Airworthiness Directives; Bell Helicopter Textron Inc.-Manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) applicable to Bell Helicopter Textron Inc. (BHTI)-manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 helicopters. This AD would require removing and replacing certain main rotor mast (mast) assemblies. This proposal is prompted by the crash of a BHTI-manufactured Model UH-1B due to failure of a thin-wall mast installed on the helicopter. The actions specified by the proposed AD are intended to prevent fatigue failure of the mast and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before May 8, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-01-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

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

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2000-SW-01-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2000-SW-01-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

Discussion

This document proposes the adoption of a new airworthiness directive (AD) for BHTI-manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 helicopters. This AD would require removing any mast assembly, part number (P/N) 204-011-450-001 or -005, and replacing it with an airworthy mast assembly. This proposal is prompted by the crash of a BHTI-manufactured Model UH-1B due to failure of a thin-wall mast assembly, P/N 204-011-450-001, as the result of undetected fatigue cracking in the stabilizer bar damper spline. Metallurgical examination of the failed part by the National Transportation Safety Board (NTSB) Materials Laboratory revealed fatigue features on the crack faces adjacent to the upper groove on the stabilizer bar damper splice. Several other cracks were noted in the same area during visual examination. The mast was reported to have accumulated 4006 hours time-in-service. As a result of the accident investigation, the NTSB recommended among other things that the FAA issue an AD requiring that “thin-walled” rotor masts be replaced with “thick-walled” rotor masts. The FAA agrees with this recommendation. This condition, if not corrected, could result in fatigue failure of the mast and subsequent loss of control of the helicopter.

The FAA has reviewed Garlick Helicopters, Inc. Service Bulletin UH1-97-06, dated September 26, 1997, which describes procedures for removing all mast tubes, P/N 204-011-450-001, from service for Garlick's type-certificated Model HH-1K, TH-1F, TH-1L, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters. The service bulletin also establishes a maximum torque event cycle count of 300,000 for the P/N 204-011-450 (all other dashes) mast tube.

Since an unsafe condition has been identified that is likely to exist or develop on other Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 helicopters of the same type designs, the proposed AD would require removing any mast assembly, P/N 204-011-450-001 or -005, from service and replacing it with an airworthy mast assembly.

The FAA estimates that 75 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately 10 work hours per helicopter to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Replacing a mast assembly would cost approximately $8,862. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $709,650 to replace all the masts in the fleet.

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

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.