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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-SW-68-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 Eurocopter Canada Ltd. Model BO 105 LS A-3 helicopters. That AD currently requires, before further flight, creating a component log card or equivalent record, and determining the calendar age and number of flights on each tension-torsion (TT) strap, and inspecting and removing, as necessary, certain unairworthy TT straps. This action would establish a life limit for certain main rotor TT straps. This proposal is prompted by an accident in which a main rotor blade (blade) separated from a Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 helicopter due to fatigue failure of a TT strap. The same part-numbered TT strap is used on the Model BO 105 LS A-3 helicopters. The actions specified by this AD are intended to prevent fatigue failure of a TT strap, loss of a blade, and subsequent loss of control of the helicopter. 

# DATES:

Comments must be received on or before August 18, 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-68-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: 9-asw-adcomments@faa.gov. Comments may be inspected at the Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

# FOR FURTHER INFORMATION CONTACT:

Charles Harrison, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, Fort Worth, Texas 76193-0110, telephone (817) 222-5128, 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 mailed comments 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-68-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-68-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. 

## Discussion 

                    On October 4, 1999, the FAA issued AD 99-20-13, Amendment 39-11371 (64 FR 56156, October 18, 1999), applicable to Eurocopter Canada Ltd. Model BO 105 LS A-3 helicopters. That AD requires, before further flight, creating a component log card or                           ( print page 37925)                        equivalent record and determining the calendar age and number of flights on each TT strap. AD 99-20-13 also requires inspecting and removing, as necessary, certain unairworthy TT straps. That action was prompted by an accident in which a blade separated from an ECD Model MBB-BK 117 helicopter due to fatigue failure of a TT strap. The same part-numbered TT strap is also used on the Eurocopter Canada Ltd. Model BO 105 LS A-3 helicopters. The requirements of that AD are intended to prevent failure of a TT strap, loss of a blade, and subsequent loss of control of the helicopter.                 

Since the issuance of that AD, we have determined the need to establish a life limit for the TT strap. We have also determined that the graduated inspection criteria and TT strap lives specified in the current AD are no longer necessary after a life limit is established. 

Eurocopter Canada issued Alert Service Bulletin BO 105 LS A-3 No. ASB-BO 105 LS-10-10, dated September 1, 1999 (ASB). The ASB describes procedures for determining the total accumulated installation time and number of flights on each TT strap. The ASB also specifies inspecting and replacing, as necessary, certain unairworthy TT straps. Transport Canada Civil Aviation, the airworthiness authority for Canada, classified this ASB as mandatory and issued AD CF-99-24R1, dated September 22, 1999, applicable to the Eurocopter Canada Model BO 105 LS A-3 helicopters to ensure the continued airworthiness of these helicopters in Canada. 

Since an unsafe condition has been identified on the ECD Model MBB-BK-117 that is likely to exist or develop on Eurocopter Canada Ltd., Model BO 105 LS A-3 helicopters registered in the United States, the proposed AD would require establishing a life limit for the TT straps of 120 months or 25,000 flights, whichever occurs first. 

The FAA estimates that 20 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 16 work hours per helicopter to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $10,400 per helicopter. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $227,200. 

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 does 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 39-11371 (64 FR 56156, October 18, 1999), and by adding a new airworthiness directive (AD), to read as follows: 

**Eurocopter Canada Ltd.:**                                 Docket No. 99-SW-68-AD. Supersedes AD 99-20-13, Amendment 39-11371, Docket No. 99-SW-56-AD.                             

*Applicability:*                                 Model BO 105 LS A-3 helicopters, with part number (P/N) 2604067 (Bendix) or J17322-1 (Lord) rotor tension torsion (TT) strap, 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 (d) 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 been eliminated, the request should include specific proposed actions to address it.

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

To prevent fatigue failure of a TT strap, loss of a main rotor blade (blade), and subsequent loss of control of the helicopter, accomplish the following: 

(a) Before further flight, 

(1) Create a component log card or equivalent record for each TT strap. 

(2) Review the history of each helicopter and TT strap. Determine the age since initial installation on any helicopter (age) and the number of flights on each TT strap. Enter both the age and the number of flights for each TT strap on the component log card or equivalent record. When the number of flights is unknown, multiply the number of hours time-in-service (TIS) by 5 to determine the number of flights. If a TT strap has been previously used at any time on Model BO-105LS A-3 “SUPER LIFTER”, BO-105 CB-5, BO-105 CBS-5, BO-105 DBS-5, or any MBB-BK 117 series helicopter, multiply the total number of flights accumulated on those other models by a factor of 1.6 and then add that result to the number of flights accumulated on the helicopters affected by this AD. 

(3) Remove any TT strap from service if the total hours TIS or number of flights and age cannot be determined. 

(b) Remove any TT strap, P/N 2604067 or J17322-1, that has been in service 120 months since initial installation on any helicopter or accumulated 40,000 flights (a flight is a takeoff and a landing). Replace the TT strap with an airworthy TT strap. 

(c) This AD revises the Airworthiness Limitations Section of the maintenance manual by establishing a life limit for the TT strap, P/N 2604067 and J17322-1, of 120 months or 40,000 flights, whichever occurs first. 

(d) 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.

(e) Special flight permits may be issued in accordance with §  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. 

# Note 3:

The subject of this AD is addressed in Transport Canada Civil Aviation, Canada, AD CF-99-24R1, dated September 22, 1999.

      ( print page 37926)    
Issued in Fort Worth, Texas, on June 9, 2000. 

Eric Bries, 

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. 

[FR Doc. 00-15425 Filed 6-16-00; 8:45 am] 

BILLING CODE 4910-13-U