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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-250-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 all British Aerospace (Jetstream) Model 4101 airplanes. This proposal would require revising the Airworthiness Limitations Section of the Instructions for Continued Airworthiness to incorporate life limits for certain items and inspections to detect fatigue cracking in certain structures. This proposal is prompted by issuance of a revision to the airworthiness limitations of the British Aerospace J41 Aircraft Maintenance Manual. The actions specified by the proposed AD are intended to ensure that fatigue cracking of certain structural elements is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes. 

# DATES:

Comments must be received by November 20, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-250-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 99-NM-250-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 British Aerospace Regional Aircraft American Support, 13850 Mclearen Road, Herndon, Virginia 20171. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. 

# FOR FURTHER INFORMATION CONTACT:

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149. 

# 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NM-250-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. 99-NM-250-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, has notified the FAA that a revision to Section 05-10-10, “Airworthiness Limitations Description and Operation,” of the British Aerospace J41 Aircraft Maintenance Manual (AMM) has been issued. [The FAA refers to the information included in that section of the AMM as the Airworthiness Limitations Section (ALS).] This revised section affects all British Aerospace (Jetstream) Model 4101 airplanes. The section provides mandatory replacement times and structural inspection intervals approved under section 25.571 of the Joint Aviation Requirements and the Federal Aviation Regulations (14 CFR 25.571). As airplanes gain service experience, or as results of post-certification testing and evaluation are obtained, it may become necessary to add additional life limits or structural inspections to ensure the continued structural integrity of the airplane. 

                    The CAA advises that analysis of fatigue test data has revealed that certain inspections must be performed at specific intervals to preclude fatigue cracking in certain areas of the airplane. In addition, the CAA advises that certain life limits must be imposed for various components on these airplanes to preclude the onset of fatigue cracking in those components. Such fatigue cracking, if not corrected, could adversely affect the structural integrity of these airplanes.                           ( print page 63024)    

## Explanation of Relevant Service Information 

British Aerospace has issued a revision to Section 05-10-10, “Airworthiness Limitations Description and Operation,” dated July 15, 1999, of the British Aerospace J41 Aircraft Maintenance Manual (AMM). This revised section of the AMM describes airworthiness limitations and mandatory life limits for the main landing gear, nose landing gear, fuel system, flap control system, and main baggage bay door. The section also describes new inspections and compliance times for inspection and replacement actions. Accomplishment of those actions will preclude the onset of fatigue cracking of certain structural elements of the airplane. 

The CAA has approved Section 05-10-10 of the AMM to assure the continued airworthiness of these airplanes in the United Kingdom. The CAA has not issued a corresponding airworthiness directive, although accomplishment of the additional life limits and structural inspections contained in the AMM may be considered mandatory for operators of these airplanes in the United Kingdom. 

## FAA's Conclusions 

The FAA has reviewed the revision to Section 05-10-10 of the AMM and all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States. Pursuant to the bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. The FAA has determined that the revision to Section 05-10-10 of the AMM must be incorporated into the Airworthiness Limitations Section (ALS) of the Instructions for Continued Airworthiness. 

## Explanation of Requirements of Proposed Rule 

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require a revision to the ALS of the Instructions for Continued Airworthiness to incorporate inspections to detect fatigue cracking of certain Significant Structural Items and to revise life limits for certain equipment and various components that are specified in the previously referenced maintenance document. 

## Explanation of Action Taken by the FAA 

In accordance with airworthiness standards requiring “damage tolerance assessments” for transport category airplanes [§ 25.1529 of the Federal Aviation Regulations (14 CFR 25.1529), and the Appendices referenced in that section], all products certificated to comply with that section must have Instructions for Continued Airworthiness (or, for some products, maintenance manuals) that include an ALS. That section must set forth: 
    - Mandatory replacement times for structural components,
    - Structural inspection intervals, and
    - Related approved structural inspection procedures necessary to show compliance with the damage-tolerance requirements.

Compliance with the terms specified in the ALS is required by sections 43.16 (for persons maintaining products) and 91.403 (for operators) of the Federal Aviation Regulations (14 CFR 43.16 and 91.403). 

In order to require compliance with these inspection intervals and life limits, the FAA must engage in rulemaking, namely the issuance of an AD. For products certificated to comply with the referenced part 25 requirements, it is within the authority of the FAA to issue an AD requiring a revision to the ALS that includes reduced life limits, or new or different structural inspection requirements. These revisions then are mandatory for operators under § 91.403(c) of the Federal Aviation Regulations (14 CFR 91.403), which prohibits operation of an airplane for which airworthiness limitations have been issued unless the inspection intervals specified in those limitations have been complied with.

After that document is revised, as required, and the AD has been fully complied with, the life limit or structural inspection change remains enforceable as a part of the airworthiness limitations. (This is analogous to AD's that require changes to the Limitations Section of the Airplane Flight Manual.) 

Requiring a revision of the airworthiness limitations, rather than requiring individual inspections, is advantageous for operators because it allows them to record AD compliance status only once—at the time they make the revision—rather than after every inspection. It also has the advantage of keeping all airworthiness limitations, whether imposed by original certification or by AD, in one place within the operator's maintenance program, thereby reducing the risk of non-compliance because of oversight or confusion. 

## Cost Impact 

The FAA estimates that 59 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed actions, 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 $3,540, or $60 per airplane. 

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 AD were not adopted. 

## 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: 

      ( print page 63025)    

# 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: 

**British Aerospace Regional Aircraft [Formerly Jetstream Aircraft Limited; British Aerospace (Commercial Aircraft) Limited:**                                 Docket 99-NM-250-AD.                             

*Applicability:*                                 All Model Jetstream 4101 airplanes, 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 (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 ensure continued structural integrity of these airplanes, accomplish the following:                             

## Airworthiness Limitations Revision 

(a) Within 30 days after the effective date of this AD, revise the Airworthiness Limitations Section (ALS) of the Instructions for Continued Airworthiness by incorporating Section 05-10-10, “Airworthiness Limitations Description and Operation,” dated July 15, 1999, of the British Aerospace J41 Aircraft Maintenance Manual (AMM) into the ALS. 

(b) Except as provided by paragraph (c) of this AD: After the actions specified in paragraph (a) of this AD have been accomplished, no alternative inspections or inspection intervals may be approved for the structural elements specified in the document listed in paragraph (a) of this AD. 

## Alternative Methods of Compliance 

(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, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116. 

## Special Flight Permits 

(d) 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 airplane to a location where the requirements of this AD can be accomplished. 

Issued in Renton, Washington, on October 16, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-27052 Filed 10-19-00; 8:45 am] 

BILLING CODE 4910-13-P