Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
This document proposes superseding an existing airworthiness directive (AD) for Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters; and Southwest Florida Aviation Model SW204, SW204HP, SW205, and SW205A-1 helicopters, manufactured by Bell Helicopter Textron, Inc. (BHTI) for the Armed Forces of the United States. That AD currently requires updating the product identification, extending the application of the AD to other helicopter models, continuing the existing retirement time for certain main rotor tension-torsion (TT) straps, and adding the TT strap part numbers to the applicability. This action proposes to require removing certain serial-numbered TT straps from service, reduce the retirement life for other TT straps, and establish a retirement life in terms of calendar time in addition to hours time-in-service (TIS) for certain other affected TT straps. This action would also add two model helicopters to the applicability of the AD. This proposal is prompted by fatigue cracking in certain TT straps that have stainless steel filament windings and a determination that corrosion damage, which is related to calendar time, necessitates a calendar time retirement life for certain TT straps in addition to the retirement life based on hours TIS. This proposal is also prompted by fatigue cracking in other TT straps with encased thin stainless steel plates. These proposals are based on the service history of helicopters that are the same or similar in type design to the helicopters to which this AD would apply. The actions specified by the proposed AD are intended to prevent failure of a TT strap, loss of a main rotor blade, and subsequent loss of control of the helicopter.
Comments must be received on or before June 21, 2010.
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 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:
Michael Kohner, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 2601 Meacham Blvd., Fort Worth, Texas 76193, telephone (817) 222-5170, fax (817) 222-5783.End Further Info End Preamble Start Supplemental Information
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- 2010-0427, Directorate Identifier 2008-SW-72-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 our 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.
On July 31, 1980, we issued AD 80-17-09, Amendment 39-3876 (45 FR 54014, August 14, 1980), Docket No. 80-ASW-25. That AD required replacing certain TT straps on or before attaining 1,200 hours TIS or 24 months, whichever occurs first, for the BHTI Model 204B, 205A-1, 212, 214B, 214B-1, and the Model UH-1 series military surplus helicopters. That action was prompted by an offshore accident of a BHTI Model 212 helicopter in which a TT strap reportedly failed in flight after 2,140 hours TIS with resulting loss of the main rotor blade. The requirements of that AD were intended to prevent failure of a TT strap, loss of a main rotor blade, and subsequent loss of control of the helicopter.
On September 18, 2002, we issued AD 2002-20-01, Amendment 39-12895 (67 FR 61771, October 2, 2002), Docket No. 2001-SW-41-AD, for the restricted category Model HH-1K, SW204, SW204HP, SW205, SW205A-1, TH-1F, Start Printed Page 20934TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters to require updating the product identification, extending the applicability to other helicopter models, continuing the existing retirement time for certain TT straps, and adding the TT strap part numbers to the applicability. That action was prompted by the need to expand the applicability to additional restricted category helicopters and to add two part numbers to the applicability. The requirements of that AD are intended to prevent failure of a TT strap, loss of a main rotor blade, and subsequent loss of control of the helicopter. AD 2002-20-01 contains the requirements from AD 80-17-09 for the Model UH-1 series military surplus helicopters.
Since issuing AD 2002-20-01, we have determined that an unsafe condition exists if TT straps, BHTI part number (P/N) 204-012-112-5 or Bendix Energy Controls Co. (Bendix) P/N 2601399, with a serial number (S/N) of 41623 through 54362, or BHTI P/N 204-012-112-7 or Bendix P/N 2601400, with a S/N of 11415 or higher, are allowed to remain in service. These TT straps have stainless steel filament windings encased in a urethane cover and were manufactured using Caytur 21 as the urethane-curing accelerator. Caytur 21 contains chlorides which are retained in the urethane cover after cure resulting in corrosion problems with the encased steel wires. Those part-numbered TT straps made outside the affected S/N ranges were manufactured using a MOCA curing agent and do not pose the same aggravated corrosion problem.
An unsafe condition also exists if TT straps, P/N 204-011-113-1 or 204-012-112-1, are used beyond a certain number of hours TIS due to the possibility of fatigue cracks occurring in either the encased thin stainless steel plates or filament windings, respectively. These particular TT straps are of older designs and a reduced life in hours TIS is needed to preclude a fatigue failure. TT straps, P/N 204-011-113-1, have the encased stack of thin steel stainless plates. TT straps, P/N 204-012-112-1, have encased filament windings with a lower strength, smaller diameter wire and a different urethane coating which is more susceptible to react with the wire material than the other TT straps of the same design. Service history has shown that the retirement life for both TT straps, P/N 204-011-113-1 or 204-012-112-1, needs to be reduced.
We have also determined that an unsafe condition exists if certain other TT straps with encased stainless steel filament windings are allowed to remain in service beyond a specified calendar time or beyond a specified number of hours TIS. The calendar time retirement life is needed to prevent failure caused by corrosion. The hours TIS retirement life is needed to prevent a fatigue failure in the filament windings. In addition, a need exists to clarify the TT strap manufacturer, acknowledge the current Type Certificate owners, and add the model AH-1G and AH-1S helicopters to the applicability.
The previously described unsafe conditions are likely to exist or develop on other helicopters of the same type designs. Therefore, the proposed AD would supersede AD 2002-20-01 and require removing certain serial-numbered TT straps from service, replacing certain TT straps at specified intervals, revising the Airworthiness Limitations section of the maintenance manual or the Instructions for Continued Airworthiness (ICAs) by establishing new or maintaining current retirement lives for certain TT straps, and recording the life limit of the TT straps on the component history cards or equivalent records.
These proposed actions are based on the service history of certain TT straps manufactured with stainless steel filament windings or thin stainless steel plates encased in a urethane coating. TT strap failures have occurred in both types of TT straps. Some of the failures were attributed to undetected moisture penetration through the urethane coating which led to corrosion pitting in the stainless steel wires and subsequent fatigue failure of the TT strap. Other failures were attributed to fatigue cracking in the stainless steel plates or filament windings which led to a fatigue failure of the TT strap. A fatigue failure of the TT strap during flight will result in a loss of main rotor blade and subsequent loss of control of the helicopter.
We estimate that 716 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 8 work hours per helicopter to replace a set of TT straps (2 TT straps), and that the average labor rate is $85 per work hour. Required parts would cost approximately $12,500 for 2 TT straps. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $329,500, assuming that 25 TT strap sets (50 TT straps) would be replaced.
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 an 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, 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.Start List of Subjects
List of Subjects in 14 CFR Part 39End 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:
2. Section 39.13 is amended by removing Amendment 39-12895 (67 FR Start Printed Page 2093561771, October 2, 2002), and by adding a new airworthiness directive (AD), to read as follows:
Arrow Falcon Exporters, Inc. (previously Utah State University); California Department of Forestry; Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); Garlick Helicopters, Inc.; Global Helicopter Technology, Inc.; Hagglund Helicopters, LLC (previously Western International Aviation, Inc.); International Helicopters, Inc.; Precision Helicopters, LLC; Robinson Air Crane, Inc.; San Joaquin Helicopters (previously Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft (previously US Helicopters, Inc., UNC Helicopter, Inc., Southern Aero Corporation, and Wilco Aviation); Smith Helicopters; Southern Helicopter, Inc.; Southwest Florida Aviation International, Inc. (previously Jamie R. Hill and Southwest Florida Aviation); Tamarack Helicopters, Inc. (previously Ranger Helicopter Services, Inc.); US Helicopter, Inc. (previously UNC Helicopter, Inc.); West Coast Fabrication; and Williams Helicopter Corporation (previously Scott Paper Co.) Model AH-1G, AH-1S, HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P Helicopters; and Southwest Florida Aviation Model UH-1B (SW204 and SW204HP) and UH-1H (SW205) Helicopters: Docket No. FAA-2010-0427; Directorate Identifier 2008-SW-72-AD. Supersedes AD 2002-20-01, Amendment 39-12895, Docket No. 2001-SW-41-AD.
Applicability: Model AH-1G, AH-1S, HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters, with Bell Helicopter Textron, Inc. (BHTI) main rotor tension-torsion (TT) strap, part number (P/N) 204-011-113-1, 204-012-112-1. 204-012-112-5, 204-012-112-7, 204-012-122-1, 204-012-122-5, 204-310-101-101, or Bendix Energy Controls Co. (Bendix) P/N 2601139, 2601399, 2601400, or 2606650, installed, certificated in any category.
Compliance: Within 25 hours time-in-service (TIS), or one month, whichever occurs first, unless accomplished previously.
To prevent failure of a TT strap, loss of a main rotor blade, and subsequent loss of control of the helicopter, accomplish the following:
(a) Remove any TT strap, P/N 204-012-112-5 or 2601399, with a serial number (S/N) of 41623 through 54362, or P/N 204-012-112-7 or 2601400, with a S/N of 11415 or higher, and replace it with an airworthy TT strap. Any TT strap required to be removed in accordance with this paragraph is unairworthy and is not eligible for reinstallation on any helicopter.
(b) Remove any TT strap P/N that has been in service for the length of time or longer than the retirement life listed in Table 1 of this AD and replace it with an airworthy TT strap.
|204-011-113-1||200 hours TIS.|
|204-012-112-1||1,000 hours TIS.|
|204-012-112-5 or 2601399, S/N 1 through 41622||1,200 hours TIS or 24 months since the initial installation on any helicopter, whichever occurs first.|
|204-012-112-5 or 2601399, S/N 54363 and higher|
|204-012-112-7 or 2601400, S/N 1 through 11414|
(c) Revise the Airworthiness Limitations section of the maintenance manual or the Instructions for Continued Airworthiness (ICAs) by establishing or maintaining the current retirement life for each TT strap listed in Table 1 of this AD by marking pen and ink changes or inserting a copy of this AD into the maintenance manual or ICAs.
(d) Record the life limit for each TT strap listed in Table 1 of this AD on the component history cards or equivalent record.
(e) 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, Rotorcraft Directorate, Rotorcraft Certification Office, FAA, ATTN: Michael Kohner, Aviation Safety Engineer, 2601 Meacham Blvd., Fort Worth, Texas 76193, telephone (817) 222-5170, fax (817) 222-5783, for information about previously approved alternative methods of compliance.
(f) Special flight permits will not be issued.
Issued in Fort Worth, Texas, on April 14, 2010.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2010-9293 Filed 4-21-10; 8:45 am]
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