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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-405-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes. This proposal would require an inspection to determine the serial numbers of geared rotary actuators (GRA) for the leading edge slats, and replacement of certain actuators with new or reworked actuators. This action is necessary to prevent a fractured spring washer in a GRA, which could lead to a disconnect in the GRA, and result in a slat skew condition and consequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition. 

      ( print page 26820)    

# DATES:

Comments must be received by June 29, 2001. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-405-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-405-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text. 

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. 

# FOR FURTHER INFORMATION CONTACT:

Barbara Mudrovich, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2983; fax (425) 227-1181. 

# 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 shall 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 action may be changed in light of the comments received. 

Submit comments using the following format: 
    - Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
    - For each issue, state what specific change to the proposed AD is being requested.
    - Include justification (e.g., reasons or data) for each request.

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 submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-405-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, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-405-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

The FAA has received reports indicating that certain geared rotary actuators (GRA) for the leading edge slats on certain Boeing Model 757 series airplanes have been assembled with discrepant spring washers. The discrepant spring washers were not adequately processed during the phase of manufacture in which cadmium plating is applied. A fractured spring washer could lead to a disconnect between the input shaft or input plate and the output plate or splined gearshaft, which could result in a skew condition for the leading edge slat if one of the two actuators on each slat continues to drive the slat. The serial numbers of all affected GRAs are known. 

Certain airplanes have had an enhanced slat skew or loss detection system installed either during production or according to Boeing Service Bulletin 757-27-0126, dated May 11, 2000. For these airplanes, a slat skew condition is not an airworthiness concern. 

However, for airplanes without an enhanced slat skew or loss detection system, a slat skew condition, if not detected by the flight crew, could result in reduced controllability of the airplane. 

## Explanation of Relevant Service Information 

The FAA has reviewed and approved Boeing Alert Service Bulletins 757-27A0133 (for Model 757-200, 757-200CB, and 757-200PF series airplanes) and 757-27A0134 (for Model 757-300 series airplanes), both dated October 11, 2000. Those service bulletins describe procedures for a one-time inspection to determine the serial numbers of GRAs for the leading edge slats. If GRAs with certain serial numbers are installed, the service bulletin describes procedures for replacing affected GRAs with new or reworked parts. Accomplishment of the actions specified in the applicable service bulletin is intended to adequately address the identified unsafe condition. 

The Boeing service bulletins refer to Hamilton Sundstrand Service Bulletins 5006397/755299-27-21 and 5006398/755300-27-21, both dated January 24, 2000, as sources for the identification of affected part numbers and serial numbers, as well as instructions for reworking affected GRAs. 

## Explanation of Requirements of Proposed Rule 

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the applicable Boeing service bulletin described previously. 

## Explanation of Applicability 

While only certain Boeing Model 757 series airplanes had the GRAs with the discrepant spring washers installed in production, it is possible that the affected GRAs have been installed as spares on other Boeing Model 757 series airplanes. Therefore, the FAA finds that the unsafe condition addressed by this proposed AD may occur on any Boeing Model 757 series airplane manufactured on or prior to the effective date of this AD. However, paragraph (d) of this AD prohibits installation of the affected parts after the effective date of this AD; thus, airplanes with a date of manufacture after the effective date of this AD would not be subject to this proposed AD. 

## Cost Impact 

                    There are approximately 950 airplanes of the affected design in the worldwide fleet. The FAA estimates that 606 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 20 work hours per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $727,200, or $1,200 per airplane.                           ( print page 26821)    

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. 

Should an operator be required to accomplish the replacement of all GRAs on an airplane, it would take approximately 30 work hours per airplane (1.5 work hours per actuator), at an average labor rate of $60 per work hour. Required parts may be provided by the parts manufacturer at no cost to the operator. Based on these figures, the cost impact of the proposed replacement is estimated to be up to $1,800 per airplane. 

## Regulatory Impact 

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 adding the following new airworthiness directive: 

**Boeing:**                                 Docket 2000-NM-405-AD.                             

*Applicability:*                                 Model 757 series airplanes with a date of manufacture that is on or before the effective date of this AD, certificated in any category.                             

# Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes 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 (e) 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 fractured spring washer in a geared rotary actuator (GRA) for the leading edge slats, which could lead to a disconnect in the GRA, and result in a slat skew condition and consequent reduced controllability of the airplane, accomplish the following: 

## Inspection To Determine Serial Numbers 

(a) At the applicable compliance time specified in paragraph (a)(1) or (a)(2) of this AD, inspect the 20 geared rotary actuators (GRA) for the leading edge slats to determine the part number series and serial number for each GRA, according to Boeing Alert Service Bulletin 757-27A0133 (for Model 757-200, 757-200CB, and 757-200PF series airplanes), or 757-27A0134 (for Model 757-300 series airplanes), both dated October 11, 2000; as applicable. 

(1) For Boeing 757-200 series airplanes with line numbers (L/N) 1 through 803, on which an enhanced slat skew or loss detection system has NOT been installed according to Boeing Service Bulletin 757-27-0126, dated May 11, 2000, or Boeing Production Revision Record 54755: Do the inspection within 18 months after the effective date of this AD. 

(2) For airplanes other than those identified in paragraph (a)(1) of this AD: Do the inspection within 36 months after the effective date of this AD. 

## If No Subject GRA Is Installed—No Further Action 

(b) If no GRA has a part number series and serial number listed under Section 1.A. of Hamilton Sundstrand Service Bulletins 5006397/755299-27-21 or 5006398/755300-27-21, both dated January 24, 2000: No further action is required by this AD. 

## If Any Subject GRAs Are Installed—Corrective Actions 

(c) For any GRA with a part number series and serial number listed under Section 1.A. of Hamilton Sundstrand Service Bulletins 5006397/755299-27-21 or 5006398/755300-27-21, both dated January 24, 2000: At the applicable compliance time specified in paragraph (c)(1) or (c)(2) of this AD, replace the subject GRA with a new or reworked GRA, according to Boeing Alert Service Bulletin 757-27A0133 (for Model 757-200, 757-200CB, and 757-200PF series airplanes), or 757-27A0134 (for Model 757-300 series airplanes), both dated October 11, 2000; as applicable. 

(1) For Boeing 757-200 series airplanes with line numbers (L/N) 1 through 803, on which an enhanced slat skew or loss detection system has NOT been installed according to Boeing Service Bulletin 757-27-0126, dated May 11, 2000, or Boeing Production Revision Record 54755: Replace any subject GRA within 18 months after the effective date of this AD. 

(2) For airplanes other than those identified in paragraph (c)(1) of this AD: Replace any subject GRA within 36 months after the effective date of this AD. 

## Spares 

(d) After the effective date of this AD, no one may install a GRA that has a part number series and serial number listed under Section 1.A. of Hamilton Sundstrand Service Bulletins 5006397/755299-27-21 or 5006398/755300-27-21, both dated January 24, 2000, on any airplane. 

## Alternative Methods of Compliance 

(e) 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, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. 

# Note 2:

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

## Special Flight Permits 

(f) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. 

      ( print page 26822)    
Issued in Renton, Washington, on May 9, 2001. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-12174 Filed 5-14-01; 8:45 am] 

BILLING CODE 4910-13-P