
[Federal Register: April 22, 2008 (Volume 73, Number 78)]
[Proposed Rules]               
[Page 21556-21559]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22ap08-24]                         


[[Page 21556]]

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

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; 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 Helicopter Model CH-3E; Robinson 
AirCrane, Inc. Model CH-3E, CH-3C, HH-3C and HH-3E; and Siller 
Helicopters Model CH-3E and SH-3A Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This amendment proposes superseding an existing airworthiness 
directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-
61A, D, E, L, N, NM, R, and V helicopters. The existing AD currently 
requires determining whether the main rotor shaft (MRS) was used in 
repetitive external lift (REL) operations. The existing AD also 
requires a nondestructive inspection (NDI) for cracks, replacing any 
unairworthy MRS with an airworthy MRS, appropriately marking the MRS, 
making a logbook entry, and establishing retirement lives for each REL 
MRS. This proposed AD would contain some of the same requirements but 
would determine new retirement lives for each MRS. The REL retirement 
life would be based on hours time-in-service (TIS) or lift cycles, 
whichever occurs first. The Non-REL retirement life would be reduced 
and would only be based on hours TIS. This proposed AD would also 
require the operator to remove from service any MRS with oversized 
dowel pin bores. Also, certain restricted category models that were 
inadvertently omitted in the current AD would be added to the 
applicability. This proposed AD is prompted by the manufacturer's 
reevaluation of the retirement life for the MRS based on torque, 
ground-air-ground (GAG) cycle, and fatigue testing. The actions 
specified by the proposed AD are intended to prevent MRS structural 
failure, loss of power to the main rotor, and subsequent loss of 
control of the helicopter.

DATES: Comments must be received on or before June 23, 2008.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    You may get the service information identified in this proposed AD 
from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Tech 
Support, 6900 Main Street, Stratford, Connecticut 06614, phone (203) 
386-3001, fax (203) 386-5983.
    You may examine the comments to this proposed AD in the AD docket 
on the Internet at http://www.regulations.gov.

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.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any written data, views, or arguments 
regarding this proposed AD. Send your comments to the address listed 
under the caption ADDRESSES. Include the docket number ``FAA-2008-0442, 
Directorate Identifier 2007-SW-24-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact 
with FAA personnel concerning this proposed rulemaking. Using the 
search function of the docket Web site, you can find and read the 
comments to any of our dockets, including the name of the individual 
who sent or signed 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).

Examining the Docket

    You may examine the docket that contains the proposed AD, any 
comments, and other information in person at the Docket Operations 
office between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Operations office (telephone (800) 647-5527) is 
located in Room W12-140 on the ground floor of the West Building at the 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after receipt.

Discussion

    In 1995 a Model S-58T helicopter lost transmission drive due to 
fatigue cracking on the MRS flange connection. Due to similarities 
between the Model S-58T and the S-61 MRS drive connection, Sikorsky 
conducted a review of the Model S-61 MRS cracking history. This review 
identified similar fatigue cracking mode origins in similar locations 
in both the Model S-61 and the S-58T MRS.
    On December 7, 1998, the FAA issued AD 98-26-02, Amendment 39-10943 
(63 FR 69177), Docket No. 96-SW-29-AD, for Sikorsky Model S-61A, D, E, 
L, N, NM, R, and V helicopters. AD 98-26-02 requires an NDI for cracks, 
replacing any unairworthy MRS with an airworthy MRS, appropriately 
marking the MRS by following Sikorsky Alert Service Bulletin (ASB) 
61B35-68, dated July 19, 1996, and making logbook entries. AD 98-26-02 
also establishes retirement lives of 1,500 hours TIS for unmodified MRS 
assemblies used in REL operations and 2,200 hours TIS for modified MRS 
assemblies used in REL operations. That action was prompted by four 
reports of cracks in helicopter MRSs used in REL operations. That 
condition, if not corrected, could result in MRS structural failure, 
loss of power to the main rotor, and subsequent loss of control of the 
helicopter.
    Since issuing AD 98-26-02, an investigation of REL operations 
revealed the REL mission profile parameters have changed significantly 
from those previously used to calculate the MRS retirement lives. The 
original MRS was certified by analysis in shaft bending only. Due to 
the service history, Sikorsky performed fatigue testing with Torque GAG 
cycles for both REL and Non-REL spectrums. The results of the fatigue 
testing with torque GAG cycles prompted changes in certain life limits. 
This information has led to the need for new retirement criteria for 
MRSs used in both REL and non-REL operations.

[[Page 21557]]

    Sikorsky has issued Customer Service Notice (CSN) No. 6135-10A and 
Sikorsky Service Bulletin (SB) No. 61B35-53A, both dated April 19, 
2004. The CSN and the SB apply to Model S-61L, N, and NM (serial number 
(S/N) 61454), and R series transport category helicopters; and S-61A, 
D, E, and V series restricted category helicopters. The CSN specifies 
replacing the planetary assembly and MRS assembly attaching hardware 
with high strength hardware. The CSN also specifies reworking the dowel 
retainer to increase hole chamfer and related countersink diameters. 
The SB specifies replacing the existing planetary matching plates with 
new steel matching plates during overhaul at the operator's discretion.
    Also, Sikorsky has issued ASB No. 61B35-69, dated April 19, 2004 
(ASB 61B35-69), which supersedes ASB 61B35-68B. ASB 61B35-69 provides 
updated procedures for determining REL and Non-REL status, assigns new 
REL and Non-REL MRS retirement lives, and provides a method for marking 
the REL MRS.
    We have identified an unsafe condition that is likely to exist or 
develop on other Sikorsky model helicopters of these same type designs. 
Therefore, the proposed AD would supersede AD 98-26-02 to require the 
following:
     Within 10 hours TIS for certain part-numbered MRSs:
    [cir] Create a component history card or equivalent record.
    [cir] Count and, 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.
    [cir] If you do not have records of hours TIS on an individual MRS, 
substitute helicopter hours TIS.
     Determine whether the MRS is an REL or Non-REL MRS by 
using a 250-hour TIS moving average.
    [cir] Upon reaching 250 hours TIS, calculate the first moving 
average of lift cycles. If the calculation results in more than 6 lift 
cycles per hour TIS, the MRS is an REL MRS. If the calculation results 
in 6 or less lift cycles per hour TIS, the MRS is a Non-REL MRS. If you 
know only a portion of the number of the lift cycles during the 
previous 250 hours TIS, add that known number to a number calculated by 
multiplying the number of hours TIS for which you do not know the lift 
cycles by a factor of 30 to arrive at the accumulated number of lift 
cycles.
    [cir] If you determine the MRS is a Non-REL MRS based on the 
previous calculation of the 250-hour TIS moving average for lift 
cycles, thereafter at intervals of 50 hour TIS, recalculate the average 
lift cycles per hour TIS. If the calculation results in more than 6 
lift cycles per hour TIS, the MRS is an REL MRS. If the calculation 
results in 6 or less lift cycles per hour TIS, the MRS is a Non-REL 
MRS. If you know only a portion of the number of the lift cycles during 
the next interval of 50 hours TIS, add that known number to a number 
calculated by multiplying the number of hours TIS for which you do not 
know the lift cycles by a factor of 30 to arrive at the accumulated 
number of lift cycles for that interval.
    [cir] 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.
     Within 5 hours TIS after determining the MRS is an REL 
MRS, identify it as an REL MRS by etching ``REL'' on the outside 
diameter of the MRS near the part serial number.
     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.
     For each REL MRS, within 1,100 hours TIS, conduct an NDI 
for cracks in the MRS. If a crack is found, replace it with an 
airworthy MRS before further flight.
     Replace each MRS with an airworthy MRS on or before 
reaching the revised retirement life as follows:
    [cir] For an REL MRS that is not modified (unmodified REL MRS); 
establish a retirement life of 30,000 lift cycles or 1,500 hours TIS, 
whichever occurs first. Replace it on or before accumulating 30,000 
lift cycles or 1,500 hours TIS, whichever comes first. For an 
unmodified REL MRS installed on a helicopter on the effective date of 
this AD that has accumulated more than 30,000 lift cycles or 1,350 
hours TIS, replace it within 150 hours TIS or upon removal, whichever 
occurs first.
    [cir] For an REL MRS that is modified; establish a retirement life 
of 30,000 lift cycles or 5,000 hours TIS, whichever occurs first. 
Replace it on or before accumulating 30,000 lift cycles or 5,000 hours 
TIS, whichever comes first. For modified REL MRS installed on a 
helicopter on the effective date of this AD that has accumulated more 
than 30,000 lift cycles or 4,500 hours TIS, replace it within 500 hours 
TIS or upon removal, whichever occurs first.
    [cir] For a Non-REL MRS, reduce the retirement life to 13,000 hours 
TIS. For a Non-REL MRS installed on a helicopter on the effective date 
of this AD that has accumulated more than 11,500 but less than 40,500 
hours TIS, replace it within 1,500 hours TIS, or upon removal, 
whichever occurs first.
     Record the revised retirement life on the MRS component 
history card or equivalent record.
     Within 50 hours TIS, remove from service any MRS with 
oversized (0.8860'' or greater) dowel pin bores.

Do the actions by following the specified portions of the service 
information described previously.
    We estimate that this proposed AD would affect 60 helicopters of 
U.S. registry, and the NDI inspection, remarking, and replacing an MRS 
would take about 2.2 work hours per helicopter at an average labor rate 
of $80 per work hour. Required parts would cost about $50 for the 
supplies required for the NDI inspection and $47,438 for each MRS per 
helicopter. Based on these figures, we estimate the total cost impact 
of the proposed AD on U.S. operators to be $2,859,840, assuming, after 
an NDI, one MRS would be replaced on each helicopter in the fleet 
because of the revised life, cracks, or oversized dowel pin bores and 
the recordkeeping cost would be negligible.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. Additionally, 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 that the 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); 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 a draft economic evaluation of the estimated costs to 
comply with this proposed AD. See the AD docket to examine the draft 
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,

[[Page 21558]]

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, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by removing Amendment 39-10943 (63 FR 
69177, December 16, 1998), and by adding a new airworthiness directive 
(AD), to read as follows:

Sikorsky Aircraft Corporation; Croman Corporation; Carson 
Helicopters, Inc.; Glacier Helicopter; Robinson Aircrane, Inc.; and 
Siller Helicopters: Docket No. FAA-2008-0442. Directorate Identifier 
2007-SW-24-AD. Supersedes AD 98-26-02, Amendment 39-10943, Docket 
No. 96-SW-29-AD.

Applicability

    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.

Compliance

    Required as indicated.
    To prevent MRS structural failure, loss of power to the main 
rotor, and subsequent loss of control of the helicopter, do the 
following:
    (a) Within 10 hours time-in-service (TIS), unless done 
previously:
    (1) Create a component history card or equivalent record for 
each MRS.
    (2) Count and, at the end of each days 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.
    (3) If you do not have records of the hours TIS on an individual 
MRS, substitute the helicopter's hours TIS.
    (b) Determine whether the MRS is a repetitive external lift 
(REL) or Non-REL MRS operation by using a 250-hour TIS moving 
average.
    (1) Upon reaching 250 hours TIS, calculate the first moving 
average of lift cycles by following the instructions in Section I of 
Appendix I of this AD.
    (i) If the calculation results in more than 6 lift cycles per 
hour TIS, the MRS is an REL MRS.
    (ii) If the calculation results in 6 or less lift cycles per 
hour TIS, the MRS is a Non-REL MRS.
    (iii) If you know only a portion of the number of the lift 
cycles during the previous 250 hours TIS, add the known number to a 
number calculated by multiplying the number of hours TIS for which 
you do not know the lift cycles by a factor of 30 to arrive at the 
accumulated number of lift cycles for that interval. Then, calculate 
the lift cycles per hour TIS as described in paragraph (b)(1) of 
this AD.
    (2) If you determine the MRS is a Non-REL MRS based on the 
previous calculation of the 250-hour TIS moving average for lift 
cycles, thereafter at intervals of 50 hour TIS, recalculate the 
average lift cycles per hour TIS. Recalculate the average lift 
cycles by following the instructions in Section II of Appendix 1 of 
this AD.
    (i) If the calculation results in more than 6 lift cycles per 
hour TIS, the MRS is an REL MRS.
    (ii) If the calculation results in 6 or less lift cycles per 
hour TIS, the MRS is a Non-REL MRS.
    (iii) If you know only a portion of the number of the lift 
cycles during the next interval of 50 hours TIS, add the known 
number to a number calculated by multiplying the number of hours TIS 
for which you do not know the lift cycles by a factor of 30 to 
arrive at the accumulated number of lift cycles. Then, calculate the 
lift cycles per hour TIS as described in paragraph (b)(2) of this 
AD.
    (3) 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.

    Note 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. You can obtain this AOL from the manufacturer at 
the address stated in the ADDRESSES portion of this AD.

    (c) Within 5 hours TIS, after determining the MRS is an REL MRS, 
identify it as an REL MRS by etching ``REL'' on the outside diameter 
of the MRS near the part S/N. Identify the REL MRS by following the 
Accomplishment Instructions, paragraph 3.C., of Sikorsky Alert 
Service Bulletin 61B35-69, dated April 19, 2004 (ASB 61B35-69).
    (d) 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.
    (e) For each REL MRS, within 1,100 hours TIS, conduct a non-
destructive inspection (NDI) for cracks in the MRS. If a crack is 
found in an MRS, replace it with an airworthy MRS before further 
flight.
    (f) Replace each MRS with an airworthy MRS on or before reaching 
the revised retirement life as follows:
    (1) For an REL MRS that is not modified by following Sikorsky 
Customer Service Notice 6135-10, dated March 18, 1987, and Sikorsky 
ASB No. 61B35-53, dated December 2, 1981 (unmodified REL MRS); 
establish a retirement life of 30,000 lift cycles or 1,500 hours 
TIS, whichever occurs first. Replace it on or before accumulating 
30,000 lift cycles or 1,500 hours TIS, whichever comes first. For an 
unmodified REL MRS installed on a helicopter on the effective date 
of this AD that has accumulated more than 30,000 lift cycles or 
1,350 hours TIS, replace it within 150 hours TIS or upon removal, 
whichever occurs first.
    (2) For an REL MRS that is modified by following Sikorsky 
Customer Service Notice 6135-10, dated March 18, 1987, and Sikorsky 
ASB No. 61B35-53, dated December 2, 1981 (modified REL MRS); 
establish a retirement life of 30,000 lift cycles or 5,000 hours 
TIS, whichever occurs first. Replace it on or before accumulating 
30,000 lift cycles or 5,000 hours TIS, whichever comes first. For a 
modified REL MRS installed on a helicopter on the effective date of 
this AD that has accumulated more than 30,000 lift cycles or 4,500 
hours TIS, replace it within 500 hours TIS or upon removal, 
whichever occurs first.
    (3) For a Non-REL MRS, reduce the retirement life to 13,000 
hours TIS. For a Non-REL MRS installed on a helicopter on the 
effective date of this AD that has accumulated more than 11,500 but 
less than 40,500 hours TIS, replace it within 1,500 hours TIS, or 
upon removal, whichever occurs first. If the

    Note: non-REL MRS has accumulated more than 40,500 hours TIS, 
replace it on or before it reaches 42,000 hours TIS.

    (g) This AD establishes or revises the retirement lives of the 
MRS as indicated in paragraphs (f)(1) through (f)(3) of this AD.
    (h) Record the revised retirement life on the MRS component 
history card or equivalent record.
    (i) Within 50 hours TIS, remove from service any MRS with 
oversized (0.8860'' or greater diameter) dowel pin bores.

    Note 2: The Overhaul and Repair Instruction (ORI) Number 6135-
281, Part B, Step 5, or ORI 6137-041, Section III, Oversize Dowel 
Pin Bore Repair and identified on the flange as TS-281 or TS-041-3, 
pertains to the subject of this AD.


[[Page 21559]]


    (j) 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, FAA, 
ATTN: 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, for information 
about previously approved alternative methods of compliance.

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.

    Issued in Fort Worth, Texas, on April 10, 2008.
David A. Downey,
Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. E8-8642 Filed 4-21-08; 8:45 am]

BILLING CODE 4910-13-P
