDRESSES.**

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Safety

## The Proposed Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: 

# PART 39—AIRWORTHINESS DIRECTIVES 

1. The authority citation for part 39 continues to read as follows: 

Authority:49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 

2. Section 39.13 is amended by removing Amendment 39-11207 (64 FR 33747, June 24, 1999), and by adding a new airworthiness directive (AD), to read as follows: 

**Bell Helicopter Textron Canada:**                                 Docket No. 99-SW-80-AD. Supersedes AD 99-13-12, Amendment 39-11207, Docket No. 99-SW-23-AD.                             

*Applicability:*                                 Model 206L, serial numbers (S/N) 45004 through 45049, 45051 through 45153, and 46601 through 46617; Model 206L-1, S/N 45154 through 45790; Model 206L-3, S/N 51001 through 51612; and Model 206L-4, S/N 52001 through 52163, 52165 through 52212, and 52214 through 52216, with tailboom, part number (P/N) 206-033-004-all dash numbers, installed, certificated in any category.                             

# Note 1:

                                    This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (g) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not                                           ( print page 20929)                                        been eliminated, the request should include specific proposed actions to address it.                                

*Compliance:*                                 Required as indicated, unless accomplished previously.                             

To detect a crack in the tailboom skin and to prevent separation of the tailboom from the helicopter and subsequent loss of control of the helicopter, accomplish the following: 

(a) Before further flight and thereafter at intervals not to exceed 10 hours time-in-service (TIS) until accomplishing the one-time fluorescent-penetrant inspection (FPI) required by paragraph (c)(2) of this AD, visually inspect for any crack in the shaded areas shown in Figure 1. Use a 10-power or higher magnifying glass. If a crack is found, replace the tailboom with an airworthy tailboom modified according to the requirements of paragraph (e) of this AD before further flight. 

(b) At intervals not to exceed 5 hours TIS, visually check for any crack in the tailboom as depicted by the shaded areas shown in Figure 1. If any crack is found, replace the tailboom with an airworthy tailboom modified according to the requirements of paragraph (e) of this AD before further flight. The visual check may be performed by an owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with paragraph (b) of this AD in accordance with sections 43.11 and 91.417 (a)(2)(v) of the Federal Aviation Regulations (14 CFR sections 43.11 and 91.417 (a)(2)(v)). 

(c) Within 50 hours TIS: 

(1) Remove all 4 horizontal stabilizer supports, P/N 206-023-100-all dash numbers, from the tailboom and the horizontal stabilizer. 

                                (2) Perform a one-time FPI of the edges of the tailboom skins for any crack around the left and right horizontal stabilizer openings (Figure 1). Remove paint and primer to inspect the edges and exterior skin surface in the skin area at least                                 3/4                                 inch around the edges of the horizontal stabilizer openings.                             

(3) If a crack is found, replace the tailboom with an airworthy tailboom modified according to the requirements of paragraph (e) of this AD before further flight. 
      ( print page 20930)          ( print page 20931)    
(d) At intervals not to exceed 100 hours TIS after completion of the FPI, accomplish the following: 

(1) Remove all 4 horizontal stabilizer supports, P/N 206-023-100-all dash numbers, from the tailboom and the horizontal stabilizer. 

(2) Visually inspect the entire edge of the horizontal stabilizer opening on both sides of the tailboom for any crack using a 10-power or higher magnifying glass. 

(3) If a crack is found, replace the tailboom with an airworthy tailboom modified according to the requirements of paragraph (e) of this AD before further flight. 

(e) Within the next 300 hours TIS, inspect and modify the tailboom in accordance with Parts I, II, and III of Bell Helicopter Textron Canada (BHTC) Alert Service Bulletin 206L-99-115, Revision D, dated January 26, 2000 (ASB). If a crack is found while accomplishing Part I of the ASB, replace the tailboom with an airworthy tailboom modified as required by this paragraph before further flight. After accomplishing the modification, inspect the modified tailboom at intervals not to exceed 1200 hours TIS in accordance with Part IV of the ASB. 

(f) Modifying and inspecting the tailboom in accordance with paragraph (e) of this AD is terminating action for the requirements of paragraphs (a) through (d) of this AD. 

(g) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Regulations Group, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Regulations Group. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Regulations Group.

(h) Special flight permits may be issued for a one-time flight, not to exceed 5 hours TIS and a maximum of one landing in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199), to operate the helicopter to a location where the requirements of this AD can be accomplished. The visual preflight check required by paragraph (b) of this AD must be accomplished prior to making a one-time flight. 

# Note 3:

The subject of this AD is addressed in Transport Canada (Canada) AD CF-98-42R3, dated February 17, 2000.

Issued in Fort Worth, Texas, on April 12, 2000. 

Henry A. Armstrong, 

Manager, Rotorcraft Directorate, Aircraft Certification Service. 

BILLING CODE 4910-13-U

BILLING CODE 4910-13-C

[FR Doc. 00-9819 Filed 4-18-00; 8:45 am] 

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