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[Federal Register Volume 78, Number 141 (Tuesday, July 23, 2013)]
[Proposed Rules]
[Pages 44052-44054]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-17627]

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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: Supplemental notice of proposed rulemaking (SNPRM); reopening 
of the comment period.

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SUMMARY: We are revising an earlier proposed 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, which proposed establishing new fatigue life 
limits for certain GE engine gas generator turbine (GGT) rotor parts. 
The proposed AD was 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 (LCF) events instead of hours time-in-
service. This action would retain the previously proposed requirements 
but correct the life limit formula for a certain GGT rotor part. The 
proposed actions are intended 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 September 23, 
2013.

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

Discussion

    On August 30, 2012, we issued a notice of proposed rulemaking 
(NPRM) (77 FR 55166, September 7, 2012) for Sikorsky Model S-70, S-70A, 
S-70C, S-70C (M), and S-70C (M1) helicopters with GE T700-GE-401C or 
T700-GE-701C engines installed. The NPRM proposed to require 
establishing a new life limit for certain GGT rotor parts based upon 
the accumulated LCF events of the GGT rotor parts. The NPRM was 
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 LCF 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.

[[Page 44053]]

Actions Since Previous NPRM Was Issued

    Since we issued the previous NPRM (77 FR 55166, September 7, 2012), 
we became aware that GE has issued T700 Turboshaft Engine Service 
Bulletin (ESB) 72-0041, Revision 1, dated March 12, 2010 (ESB 72-0041), 
to correct the formula under the ``T700-GE-401C Stage 2 Disk PN 
6064T12P01/P03 LCF Limit Diagram'' in Figure 6. Other than this 
correction, the specifications in ESB 72-0041 remain the same.
    This SNPRM proposes to retain the previously proposed requirements 
but apply the correct life limit formula depicted in Figure 6 of ESB 
72-0041, Revision 1. Also, we are correcting a typographical error in 
the preamble of the previous NPRM in the ``Related Service 
Information,'' which referenced the ESB number as 72-041 rather than 
72-0041. As a result, we have determined that it is necessary to reopen 
the comment period to provide additional opportunity for the public to 
comment.

Comments

    We gave the public the opportunity to comment on the original NPRM 
(77 FR 55166, September 7, 2012), but we did not receive any comments.

FAA's Determination

    We are proposing this SNPRM because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of these same type 
designs.

Proposed Requirements of the SNPRM

    This SNPRM would retain the proposed requirements of the previous 
NPRM and would also propose inserting into the airworthiness 
limitations section of the maintenance manual or the instructions for 
continued airworthiness the figures contained in ESB No. T700 S/B 72-
0041, Revision 1, dated March 12, 2010, instead of ESB No. T700 S/B 72-
0041, dated October 1, 2008.

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 above, 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

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. 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.

(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) Comments Due Date

    We must receive comments by September 23, 2013.

(d) 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.

(e) Required Actions

    (1) Before further flight, insert into the airworthiness 
limitations 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, 
Revision 1, dated March 12, 2010, 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:

[[Page 44054]]

    (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 (e)(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 (e)(2)(ii)(A) of this AD 
times the LCF1 retirement life determined by following paragraph 
(e)(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.

(f) Special Flight Permit

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

(g) 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.

(h) 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.

(i) Subject

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

    Issued in Fort Worth, Texas, on July 11, 2013.
Kim Smith,
Directorate Manager, Rotorcraft Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-17627 Filed 7-22-13; 8:45 am]
BILLING CODE 4910-13-P
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