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,
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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 39AIRWORTHINESS 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 3910943 (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. FAA20080442. Directorate Identifier 2007SW24AD. Supersedes AD 982602, Amendment 3910943, Docket No. 96SW29AD.

Applicability

Model S61A, D, E, L, N, NM (serial number (S/N) 61454), R, V, CH3C, CH3E, HH3C, HH3E, SH3A, and SH3H helicopters with main rotor shaft (MRS), part number (P/N) S613520640001, S613520640 002, or S613723040001, 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 timeinservice (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 NonREL MRS operation by using a 250hour 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 NonREL 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 NonREL MRS based on the previous calculation of the 250hour 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 NonREL 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 250hour 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) CCS61AOL040005, 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 61B3569, dated April 19, 2004 (ASB 61B3569). (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 613510, dated March 18, 1987, and Sikorsky ASB No. 61B3553, 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 613510, dated March 18, 1987, and Sikorsky ASB No. 61B3553, 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 NonREL MRS, reduce the retirement life to 13,000 hours TIS. For a NonREL 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: nonREL 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 6137041, Section III, Oversize Dowel Pin Bore Repair and identified on the flange as TS281 or TS0413, pertains to the subject of this AD.
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(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,

FOR FURTHER INFORMATION CONTACT Jeffrey Lee, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 2387161, fax (781) 2387170.