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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-220-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

      ( print page 22480)    

# ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period. 

# SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes. The proposed AD would have required an eddy current inspection to detect cracks in the upper girder of the two main landing gear (MLG) brackets; and repair of a cracked bracket followed by repetitive inspections, or replacement of a cracked MLG bracket with an improved bracket, as applicable. The proposed AD also provided for an optional terminating action for certain proposed requirements. That proposal was prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. This new action revises the proposed rule by adding new repetitive inspections for certain airplanes, and extending the repetitive interval for the repetitive inspections for other airplanes. The actions specified by this new proposed AD are intended to detect and correct cracks in the upper girder of the MLG bracket, which could progress into the vertical stiffeners of the MLG bracket and result in reduced structural integrity of the landing gear. 

# DATES:

Comments must be received by May 29, 2001. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-220-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-220-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 Fokker Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands. 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, 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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NM-220-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-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the                     **Federal Register**                     on November 15, 1999 (64 FR 61796). That NPRM would have required an eddy current inspection to detect cracks in the upper girder of the two main landing gear (MLG) brackets; and repair of a cracked bracket followed by repetitive inspections, or replacement of a cracked MLG bracket with an improved bracket, as applicable. That NPRM also provided for optional terminating action for certain requirements of the proposed AD. That NPRM was prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The conditions described in that NPRM, if not corrected, could result in cracks in the upper girder of the MLG bracket, which could progress into the vertical stiffeners of the MLG bracket and result in reduced structural integrity of the landing gear.                 

## Explanation of New Service Information 

Since the issuance of that NPRM, Fokker has issued Service Bulletin F28/57-90, Revision 1, dated August 28, 2000. (The NPRM referenced Fokker Service Bulletin F28/57-90, dated March 1, 1999, as the appropriate source of service information for certain proposed actions.) Revision 1 of the service bulletin describes actions similar to those in the original issue of the service bulletin, but recommends new repetitive inspections for airplanes on which no cracking is detected, and increases the repetitive inspection interval from 12 months to 18 months for airplanes on which cracking is detected. Revision 1 of the service bulletin also clarifies the accomplishment instructions by providing more detailed instructions for the eddy current inspections. 

The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, classified Service Bulletin F28/57-90, Revision 1, as mandatory, and issued Dutch airworthiness directive 1999-045/2, dated October 31, 2000, in order to assure the continued airworthiness of these airplanes in the Netherlands. 

## Comments 

                    Due consideration has been given to the comments received in response to the NPRM. Certain comments have resulted in changes to the proposed                           ( print page 22481)                        rule, and these comments are addressed below.                 

## Request To Add Repetitive Inspections, Extend Inspection Interval 

One commenter requests that the FAA revise the repetitive inspection interval, as proposed in paragraph (a)(2) of the NPRM, to correspond with the inspection interval that the airplane manufacturer intends to incorporate in the Structural Inspection Program (SIP) Document. The interval to which the commenter refers is the 18-month repetitive inspection interval for both uncracked and repaired fittings of the MLG brackets, as provided in Revision 1 of the service bulletin, described previously. As stated above, the FAA has revised the proposal in this supplemental NPRM according to the changes in Revision 1 of the service bulletin. No further change to the proposal is necessary related to this comment. 

## Request To Correct a Typographical Error 

A commenter points out that, in the “Differences Between Proposed Rule, Foreign Airworthiness Directive, and Service Bulletin” section of the NPRM, the FAA states that replacement of a cracked MLG bracket would be required if a crack exceeds 0.0591 inch (15mm) in length. The commenter notes that the referenced crack length should be “0.591.” The FAA acknowledges that this was a typographical error, and has ensured that the correct crack length is stated in the parallel section of this supplemental NPRM. 

## Explanation of Change to Cost Impact Information 

In the “Cost Impact” section of the NPRM, the FAA stated that the proposed AD would affect six airplanes of U.S. registry. Since the issuance of the NPRM, two additional airplanes subject to this proposed AD have been added to the U.S. Register. The FAA has revised the “Cost Impact” section of this supplemental NPRM accordingly. 

## Explanation of New Requirements of Proposal 

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, this new proposed AD would require repetitive eddy current inspections to detect cracks in the upper girder of the two MLG brackets; and repair of a cracked bracket or replacement of a cracked bracket with an improved bracket, as applicable. Such replacement would terminate the requirements of this proposed AD. For airplanes on which no cracking is detected, replacement of an existing bracket with an improved bracket is provided as an optional terminating action for the repetitive inspections. The actions would be required to be accomplished according to Fokker Service Bulletin F28/57-90, Revision 1 (described previously), and Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999 (described in the original NPRM), except as noted below. (Operators should note that, although Fokker Proforma Service Bulletin F28/57-92 has not been revised since the original NPRM, a difference between the proposal and that service bulletin that was cited in the original NPRM is restated below for the convenience of operators.) 

## Differences Between Supplemental NPRM, Foreign Airworthiness Directive, and Service Bulletins 

This supplemental NPRM differs from Fokker Service Bulletin F28/57-90, Revision 1, and the parallel Dutch airworthiness directive in that it would require, prior to further flight, replacement of a cracked MLG bracket with an improved bracket, if a crack exceeds 0.591 inch (15 mm) in length. The service bulletin and the Dutch airworthiness directive specify replacement of a cracked MLG bracket prior to further flight only if a crack exceeds 1.576 inches (40 mm) in length. The FAA has determined that, because of the safety implications and consequences associated with such cracking, any subject MLG bracket that is found to have a crack that exceeds 0.591 (15 mm) in length must be replaced prior to further flight. 

Operators should note that Fokker Service Bulletin F28/57-90, Revision 1, and the Dutch airworthiness directive specify to replace a cracked MLG bracket in accordance with Fokker Proforma Service Bulletin F28/57-92, or to contact the manufacturer for replacement instructions. However, this supplemental NPRM would require replacement of a cracked MLG bracket to be accomplished in accordance with Fokker Proforma Service Bulletin F28/57-92. 

Operators also should note that, although Fokker Proforma Service Bulletin F28/57-92, including any appendix referenced in that proforma service bulletin, may specify that the manufacturer may be contacted if any discrepancies are found during the replacement of the MLG bracket, this proposal would require correction of the discrepancies in accordance with a method approved by the FAA, or the RLD (or its delegated agent). In light of the type of corrective action that would be required to address the identified unsafe condition, and in consonance with existing bilateral airworthiness agreements, the FAA has determined that, for this supplemental NPRM, corrective action approved by either the FAA or the RLD would be acceptable for compliance with this proposed AD. 

## Conclusion 

Since the changes described above expand the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment. 

## Cost Impact 

The FAA estimates that 8 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 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 $960, or $120 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 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. 

## 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                           ( print page 22482)                        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: 

**Fokker Services B.V.:**                                 Docket 99-NM-220-AD.                             

*Applicability:*                                 Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes; serial numbers 11003 through 11091 inclusive, 11094 through 11171 inclusive, 11991, and 11992; 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 (f) 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 detect and correct cracks in the upper girder of the main landing gear (MLG) bracket, which could progress into the vertical stiffeners of the MLG bracket and result in reduced structural integrity of the landing gear, accomplish the following: 

## Repetitive Inspections and Corrective Actions 

(a) Within 12 months after the effective date of this AD, perform an eddy current inspection of the upper girder of the MLG brackets on the left and right sides of the airplane for cracks, in accordance with the Accomplishment Instructions of Fokker Service Bulletin F28/57-90, Revision 1, dated August 28, 2000. 

(1) If no cracks are found, repeat the inspection at least every 18 months, until accomplishment of paragraph (d) of this AD. 

(2) Except as provided by paragraph (c) of this AD, if any crack is found, prior to further flight, repair as specified in paragraph C.(1) of the Accomplishment Instructions of the service bulletin, in accordance with the service bulletin. Thereafter, repeat the eddy current inspection at intervals not to exceed 18 months, until accomplishment of paragraph (d) of this AD. 

# Note 2:

Inspections accomplished before the effective date of this AD in accordance with Fokker Service Bulletin F28/57-90, dated March 1, 1999, are considered acceptable for compliance with paragraph (a) of this AD.

## Reporting Requirement 

                                (b) Within 10 days after accomplishing each inspection required by paragraph (a) of this AD, submit a report of the inspection results to: Fokker Services B.V., Technical Services, Attn: Manager Airline Support, P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501*et seq.*) and have been assigned OMB Control Number 2120-0056.                             

## Replacement 

(c) For airplanes on which a crack greater than 0.591 inch (15 mm) in length is found: Except as provided by paragraph (e) of this AD, prior to further flight, replace the cracked MLG bracket with a new, improved bracket (including measuring the position of the existing MLG bracket, removing the existing bracket and attachment fittings, checking alignment of the fastener holes, measuring gaps, installing a shim, and aligning the new bracket); in accordance with Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999. Such replacement constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD. 

## Optional Terminating Action 

(d) Except as provided by paragraph (e) of this AD, replacement of the MLG bracket with a new, improved bracket (including measuring the position of the existing MLG bracket, removing the existing bracket and attachment fittings, checking alignment of the fastener holes, measuring gaps, installing a shim, and aligning the new bracket), in accordance with Fokker Proforma Service Bulletin F28/57-92, dated July 1, 1999; constitutes terminating action for the repetitive inspections specified in paragraph (a) of this AD for the replaced bracket. 

(e) If any discrepancy is detected during accomplishment of the replacement procedures, and the service bulletin or any appendix to the service bulletin specifies to contact Fokker for appropriate  action: Prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate; or the Rijksluchtvaartdienst (or its delegated agent). 

## Alternative Methods of Compliance 

(f) 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 3:

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 

(g) 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. 

# Note 4:

The subject of this AD is addressed in Dutch airworthiness directive 1999-045/2, dated October 31, 2000.

Issued in Renton, Washington, on April 30, 2001. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-11227 Filed 5-3-01; 8:45 am] 

BILLING CODE 4910-13-U