# AGENCY:

 Federal Aviation Administration, DOT. 

# ACTION:

 Notice of proposed rulemaking (NPRM). 

# SUMMARY:

 This document proposes to revise an existing airworthiness directive (AD), applicable to Aerospatiale (Societe Nationale Industrielle Aerospatiale) (SNIAS) (now known as Eurocopter France) Model AS 350 and AS 355 series helicopters that currently requires repetitive inspections of the main rotor head components, the main gearbox (MGB) suspension bars, and the ground resonance prevention system components at intervals not to exceed 400 hours time-in-service (TIS). This action would require the same inspections, but at intervals not to exceed 500 hours TIS. This proposal is prompted by reports of confusion and unnecessary costs associated with the difference in the current 400 hours TIS inspection interval and the current manufacturer's master service recommendation of 500 hours TIS inspection interval. The actions specified by the proposed AD are intended to eliminate confusion and unnecessary costs and to prevent ground resonance due to reduced structural stiffness, which could lead to failure of a main rotor head or MGB suspension component and subsequent loss of control of the helicopter. 

# DATES:

 Comments must be received by March 20, 2000. 

# ADDRESSES:

 Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 98-SW-82-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. 

The service information referenced in the proposed rule may be obtained from American Eurocopter Corporation, 2701 Forum Drive, Grand Prairie, Texas 75053-4005, telephone (972) 641-3460, fax (972) 641-3527. 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:

Jim Grigg, Aerospace Engineer, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5490, fax (817) 222-5961. 

# 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                     Start Printed Page 3166                    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 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 No. 98-SW-82-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. 98-SW-82-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. 

## Discussion 

Following the issuance of our emergency priority letter AD on July 30, 1986, on March 3, 1987, the FAA issued AD 86-15-10, Amendment 39-5517 (52 FR 13233, April 22, 1987), to require an initial inspection within 10 hours time-in-service and repetitive inspections of the main rotor head components, the MGB suspension bars, and the ground resonance prevention system components at intervals not to exceed 300 hours TIS. That action was prompted by three reports of main rotor head component damage and MGB suspension bar damage in Model AS 355 helicopters that exhibited severe vibrations on approach or landing. That condition, if not corrected, could result in failure or unacceptable deterioration of the main rotor head, MGB suspension, or ground resonance prevention components which could result in failure of a main rotor head or MGB suspension component, and subsequent loss of control of the helicopter. On February 8, 1990, the FAA revised AD 86-15-10 (55 FR 5833, February 20, 1990), to require the same actions, except the repetitive inspections were required at intervals not to exceed 400 hours TIS. That action was prompted by reports of confusion and unnecessary costs caused by the differences in inspection intervals between AD 86-15-10 and the manufacturer's service bulletins that were incorporated by reference into that AD. 

Since the issuance of that AD, no further incidents have occurred. The master maintenance interval has shifted from 400 to 500 hours TIS. Since flight safety will not be adversely impacted, and to alleviate any confusion between the AD and the master maintenance interval, the FAA proposes to revise the AD to match the master maintenance interval. 

These helicopter models are manufactured in France and are 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 Direction Generale De L'Aviation Civile (DGAC) has kept the FAA informed of the situation described above. The FAA has reviewed 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. 

Since an unsafe condition has been identified that is likely to exist or develop on other Eurocopter France AS-350B, BA, B1, B2, C, D, and D1, and AS-355E, F, F1, F2 helicopters of the same type design, the proposed AD would revise AD 86-15-10 R1 to require repetitive inspections of the main rotor head components, the MGB suspension bars, and the ground resonance prevention system components at intervals not to exceed 500 hours TIS. 

The FAA has determined that this regulation is relieving in nature and imposes no additional costs or regulatory burden on any person. 

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), 40114, 44701. 

§ 39.13 

2. Section 39.13 is amended by removing Amendment 39-5517 (52 FR 13233, April 22, 1987) and Amendment 39-6515 (55 FR 5833, February 20, 1990), and by adding a new airworthiness directive (AD), to read as follows: 

**EUROCOPTER FRANCE:**                             Docket No. 98-SW-82-AD. Revises AD 86-15-10, Amendment 39-5517 and AD 86-15-10 R1, Amendment 39-6515.                        

*Applicability:*                             Model AS-350B, BA, B1, B2, C, D, and D1, and AS-355E, F, F1, F2 helicopters, 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 (f) 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 as indicated, unless accomplished previously.                             

                                To prevent ground resonance due to reduced structural stiffness, which could lead to failure of a main rotor head or main gearbox (MBG) suspension component and                                 Start Printed Page 3167                                subsequent loss of control of the helicopter, accomplish the following:                             

(a) Within 10 hours time-in-service (TIS): 

(1) For Model AS-350B, BA, B1, B2, C, D, and D1 helicopters, inspect the main rotor head components, the MGB suspension bars (struts), and the landing gear ground resonance prevention components (aft spring blades and hydraulic shock absorbers) in accordance with paragraph CC.3 of Aerospatiale Service Bulletin (SB) No. 01.17a (not dated). 

(2) For Model AS-355E, F, F1, F2 helicopters, inspect the main rotor head components, the MGB suspension bars (struts), and the landing gear ground resonance prevention components (aft spring blades and hydraulic shock absorbers) in accordance with paragraph CC.3 of SB No. 01.14a (not dated). 

(b) Rework or replace damaged components in accordance with SB No. 01.17a or SB No. 01.14a, as applicable. 

(c) Repeat the inspections and rework required by paragraphs (a) and (b) of this AD at intervals not to exceed 500 hours TIS. 

(d) If the helicopter is subjected to a hard landing or to high surface winds, when parked without effective tiedown straps installed, repeat the inspections required by paragraph (a) of this AD for the main rotor head star arms and the MGB suspension bars before further flight. 

(e) In the event of a landing which exhibits abnormal self-sustained dynamic vibrations (ground resonance type vibrations), repeat all the inspections contained in paragraph (a) of this AD. 

(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, FAA, Regulations Group, Rotorcraft Directorate. 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. 

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

Issued in Fort Worth, Texas, on January 11, 2000. 

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 00-1370 Filed 1-19-00; 8:45 am] 

BILLING CODE 4910-13-U