Airworthiness Directives; Hiller Aircraft Corporation Model UH- 12A, UH-12B, UH-12C, UH-12D, and UH-12E Helicopters

[Federal Register Volume 60, Number 110 (Thursday, June 8, 1995)] [Rules and Regulations] [Pages 30184-30186] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 95-13410]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-SW-13-AD; Amendment 39-9252; AD 95-12-02]

Airworthiness Directives; Hiller Aircraft Corporation Model UH- 12A, UH-12B, UH-12C, UH-12D, and UH-12E Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that is applicable to Hiller Aircraft Corporation (Hiller) Model UH-12A, UH- 12B, UH- [[Page 30185]] 12C, UH-12D, and UH-12E helicopters. This action requires a dye-penetrant inspection of the head of the main rotor outboard tension-torsion (T-T) bar pin for cracks; a visual inspection of the outboard T-T bar pin for proper alignment, and an adjustment, if necessary; and, installation of shims at the inboard end of the drag strut. This amendment is prompted by two accidents involving failure of the outboard T-T bar pin on Hiller UH-12E helicopters. The actions specified by this AD are intended to prevent cracks in the head area of the outboard T-T bar pin, which could result in loss of in-plane stability of the main rotor blade and subsequent loss of control of the helicopter.

DATES: Effective on June 23, 1995. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of June 23, 1995. Comments for inclusion in the Rules Docket must be received on or before August 7, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Assistant Chief Counsel, Attention: Rules Docket No. 95-SW-13-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. The service information referenced in this AD may be obtained from Hiller Aircraft Corporation, 7980 Enterprise Drive, Newark, California 94560-3497. This information may be examined at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Charles Matheis, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., Lakewood, California 90712-4137, telephone (310) 627- 5235, fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is applicable to Hiller Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters. This AD is prompted by two accidents, both involving Model UH-12E helicopters, in which failure of the outboard T-T bar pin, part number (P/N) 51452, was subsequently determined to be the cause of the accidents. The Hiller Model UH-12E helicopter main rotor system design is similar to the main rotor system design of the Hiller Model UH-12A, UH-12B, UH-12C, and UH-12D helicopters. The outboard T-T bar pin extends from the main rotor blade root fork and serves as an attachment point for the inboard end of the main rotor blade drag strut. The drag strut fixes the in-plane stability of the main rotor blade and transfers the drag forces applied by the main rotor blade to the main rotor hub. The National Transportation Safety Board (NTSB) issued Safety Recommendation A-94-189, dated November 30, 1994, which states that both failures resulted from fatigue cracks that originated from the bolt through-hole of an outboard T-T bar pin. The NTSB investigation revealed that improper alignment and excessive play between the outboard T-T bar pin and the inboard end of the drag strut can introduce large operating stresses in the head of the outboard T-T bar pin. A fracture of the outboard T-T bar pin allows the main rotor blade to rotate freely about the blade hub, resulting in a loss of in-plane stability. Any cracks in the head of the outboard T-T bar pin create an unsafe condition. Due to the criticality of the outboard T-T bar pin in maintaining main rotor blade stability, and the relatively short compliance time, this AD is being issued immediately to correct an unsafe condition. The actions required by this AD include an inspection for cracks in the head of the outboard T-T bar pin using a dye- penetrant inspection method; an inspection to ensure the proper alignment of the outboard T-T bar pin; and, the installation of shims between the inboard end of the drag strut and the outboard T-T bar pin. The FAA has determined that correcting any misalignment can reduce large stresses, and can therefore reduce the likelihood of cracking the head of the outboard T-T bar pin. That condition, if not corrected, could result in loss of in-plane stability of the main rotor blade and subsequent loss of control of the helicopter. The FAA has reviewed Hiller Aviation Service Bulletin (SB) No. 51- 9, dated April 8, 1983, which describes procedures for the installation of shims between the inboard end of the drag strut and the outboard T-T bar pin; and Hiller Aviation Service Letter (SL) 51-2, dated March 31, 1978, which describes procedures for an inspection to ensure proper alignment of the outboard T-T bar pin, and an inspection of the head of the outboard T-T bar pin for cracks using a dye-penetrant inspection method. The FAA has determined that the compliance times prescribed in those service documents are not adequate to ensure safety of flight, and is revising those compliance times in this AD. Since an unsafe condition has been identified that is likely to exist or develop on other Hiller Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters of the same type design, this AD is being issued to prevent cracks in the head area of the outboard T-T bar pin. This AD requires, within 25 hours time-in-service (TIS) or at the next 100 hours TIS inspection, whichever occurs first, and thereafter at intervals not to exceed 100 hours TIS: (1) an inspection of the alignment of the outboard T-T bar pin and an adjustment, if necessary; and (2) an inspection for cracks in the head of the outboard T-T bar pin using a dye penetrant inspection method. Additionally, this AD requires, within 25 hours TIS or at the next 100 hours TIS inspection, whichever occurs first, the installation of shims between the inboard end of the drag strut and the outboard T-T bar pin. The procedures to perform these actions are required to be accomplished in accordance with the service bulletin and service letter described previously, but in accordance with the compliance times stated in this AD. Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

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, [[Page 30186]] 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 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. 95-SW-13-AD.'' The postcard will be date stamped and returned to the commenter. The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR section 11.89.

Sec. 39.13 [Amended]

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

95-12-02 Hiller Aircraft Corporation: Amendment 39-9252. Docket No. 95-SW-13-AD.

Applicability: Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters, 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 (e) 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 cracks in the head area of the main rotor outboard tension-torsion (T-T) bar pin, which could result in loss of in- plane stability of the main rotor blade and subsequent loss of control of the helicopter, accomplish the following: (a) Within 25 hours time-in-service (TIS) after the effective date of this AD, or at the next 100 hours TIS inspection, whichever occurs first, and thereafter at intervals not to exceed 100 hours TIS, inspect the alignment of the outboard T-T bar pin, part number (P/N) 51452, and adjust the alignment, if necessary, in accordance with Hiller Aviation Service Letter (SL) 51-2, dated March 31, 1978. (b) Inspect the head of the outboard T-T bar pin for cracks using a dye-penetrant inspection method. (c) Report the results of the dye-penetrant inspections required by paragraph (b) of this AD within 7 days following each inspection to the Manager, Los Angeles Aircraft Certification Office, Attention: Charles Matheis, ANM-120L, 3960 Paramount Blvd., Lakewood, California 90712-4137. Include the helicopter model number, serial number, and total TIS of the outboard T-T bar pin in the report. Reporting requirements have been approved by the Office of Management and Budget and assigned OMB control number 2120-0056. (d) Within 25 hours TIS after the effective date of this AD, or at the next 100 hours TIS inspection, whichever occurs first, install shims between the inboard end of the drag strut and the outboard T-T bar pin in accordance with the Accomplishment Instructions of Hiller Aviation Service Bulletin No. 51-9, dated April 8, 1983. (e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Los Angles 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, Los Angeles 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 Los Angeles Aircraft Certification Office.

(f) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR sections 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished. (g) The inspections, modifications, and adjustments, if necessary, shall be done in accordance with Hiller Aviation Service Bulletin No. 51-9, dated April 8, 1983, and Hiller Aviation Service Letter 51-2, dated March 31, 1978. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Hiller Aircraft Corporation, 7980 Enterprise Drive, Newark, California 94560-3497. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC. (h) This amendment becomes effective on June 23, 1995.

Issued in Fort Worth, Texas, on May 25, 1995. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 95-13410 Filed 6-7-95; 8:45 am] BILLING CODE 4910-13-P