AD 99-07-01 ACTIVE

This amendment supersedes an existing priority letter airworthiness directive (AD), applicable to Sikorsky Model S-76C helicopters, that currently requires, before further flight, inserting new operating limitations and performance data into the Rotorcraft Flight Manual (RFM) which require lower allowable gross weights for certain operational conditions. This amendment requires the same actions as the priority letter AD, but updates the previously referenced RFM's. This amendment is prompted by the discovery that the RFM's referenced in the priority letter AD have been revised. The actions specified by this AD are intended to provide the correct RFM references and to prevent an inability to achieve the published One-Engine-Inoperative (OEI) performance and subsequent loss of control of the helicopter.

Final rule; request for comments

99-07-01 SIKORSKY AIRCRAFT CORPORATION: Amendment 39-11083. Docket No. 99-SW-22-AD. Supersedes Priority Letter AD 99-05-01, Docket No. 99-SW-18-AD.

Applicability: Model S-76C helicopters, with Turbomeca Arriel 2S1 engines with an engine Hydromechanical Unit (HMU), part number 0.292.92.822.0, 0.292.92.808.0, 0.292.92.813.0, or 0.292.92.828.0, 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 (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 before further flight, unless accomplished previously.

To prevent an inability to achieve the published One-Engine Inoperative performance and subsequent loss of the helicopter, accomplish the following:

(a) Insert the following into the Operating Limitations section and Performance Data section, as appropriate, of Rotorcraft Flight Manual (RFM) SA 4047-76C-10:

RFM (Basic), original approval date June 19, 1996, Revision 7, dated February 1, 1999;

RFM Supplement No. 8, original approval date August 28, 1997, Revision 1, dated February 1, 1999; and

RFM Supplement No. 9, original approval date August 28, 1997, Revision 1, dated February 1, 1999.

(b) This AD revises the Operating Limitations section and Performance Data section of the RFM by requiring lower allowable gross weights for certain operational conditions.

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

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

(d) 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.

(e) This amendment becomes effective on April 7, 1999.

On February 18, 1999, the FAA issued AD 99-05-01, Docket No. 99-SW-18-AD, to require, before further flight, inserting new operating limitations and performance data into the RFM which require lower allowable gross weights for certain operational conditions. That action was prompted by an incident in which the design of the engine Hydromechanical Unit (HMU) prevented the fuel metering valve from delivering the fuel flow required to obtain 30-second OEI performance. That condition, if not corrected, could result in an inability to achieve the published OEI performance and subsequent loss of the helicopter.

Since the issuance of that AD, the FAA has discovered that the RFM's referenced in the priority letter AD have been revised. The FAA is superseding the priority letter AD to eliminate any confusion that may arise from referencing RFM's that have been revised.

Since an unsafe condition has been identified that is likely to exist or develop onother Sikorsky Model S-76C helicopters of the same type design, this AD supersedes AD 99-05-01 to require, before further flight, inserting new operating limitations and performance data into the RFM which require lower allowable gross weights for certain operational conditions. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, inserting new operating limitations and performance data into the RFM is required prior to further flight and this AD must be issued immediately.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

The FAA estimates that 17 helicopters will be affected by this proposed AD, that it will take approximately 0.5 work hour to insert the pages into the RFM, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $510.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 99-SW-22-AD." The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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, 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 (AD), Amendment 39-11083, to read as follows:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional
Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-22-AD, 2601 Meacham Blvd., Room 663, Fort Worth,
Texas 76137.

Wayne Gaulzetti, Aerospace Engineer, FAA, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7156, fax (781) 238-7199