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[Federal Register Volume 77, Number 174 (Friday, September 7, 2012)]
[Proposed Rules]
[Pages 55166-55168]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-22064]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0945; Directorate Identifier 2010-SW-110-AD]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation 
(Sikorsky) Model Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for the 
Sikorsky Model S-70, S-70A, S-70C, S-70C (M), and S-70C (M1) 
helicopters with General Electric (GE) T700-GE-401C or T700-GE-701C 
engines installed. This proposed AD is prompted by a reevaluation of 
the method for determining the life limit for certain GE engine gas 
generator turbine (GGT) rotor parts and the determination that these 
life limits need to be based on low cycle fatigue events instead of 
hours time-in-service. The proposed actions are intended to establish 
new fatigue life limits for certain GGT rotor parts to prevent fatigue 
failure of a GGT rotor part, engine failure, and subsequent loss of 
control of the helicopter.

DATES: We must receive comments on this proposed AD by November 6, 
2012.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Docket: Go to http://www.regulations.gov. Follow the online instructions for sending your 
comments electronically.
     Fax: 202-493-2251.
     Mail: Send comments to the U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001.
     Hand Delivery: Deliver to the ``Mail'' address between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Examining the AD Docket: You may examine the AD docket on the 
Internet at http://www.regulations.gov or in person at the Docket 
Operations Office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The AD docket contains this proposed AD, the 
economic evaluation, any comments received, and other information. The 
street address for the Docket Operations Office (telephone 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD 
docket shortly after receipt.
    For service information identified in this proposed AD, contact 
Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical 
Support, mailstop s581a, 6900 Main Street, Stratford, CT, telephone 
(800) 562-4409, email address tsslibrary@sikorsky.com, or at http://www.sikorsky.com. You may review a copy of the referenced service 
information at the FAA, Office of the Regional Counsel, Southwest 
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Michael Davison, Flight Test Engineer, 
New England Regional Office, FAA, 12 New England Executive Park, 
Burlington, MA 01803; phone: (781) 238-7156; fax: (781) 238-7170; 
email: michael.davison@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to participate in this rulemaking by submitting 
written comments, data, or views. We also invite comments relating to 
the economic, environmental, energy, or federalism impacts that might 
result from adopting the proposals in this document. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. To 
ensure the docket does not contain duplicate comments, commenters 
should send only one copy of written comments, or if comments are filed 
electronically, commenters should submit only one time.
    We will file in the docket all comments that we receive, as well as 
a report summarizing each substantive public contact with FAA personnel 
concerning this proposed rulemaking. Before acting on this proposal, we 
will consider all comments we receive on or before the closing date for 
comments. We will consider comments filed after the comment period has 
closed if it is

[[Page 55167]]

possible to do so without incurring expense or delay. We may change 
this proposal in light of the comments we receive.

Discussion

    We propose to adopt a new AD for the specified helicopters with GE 
part-numbered T700-GE-401C or specified T700-GE-701C engines installed. 
This proposed AD would require establishing a new life limit for 
certain GGT rotor parts based upon the accumulated low cycle fatigue 
events of the GGT rotor parts. This proposed AD is prompted by the 
determination that the affected engines could fail due to fatigue 
unless the life limits of certain GE engine rotor parts are changed 
from hours time-in-service to low cycle fatigue events. The GE T700-GE-
701C engine is used in the military's UH-60 fleet. Analysis and 
experience with this engine have caused the military to reduce the life 
limit of certain GGT rotor parts and to revise their maintenance 
documentation to reflect these revised life limits. The Sikorsky Model 
S-70 helicopters are similar to the military's UH-60 fleet, some of 
which have been certificated by the FAA in the restricted category. The 
GE T700-GE-701C engine has not been type-certificated by the FAA for 
civil use, except to the extent that it is a part of a restricted 
category Model S-70 helicopter.

FAA's Determination

    We are proposing this AD because we evaluated all known relevant 
information and determined that an unsafe condition exists and is 
likely to exist or develop on other helicopters of these same type 
designs.

Related Service Information

    GE has issued GE T700 Turboshaft Engine Service Bulletin (ESB) 72-
0038, dated October 1, 2008, for the T700-GE-701C engine (ESB 72-0038) 
and GE T700 Turboshaft ESB 72-0041, dated August 21, 2009, for the 
T700-GE-401C engine (ESB SB 72-041). These ESBs define a ``full-cycle 
event'' and a ``partial cycle event,'' specify a method of calculating 
the low cycle fatigue (LCF) life limit using formulas and LCF Limit 
Diagrams, and specify counting LCF events to determine the remaining 
fatigue life for specified GGT rotor parts. Finally, the ESBs specify 
removing each life-limited rotor part from service when its newly-
established LCF life limit is reached.

Proposed AD Requirements

    This proposed AD would require, before further flight:
     Inserting the LCF limit diagrams into the airworthiness 
limitation section of the maintenance manual or instructions for 
continued airworthiness, shown in Figures 2 through 7 (pages 9 through 
14) of ESB 72-0041 or Figures 2 through 4 (pages 10 through 12) of ESB 
72-0038.
     Obtaining the actual LCF1 and LCF2 count from the engine 
``history recorder'' (HR), and calculating the LCF1 and LCF2 fatigue 
retirement life for each GGT rotor part.
     Replacing each GGT rotor part that has reached the new 
fatigue cycle life limit with an airworthy rotor part.
     Calculating the life limit for the GGT rotor part with the 
hours time-in-service for the part as shown in Table 1 of ESB 72-0041, 
for those helicopters with the GE T700-GE-401C engine where the number 
of low cycle fatigue events cannot be determined manually from the HR 
or by combining both manual and HR counts.
     Before further flight, beginning or continuing to count 
the full and partial low fatigue cycle events and recording on the 
component card or equivalent record that count at the end of each day 
for which the HR is inoperative.

Costs of Compliance

    We estimate that this proposed AD would affect 9 helicopters of 
U.S. registry. We estimate that operators may incur the following costs 
in order to comply with this AD:
     A minimal amount for work hours and labor costs because 
these parts are replaced as part of the periodic maintenance on the 
helicopter;
     A minimal amount of time to calculate the new retirement 
life;
     $360,000 to replace the GGT rotor parts per helicopter; 
and
     $3,240,000 to replace the GGT rotor parts for the entire 
U.S. operator fleet.

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.

Regulatory Findings

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed, I certify 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);
    3. Will not affect intrastate aviation in Alaska to the extent that 
it justifies making a regulatory distinction; and
    4. 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 proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new 
Airworthiness Directive (AD):

Sikorsky Aircraft Corporation: Docket No. FAA-2012-0945; Directorate 
Identifier 2010-SW-110-AD.

(a) Applicability

    This AD applies to Model S-70, S-70A, S-70C, S-70C (M), and S-
70C (M1) helicopters with General Electric (GE) T700-GE-401C or 
T700-GE-701C part-numbered engines, certificated in any category.

[[Page 55168]]

(b) Unsafe Condition

    This AD defines the unsafe condition as a critical engine part 
remaining in service beyond its fatigue life because the current 
life limit is based on hours time-in-service (TIS) instead of 
fatigue cycles. This condition could result in fatigue failure of an 
engine rotor part, engine failure, and subsequent loss of control of 
the helicopter.

(c) Compliance

    You are responsible for performing each action required by this 
AD within the specified compliance time unless it has already been 
accomplished prior to that time.

(d) Required Actions

    (1) Before further flight, insert into the airworthiness 
limitation section of the maintenance manual or instructions for 
continued airworthiness the low cycle fatigue (LCF) limit diagrams 
shown in Figures 2 through 7 (pages 9 through 14) of GE T700 
Turboshaft Engine Service Bulletin (ESB) No. T700 S/B 72-0041, dated 
August 21, 2009, for helicopters with the GE T700-GE-401C engine, or 
Figures 2 through 4 (pages 10 through 12) of GE T700 Turboshaft ESB 
No. T700 S/B 72-0038, dated October 1, 2008, for helicopters with 
the GE T700-GE-701C engine. The diagonal line on each diagram 
represents the new cycle life limit (a combination of full low cycle 
fatigue events (LCF1) and partial low cycle fatigue events (LCF2) as 
those terms are defined in the Accomplishment Instructions, 
paragraphs 3.A.(1) and 3.A.(2) of each ESB) for each gas generator 
turbine (GGT) rotor part. A combination of LCF1 and LCF2, which 
results in a number below the diagonal line of the applicable 
diagram for each engine, indicates that the part has not reached its 
fatigue life limit.
    (2) Before further flight:
    (i) Obtain the actual LCF1 and LCF2 count from the engine 
``history recorder'' (HR);
    (ii) Calculate the LCF1 and LCF2 fatigue retirement life for 
each GGT rotor part as follows:
    (A) Determine the actual LCF ratio by dividing the total actual 
LCF2 cycle count obtained from the HR by the total actual LCF1 cycle 
count obtained from the HR. Add to the actual counts from the HR any 
actual additional fatigue cycle incurred during any period in which 
the HR was inoperative.
    (B) Determine the LCF1 retirement life by dividing the maximum 
number of LCF2 events obtained from the applicable diagram for each 
engine by the sum of the actual LCF ratio obtained by following 
paragraph (d)(2)(ii)(A) of this AD plus the quotient of the maximum 
number of LCF2 events from the applicable diagram for each engine 
divided by the maximum number of LCF1 events from the applicable 
diagram for each engine.
    (C) Determine the LCF2 retirement life by multiplying the actual 
LCF ratio obtained by following paragraph (d)(2)(ii)(A) of this AD 
times the LCF1 retirement life determined by following paragraph 
(d)(2)(ii)(B) of this AD.
    (iii) Replace each GGT rotor part that has reached the new 
fatigue cycle life limit with an airworthy rotor part.
    (3) For helicopters with the GE T700-GE-401C engine, if you 
cannot determine the number of low cycle fatigue events manually 
from the HR or by combining both manual and HR counts, then the life 
limit for the GGT rotor part is the hours TIS for the part as shown 
in Table 1 of ESB No. T700 S/B 72-0041, dated August 21, 2009.
    (4) Before further flight, begin or continue to count the full 
and partial low fatigue cycle events and record on the component 
card or equivalent record that count at the end of each day for 
which the HR is inoperative.

(e) Special Flight Permit

    Special flight permits will not be issued to allow flight in 
excess of life limits.

(f) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Boston Aircraft Certification Office, FAA, may 
approve AMOCs for this AD. Send your proposal to: Michael Davison, 
Flight Test Engineer, New England Regional Office, FAA, 12 New 
England Executive Park, Burlington, MA 01803; phone: (781) 238-7156; 
fax: (781) 238-7170; email: michael.davison@faa.gov.
    (2) For operations conducted under 14 CFR part 119 operating 
certificate or under 14 CFR part 91, subpart K, we suggest that you 
notify your principal inspector, or lacking a principal inspector, 
the manager of the local flight standards district office or 
certificate holding district office before operating any aircraft 
complying with this AD through an AMOC.

(g) Additional Information

    For service information identified in this AD, contact Sikorsky 
Aircraft Corporation, Attn: Manager, Commercial Technical Support, 
mailstop s581a, 6900 Main Street, Stratford, CT, telephone (800) 
562-4409, email address tsslibrary@sikorsky.com, or at http://www.sikorsky.com. You may review a copy of the referenced service 
information at the FAA, Office of the Regional Counsel, Southwest 
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

(h) Subject

    Joint Aircraft Service Component (JASC) Code: 7250: Turbine 
Section.

    Issued in Fort Worth, Texas, on August 30, 2012.
Kim Smith,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2012-22064 Filed 9-6-12; 8:45 am]
BILLING CODE 4910-13-P
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