Airworthiness Directives; Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH- 55A Series Helicopters

[Federal Register Volume 61, Number 211 (Wednesday, October 30, 1996)] [Proposed Rules] [Pages 55937-55939] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 96-27755]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-10-AD]

Airworthiness Directives; Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH- 55A Series Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH- 55A series helicopters. This proposal would require a visual inspection of the bond line between the main rotor blade (blade) abrasion strip (abrasion strip) and the blade for voids, separation, or lifting of the abrasion strip; a visual inspection of the adhesive bead around the perimeter of the abrasion strip for erosion, cracks, or blisters; a tap (ring) test of the blade abrasion strip for evidence of debonding or hidden corrosion voids; and removal of any blade with an unairworthy abrasion strip and replacement with an airworthy blade. This proposal is prompted by four reports that indicate that debonding and corrosion have occurred on certain blades where the blade abrasion strip attaches to the blade skin. The actions specified by the proposed AD are intended to prevent loss of the abrasion strip from the blade and subsequent loss of control of the helicopter.

DATES: Comments must be received by December 30, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-SW-10-AD, 2601

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Meacham Blvd., Room 663, Fort Worth, Texas 76137. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Mr. Jeff Casale, Aerospace Engineer, FAA, New York Aircraft Certification Office, Airframe and Propulsion Branch, Engine and Propeller Directorate, 10 Fifth Street, 3rd Floor, Valley Stream, New York 11581-1200, telephone (516) 256-7521, fax (516) 568-2716.

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. 96-SW-10-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 Assistant Chief Counsel, Attention: Rules Docket No. 96-SW-10-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

Discussion

This document proposes to adopt a new airworthiness directive (AD) that is applicable to certain serial-numbered main rotor blades installed on Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH-55A series helicopters. Reports indicate that debonding and corrosion have occurred on certain main rotor blades where the main rotor blade abrasion strip attaches to the main rotor blade skin. This condition, if not corrected, could result in loss of the abrasion strip from the main rotor blade and subsequent loss of control of the helicopter. The FAA has reviewed Schweizer Service Bulletin (SB) B-259.1, dated August 22, 1995, for the Model 269A, 269A-1, 269B, 269C, and TH-55A series helicopters, and SB DB-001.1, dated August 22, 1995, for the Model 269D series helicopters, which describe procedures for a visual inspection of the bond line between the abrasion strip and the main rotor blade for voids, separation, or lifting of the abrasion strip; a visual inspection of the adhesive bead around the perimeter of the abrasion strip for erosion, cracks, or blisters; a tap (ring) test of the blade abrasion strip for evidence of debonding or hidden corrosion voids; and removal of any blade with a defective abrasion strip for return to Schweizer Aircraft Corporation or an FAA-approved repair facility for repair. If any deterioration of the abrasion strip adhesive bead is discovered, the service bulletins prescribe restoration of the bead in accordance with the applicable maintenance manual. If an abrasion strip void is found or suspected, the blade must be removed and may be returned to Schweizer Aircraft Corporation or an FAA-approved repair facility for repair. Since an unsafe condition has been identified that is likely to exist or develop on other Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH-55A series helicopters of the same type design, the proposed AD would require, on each blade, a visual inspection of the bond line between the abrasion strip and the main rotor blade for voids, separation, or lifting of the abrasion strip; a visual inspection of the adhesive bead around the perimeter of the abrasion strip for erosion, cracks, or blisters; a tap (ring) test of the blade abrasion strip for evidence of debonding or hidden corrosion voids; and removal of any blade with a defective abrasion strip and replacement with an airworthy blade. If any deterioration of the abrasion strip adhesive bead is discovered, restoration of the bead in accordance with the applicable maintenance manual is proposed. If an abrasion strip void is found or suspected, removing and replacing the blade with an airworthy blade is proposed. The FAA estimates that 100 helicopters of U.S. registry would be affected by this proposed AD, that it would take approximately one- third of a work hour per helicopter to conduct the initial inspections; approximately one-third of a work hour to conduct the repetitive inspections; approximately 11 work hours to remove and reinstall a blade; and approximately 32 work hours to repair the blade; and that the average labor rate is $60 per work hour. Required parts (replacement abrasion strips) would cost approximately $57 per main rotor blade abrasion strip (each helicopter has three main rotor blades). Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $135,850 per year for the first year and $133,850 for each year thereafter, assuming one-sixth of the affected blades in the fleet are removed, repaired, and reinstalled each year, and that all affected helicopters are subjected to one repetitive inspection each year. The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 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

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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 USC 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

Schweizer Aircraft Corporation and Hughes Helicopters, Inc.: Docket No. 96-SW-10-AD.

Applicability: Model 269A, 269A-1, 269B, and TH-55A series helicopters with main rotor blades, part number (P/N) 269A1190-1, serial numbers (S/N) S0001 through S0012 installed; and Model 269C and Model 269D series helicopters with main rotor blades, P/N 269A1185-1, S/N S222, S312, S313, S325 through S327, S339, S341, S343, S346, S347, S349 through S367, S369 through S377, S379 through S391, S393 through S395, S397, S399, S401 through S417, S419 through S424, S426 through S449, S451 through S507, S509 through S513, S516 through S527, S529 through S540, S542, S544 through S560, S562 through S584, S586 through S595, S597 though S611, S620 through S623, S625, S628, S633, S641 through S644, S646, S653, S658, S664, S665, and S667, 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 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 use the authority provided in paragraph (d) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously. To prevent loss of the abrasion strip from the main rotor blade and subsequent loss of control of the helicopter, accomplish the following: (a) Within the next 50 hours time-in-service (TIS), or within 90 calendar days after the effective date of this AD, whichever is earlier, or prior to installing an affected replacement main rotor blade, and thereafter at intervals not to exceed 50 hours TIS from the date of the last inspection or replacement installation: (1) Visually inspect the adhesive bead around the perimeter of each main rotor blade abrasion strip for erosion, cracks, or blisters. (2) Visually inspect the bond line between each abrasion strip and each main rotor blade skin for voids, separation, or lifting of the abrasion strip. (3) Inspect each main rotor blade abrasion strip for debonding or hidden corrosion voids using a tap (ring) test as described in the applicable maintenance manual. (b) If any deterioration of an abrasion strip adhesive bead is discovered, prior to further flight, restore the bead in accordance with the applicable maintenance manual. (c) If abrasion strip debonding, separation, or a hidden corrosion void is found or suspected, prior to further flight, remove the blade with the defective abrasion strip and replace it with an airworthy blade. (d) 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, New York Aircraft 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, New York Aircraft Certification Office.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York Aircraft Certification Office.

(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished, provided the abrasion strip has not started to separate or debond from the main rotor blade.

Issued in Fort Worth, Texas, on October 22, 1996. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 96-27755 Filed 10-29-96; 8:45 am] BILLING CODE 4910-13-P