This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

24363 

Vol. 78, No. 80 

Thursday, April 25, 2013 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2008–0442; Directorate 

Identifier 2007–SW–24–AD] 

RIN 2120–AA64 

Airworthiness Directives; Various 

Sikorsky-Manufactured Transport and 

Restricted Category Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Supplemental notice of 

proposed rulemaking (SNPRM); 

reopening of comment period. 

SUMMARY: We are revising the proposals 

in an earlier notice of proposed 

rulemaking (NPRM) for certain Sikorsky 

Aircraft Corporation (Sikorsky) Model 

S–61A, D, E, L, N, NM (serial number 

61454), R, and V; Croman Corporation 

Model SH–3H, Carson Helicopters, Inc., 

Model S–61L; Glacier Helicopters, Inc. 

Model CH–3E; Robinson Air Crane, Inc. 

Model CH–3E, CH–3C, HH–3C, and 

HH–3E; and Siller Helicopters Model 

CH–3E and SH–3A helicopters. The 

NPRM proposed superseding an existing 

AD but retaining some requirements of 

that AD, removing certain dowel pin 

bores, expanding the applicability to 

include additional helicopters, and 

implementing a new retirement life for 

each main rotor shaft (MRS) based on a 

reevaluation of the MRS service life. 

This SNPRM is prompted by the 

comments received in response to the 

NPRM and a reevaluation of the relevant 

data. The proposed actions are intended 

to prevent MRS structural failure, loss of 

power to the main rotor, and subsequent 

loss of control of the helicopter. 

DATES: We must receive comments on 

this SNPRM by June 24, 2013. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Docket: Go to 

http://www.regulations.gov. Follow the 

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 Management Facility between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. The AD 

docket contains this proposed AD, the 

regulatory evaluation, any comments 

received, and other information. The 

street address for the Docket Office 

(phone: 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 AD, contact Sikorsky Aircraft 

Corporation, Attn: Manager, 

Commercial Technical Support, 

mailstop s581a, 6900 Main Street, 

Stratford, CT, telephone (203) 383–4866, 

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, 2601 Meacham Blvd., 

Room 663, Fort Worth, Texas 76137. 

FOR FURTHER INFORMATION CONTACT: 

Jeffrey Lee, Aviation Safety Engineer, 

Boston Aircraft Certification Office, 12 

New England Executive Park, 

Burlington, MA 01803, telephone (781) 

238–7161, fax (781) 238–7170, email 

jeffrey.lee@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 April 10, 2008, we issued an 

NPRM (73 FR 21556, April 22, 2008) 

proposing to amend 14 CFR part 39 to 

include an AD for Sikorsky Aircraft 

Corporation Model S–61A, D, E, L, N, 

NM, R, and V; Croman Corporation 

Model SH–3H, Carson Helicopters, Inc. 

Model S–61L; Glacier Helicopters, Inc. 

Model CH–3E; Robinson Air Crane, Inc. 

Model CH–3E, CH–3C, HH–3C and HH– 

3E; and Siller Helicopters Model CH–3E 

and SH–3A helicopters. That NPRM 

proposed superseding AD 98–26–02, 

published in the Federal Register on 

December 16, 1998 (63 FR 69177), that 

only applied to the affected Sikorsky 

model helicopters. That NPRM 

proposed retaining some of the 

requirements of the existing AD but also 

proposed determining a new retirement 

life for each MRS, removing from 

service any MRS with oversized dowel 

pin bores, and expanding the 

applicability to include certain 

restricted category models that were 

inadvertently omitted in the current AD. 

That NPRM was prompted by the 

manufacturer’s reevaluation of the 

retirement life for the MRS based on 

torque, ground-air-ground (GAG) cycle, 

and fatigue testing. Those proposals 

were intended to prevent MRS 

structural failure, loss of power to the 

main rotor, and subsequent loss of 

control of the helicopter. 

Actions Since Previous NPRM Was 

Issued 

Since we issued the NPRM (73 FR 

21556, April 22, 2008), we have 

determined a need to revise the 

proposed requirements, based on our 

review of the data and the comments 


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received. These supplemental proposals 

are intended to extend the hours timein-service (TIS) required for identifying 

the MRS as a repetitive external lift 

(REL) MRS to coincide with the 

nondestructive inspection (NDI) so that 

only one disassembly of the shaft is 

required, which would reduce the down 

time required to disassemble the shaft. 

Also, this action proposes to extend the 

time required to replace the MRS. 

This action also proposes to modify a 

paragraph in the AD that imposes a 

factor of 30 for unknown flight time. 

This has been changed to a factor of 

13.6. This action proposes to add the 

determination of the shaft cycle count 

for the purpose of establishing the life 

limit. Also, this action proposes to allow 

additional Revision A service 

information that can be used to modify 

an REL MRS for its life limit 

determination. 

We are reopening the comment period 

to allow the public to comment on these 

proposed changes. 

Comments 

We gave the public the opportunity to 

comment on the previous NPRM (73 FR 

21556, April 22, 2008). The following 

presents the comments received on the 

NPRM, and the FAA’s response to those 

comments. 

Request 

One commenter stated there was a 

difference between AD 98–26–02 and 

the NPRM in how many lifts constitute 

the shaft being REL. The commenter 

stated that a shaft that had 6 lifts per 

hour is REL under AD 98–26–02 but 

would not be considered REL (more 

than 6 lift cycles per hour) under the 

NPRM. 

We agree. The proposed AD is 

changed to match AD 98–26–02. Those 

shafts that have 6 or more lifts per hour 

are REL shafts. 

Two commenters commented on the 

requirement to identify the REL MRS. 

One commenter stated that the 

compliance time to identify the REL 

MRS should be extended from 5 hours 

to 10 hours. Another commenter asked 

if the identification of REL MRS on the 

component history card would be 

sufficient and stated that the marking 

requirement of the REL MRS would 

require an extended down time and lost 

revenue. 

We partially agree. We still believe 

the physical REL MRS should be 

identified and marking the component 

history card alone is insufficient. 

However, to avoid unnecessary down 

time, we are proposing to mark the MRS 

to coincide with the NDI at 1,100 hours 

TIS, at which time, the shaft would be 

disassembled anyway thus avoiding 

unnecessarily disassembling the MRS 

just to mark it. 

One commenter stated that 

mentioning the identification of the TS– 

281 marking in the proposed ‘‘Note 2’’ 

could result in a serviceable MRS being 

rejected. The commenter further states 

that an MRS can have the TS–281 

marking but not have oversized dowel 

pin holes. 

We disagree. The proposed AD would 

not require all shafts marked with the 

TS–281 marking to be removed from 

service. Only those shafts that have 

oversized dowel pin bores would be 

required to be removed from service. 

A commenter stated that compliance 

time (grace period) should be extended 

for the MRS over life limit because the 

steel plates referenced in the service 

information may not be available. 

Another commenter, the manufacturer, 

further stated that cycle limits should be 

added to the grace period. 

We disagree. Providing a grace period 

within which to comply with a 

retirement life essentially extends the 

retirement life and would not be 

appropriate. Also, this AD does not 

mandate modifying the configuration 

using the steel plates in SB 61B35–53A, 

and therefore the availability of that part 

does not factor into the compliance 

times identified. 

Another commenter stated that the 

lack of documented failures supports 

keeping the existing life limits in place 

and does not support the additional 

cycle limits to the MRS due to flawed 

testing. The commenter further stated 

that there have been no reported cracks 

in the MRS in the 9+ years since issuing 

AD 98–26–02. The commenter also 

stated that the life limits were generated 

using a flawed test program. Based on 

an approved Rotorcraft Flight Manual, 

the chart shows that at above 20 degrees 

Celsius and 1000-foot pressure altitude, 

the helicopter cannot produce 103 per 

cent torque. The capability of the 

helicopter reaching 103 percent torque 

was one of the reasons the commenter 

gave that the testing was flawed. Due to 

that capability, the testing at the 96 

percent torque value was indicated to be 

more realistic (the test specimen lasted 

for longer than 1.4 million cycles). The 

second example of flawed testing given 

by the commenter was that using the 

200,000 cycle in the presentation and 

without using the mean or working 

curve, the factor of 30 gives an 

equivalent time of over 6,660 flight 

hours. This would allow several 1000- 

hour inspections based on the overhaul 

manual to remove any of the fretting 

damage. Therefore, the fretting damage 

would have been repaired, resulting in 

a significant increase in cycles to 

failure. 

We partially agree. During certain 

operations, the helicopter can reach 103 

percent torque depending on the 

temperature and altitude adjustments. 

The ability of the helicopter to reach 

103 percent torque was one of the 

reasons given for flawed testing. Based 

on logging surveys conducted by 

Sikorsky, the current usage spectrum of 

some operators exceeds those that 

generated the MRS life limits. However, 

there have been no new reported cracks. 

During the time histories of engine 

torque available during an operator 

logging survey, the 103 per cent engine 

torque was seen during those 

operations. Because the torque value 

can be reached during logging 

operations, it is a realistic torque value 

for determining the new life limit. 

The second example provided of 

flawed testing is based on inspecting the 

specimen by following the overhaul 

manual and repairing any damage. 

However, when performing fatigue tests 

for life limit certification of the 

helicopter, these tests are carried out for 

the life of the part without any stoppage 

for inspections or repairs. The allowable 

cycles are further reduced due to the 

limited number of test specimens to 

represent the manufacturing variability 

and other unknown factors. Therefore, 

those cycles are modified using a 

reduction factor to determine a life 

limit. Since the testing to determine life 

limits does not consider repairs, the 

testing performed was not flawed. 

Therefore, we are proposing to retain 

the new life limits. 

The same commenter stated that the 

lack of documented failures supports 

keeping the existing life limits in place 

and does not support the additional 

cycle limits to the MRS because the 

30,000 cycle limit would reduce the 

actual flight hour time to as low as 1,000 

hours (using imposed 30 cycles per 

flight hour factor). The commenter 

further stated that the significant 

decrease in life limit from 2,200 hours 

to 1,000 hours is not justified. 

We partially agree. Providing the 

factor of 30 to the unknown flight time 

to determine the component lift cycle 

count would reduce the existing life 

limit to below those of AD 98–26–02. 

Therefore, we are modifying the 

requirements by imposing a factor of 

13.6 for the lift cycle count to the 

unknown flight time. 

The manufacturer stated that we 

should require incorporating Customer 

Service Notice (CSN) 6135–10A and 

Alert Service Bulletin (ASB) 61B35–53A 

for unmodified REL MRS and reference 

these instead of the prior revisions. The 


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commenter further stated that we 

should require replacing the planetary 

assembly and MRS assembly attaching 

hardware with the high strength steel 

hardware for unmodified REL MRS 

because the titanium planetary plates 

have a history of cracks in REL 

operations. 

We partially agree. The titanium 

plates continue to be airworthy so long 

as the compliance times for the 

unmodified REL MRS times are 

followed. Because they are still 

airworthy parts, incorporating CSN 

6135–10A and ASB 61B35–53A, both 

dated April 29, 2004, will not be 

required for unmodified REL MRS. 

Operators continuing to use the 

unmodified REL MRS will continue to 

have a lower life limit as identified in 

AD 98–26–02 for the unmodified REL 

MRS in comparison to the life of a 

modified REL MRS. However, the later 

versions of the CSN and ASB (Revision 

A) will not be incorporated because that 

is unnecessary to correct the unsafe 

condition. The previous versions are 

equivalent to CSN 6135–10A and ASB 

61B35–53A for determining a modified 

REL MRS configuration. Therefore, for 

modified REL MRS, we propose adding 

CSN 6135–10A and ASB 61B35–53A to 

provide credit for those modified by 

following the original ASB and CSN or 

revision A to those documents. 

The manufacturer also stated that the 

compliance time (grace period) for the 

non-REL MRS should be reduced to 150 

from 1500 hours TIS. 

We disagree. Sikorsky issued ASB 

61B35–69, which specified replacing a 

non-REL MRS at the next main gearbox 

overhaul or within 6 months. However, 

as these shafts have exceeded the life 

limit for the part, it should be replaced 

with an airworthy part. Therefore, we 

are proposing to remove the grace 

period. 

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 helicopters 

of these same type designs. Certain 

changes described above expand the 

scope of the original NPRM. As a result, 

we have determined that it is necessary 

to reopen the comment period to 

provide additional opportunity for the 

public to comment on this SNPRM. 

Proposed AD Requirements 

This proposed AD would retain some 

of the requirements from the current AD 

98–26–02 (63 FR 69177, December 16, 

1998): Recording the number of external 

lift cycles, determining whether the 

shaft is REL or non-REL, marking the 

REL shafts at the time of the NDI, and 

conducting an NDI for shafts used in 

REL operations and replacing it if a 

crack is found. 

The proposed AD would also require 

calculating a 250-hour TIS moving 

average of lift cycles to determine 

whether the MRS is an REL MRS, 

determine a new retirement life for each 

MRS based on hour TIS and lift cycles, 

remove from service any MRS with 

oversized dowel pin bores, and expand 

the applicability to include certain 

restricted category models that were 

inadvertently omitted in the existing 

AD. Also, this proposed action would 

extend the retirement life of modified 

REL MRS from 2,200 hours TIS to 5,000 

hours TIS but also implement lift-cycle 

retirement lives. Lastly, this action 

proposes allowing the use of Revision A 

service information to modify the REL 

MRS for life limit determination. 

Costs of Compliance 

We estimate that this proposed AD 

would affect 60 helicopters of U.S. 

registry. We estimate that operators may 

incur the following costs in order to 

comply with this proposed AD: It would 

take about 2.2 work hours to NDI an 

REL MRS at $85 per work hour plus a 

$50 consumable cost, for a total cost of 

$237 per helicopter and $14,220 for the 

U.S. fleet. It would take 2.2 work hours 

at $85 per work hour to replace an MRS, 

and parts would cost $44,753, for a total 

cost of $44,940 per helicopter. 

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. 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by 

removing Amendment 39–10943 (63 FR 

69177, December 16, 1998), and by 

adding the following new airworthiness 

directive (AD): 

Sikorsky Aircraft Corporation; Croman 

Corporation; Carson Helicopters, Inc.; 

Glacier Helicopters, Inc.; Robinson Air 

Crane, Inc.; and Siller Helicopters: 

Docket No. FAA–2008–0442; Directorate 

Identifier 2007–SW–24–AD. 

(a) Applicability 

This AD applies to Model S–61A, D, E, L, 

N, NM (serial number (S/N) 61454), R, V, 

CH–3C, CH–3E, HH–3C, HH–3E, SH–3A, and 

SH–3H helicopters with main rotor shaft 

(MRS), part number (P/N) S6135–20640–001, 

S6135–20640–002, or S6137–23040–001, 

installed, certificated in any category. 

(b) Unsafe Condition 

This AD defines the unsafe condition as 

MRS structural failure, loss of power to the 

main rotor, and subsequent loss of control of 

the helicopter. 


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(c) Affected ADs 

This AD supersedes AD 98–26–02 (63 FR 

69177, December 16, 1998), Amendment 39– 

10943, Docket No. 96–SW–29–AD. 

(d) Comments Due Date 

We must receive comments by June 24, 

2013. 

(e) 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. 

(f) Required Actions 

(1) Within 10 hours time-in-service (TIS): 

(i) Create a component history card or 

equivalent record for each MRS. 

(ii) If there is no record of the hours TIS 

on an individual MRS, substitute the 

helicopter’s hours TIS. 

(iii) If the record of lift cycles on an 

individual MRS is incomplete, add the 

known number of lift cycles to a number 

calculated by multiplying the number of 

hours TIS of the individual MRS by the 

average lift cycles calculated according to the 

instructions in Section I of Appendix I of this 

AD or by a factor of 13.6, whichever is 

higher. 

(iv) At the end of each day’s operations, 

record the number of external lift cycles (lift 

cycles) performed and the hours TIS. An 

external lift cycle is defined as a flight cycle 

in which an external load is picked up, the 

helicopter is repositioned (through flight or 

hover), and the helicopter hovers and 

releases the load and departs or lands and 

departs. 

(2) Within 250 hours TIS, determine 

whether the MRS is a repetitive external lift 

(REL) or non-REL MRS. 

(i) Calculate the first moving average of lift 

cycles by following the instructions in 

Section I of Appendix I of this AD. 

(A) If the calculation results in 6 or more 

lift cycles per hour TIS, the MRS is an RELMRS. 

(B) If the calculation results in less than 6 

lift cycles per hour TIS, the MRS is a NonREL MRS. 

(ii) If the MRS is a Non-REL MRS based on 

the calculation performed in accordance with 

paragraph (e)(2)(i), thereafter at intervals of 

50 hour TIS, recalculate the average lift 

cycles per hour TIS by following the 

instructions in Section II of Appendix 1 of 

this AD. 

(iii) Once an MRS is determined to be an 

REL MRS, you no longer need to perform the 

250-hour TIS moving average calculation, but 

you must continue to count and record the 

lift cycles and number of hours TIS. 

(iv) If an MRS is determined to be an REL 

MRS, it remains an REL MRS for the rest of 

its service life and is subject to the retirement 

times for an REL MRS. 

(3) Within 1,100 hours TIS: 

(i) Conduct a Non-Destructive Inspection 

for a crack on each MRS. If there is a crack 

in an MRS, before further flight, replace it 

with an airworthy MRS. 

(ii) If an MRS is determined to be an REL 

MRS, identify it as an REL MRS by etching 

‘‘REL’’ on the outside diameter of the MRS 

near the part S/N by following the 

Accomplishment Instructions, paragraph 

3.C., of Sikorsky Alert Service Bulletin (ASB) 

61B35–69, dated April 19, 2004. 

(4) Replace each MRS with an airworthy 

MRS on or before reaching the revised 

retirement life as follows: 

(i) For an REL MRS that is not modified by 

following Sikorsky Customer Service Notice 

(CSN) 6135–10, dated March 18, 1987, and 

ASB No. 61B35–53, dated December 2, 1981 

(unmodified REL MRS), the retirement life is 

30,000 lift cycles or 1,500 hours TIS, 

whichever occurs first. 

(ii) For an REL MRS that is modified by 

following Sikorsky CSN 6135–10, dated 

March 18, 1987, and Sikorsky ASB No. 

61B35–53 dated December 2, 1981, or CSN 

6135–10A, Revision A, and ASB 61B35–53A, 

Revision A, both dated April 19, 2004 

(modified REL MRS), the retirement life is 

30,000 lift cycles or 5,000 hours TIS, 

whichever occurs first. 

(iii) For a non-REL MRS, the retirement life 

is 13,000 hours TIS. 

(5) Establish or revise the retirement lives 

of the MRS as indicated in paragraphs 

(e)(4)(i) through (e)(4)(iii) of this AD by 

recording the new or revised retirement life 

on the MRS component history card or 

equivalent record. 

(6) Within 50 hours TIS, remove from 

service any MRS with oversized (0.8860′′ or 

greater diameter) dowel pin bores. 

(g) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Boston Aircraft 

Certification Office, FAA, may approve 

AMOCs for this AD. Send your proposal to 

Jeffrey Lee, Aviation Safety Engineer, Boston 

Aircraft Certification Office, 12 New England 

Executive Park, Burlington, MA 01803, 

telephone (781) 238–7161, fax (781) 238– 

7170, email jeffrey.lee@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 

(1) Sikorsky Aircraft Corporation issued an 

All Operators Letter (AOL) CCS–61–AOL– 

04–0005, dated May 18, 2004, with an 

example and additional information about 

tracking cycles and the moving average 

procedure. This AOL is not incorporated by 

reference but contains additional information 

about the subject of this AD. 

(2) The Overhaul and Repair Instruction 

(ORI) Number 6135–281, Part B, Step 5, and 

ORI 6137–041, Section III, Oversize Dowel 

Pin Bore Repair and identified on the flange 

as TS–281 or TS–041–3, which is not 

incorporated by reference, contains 

additional information about the subject of 

this AD. 

(3) For more information about the AOL or 

the ORI, contact Sikorsky Aircraft 

Corporation, Attn: Manager, Commercial 

Technical Support, mailstop s581a, 6900 

Main Street, Stratford, CT, telephone (203) 

383–4866, 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, 2601 

Meacham Blvd., Room 663, Fort Worth, 

Texas 76137. 

APPENDIX I 

Section I: The First Moving Average of Lift 

Cycles per Hour TIS 

The first moving average calculation is 

performed on the MRS assembly when the 

external lift component history card record 

reflects that the MRS assembly has reached 

its first 250 hours TIS. To perform the 

calculation, divide the total number of lift 

cycles performed during the first 250 hours 

TIS by 250. The result will be the first 

moving average calculation of lift cycles per 

hour TIS. 

Section II: Subsequent Moving Average of Lift 

Cycles per Hour TIS 

Subsequent moving average calculations 

are performed on the MRS assembly at 

intervals of 50 hour TIS after the first moving 

average calculation. Subtract the total 

number of lift cycles performed during the 

first 50-hour TIS interval used in the 

previous moving average calculation from the 

total number of lift cycles performed on the 

MRS assembly during the previous 300 hours 

TIS. Divide this result by 250. The result will 

be the next or subsequent moving average 

calculation of lift cycles per hour TIS. 

Section III: Sample Calculation for 

Subsequent 50 Hour TIS Intervals 

Assume the total number of lift cycles for 

the first 50 hour TIS interval used in the 

previous moving average calculation = 450 

lift cycles and the total number of lift cycles 

for the previous 300 hours TIS = 2700 lift 

cycles. The subsequent moving average of lift 

cycles per hour TIS = (2700–450) divided by 

250 = 9 lift cycles per hour TIS. 

(i) Subject 

Joint Aircraft Service Component (JASC) 

Code: 6320, Main Rotor Gearbox. 

Issued in Fort Worth, Texas, on April 16, 

2013. 

Lance T. Gant, 

Acting Manager, Rotorcraft Directorate, 

Aircraft Certification Service. 

[FR Doc. 2013–09767 Filed 4–24–13; 8:45 am] 

BILLING CODE 4910–13–P 


wreier-aviles on DSK5TPTVN1PROD with PROPOSALS