[Federal Register Volume 70, Number 206 (Wednesday, October 26, 2005)]
[Rules and Regulations]
[Pages 61721-61723]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-21256]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-22757; Directorate Identifier 2005-SW-32-AD; 
Amendment 39-14345; AD 2005-22-01]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) for 
the Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, B, and C 
helicopters. This action requires certain inspections of the main rotor 
lower bifilar arm assembly in the attachment area around the lower 
bifilar lugs for a crack. If a

[[Page 61722]]

crack is found on any bifilar lug, this AD requires replacing the 
bifilar arm assembly with an airworthy bifilar arm assembly. If no 
crack is found, this AD requires a one-time test for the required 
torque on the lug nuts and, if necessary, applying the required torque 
and conducting the torque stabilization tests. This amendment is 
prompted by four reports of cracked bifilars. The actions specified in 
this AD are intended to prevent failure of a bifilar lug, damage to the 
main rotor control system, and subsequent loss of control of the 
helicopter.

DATES: Effective November 10, 2005.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 10, 2005.
    Comments for inclusion in the Rules Docket must be received on or 
before December 27, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this AD:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically;
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically;
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street SW., Nassif Building, Room PL-401, 
Washington, DC 20590;
     Fax: (202) 493-2251; or
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. 
and 5 p.m., Monday through Friday, except Federal holidays. You may get 
the service information identified in this AD from Sikorsky Aircraft 
Corporation, Attn: Manager, Commercial Tech Support, 6900 Main Street, 
Stratford, Connecticut 06614, phone (203) 386-3001, fax (203) 386-5983.

Examining the Docket

    You may examine the docket that contains the AD, any comments, and 
other information on the Internet at http://dms.dot.gov, or in person 
at the Docket Management System (DMS) Docket Offices between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The Docket 
Office (telephone (800) 647-5227) is located on the plaza level of the 
Department of Transportation Nassif Building at the street address 
stated in the ADDRESSES section. Comments will be available in the AD 
docket shortly after the DMS receives them.

FOR FURTHER INFORMATION CONTACT: Tracy Murphy, Aviation Safety 
Engineer, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, MA 01803, telephone (781) 238-7172, fax 
(781) 238-7170.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD for Sikorsky 
Model S-76A, B, and C helicopters. This action requires certain 
inspections of the main rotor lower bifilar arm assembly around the 
lower bifilar lugs for a crack. If a crack is found on any bifilar lug, 
this AD requires replacing the bifilar arm assembly with an airworthy 
bifilar arm assembly. If no crack is found, this AD requires a one-time 
test for the required torque on the lug nuts and, if necessary, 
applying the required torque and conducting the torque stabilization 
tests. This amendment is prompted by four reports of cracked bifilars. 
The actions specified in this AD are intended to prevent failure of a 
bifilar lug, damage to the main rotor system, and subsequent loss of 
control of the helicopter.
    Sikorsky issued Alert Service Bulletin No. 76-65-62, dated December 
14, 2004 (ASB), after receiving two reports of cracks in the lug areas 
of helicopters. Sikorsky states that cracked lugs were found despite 
the lower support lug joining being torqued and stabilized. For a 
bifilar with more than 1500 hours, the ASB specifies performing, within 
100 flight hours from the issue date of the ASB, a one-time inspection 
of the lower bifilar support lugs for cracks in the lug attachment 
areas. These are considered interim actions until terminating action 
can be taken. Sikorsky has designed and is currently testing a new main 
rotor hub pilot fitting (pilot fitting).
    Since Sikorsky issued the ASB, the FAA has received two more 
reports for a total of four reports of cracked bifilars. The additional 
reports indicate that cracks have become more severe. Therefore, this 
AD will require a repeat inspection of the arm assembly in addition to 
the inspections in the ASB. Also, this AD is effective for helicopters 
with a pilot fitting, part number (P/N) 76103-08003-101, which is 
different from what the ASB specifies. Investigation has shown the root 
cause of the failure is not the bifilar itself but the mating part that 
attaches the bifilar to the main rotor hub, called the pilot fitting. 
This fitting is transferring the load too abruptly into the bifilar. 
The ongoing fatigue testing is with the production bifilar and the 
redesigned pilot fitting. If the tests are successful, terminating 
action likely will include installing the new pilot fitting. The 
frequency of reports and the severity of the failures prompted this AD. 
In the most recent report, six of the six lugs had separated from the 
bifilar.
    This unsafe condition is likely to exist or develop on other 
helicopters of these same type designs. Therefore, this AD is being 
issued to prevent failure of a bifilar lug, damage to the main rotor 
system, and subsequent loss of control of the helicopter. This AD 
requires the following for helicopters with a pilot fitting, part 
number (P/N) 76103-08003-101, with 1500 or more hours time-in-service 
(TIS):
     Within 50 hours TIS, unless accomplished previously, and 
thereafter at intervals not to exceed 50 hours TIS, inspect the bifilar 
arm assembly for a crack in the lug attachment area.
     If you find a crack on any bifilar arm assembly lug, 
before further flight, replace the bifilar arm assembly with an 
airworthy bifilar arm assembly.
     If no crack is found at the initial inspection, perform a 
one-time torque test. The torque test is not required at the recurring 
inspection intervals of the bifilar arm assembly.
    Accomplish the actions by following the specified portions of the 
ASB described previously.
    The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
structural integrity of the helicopter. This AD requires the affected 
helicopters to be inspected and undergo a torque test within 50 hours 
TIS. If you find a crack in the bifilar lug attachment area, this AD 
requires replacing any unairworthy bifilar arm assembly with an 
airworthy bifilar arm assembly before further flight. Therefore, this 
AD must be issued immediately.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.
    We estimate that this AD will:
     Affect 216 helicopters,
     Take about 4 work hours for each inspection (including the 
torque stabilization tests), assuming 6 inspections per year, and 4 
hours to replace the bifilars, assuming a total of 2 bifilar arm 
assemblies need replacing, and
     Cost about $19,727 for a bifilar arm assembly.
    Based on these figures, we estimate the total cost impact of the AD 
on U.S. operators to be $376,934.

[[Page 61723]]

Comments Invited

    This AD is a final rule that involves requirements that affect 
flight safety and was not preceded by notice and an opportunity for 
public comment; however, we invite you to submit any written data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-22757; 
Directorate Identifier 2005-SW-32-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the AD. We will consider 
all comments received by the closing date and may amend the AD in light 
of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this AD. Using the search function of our docket 
web site, you can find and read the comments to any of our dockets, 
including the name of the individual who sent the comment. You may 
review the DOT's complete Privacy Act Statement in the Federal Register 
published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

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 DMS 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, 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

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

2005-22-01 Sikorsky Aircraft Corporation: Amendment 39-14345. Docket 
No. FAA-2005-22757; Directorate Identifier 2005-SW-32-AD.

    Applicability: Model S-76A, B, and C, with a main rotor hub 
pilot fitting (pilot fitting), part number (P/N) 76103-08003-101, 
with 1500 or more hours time-in-service (TIS), installed, 
certificated in any category.
    Compliance: Required as indicated.
    To prevent failure of a bifilar lug, damage to the main rotor 
system, and subsequent loss of control of the helicopter, accomplish 
the following:
    (a) Within 50 hours TIS, and thereafter at intervals not to 
exceed 50 hours TIS, inspect the lower bifilar arm assembly for a 
crack in the lug attachment area. Conduct the inspection of the 
lower bifilar arm assembly by following the Accomplishment 
Instructions, paragraph 3.A.(1) through 3.A.(6), of Sikorsky Alert 
Service Bulletin No. 76-65-62, dated December 14, 2004 (ASB).
    (1) If you find a crack on any bifilar arm assembly lug, before 
further flight, replace the bifilar arm assembly with an airworthy 
bifilar arm assembly.
    (2) If no crack is found at the initial inspection, perform a 
one-time torque test. Perform the torque test and the additional 
torque procedures as stated in the Accomplishment Instructions, 
paragraph 3.B.(1) through 3.B.(3) of the ASB. The torque test is not 
required at the recurring inspection intervals of the lower bifilar 
arm assembly.
    (b) 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 Boston Aircraft Certification Office, FAA, for 
information about previously approved alternative methods of 
compliance.
    (c) Inspect the lower bifilar arm assembly and perform the 
torque test by following the specified portions of Sikorsky Alert 
Service Bulletin No. 76-65-62, dated December 14, 2004. 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 Tech Support, 6900 Main Street, Stratford, Connecticut 
06614, phone (203) 386-3001, fax (203) 386-5983. Copies may be 
inspected 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.
    (d) This amendment becomes effective on November 10, 2005.

    Issued in Fort Worth, Texas, on October 17, 2005.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 05-21256 Filed 10-25-05; 8:45 am]
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