AD 98-12-22

This amendment adopts a new airworthiness directive (AD), applicable to Bell Helicopter Textron Canada (BHTC) Model 407 helicopters that requires shimming the tail rotor drive system bearing supports (bearing supports). This amendment is prompted by reports of cracked bearing hangar support arms in the area of the fillet radius. The actions specified by this AD are intended to prevent failure of the bearing supports, which could result in excessive tail rotor drive system vibration, loss of tail rotor drive, and subsequent loss of control of the helicopter.

Final rule

98-12-22 BELL HELICOPTER TEXTRON CANADA: Amendment 39-10576. Docket No. 98-SW-10-AD.

Applicability: Model 407 helicopters, serial numbers 53000, 53002 through 53065, 53067, and 53069 through 53075, certificated in any category.

NOTE 1: This AD applies to each helicopter 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 helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD.

Compliance: Required within 25 hours time-in-service, unless accomplished previously.

To prevent failure of the bearing supports, which could result in excessive tail rotor drive system vibration, loss of tail rotor drive, and subsequent loss of control of the helicopter, accomplish the following:

(a) Shim the tail rotor drive system bearing supports in accordance with the Accomplishment Instructions contained in Bell Helicopter Textron Alert Service Bulletin No. 407-97-7, dated February 27, 1997.

(b) 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, Rotorcraft Certification Office, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Certification Office.

(c) 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 helicopter to a location where the requirements of this AD can be accomplished.

(d) The shimming shall be done in accordance with Bell Helicopter Textron Alert Service Bulletin No. 407-97-7, dated February 27, 1997. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Bell Helicopter Textron Canada, 12,800 Rue de l'Avenir, Mirabel, Quebec JON1LO, telephone (800) 463-3036, fax (514) 433-0272. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Transport Canada (Canada) AD No. CF-97-08, dated May 30, 1997.

(e) This amendment becomes effective on July 15, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to BHTC helicopters was published in the Federal Register on April 1, 1998 (63 FR 15790). That action proposed to require shimming the bearing supports within the next 25 hours time-in-service.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for small editorial change. The FAA has determined that these changes will neither increase the scope of the AD nor increase the economic burden on any operator.

The FAA estimates that 160 helicopters of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per helicopter to accomplish the shimming of the bearing support, and that the average labor rate is $60 per work hour. Required parts will cost approximately $30 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $43,200.

The regulations adopted herein will 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 final rule does 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) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: