[Federal Register Volume 66, Number 20 (Tuesday, January 30, 2001)]
[Proposed Rules]
[Pages 8184-8186]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-2428]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-SW-40-AD]
RIN 2120-AA64


Airworthiness Directives; Sikorsky Aircraft Corporation Model S-
76A Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes revising an existing airworthiness 
directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A 
helicopters. That AD currently requires a one-time inspection of the 
tail rotor blade (blade) spar elliptical centering plug (centering 
plug) for disbonding and the addition of a retaining pad on the pitch 
change shaft between the output tail rotor gearbox flange and the 
inboard tail rotor spar. This action would contain the same 
requirements as the existing AD but would clarify that the 500-hour 
time-in-service (TIS) repetitive inspections, which could cause 
inadvertent damage, are not required. This AD would also incorporate by 
reference a revised alert service bulletin (ASB) that does not include 
the 500-hour TIS repetitive inspections. This proposal is prompted by 
operator confusion about whether the current AD continues to require 
the 500-hour TIS repetitive inspections. The proposed AD is intended to 
verify that the FAA has determined that the 500-hour TIS repetitive 
inspections are not required to prevent the centering plug from 
disbonding and moving out of position, loss of tail rotor control, and 
subsequent loss of control of the helicopter.

DATES: Comments must be received on or before April 2, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2000-SW-40-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at the following address: [email protected]. 
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.

FOR FURTHER INFORMATION CONTACT: Richard Noll, Aviation Safety 
Engineer, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, MA 01803, telephone (781) 238-7160, fax 
(781) 238-7199.

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 the closing date for comments 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 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. 2000-SW-40-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. 2000-SW-40-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137.

Discussion

    On June 30, 1994, the FAA issued AD 94-14-20, Amendment 39-8969 (59 
FR 41238, August 11, 1994), to require inspecting each blade centering 
plug for disbonding; adding a retaining pad on the pitch change shaft 
between the tail rotor output gearbox flange and the inboard blade 
spar; and removing the 500-hour repetitive inspection. That action was 
prompted by successful service experience and an improved bonding 
procedure. The requirements of that AD are intended to prevent the 
centering plug from disbonding and moving out of position, loss of tail 
rotor control, and subsequent loss of control of the helicopter.

[[Page 8185]]

    Since the issuance of that AD, Sikorsky has issued revised ASB 76-
65-35B, dated October 2, 1997, to supersede the basic ASB. The revised 
ASB amplifies the basic procedures and specifies that the recurring 
inspection interval (formerly 500-hours time-in-service (TIS)) is the 
interval specified in the S-76A Airworthiness Limitations and 
Inspection Schedule. The ASB also revises the text referencing 
consumables by changing military specifications to commercial 
equivalents.
    The FAA has become aware that 500-hour TIS repetitive inspections 
are being conducted because of the misconception that AD 94-14-20 
mandates the entire ASB. These repetitive inspections could result in 
inadvertent damage to the tail rotor blades. The FAA understands how 
this confusion could occur since the AD language does inadvertently 
incorporate all the inspection requirements of Sikorsky Aircraft Alert 
Service Bulletin 76-15-35A, Revision A, dated February 29, 1984. 
However, that was not the intent of the AD as explained in the preamble 
to AD 94-14-20. The FAA intended to eliminate the 500-hour TIS 
repetitive inspections for centering plug disbonding. Incorporating 
specific portions of ASB 76-65-35B, dated October 2, 1997, that does 
not contain the 500-hour TIS repetitive inspections will clarify the 
intended AD requirements.
    We have identified an unsafe condition that is likely to exist or 
develop on other Sikorsky Model S-76A helicopters of the same type 
design. The proposed AD would revise AD 94-14-20 and would retain the 
same basic requirements but would incorporate by reference portions of 
the revised ASB and would clarify that the repetitive inspections are 
not required by the AD.
    The FAA estimates that this proposed AD would affect 150 
helicopters of U.S. registry. The revised AD would not impose any 
additional burden or costs.
    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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-8969 (59 FR 
41238, August 11, 1994), and by adding a new airworthiness directive 
(AD), to read as follows:

Sikorsky Aircraft Corporation: Docket No. 2000-SW-40-AD. Revises AD 
94-14-20, Amendment 39-8969, Docket No. 93-SW-13-AD.

    Applicability: Model S-76A helicopters, with tail rotor blade 
(blade) assembly, part number (P/N) 76101-05001 (all dash numbers) 
or 76101-05101 (all dash numbers), installed with more than 130 
hours time-in-service (TIS), 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 within 25 hours TIS, unless accomplished 
previously.
    To prevent the blade spar elliptical centering plug (centering 
plug) from disbonding and moving out of position, loss of tail rotor 
control, and subsequent loss of control of the helicopter, 
accomplish the following:
    (a) Inspect the centering plug for disbonding of the 
polyurethane filler that fills the space between the aluminum 
centering plug and the graphite spar in accordance with the 
Accomplishment Instructions, paragraph 3.A.(1) and (2), of Sikorsky 
Aircraft Corporation Alert Service Bulletin No. 76-65-35B, dated 
October 2, 1997 (ASB).

    Note 2: The 500-hours TIS repetitive inspections contained in 
the Accomplishment Instructions, paragraph 3.D., of Sikorsky 
Aircraft Corporation Alert Service Bulletin 76-65-35A, Revision A, 
dated February 29, 1984, are not required by this AD.

    (1) If the inspection of the centering plug reveals disbonding 
of \1/2\-inch or less in length, install a retaining pad, P/N 76102-
05004-111, in accordance with the Accomplishment Instructions, 
paragraph 3.C., of the ASB.
    (2) For disbonds greater than \1/2\-inch in length, repair the 
blade assembly in accordance with the Accomplishment Instructions, 
paragraph 3.B.(1), of the ASB except you are not required to contact 
Sikorsky Worldwide Customer Service. If blades are found with 
polyurethane filler excessively cracked or deteriorated to extent of 
breaking away from the spar or aluminum plug by 0.005-inch or 
greater, replace the blade with an airworthy blade.
    (3) For spars with complete spar to centering plug disbond in 
which the polyurethane filler is intact and remains fully bonded to 
the centering plug, repair the blade assembly in accordance with the 
Accomplishment Instructions, paragraph 3.B.(2), of the ASB.
    (4) For spars with complete polyurethane filler to centering 
plug disbond in which the polyurethane filler is intact and remains 
fully bonded to the spar, repair the blade assembly in accordance 
with the Accomplishment Instructions, paragraph 3.B.(3) of the ASB.
    (b) Install a retaining pad, P/N 76102-05004-111, in accordance 
with the Accomplishment Instructions, paragraph 3.C., of the ASB.
    (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 3: 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 14 
CFR 21.197 and 21.199 to operate the helicopter to a location where 
the requirements of this AD can be accomplished if a retaining pad 
has been installed.


[[Page 8186]]


    Issued in Fort Worth, Texas, on January 22, 2001.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 01-2428 Filed 1-29-01; 8:45 am]
BILLING CODE 4910-13-U