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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-SW-67-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes adopting a new airworthiness directive (AD) for Robinson Helicopter Company (RHC) Model R44 helicopters. This proposal would require establishing a life limit of 2200 hours time-in-service (TIS) for affected horizontal stabilizers. This proposal is prompted by engineering analysis, which indicates that certain vertical-to-horizontal stabilizer attach channels (channels) will crack sooner than the original life limit of the horizontal stabilizer. The actions specified by the proposed AD are intended to prevent a crack through a channel, separation of the stabilizers, and subsequent loss of directional control of the helicopter. 

# DATES:

The FAA must receive any comments on this proposal by August 24, 2001.

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-67-AD, 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:

Fred Guerin, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5232, fax (562) 627-5210. 

# 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 will be considered before taking action on the proposed rule. The proposals contained in this document 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 proposal must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2000-SW-67-AD.” The postcard will be date stamped and returned to the commenter. 

## Discussion 

This document proposes adopting a new AD for RHC Model R44 helicopters to require establishing a life limit of 2200 hours TIS for affected horizontal stabilizers and removing, inspecting, and replacing certain channels with airworthy channels. This proposal is prompted by engineering analysis which indicates that a fatigue crack may develop through the inboard attachment hole for the nutplate, part number (P/N) NAS697A4, on channels, P/N D283-1 and -2, sooner than the original life limit of 4,000 hours TIS. This condition, if not corrected, could result in a fatigue crack on the channels, P/N D283-1 and -2, that attach the vertical and horizontal stabilizers, separation of the vertical and horizontal stabilizers after 2200 hours TIS, and subsequent loss of directional control of the helicopter. 

The FAA has reviewed RHC Service Bulletin No. SB-39, dated September 12, 2000 (SB), which specifies replacing affected channels during overhaul at 2200 hours TIS. The FAA agrees that channels, P/N D283, with nutplate, P/N NAS697A4, are considered unairworthy after 2200 hours TIS. 

We have identified an unsafe condition that is likely to exist or develop on other RHC Model R44 helicopters of these same type designs. The proposed AD would require the following before 2200 hours TIS:
    - Removing the vertical stabilizer to inspect the nutplate on channels, P/N D283-1 and -2.
    - Replacing channels installed with nutplate, P/N NAS697A4, with channels, P/N D296-1 and -2.

This proposal would revise the Limitations section of the maintenance manual by establishing a life limit of 2200 hours TIS for stabilizer, P/N CO44-1, with channels, P/N D283-1 or -2, installed. 

## Regulatory Impact 

                    We estimate that 3 helicopters of U.S. registry would be affected by this proposed AD and that it would take approximately                     1/2                     work hour per helicopter to inspect the horizontal stabilizer and replace channels. The average labor rate is $60 per work hour. The manufacturer states in the SB that there will be no charge for the parts. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $90.                 

                    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                           ( print page 33654)                        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. You can get a copy of the draft regulatory evaluation prepared for this action from the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the mailing address listed under the caption                     **ADDRESSES.**

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Safety

## The Proposed Amendment 

Accordingly, under 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. The FAA amends § 39.13 by adding the following new airworthiness directive: 

**Robinson Helicopter Company:**                                 Docket No. 2000-SW-67-AD.                            

*Applicability:*                                 Model R44 helicopters, with horizontal stabilizer assembly (assembly), part number (P/N) C044-1; horizontal stabilizer serial number (S/N) 0009 through 0224, except S/N 0018, 0090, 0094, 0111, 0129, 0144, 0161, 0178, 0201, and 0223, 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 (c) 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 a crack through a vertical-to-horizontal stabilizer attach channel (channel), which can cause separation of the stabilizers and subsequent loss of control of the helicopter, accomplish the following: 

(a) Before accumulating 2200 hours time-in-service (TIS) on the assembly: 

(1) Remove the vertical stabilizer to inspect the nutplate on channels, P/N D283-1 and -2. 

(2) If the nutplates are P/N MS21086L4, no further action is required by this AD. 

(3) If the nutplates are P/N NAS697A4, replace the channels with airworthy channels, P/N D296-1 or -2. 

# Note 2:

Robinson Helicopter Company Service Bulletin SB-39, dated September 12, 2000, pertains to the subject of this AD.

(b) This AD revises the Limitations section of the maintenance manual by establishing a retirement life of 2200 hours TIS for assembly, P/N CO44-1, with channels, P/N D283-1 or -2, with nutplates, P/N NAS697A4, installed. 

(c) 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, Los Angeles Aircraft Certification Office (LAACO), FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, LAACO. 

# Note 3:

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

(d) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished. 

Issued in Fort Worth, Texas, on June 12, 2001. 

Eric Bries, 

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. 

[FR Doc. 01-15795 Filed 6-22-01; 8:45 am] 

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