Document ID: FAA-2008-0609-0004
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Sikorsky Aircraft Corp. Model S-76A, S-76B, and S-76C Helicopters
Posted Date: 2010-09-13T04:00Z

[Federal Register: September 13, 2010 (Volume 75, Number 176)]
[Rules and Regulations]               
[Page 55453-55455]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr13se10-1]                         

========================================================================
Rules and Regulations
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains regulatory documents 
having general applicability and legal effect, most of which are keyed 
to and codified in the Code of Federal Regulations, which is published 
under 50 titles pursuant to 44 U.S.C. 1510.

The Code of Federal Regulations is sold by the Superintendent of Documents. 
Prices of new books are listed in the first FEDERAL REGISTER issue of each 
week.

========================================================================

[[Page 55453]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0609; Directorate Identifier 2008-SW-24-AD; 
Amendment 39-16408 AD 2010-17-16]
RIN 2120-AA64

 
Airworthiness Directives; Sikorsky Aircraft Corporation Model S-
76A, S-76B, and S-76C Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: We are adopting a new airworthiness directive (AD) for 
Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, S-76B, and S-76C 
helicopters. This AD requires an initial and recurring inspections of 
the tail rotor vertical stabilizer aft spar assembly (aft spar 
assembly) for a crack, loose or working fasteners, and corrosion, and, 
if any are found, further inspections of the vertical stabilizer 
forward spar assembly (forward spar assembly). Repairing or replacing 
any unairworthy part before further flight is also required. This AD 
also requires a recurring track-and-balance of the tail rotor. Finally, 
this AD requires installing a vertical stabilizer modification kit, 
which is terminating action for the requirements of the AD. This AD is 
prompted by 26 reports of fatigue cracks in the aft spar assembly web 
and outer caps. The actions specified by this AD are intended to detect 
and correct an unbalanced or out-of-track tail rotor, which could lead 
to increased vibrations, a fatigue crack, loss of a portion of the 
vertical stabilizer and subsequent loss of control of the helicopter.

DATES: Effective October 18, 2010.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 18, 2010.

ADDRESSES: You may get the service information identified in this AD 
from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical 
Support, mailstop s581a, 6900 Main Street, Stratford, Connecticut 
06614, phone (203) 383-4866, e-mail address tsslibrary@sikorsky.com.
    Examining the Docket: You may examine the docket that contains this 
AD, any comments, and other information on the Internet at http://
www.regulations.gov or at the Docket Operations office, West Building 
Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Nicholas Faust, Aviation Safety 
Engineer, 16 New England Executive Park, Burlington, MA 01803; 
telephone: (781) 238-7763; fax: (781) 238-7170.

SUPPLEMENTARY INFORMATION: A proposal to amend 14 CFR part 39 to 
include an AD for certain Sikorsky Model S-76A, S-76B, and S-76C 
helicopters was published in the Federal Register on June 4, 2008 (73 
FR 31780). The proposed action applied to Sikorsky Model S-76A, S-76B, 
and S-76C helicopters with any of the following part-numbered aft spar 
assemblies installed:

------------------------------------------------------------------------
                                                      Aft spar assembly
                  Helicopter model                    part number  (P/N)
------------------------------------------------------------------------
S-76A..............................................      76201-05002-114
                                                         76201-05002-115
S-76B and S-76C....................................      76201-05002-047
                                                         76201-05002-048
                                                         76201-25002-041
                                                         76201-25002-044
                                                         76201-25002-045
                                                         76201-25002-046
------------------------------------------------------------------------

That action proposed to require, for any spar assembly that has 1,000 
or more hours time-in-service (TIS), within 30 days and thereafter at 
intervals not to exceed 50 hours TIS, inspecting the aft spar assembly, 
and if you find a crack, a loose or working fasteners, or corrosion, 
inspecting the forward spar assembly before further flight and 
replacing or repairing any unairworthy part with an airworthy part 
before further flight. The action also proposed to require, within 30 
days and thereafter at intervals not to exceed 200 hours TIS, track-
and-balance of the tail rotor. Accomplishing the tail rotor track-and-
balance would involve both a pilot and mechanic. The pilot's function 
would be to operate the helicopter to a ``light on wheels'' state--
almost to the point of takeoff, and the mechanic would accomplish the 
vibration measurements. Also, proposed was requiring, on or before 
December 31, 2010, installing a vertical stabilizer modification kit, 
P/N 76070-20562, 76070-20563, or 76070-20564, which would be 
terminating action for the requirements of the proposed AD.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the one comment received from the manufacturer.
    Sikorsky states that the effectivity should also include the 
aircraft serial number as referenced in their Alert Service Bulletin 
(ASB) No. 76-55-21. Sikorsky recommends the following wording ``Note 
All S-76 helicopter serial numbers greater than 760578 but not 
including helicopter serial number 762976 are not affected.'' Sikorsky 
states that ``this would ease the operator burden for aircraft built 
after the affected population of verifying the spar part numbers to 
show compliance with the AD.'' We concur with Sikorsky's recommendation 
to limit the applicability to only specified serial numbered 
helicopters and have revised the AD accordingly. Further, we 
inadvertently omitted the dash numbers to the part numbers of the 
modification kits contained in paragraph (c) of the proposed AD; ``-
011'' has been added to each of the part numbers in this final rule.
    We have reviewed the following service information:
     Sikorsky Alert Service Bulletin (ASB) No. 76-55-20A, 
Revision A, dated November 11, 2003 (76-55-20A), that applies to 
Sikorsky Model S-76A and Model S-76C helicopters and describes 
procedures for a one-time inspection of the vertical stabilizer aft 
spar assembly for cracks, loose or working fasteners, and/or corrosion, 
and if necessary an inspection of the forward spar assembly.
     ASB No. 76-65-58A, Revision A, dated November 11, 2003 
(76-65-58A), that applies to all Sikorsky Model S-76

[[Page 55454]]

serial numbered helicopters up to and including 760526 and describes 
procedures for an initial enhanced tail rotor balance check.
    We have also reviewed ASB No. 76-55-21, dated February 9, 2006 (76-
55-21), that Sikorsky references it its comment. ASB 76-55-21 applies 
to all Sikorsky S-76 serial numbered helicopters up to an including 
760578 and 762976 and specifies the installation of a structural 
enhancement kit which strengthens the aft spar assembly, improves the 
fatigue strength capability of the vertical stabilizer, and extends the 
vertical stabilizer inspection. We do not reference ASB No. 76-55-21 in 
the compliance instructions of this AD.
    This AD differs from ASB 76-55-20A and ASB 76-65-58A in that the 
incorporated by reference provisions described in ASB No. 76-55-20A are 
required for the Model S-76B helicopters as well as for the Model S-76A 
and Model S-76C helicopters. Also, this AD requires repetitive 
inspections of the aft spar assembly and the forward spar assembly, if 
necessary, and repetitive track-and-balance of the tail rotor, whereas 
the two ASBs specify only a one-time tail rotor balance check and an 
aft spar assembly inspection and, if necessary, a one-time forward spar 
assembly inspection.
    After careful review of the available data, including the comment 
noted above, we have determined that air safety and the public interest 
require the adoption of the rule with the changes described previously. 
We have also increased the labor rate for performing the required 
actions from $80 to $85 per work-hour. We have determined that these 
changes will not significantly increase the economic burden on any 
operator nor increase the scope of the AD.
    We estimate that this AD will affect 216 helicopters of U.S. 
registry. We also estimate that the inspections for a crack, a loose or 
working fastener, or corrosion will take approximately 7 work-hours per 
helicopter to accomplish. The tail rotor track-and-balance procedures 
and adjustments will take approximately 10 work-hours per helicopter, 
and installing the vertical stabilizer modification kit will take 
approximately 120 hours per helicopter, at an average labor rate of $85 
per work hour. The vertical stabilizer modification kit will cost 
approximately $4,250. Based on these figures, we estimate the total 
cost impact of this AD on U.S. operators to be $5,214,240, assuming 
that, on each helicopter, 12 spar assembly inspections are done 
($1,542,240), that 3 tail rotor track-and-balance procedures are done 
($550,800), that no spar assembly is repaired or replaced, and that the 
vertical stabilizer modification kit is installed.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared an economic evaluation of the estimated costs to comply 
with this AD. See the AD docket to examine the economic evaluation.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under 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

0
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]

0
2. FAA amends Sec.  39.13 by adding a new AD to read as follows:

2010-17-16 Sikorsky Aircraft Corporation: Amendment 39-16408; Docket 
No. FAA-2008-0609; Directorate Identifier 2008-SW-24-AD.

    Applicability: Model S-76A, S-76B, and S-76C helicopters, with 
serial numbers 76005 through 760578, inclusive, and serial number 
762976, with any of the following part-numbered vertical stabilizer 
aft spar assemblies having 1,000 or more hours time-in-service (TIS) 
installed, certificated in any category.

------------------------------------------------------------------------
                                                     Vertical stabilizer
                  Helicopter model                    aft spar assembly
                                                         part number
------------------------------------------------------------------------
S-76A..............................................      76201-05002-114
                                                         76201-05002-115
S-76B and S-76C....................................      76201-05002-047
                                                         76201-05002-048
                                                         76201-25002-041
                                                         76201-25002-044
                                                         76201-25002-045
                                                         76201-25002-046
------------------------------------------------------------------------

    Compliance: Required as indicated.
    To detect and correct an unbalanced or out-of-track tail rotor, 
which could lead to increased vibrations, a fatigue crack, loss of a 
portion of the vertical stabilizer, and subsequent loss of control 
of the helicopter, accomplish the following:
    (a) Within 30 days, unless accomplished previously, and 
thereafter at intervals not to exceed 50 hours TIS, inspect the 
vertical stabilizer aft spar assembly (aft spar assembly) for a 
crack, a loose or working fastener, or corrosion in accordance with 
the Accomplishment Instructions, paragraph 3.A., in Sikorsky Alert 
Service Bulletin (ASB) No. 76-55-20A, Revision A, dated November 11, 
2003 (No. 76-55-20A). For purposes of this AD, ASB No. 76-55-20A is 
applicable to Model S-76B helicopters as well as Model S-76A and S-
76C helicopters.
    (1) If a crack, a loose or working fastener, or corrosion is 
found in the aft spar assembly, before further flight:
    (i) Repair or replace any unairworthy parts and
    (ii) Inspect the vertical stabilizer forward spar assembly 
(forward spar assembly) for a crack, a loose or working fastener, or 
corrosion in accordance with the Accomplishment Instructions, 
paragraph 3.B., in ASB No. 76-55-20A. Contacting the manufacturer is 
not required by this AD.
    (2) If a crack, a loose or working fastener, or corrosion is 
found in the forward spar assembly, repair in accordance with the 
applicable maintenance manual or replace with airworthy parts before 
further flight.
    (b) Within 30 days, unless accomplished previously, and 
thereafter at intervals not to

[[Page 55455]]

exceed 200 hours TIS, track-and-balance the tail rotor in accordance 
with the Accomplishment Instructions, paragraph 3.A., in ASB No. 76-
65-58A, Revision A, dated November 11, 2003.

    Note 1: Although the ASB specifies only an initial inspection of 
the aft spar assembly and a track and balance of the tail rotor, 
this AD requires inspecting the aft spar assembly and track-and-
balancing the tail rotor repetitively.

    Note 2: The track-and-balancing of the tail rotor that is 
required by paragraph (b) of this AD involves both a pilot and 
mechanic. The pilot's function is to operate the helicopter to a 
``light on wheels'' state--almost to the point of takeoff. The 
mechanic is needed to accomplish the vibration measurements.

    (c) On or before December 31, 2010, install a vertical 
stabilizer modification kit, part number 76070-20562-011, 76070-
20563-011, or 76070-20564-011. Installing the vertical stabilizer 
modification kit is terminating action for the requirements of this 
AD.
    (d) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact the Manager, Boston Aircraft Certification Office, Engine 
and Propeller Directorate, ATTN: Nicholas Faust, Aviation Safety 
Engineer, FAA, 12 New England Executive Park, Burlington, MA 01803, 
telephone (781) 238-7763, fax (781) 238-7170, for information about 
previously approved alternative methods of compliance.
    (e) The Joint Aircraft System/Component (JASC) Code 5530 is: 
Vertical Stabilizer.
    (f) The inspections and track-and-balance shall be done in 
accordance with the specified portions of Sikorsky Alert Service 
Bulletin No. 76-55-20A, Revision A, dated November 11, 2003, and 
Sikorsky Alert Service Bulletin No. 76-65-58A, Revision A, dated 
November 11, 2003. The Director of the Federal Register approved 
this incorporation by reference in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. Copies may be obtained from Sikorsky Aircraft 
Corporation, Attn: Manager, Commercial Technical Support, mailstop 
s581a, 6900 Main Street, Stratford, Connecticut 06614, phone (203) 
383-4866, e-mail address tsslibrary@sikorsky.com. Copies may be 
inspected at the FAA, Office of the Regional Counsel, Southwest 
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas or at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal_register/code_of_federal_
regulations/ibr_locations.html.
    (g) This amendment becomes effective on October 18, 2010.

    Issued in Fort Worth, Texas, on August 12, 2010.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2010-21596 Filed 9-10-10; 8:45 am]
BILLING CODE 4910-13-P