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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-SW-27-AD] 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD) that applies to certain serial-numbered Bell Helicopter Textron, Inc. (Bell) Model 412 helicopters and Agusta S.p.A. (Agusta) Model AB412 helicopters. That AD currently requires a temporary reduction of the never-exceed velocity (Vne) limitation until an inspection of the tail rotor yoke (yoke) assembly for fatigue damage and installation of a redesigned yoke flapping stop are accomplished. Recurring periodic and special inspections to detect occurrences of yoke overload are also required. This AD would require the same actions as the previous AD but would expand the applicability of the AD to all Bell Model 412, 412CF, 412EP, and Agusta Model AB412 helicopters. This proposal is prompted by the determination that the unsafe condition exists on all Bell Model 412 and all Agusta Model AB412 helicopters, regardless of serial number. The actions specified by the proposed AD are intended to prevent static and dynamic overload damage to the yoke that could result in loss of the tail rotor and subsequent loss of control of the helicopter. 

# DATES:

Comments must be received on or before March 23, 2001. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: 9-asw-adcomments@faa.gov. Comments may be inspected at the Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed AD may be obtained from Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101, telephone (817) 280-3391, fax (817) 280-6466 for the Bell Model 412 helicopters; and Agusta S.p.A., 21017 Cascina Costa di Samarate (VA), Italy, Via Giovanni Agusta 520, telephone 39 (0331) 229111, fax 39 (0331) 229605-222595 for the Agusta Model AB412 helicopters. This information may be examined at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. 

# FOR FURTHER INFORMATION CONTACT:

Uday Garadi, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5123, fax (817) 222-5961. 

# SUPPLEMENTARY INFORMATION:

## Comments Invited 

Interested persons are invited to participate in the maksing 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 document 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 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 mailed comments submitted in response to this proposal must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 99-SW-27-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, Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. 

## Discussion 

On March 16, 1998, the FAA issued AD 98-07-03, Amendment 39-10421, Docket No. 97-SW-58-AD (63 FR 14026, March 24, 1998), applicable to Bell Model 412 helicopters, serial numbers (S/N) 33001 through 33213, 34001 through 34024, 36001 through 36121, 46400 through 46434, and 46437; and Agusta Model AB412 helicopters, S/N prior to and including S/N 25806 and S/N 25901, to require a temporary reduction of the Vne limitation until an inspection of the yoke assembly for fatigue damage and installation of a redesigned yoke flapping stop are accomplished. Recurring periodic and special inspections to detect occurrences of yoke overload are also required. That action was prompted by laboratory tests and engineering analyses which indicated that the yoke assembly is susceptible to fatigue damage due to unforeseen static and dynamic loading of the tail rotor against the original flapping stop. The requirements of that AD are intended to prevent fatigue failure of the yoke that could result in loss of control of the tail rotor and subsequent loss of control of the helicopter. A correction to a technical bulletin date referenced in that AD was issued on July 10, 1998 (63 FR 38742, July 20, 1998). 

Since the issuance of AD 98-07-03, the FAA has determined that the unsafe condition exists on all Bell Model 412, 412CF, and 412 EP and Agusta Model AB412 helicopters and that the applicability of AD 98-07-03 should have included all serial numbers of these helicopters. The proposed AD would also correct the unsafe condition, which was listed as fatigue failure and correct the reference to Registro Aeronautico Italiano AD 97-223, which was dated incorrectly in AD 98-07-03. 

Since an unsafe condition has been identified that is likely to exist or develop on all Bell Model 412 or Agusta Model AB412 helicopters of the same type designs, the proposed AD would supersede AD 98-07-03. The proposed AD would require a reduction of the Vne limitation until an inspection of the yoke assembly for static and dynamic overload damage and installation of a redesigned yoke flapping stop are accomplished and includes additional periodic and special inspections to detect a yoke overload. 

                    The FAA estimates that 135 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 6.5 work hours per helicopter to install the placard, inspect the yoke assembly, and install the yoke. Required parts would                           ( print page 6495)                        cost approximately $511 per helicopter. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $121,635.                 

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 removing Amendment 39-10421 (63 FR 14026, March 24, 1998 and 63 FR 38742, July 20, 1998), and by adding a new airworthiness directive (AD), to read as follows: 

**Bell Helicopter Textron, Inc. and Agusta S.p.A.:**                                 Docket No. 99-SW-27-AD. Supersedes AD 98-07-03, Amendment 39-10421, Docket No. 97-SW-58-AD.                             

*Applicability:*                                 Bell Helicopter Textron, Inc. Model 412, 412CF, and 412EP helicopters and Agusta S.p.A. Model AB412 helicopters, with tail rotor yoke assembly, part number (P/N) 212-011-702-all dash numbers, installed, certificated in any category.                             

# Note 1:

This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise 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 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 static and dynamic overload damage to the tail rotor yoke (yoke) that could result in loss of the tail rotor and subsequent loss of control of the helicopter, accomplish the following: 

(a) Before further flight, review the historical records of the yoke assembly for any static or dynamic overload damage history, other than normal usage, that could have imposed a bending load on the yoke but did not require replacing the yoke assembly; for example, an incident in which a damaged tail rotor blade was replaced due to a blade strike. If such a history exists, replace the yoke with an airworthy yoke. 

(b) Before further flight, unless the requirements of paragraph (c) of this AD have been accomplished previously: 

(1) Install a Never Exceed Velocity (Vne) red line at 120 knots indicated airspeed (KIAS) on the pilot and copilot airspeed indicators using red tape or paint and a slippage indicator on the instrument case and glass. 

(2) Install a placard made of material that is not easily erased, disfigured, or obscured on the instrument panel in clear view of the pilot and copilot: “Observe temporary Maximum Never Exceed (Vne) airspeed red line (marked at 120 knots indicated airspeed (KIAS)). Vne is 20 KIAS less than the value presented on the airspeed limitation placard for each ambient condition.” 

(3) Insert the applicable Bell Helicopter Textron (BHT) 412 Temporary Revision, dated August 16, 1996, into the Model 412 Rotorcraft Flight Manual (RFM) or the applicable section of Agusta AB412 Temporary Revision No. 2, dated April 17, 1997, into the Model AB412 RFM. 

(c) Within 180 calendar days: 

(1) Remove yoke assembly, P/N 212-011-702-all dash numbers, and replace it with an airworthy yoke assembly, P/N 212-011-702-all dash numbers, with zero hours time-in-service (TIS), or an airworthy yoke (regardless of TIS) that has passed a one-time x-ray diffraction inspection in accordance with BHT Alert Service Bulletin (ASB) 412-96-89, Revision A, dated October 17, 1997; BHT ASB 412CF-96-01, dated September 3, 1996; or, Agusta Bolletino Tecnico (Technical Bulletin) No. 412-65, dated April 17, 1997, whichever is applicable. 

(2) Install an airworthy tail rotor flapping stop, P/N 212-011-713-103. 

(3) After the requirements of paragraphs (c)(1) and (c)(2) of this AD are accomplished, remove the 120 KIAS redline from the pilot and copilot airspeed indicators; remove the Vne airspeed restriction placard; and remove the BHT 412 Temporary Revision, dated August 16, 1996; BHT ASB 412CF-96-01, dated September 3, 1996; or Agusta AB412 Temporary Revision No. 2, as applicable, from the RFM. 

(d) After accomplishing the requirements of paragraph (c) of this AD, at intervals not to exceed 25 hours TIS, inspect the yoke assembly and tail rotor flapping stop (stop) in accordance with Part III, Recurring 25-Hour Special Inspection and Conditional Inspection Requirement, of Bell Helicopter Textron ASB 412-96-89, Revision A, dated October 17, 1997; BHT ASB 412CF-96-01, dated September 3, 1996; or Agusta Bolletino Tecnico (Technical Bulletin) No. 412-65, dated April 17, 1997, as applicable. Replace any unairworthy yoke assembly or stop with an airworthy yoke assembly or stop before further flight. 

(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, Regulations Group, 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, Regulations Group. 

# Note 2:

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

(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 helicopter at airspeeds not to exceed 120 KIAS to a location where the requirements of this AD can be accomplished. 

# Note 3:

The subject of this AD is addressed in Registro Aeronautico Italiano (Italy) AD 97-223, dated August 1, 1997.

Issued in Fort Worth, Texas, on January 8, 2001. 

Henry A. Armstrong, 

Manager, Rotorcraft Directorate, Aircraft Certification Service. 

[FR Doc. 01-1587 Filed 1-19-01; 8:45 am] 

BILLING CODE 4910-13-U