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Proposed Rule

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

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Start Preamble Start Printed Page 21556

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.

Start Further Info

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.

End Further Info End Preamble Start Supplemental Information

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. Start Printed 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:

○ Create a component history card or equivalent record.

○ 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.

○ 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.

○ 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.

○ 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.

○ 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:

○ 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.

○ 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.

○ 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, Start Printed Page 21558Section 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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

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:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[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.

Start Printed 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.

Start Signature

Issued in Fort Worth, Texas, on April 10, 2008.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

End Signature
End Part End Supplemental Information

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

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