AD 97-20-15

This amendment supersedes an existing airworthiness directive (AD), applicable to Hiller Aircraft Corporation Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters, that currently 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 requires the same actions required by the existing AD, but allows a magnetic particle inspection of the T-T bar pin as an alternative to the currently required dye penetrant inspection, and requires reporting the results of the inspections only if cracks are found, rather than reporting all results of inspections as required by the existing AD. This amendment is prompted by an FAA analysis of a comment to the existing AD, and the fact that no cracks have been reported since the issuance of the existing AD. 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.

Final rule

97-20-15 HILLER AIRCRAFT CORPORATION: Amendment 39-10151. Docket No. 96-SW-32-AD. Supersedes AD 95-12-02, Amendment 39-9252.

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 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 hour 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) Within 25 hours TIS after the effective date of this AD, or at the next 100 hour inspection, whichever occurs first, and thereafterat intervals not to exceed 100 hours TIS, inspect the head of the outboard T-T bar pin for cracks using a dye penetrant or magnetic particle inspection method.

(c) If a crack is found as a result of the inspection required by paragraph (b) of this AD, report the results within 7 working days following the 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 hour 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 if approved by the Manager, Los Angeles 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 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished.

(g) The adjustment of the alignment of the T-T bar pin shall be done in accordance with Hiller Aviation SL 51-2, dated March 31, 1978, and the installation of the shims shall be done in accordance with Hiller Aviation Service Bulletin No. 51-9, dated April 8, 1983. These incorporations by reference were approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 on June 23, 1995. Copies may be obtained from Hiller Aircraft Corporation, 3200 Imjin Road, Marina, California 93933-5101, telephone (408) 384-4500, fax (408) 883-3648. 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 November 12, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 95-12-02, Amendment 39-9252 (60 FR 30184), which is applicable to Hiller Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters, was published in the Federal Register on January 7, 1997 (62 FR 951). That action proposed to require (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 method or a magnetic particle method. Additionally, that action proposed to require, within 25 hours TIS or at the next 100 hour inspection, whichever occurs first, the installation of shims between the inboard end of the drag strut and the outboard T-T bar pin.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comment received.

The onecommenter states that AD 95-12-02 should be eliminated, and that the requirement to report results of each 100 hour TIS inspection to the FAA should be discontinued, unless a crack is found. The commenter states that they have not experienced a T-T bar pin failure in 30 years of service history, and that if the procedures in the manufacturer's service information is followed, the AD is not needed. The FAA concurs that the reporting of the inspection should be accomplished only if the inspection reveals a crack. However, the FAA does not concur that the AD should be eliminated. The National Transportation Safety Board recommended that the FAA issue an AD to make the requirements of the applicable service information mandatory. The FAA concurred, and issued AD 95-12-02. Based on an FAA analysis, the FAA has determined that the amendment will not be removed, but the reporting requirement will be changed.

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

The FAA estimates that 700 helicopters of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $700 per pin. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $574,000, assuming one pin must be replaced on every helicopter in the fleet.

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 preparationof a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by removing Amendment 39-9252 (60 FR 30184), and by adding a new airworthiness directive (AD), Amendment 39-10151, to read as follows: