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Airworthiness Directives; Bell Helicopter Textron, Inc. Model 204B, 205A, 205A-1, 205B, and 212 Helicopters

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Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

This document publishes in the Federal Register an amendment adopting superseding Airworthiness Directive (AD) 2000-15-52, which was sent previously to all known U.S. owners and operators of Bell Helicopter Textron, Inc. Model (BHTI) Model 204B, 205A, 205A-1, 205B, and 212 helicopters by individual letters. This AD reduces the retirement index number (RIN) life limit for the main rotor mast (mast); increases the RIN factor for masts and main rotor trunnions (trunnions); applies standard RIN factors for all external load lifts; and requires a one-time inspection of the snap ring groove area of the mast. This AD also establishes RIN factors for masts and trunnions that have been previously installed on military or restricted category helicopters and removes from service those masts that have been previously installed with a hub spring. This amendment is prompted by an occurrence of a cracked mast at a lower value than the established RIN life limit. The actions specified by this AD are intended to preclude the occurrence of fatigue Start Printed Page 77786cracks in the damper clamp splined area of a mast. A crack in the damper clamp splined area could result in failure of a mast or trunnion, separation of the main rotor system, and subsequent loss of control of the helicopter.

DATES:

Effective December 28, 2000, to all persons except those persons to whom it was made immediately effective by Emergency AD 2000-15-52, issued on July 25, 2000, which contained the requirements of this amendment.

Comments for inclusion in the Rules Docket must be received on or before February 12, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-28-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: 9-asw-adcomments@faa.gov.

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FOR FURTHER INFORMATION CONTACT:

Michael Kohner, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office, Fort Worth, Texas 76193-0170, telephone (817) 222-5447, fax (817) 222-5783.

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SUPPLEMENTARY INFORMATION:

On November 13, 1998, the FAA issued AD 98-24-15 (Amendment 39-10900 (63 FR 64612, November 23, 1998), Docket No. 97-SW-20-AD. That AD required establishing a RIN tracking system for mast and trunnion torque events; creating component history cards or equivalent records; converting accumulated factored flight hours to a baseline accumulated RIN count; establishing a system for tracking increases to the accumulated RIN; and establishing a maximum accumulated RIN for certain masts and trunnions. That action was prompted by an accident involving a BHTI Model 205A-1 helicopter in which a mast failure caused a separation of the main rotor from the helicopter. A subsequent metallurgical examination revealed that the mast had fractured as a result of fatigue. Analyses and fatigue testing conducted by the manufacturer and assessed by the FAA confirmed that the remaining lives of the mast and trunnion are more accurately assessed by monitoring the number of torque events and flight hours on the helicopter rather than by monitoring only flight hours.

The FAA superseded AD 98-24-15 by issuing Emergency AD 2000-08-52 (Docket No. 2000-SW-20) on April 21, 2000. AD 2000-08-52 required a one-time special inspection for certain serial-numbered masts to detect burrs or inadequate radii in the snap ring groove areas that can cause fatigue failure. That AD was issued as a result of an accident involving a BHTI Model 212 helicopter following in-flight separation of its main rotor system. The post-accident investigation revealed a fatigue failure in the damper clamp splined area of the mast, part number (P/N) 204-011-450-007. Also, operators reported at least five other failures in the damper clamp splined area of masts, P/N 204-011-450-001, -007, and -105, in either the upper or lower snap ring grooves. That AD also reduced the maximum allowable RIN life for each affected mast and changed the RIN counting procedure to require application of a standard RIN factor for all external load lifts regardless of altitude change and the type of load lifted. The RIN factor assessed for each torque event was increased for masts installed on BHTI Model 204B and 205B helicopters. The requirements of AD 98-24-15 pertaining to trunnions, P/N 204-011-105-001 and -103, were not changed by AD 2000-08-52.

After issuing AD 2000-08-52, the FAA received a report of another cracked mast. Metallurgical inspection revealed that the mast cracked as a result of fatigue in snap ring groove radii that were smaller than the 0.020 inch minimum allowable dimension. Detailed takeoff (1,249) and lift (16,339) event data for the entire life of the mast confirmed that the accumulated RIN count at the time the fatigue crack was detected was approximately 68,000 when calculated in accordance with the most recent RIN counting procedure as defined in AD 2000-08-52. The FAA concluded that several corrections to the RIN counting procedure are required based on a review of the fatigue data and previously issued AD's.

On July 25, 2000, the FAA issued Emergency AD 2000-15-52 for BHTI Model 204B, 205A, 205A-1, 205B, and 212 helicopters. That Emergency AD reduces the RIN life limit for the mast and trunnion; increases the RIN factor for the masts and trunnions; applies standard RIN factors for all external load lifts; and requires a one-time inspection of the snap ring groove area of the mast. That Emergency AD also establishes RIN factors for masts and trunnions that have been previously installed on military or restricted category helicopters and removes from service those masts that have been previously installed with a hub spring. That action was prompted by an occurrence of a cracked mast at a lower value than the established RIN life limit. This condition, if not corrected, could result in failure of a mast or trunnion, separation of the main rotor system, and subsequent loss of control of the helicopter.

Since the unsafe condition described is likely to exist or develop on other BHTI Model 204B, 205A, 205A-1, 205B, and 212 helicopters of the same type designs, the FAA issued Emergency AD 2000-15-52 to prevent failure of a mast or trunnion, separation of the main rotor system, and subsequent loss of control of the helicopter. The AD retains the following requirements from previously issued AD 2000-08-52:

  • Reduces the allowable RIN life limit established in AD 98-24-15 for masts, P/N 204-011-450-001, -007, -105, -113, and -119;
  • Increases the RIN factor assessed for each torque event for BHTI Model 204B and 205B helicopters;
  • Applies a standard RIN factor for all external load lifts regardless of altitude change and type of load lifted; and
  • Requires a one-time special inspection of certain S/N masts for inadequate radii and presence of burrs in the snap ring groove areas.

The Emergency AD differs from AD 2000-08-52 in that it:

  • Requires, before further flight, that the accumulated RIN for all mast and trunnion history prior to the implementation of RIN counting (required by AD 98-24-15) be corrected for inadequate factors used to calculate factored hours TIS and to convert factored flight hours to accumulated RIN;
  • Increases the RIN factor for each takeoff and external load lift for masts and trunnions installed on BHTI Model 204B, 205A, and 205A-1 helicopters to properly reflect the actual level of torque (horsepower rating) applied to the mast when it is installed in these helicopter models;
  • Expands the requirement for a one-time special inspection to detect inadequate radii and burrs in the snap ring grooves to include masts with S/N's 00000 through 52720, 61433 through 61444, and 61457 through 61465, regardless of prefix;
  • Establishes RIN factors for masts and trunnions that have been previously installed on military helicopters (BHTI-manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1C, UH-1D, UH-1E, UH-1F, UH-1G, UH-1H, UH-1L, UH-1M, UH-1N, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1) and restricted category helicopters (Firefly Aviation Helicopter Services (previously Erickson Air Crane Co.); Garlick Helicopters, Inc.; Hawkins and Powers Aviation, Inc.; International Start Printed Page 77787Helicopters, Inc.; Tamarack Helicopters, Inc. (previously Ranger Helicopter Services, Inc.); Robinson Air Crane, Inc.; Williams Helicopter Corporation (previously Scott Paper Co.); Smith Helicopters; Southern Helicopter, Inc.; Southwest Florida Aviation; Utah State University; Western International Aviation, Inc.; and U.S. Helicopter, Inc.).
  • Requires the immediate removal from service of any mast that has been previously installed with a hub spring.

The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity and controllability of the helicopter. Therefore, the actions previously stated are required at the specified time intervals, and this AD must be issued immediately.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on July 25, 2000 to all known U.S. owners and operators of BHTI Model 204B, 205A, 205A-1, 205B, and 212 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.

The FAA estimates that 147 helicopters of U.S. registry will be affected by this AD. It will take approximately 10 work hours per helicopter to remove and replace the mast, if necessary; 10 work hours to remove and replace the trunnion, if necessary; and 6 work hours to inspect the mast for proper radius or a burr. The approximate time necessary for calculating the accumulated RIN, revising the Airworthiness Limitations section of the maintenance manuals, and providing the information requested to the FAA is 15 work hours per helicopter. The average labor rate is $60 per work hour. Required parts will cost approximately $9,538 to replace a mast, if necessary, and $5,300 to replace a trunnion, if necessary. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,675,506 ($11,398 per helicopter, assuming one inspection, one mast replacement, not trunnion replacement, and that the helicopter's accumulated RIN is calculated, the maintenance manuals are revised, and the requested information is submitted to the FAA).

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2000-SW-28-AD.” The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

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List of Subjects in 14 CFR Part 39

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Adoption of the Amendment

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Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (

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PART 39—AIRWORTHINESS DIRECTIVES

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

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

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[Amended]
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2. Section 39.13 is amended by removing Amendment 39-10900 (

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2000-15-52 Bell Helicopter Textron Inc.: Amendment 39-12042. Docket No. 2000-SW-28-AD. Supersedes Emergency AD 2000-08-52, Docket No. 2000-SW-20-AD, and AD 98-24-15, Amendment 39-10900, Docket No. 97-SW-20-AD.

Applicability: Model 204B, 205A, 205A-1, 205B, and 212 helicopters, with main rotor mast (mast), part number (P/N) 204-011-450-001, -007, -105, -113, or -119, or main rotor trunnion (trunnion), P/N 204-011-105-001 or -103, installed, certificated in any category.

Note 1:

This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (i) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance

Required as indicated, unless accomplished previously.

Note 2:

This AD has new requirements which must be complied with even if AD's Start Printed Page 7778898-24-15 and 2000-08-52 have already been accomplished. This AD requires the recalculation of accumulated mast and trunnion RIN and increases the RIN factors for masts and trunnions installed on certain helicopter models. This AD also expands the S/N applicability for the one-time special inspection of the mast.

To prevent failure of a mast or trunnion, separation of the main rotor system, and subsequent loss of control of the helicopter, accomplish the following:

(a) Before further flight, determine the accumulated Retirement Index Number (RIN) in accordance with the Instructions in Appendix 1 of this AD for the mast and Appendix 2 of this AD for the trunnion. If the helicopter model installation history or hours time-in-service (TIS) of the mast or trunnion is unknown, remove the mast or trunnion from service and replace it with an airworthy mast or trunnion. If the mast has been installed on certain military helicopters (BHTI-manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1C, UH-1D, UH-1E, UH-1F, UH-1G, UH-1H, UH-1L, UH-1M, UH-1N, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, or SW205A-1) or restricted category helicopters (Firefly Aviation Helicopter Services (previously Erickson Air Crane Co.); Garlick Helicopters, Inc.; Hawkins and Powers Aviation, Inc.; International Helicopters, Inc.; Tamarack Helicopters, Inc. (previously Ranger Helicopter Services, Inc.); Robinson Air Crane, Inc.; Williams Helicopter Corporation (previously Scott Paper Co.); Smith Helicopters; Southern Helicopter, Inc.; Southwest Florida Aviation; Utah State University; Western International Aviation, Inc.; and U.S. Helicopter, Inc.) and you cannot verify that hub springs have not been installed, remove the mast from service and replace it with an airworthy mast.

(b) Before further flight, replace any mast, P/N 204-011-450-113 or 119, that has accumulated 240,000 or more RIN with an airworthy mast. Before further flight, replace any mast, P/N 204-011-450-001, -007, or -105, that has accumulated 265,000 or more RIN with an airworthy mast.

(c) Before further flight, replace any trunnion, P/N 204-011-105-103, that has accumulated 240,000 or more RIN with an airworthy trunnion. Before further flight, replace any trunnion, P/N 204-011-105-001, that has accumulated 265,000 or more RIN with an airworthy trunnion.

(d) Before reaching 100,000 RIN, inspect the upper and lower snap ring grooves in the damper clamp splined area of any mast with serial number (S/N) 00000 through 52720, S/N 61433 through 61444, and S/N 61457 through S/N 61465 (regardless of prefix) for:

(1) A minimum radius of 0.020 inches around the entire circumference (see Figures 1 through 3), using a 100x or higher magnification. If any snap ring groove radius is less than 0.020 inches, replace the mast with an airworthy mast prior to exceeding 100,000 RIN.

(2) A burr, using a 200x or higher magnification. If a burr is found in any snap ring groove/spline intersection, replace the mast with an airworthy mast prior to exceeding 170,000 RIN.

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(e) Continue to calculate the accumulated RIN for the mast by multiplying all takeoff and external load lifts by the RIN factors defined in columns (D) and (G) of Table 1 of Appendix 1 of this AD.

(f) Continue to calculate the accumulated RIN for the trunnion by multiplying all takeoff and external load lifts by the RIN factors defined in columns (D) and (G) of Table 1 of Appendix 2 of this AD.

(g) Before further flight, revise the Airworthiness Limitations section of the maintenance manuals for the masts and trunnions in accordance with Figure 4.

Mast and Trunnion Life Limits

Mast part No.Hours TIS life limitRIN life limitTrunnion part No.Hours TIS life limitRIN life limit
204-011-450-0016,000265,000204-011-105-00115,000265,000
204-011-450-00715,000265,000204-011-105-10313,000240,000
204-011-450-10515,000265,000
204-011-450-11313,000240,000
204-011-450-11913,000240,000

(h) Within 10 days after completing the inspections required by this AD, provide the information contained on the AD inspection report, sample format, contained in Appendix 3 of this AD and send it to the Manager, Rotorcraft Certification Office, Federal Aviation Administration, Fort Worth, Texas, 76193-0170, USA. Reporting requirements have been approved by the Office of Management and Budget and assigned OMB control number 2120-0056.

(i) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Rotorcraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, Rotorcraft Certification Office.

(j) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR Start Printed Page 7779221.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished.

(k) This amendment becomes effective on December 28, 2000, to all persons except those persons to whom it was made immediately effective by Emergency AD 2000-15-52, issued July 25, 2000, which contained the requirements of this amendment.

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APPENDIX 1

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APPENDIX 2

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Appendix 3—Ad Compliance Inspection Report

P/N 204-011-450-001/-007/-105/-113/-119 Main Rotor Mast

Provide the following information and mail or fax it to: Manager, Rotorcraft Certification Office, Federal Aviation Administration, Fort Worth, Texas, 76193-0170, USA Fax: 817-222-5783

Operator Name:

Aircraft Registration No:

Helicopter Model:

Helicopter S/N:

Mast P/N:

Mast S/N:

Mast RIN:

Mast Total TIS:

Inspection Results

Were any radii during inspection of this mast determined to be less than 0.020 inches? If yes, what was the dimension measured?

Was a burr found in the inspected snap ring grooves?

Were cracks noted during the inspection?

Who performed this inspection?

Provide any other comments?

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Issued in Fort Worth, Texas, on December 5, 2000.

Henry A. Armstrong,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

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