[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]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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]
BILLING CODE 4910-13-P