[Federal Register Volume 64, Number 121 (Thursday, June 24, 1999)]
[Rules and Regulations]
[Pages 33743-33745]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-15901]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-26-AD; Amendment 39-11205; AD 99-11-04]
RIN 2120-AA64


Airworthiness Directives; Sikorsky Aircraft Model S-76A 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 99-11-04 which was sent 
previously to all known U.S. owners and operators of Sikorsky Aircraft 
Model S-76A helicopters by individual letters. This AD requires, before 
further flight, either revising the flight manual to show reduced 
single-engine rotorcraft performance or determining if an AC generator 
interlock system is installed. If an interlock system is installed, the 
flight manual revision is not required. This amendment is prompted by 
the discovery that Sikorsky Aircraft Model S-76A helicopters with 
Turbomeca Arriel 1S1 engines may fail to achieve the specified single-
engine rotorcraft performance if an AC generator interlock system is 
not installed. The actions specified by this AD are intended to prevent 
the inability of the rotorcraft to achieve certain published one-
engine-inoperative performance.

DATES: Effective July 9, 1999, to all persons except those persons to 
whom it was made immediately effective by Priority Letter AD 99-11-04, 
issued on May 13, 1999, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before August 23, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-26-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Robert Mann, Aerospace Engineer,

[[Page 33744]]

Boston Aircraft Certification Office, ANE-150, 12 New England Executive 
Park, Burlington, MA 01803, telephone (781) 238-7190, fax (781) 238-
7199.

SUPPLEMENTARY INFORMATION: On May 13, 1999, the FAA issued Priority 
Letter AD 99-11-04, applicable to Sikorsky Aircraft Model S-76A 
helicopters, which requires, before further flight, either revising the 
flight manual to show reduced single-engine rotorcraft performance or 
determining if an AC generator interlock system is installed. If an 
interlock system is installed, the flight manual revision is not 
required. That action was prompted by the discovery that Sikorsky 
Aircraft Model S-76A helicopters with Turbomeca Arriel 1S1 engines may 
fail to achieve the specified single-engine rotorcraft performance if 
an AC generator interlock system is not installed. This condition, if 
not corrected, could result in the inability of the rotorcraft to 
achieve certain published one-engine-inoperative performance.
    Since the unsafe condition described is likely to exist or develop 
on other Sikorsky Aircraft Model S-76A helicopters of the same type 
design, the FAA issued Priority Letter AD 99-11-04 to reduce the 
published Category ``A'' maximum takeoff and landing gross weights and 
single-engine forward climb performance limitations of the Rotorcraft 
Flight Manual (RFM), when an AC generator interlock system is not 
installed. The AD requires, before further flight, revising the RFM to 
publish reduction of Category ``A'' weight by 150 pounds and single-
engine performance by 50 feet per minute, or determining whether an AC 
generator interlock system has been installed. If the AC generator 
interlock system is not installed, the revision to the RFM is required. 
The short compliance time involved is required because the previously 
described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, revising the flight 
manual to show reduced single-engine rotorcraft performance or 
determining if an AC generator interlock system is installed is 
required before further flight, and this AD must be issued immediately.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on May 13, 1999, to all known U.S. owners and operators of 
Sikorsky Aircraft Model S-76A helicopters. These conditions still 
exist, and the AD is hereby published in the Federal Register as an 
amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 
39.13) to make it effective to all persons. There is a minor editorial 
change in this published version of the priority letter AD; the FAA has 
determined that this change will neither increase the economic burden 
on any operator nor increase the scope of the AD.
    The FAA estimates that 5 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 0.5 work hour per 
helicopter to revise 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 $150 to revise the RFM on the 
entire fleet.

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-26-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.


Sec. 39.13  [Amended]

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

AD 99-11-04  Sikorsky Aircraft Corporation: Amendment 39-11205. 
Docket No. 99-SW-26-AD.

    Applicability: Sikorsky Model S-76A helicopters with Turbomeca 
Arriel 1S1 engines installed in accordance with Supplemental Type 
Certificate SH568NE, including drawing number 76070-30601.

    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,

[[Page 33745]]

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: Before further flight, unless accomplished 
previously.
    To reduce the published Category ``A'' maximum takeoff and 
landing gross weights and single-engine forward climb performance 
limitations of the Rotorcraft Flight Manual (RFM), when an AC 
generator interlock system is not installed, accomplish the 
following:
    (a) Insert Sikorsky Model S-76A RFM Supplement (RFMS) No. 29B, 
Temporary Revision 1, dated April 9, 1999, into RFMS No. 29B, dated 
December 21, 1993, or
    (b) Determine if the AC generator interlock relays are installed 
by conducting the following inspection:
    (1) Uncover the No. 2 Relay Panel, located in the right side of 
the cockpit overhead. This panel is also referred to as the right-
hand panel.
    (2) Inspect for the presence of the AC generator interlock 
relays identified as K43 and K44 (two relays) or K46, K47, and K48 
(three relays).

    Note 2: For S-76A helicopters, serial numbers (S/N's) 760001 
through 760237, the AC generator interlock relays are wired through 
splice groups to the K31, K32, K11, and K13 relays. For S-76A 
helicopters, S/N's 760238 and higher, the AC generator interlock 
relays are wired through splice groups to the K11 and K13 relays. 
Depending on how and when each helicopter was modified, the labels 
on these relays could be K43 and K44 (two relays) or K46, K47, and 
K48 (three relays).
    Note 3: Sikorsky Aircraft Corporation Alert Service Bulletin 76-
77-4A, Revision A, dated May 5, 1999, pertains to the subject of 
this AD.

    (3) If the AC generator interlock relays are installed, no 
further action is required by this AD.
    (4) If the AC generator interlock relays are not installed, 
insert Sikorsky S-76A RFMS No. 29B, Temporary Revision 1, dated 
April 9, 1999, into RFMS No. 29B, dated December 21, 1993.
    (c) This AD revises the Limitations Section of the RFM for 
helicopters on which the AC generator interlock relays are not 
installed by inserting a new RFMS revision limiting Category ``A'' 
gross weight and reducing published climb performance.
    (d) Remove Sikorsky Model S-76A RFMS No. 29B, Temporary Revision 
1, dated April 9, 1999, inserted into RFMS No. 29B, dated December 
21, 1993, from the RFM upon installation of one of the following, as 
applicable:
    (1) For Model S-76A helicopters, S/N's 760001 through 760237, AC 
generator interlock kit (kit), part number (P/N) 33776-84790-012.
    (2) For Model S-76A helicopters, S/N's 760238 and higher, kit, 
P/N 33776-84790-011.
    (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, 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Boston Aircraft Certification Office.

    (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 to a location where 
the requirements of this AD can be accomplished.
    (g) This amendment becomes effective on July 9, 1999, to all 
persons except those persons to whom it was made immediately 
effective by Priority Letter AD 99-11-04, issued May 13, 1999, which 
contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on June 15, 1999.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-15901 Filed 6-23-99; 8:45 am]
BILLING CODE 4910-13-U