AD 98-7091

[Federal Register Volume 63, Number 53 (Thursday, March 19, 1998)] [Proposed Rules] [Pages 13379-13381] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 98-7091]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-112-AD] RIN 2120-AA64

Airworthiness Directives; Pilatus Britten-Norman Ltd. BN-2, BN- 2A, BN-2B, and BN-2T Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Britten-Norman Ltd. (Pilatus Britten-Norman) BN-2, BN-2A, BN-2B, and BN-2T series airplanes. The proposed AD would require replacing the washers on the attachment bolts of the lower fitting of the main landing gear (MLG). The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by the proposed AD are intended to prevent the bolts that attach the lower fitting of the MLG to the nacelle from becoming threadbound, which could result in structural failure of the MLG with consequent loss of control of the airplane during takeoff, taxi, or landing operations.

DATES: Comments must be received on or before April 17, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-112-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted. Service information that applies to the proposed AD may be obtained from Pilatus Britten-Norman Limited, Bembridge, Isle of Wight, United Kingdom PO35 5PR; telephone: 44-1983 872511; facsimile: 44-1983 873246. This information also may be examined at the Rules Docket at the address above.

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FOR FURTHER INFORMATION CONTACT: Mr. Roger Chudy, Aerospace Engineer, Small Airplane Directorate, Aircraft Certification Service, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone: (816) 426- 6932; facsimile: (816) 426-2169

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 that summarizes 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 No. 97-CE-112-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, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-112-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

Discussion

The Civil Airworthiness Authority (CAA), which is the airworthiness authority for the United Kingdom, notified the FAA that an unsafe condition may exist on certain Pilatus Britten-Norman BN-2, BN-2A, BN- 2B, and BN-2T series airplanes. The CAA reports that the attachment bolts of the lower fitting of the main landing gear (MLG) may become ``threadbound''. This condition results because the bolt length may be slightly longer than necessary and thus the nut bottoms out of the thread. Although all indications show that the bolt is properly torqued, the assembled parts may become loose, which could result in the MLG fitting separating from the nacelle. This condition, if not corrected in a timely manner, could result in structural failure of the MLG with consequent loss of control of the airplane during takeoff, taxi, and landing operations.

Relevant Service Information

Pilatus Britten-Norman has issued Service Bulletin (SB) BN-2/ SB.231, Initial Issue, dated October 17, 1996, which specifies procedures for replacing the washer on the attachment bolts of the lower fitting of the MLG with two thicker washers. This SB also includes torque loading specifications for the attachment bolts. The CAA classified this service bulletin as mandatory and issued British AD No. 008-10-96, dated January 31, 1997, in order to assure the continued airworthiness of these airplanes in the United Kingdom.

The FAA's Determination

This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA; reviewed all available information, including the service information referenced above; and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of the Provisions of the Proposed AD

Since an unsafe condition has been identified that is likely to exist or develop in other Pilatus Britten-Norman BN-2, BN-2A, BN-2B, and BN-2T series airplanes of the same type design registered in the United States, the proposed AD would require replacing the washers on the attachment bolts of the lower fitting of the MLG. Accomplishment of the proposed installation would be in accordance with the service information previously referenced.

Cost Impact

The FAA estimates that 80 airplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 3 workhours per airplane to accomplish the proposed action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $10 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $15,200.

Regulatory Impact

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under 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 has been placed 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.

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Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows:

Pilatus Britten-Norman Ltd: Docket No. 97-CE-112-AD.

Applicability: Models BN-2, BN-2A, BN-2A-3, BN-2A-6, BN-2A-8, BN-2A-2, BN-2A-9, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN-2B-20, BN-2B-21, BN-2B-26, BN-2B-27, and BN-2T airplanes (all serial numbers), 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 within the next 50 landings after the effective date of this AD, unless already accomplished. To prevent the bolts that attach the lower fitting of the main landing gear (MLG) to the nacelle from becoming threadbound, which could result in structural failure of the MLG with consequent loss of control of the airplane during takeoff, taxi, or landing operations, accomplish the following: (a) Replace the washers on the attachment bolts of the lower fitting of the MLG in accordance with Pilatus Britten-Norman Service Bulletin No. BN-2/SB.231, Initial Issue, dated October 17, 1996. (b) 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. (c) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri, 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(d) Questions or technical information related to Pilatus Britten-Norman Service Bulletin BN-2/SB.231, initial issue, dated October 17, 1996 should be directed to Pilatus Britten-Norman Limited, Bembridge, Isle of Wight, United Kingdom PO35 5PR; telephone: 44-1983 872511; facsimile: 44-1983 873246. This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

Note 3: The subject of this AD is addressed in British AD No. 008-10-96, dated January 31, 1997.

Issued in Kansas City, Missouri, on March 12, 1998. Michael Gallagher, Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-7091 Filed 3-18-98; 8:45 am] BILLING CODE 4910-13-U