[Federal Register Volume 59, Number 154 (Thursday, August 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-18933]


[[Page Unknown]]

[Federal Register: August 11, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-SW-13-AD; Amendment 39-8969; AD 94-14-20]

 

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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to Sikorsky Aircraft Model S-76A series helicopters, 
that currently requires an initial and repetitive inspections of the 
tail rotor (T/R) blade spar elliptical centering plug (centering plug) 
for disbonding and adds a retaining pad between the T/R gearbox output 
shaft and the inboard T/R spar. This amendment requires the same design 
changes and procedures as the previous AD, except that it would 
eliminate the 500 hours' time-in-service repetitive inspections for 
centering plug disbonding. This amendment is prompted by an improved 
bonding and repair procedure and the lack of reports concerning the 
movement or disbonding of the centering plug. The actions specified by 
this AD are intended to prevent the centering plug from disbonding and 
moving out of position, which could result in loss of tail rotor 
control, and subsequent loss of control of the helicopter.

DATES: Effective September 15, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 15, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Sikorsky Aircraft, Commercial Customer Support, 6900 Main 
Street, Stratford, Connecticut 06601-1381. This information may be 
examined at the Federal Aviation Administration (FAA), Office of the 
Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Donald F. Thompson, Aerospace 
Engineer, Airframe Section, ANE-152, FAA, Boston Aircraft Certification 
Office, New England Region, 12 New England Executive Park, Burlington, 
Massachusetts 01803, telephone (617) 238-7162, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations by superseding AD 84-06-02, Amendment 39-4829 (49 
FR 10922, March 23, 1984) which is applicable to Sikorsky Aircraft 
Model S-76A series helicopters, was published in the Federal Register 
on August 4, 1993 (58 FR 41442). That action proposed to require the 
same design changes and procedures as the previous AD, except that it 
would eliminate the 500 hours' time-in-service repetitive inspections 
for centering plug disbonding. This amendment is prompted by an 
improved bonding and repair procedure and the lack of reports 
concerning the movement or disbonding of the centering plug.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposal or the FAA's determination of the cost to the public. However, 
for consistency of word usage throughout the AD and to make the 
language more consistent with the Sikorsky Aircraft Alert Service 
Bulletin 76-65-35A, Revision A, dated February 29, 1984, the word 
``pressure'' that describes the part has been changed to ``retaining'' 
and all forms of the word ``debond'' have been changed to ``disbond.'' 
Other minor editorial changes were made, also. Therefore, the FAA has 
determined that air safety and the public interest require the adoption 
of the rule with the changes previously described. The FAA has 
determined that these changes will neither increase the economic burden 
on any operator nor increase the scope of the AD.
    There are approximately 190 Sikorsky Aircraft Model S-76A series 
helicopters of the affected design in the worldwide fleet. The FAA 
estimates that 150 helicopters of U.S. registry will be affected by 
this AD, that it will save approximately 4 work hours per helicopter by 
discontinuing the current 500 hours' time-in-service repetitive 
inspections, and that the average labor rate is $55 per work hour. 
Based on these figures, the annual cost savings of the proposed 
elimination of these AD inspections on U.S. operators is estimated to 
be $33,000 annually.
    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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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, Incorporation by 
reference, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-4829, (49 FR 
10922, March 23, 1984), and by adding a new airworthiness directive 
(AD), Amendment 39-8969, to read as follows:

AD 94-14-20 Sikorsky Aircraft: Amendment 39-8969. Docket Number 93-
SW-13-AD. Supersedes AD 84-06-02, Amendment 39-4829.

    Applicability: Model S-76A Series helicopters, certificated in 
any category.
    Compliance: Required within the next 25 hours' time-in-service 
after the effective date of this AD, unless accomplished previously.
    To prevent the tail rotor blade (T/R) spar elliptical centering 
plug (centering plug) from disbonding and moving out of position, 
which could result in loss of tail rotor control and loss of control 
of the helicopter, accomplish the following for blades, part numbers 
(P/N) 76101-05001 and 76101-05101 series, with more than 130 hours' 
time-in-service:
    (a) Remove the blades in accordance with the maintenance manual 
and inspect the centering plug for disbonding of the polyurethane 
filler that fills the space between the aluminum centering plug and 
the graphite T/R spar in accordance with Sikorsky Aircraft Alert 
Service Bulletin 76-65-35A, Revision A, dated February 29, 1984 
(ASB).
    (1) If the inspection of the centering plug shows no evidence of 
disbonding greater than one-half inch in length, install a retaining 
pad in accordance with paragraph 2.C. of the Accomplishment 
Instructions of the ASB.
    (2) For disbonds greater than one-half inch, but less than 2 
inches in length, repair the blade in accordance with paragraph 
2.B.(1) of the Accomplishment Instructions of the ASB.
    (3) For disbonds equal to or greater than 2 inches in length, 
but not complete disbonds, or for disbonded centering plugs with the 
polyurethane filler excessively cracked or deteriorated to the 
extent of breaking away from the T/R spar or the centering plug, 
remove the blade from service and replace with an airworthy blade.
    (4) For T/R spars with complete T/R spar to centering plug 
disbond in which the polyurethane filler is intact and remains fully 
bonded to the centering plug, repair in accordance with paragraph 
2.B.(2) of the Accomplishment Instructions of the ASB.
    (5) For T/R spars with complete polyurethane filler to centering 
plug disbond in which the polyurethane filler is intact and remains 
fully bonded to the T/R spar, repair in accordance with paragraph 
2.B.(3) of the Accomplishment Instructions of the ASB.
    (b) Install retaining pad, P/N 76102-05004-111, in accordance 
with paragraph 2.C. of the Accomplishment Instructions 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 when approved by the Manager, Boston Aircraft Certification 
Office. 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: 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 
Secs. 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 if a retaining pad has 
been installed.
    (e) The inspections and repair shall be done in accordance with 
Sikorsky Aircraft Alert Service Bulletin 76-65-35A, Revision A, 
dated February 29, 1984. This incorporation by reference was 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from 
Sikorsky Aircraft, Commercial Customer Support, 6900 Main Street, 
Stratford, Connecticut 06601-1381. Copies may be inspected at the 
FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas; or at the Office of the Federal Register, 
800 North Capitol Street, NW., suite 700, Washington, DC.
    (f) This amendment becomes effective on September 15, 1994.

    Issued in Fort Worth, Texas, on June 30, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-18933 Filed 8-10-94; 8:45 am]
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