AD 95-03-13

This amendment supersedes an existing airworthiness directive (AD), applicable to McDonnell Douglas Helicopter Company and Hughes Helicopters, Inc. Model 369 and OH-6A series helicopters with certain main rotor (M/R) blade assemblies or certain M/R hub lead-lag assemblies installed, that currently requires repetitive inspections and checks for cracks. This amendment requires the same inspections as the superseded AD, but would eliminate pilot checks, expand the areas of inspection, and require the application of slippage marks on each M/R blade root fitting lug and related bushings. This amendment is prompted by additional reports of cracks in the M/R blade root fittings, lugs, and adjacent blade skin, and movement of the root fitting bushings. The actions specified by this AD are intended to prevent failure of a M/R blade assembly or a M/R hub lead-lag link assembly, loss of a M/R blade, and subsequent loss of control of the helicopter.

Final rule

95-03-13 McDONNELL DOUGLAS HELICOPTER SYSTEMS and HUGHES HELICOPTERS, INC.: Amendment 39-9149. Docket No. 94-SW-05-AD. Supersedes AD 91-17-04, Amendment 39-8003.

Applicability: Model 369 and OH-6A series helicopters, with any of the following parts installed:

(1) Main rotor (M/R) blade assembly (blade assembly), part number (P/N) 369A1100-BSC, -501, -503, -505, -601, or -603; 369D21100-BSC, -503, -505, -507, -509, -511, -513, or -515; 369D21102-BSC or -501; or

(2) M/R hub lead-lag link assembly (lead-lag link assembly), P/N 369A1203-BSC, -3, or -11; 369H1203-BSC, -11, -21, or -31, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of a M/R blade assembly or a M/R hub lead-lag link assembly, loss of a M/R 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, and thereafter at intervals not to exceed 100 hours TIS from the last inspection, remove each blade assembly from the helicopter and accomplish the following:

(1) Inspect the attachment lugs of the M/R blade root fittings (root fittings) and the M/R lead-lag links (links) for cracks and the lug bushings (bushings) for looseness. Conduct the inspections in accordance with paragraph (b) of Part I of McDonnell Douglas Helicopter Company Service Information Notice HN-211.4, DN-51.6, EN-42.4, FN-31.4 (SIN), dated January 27, 1993.

(2) Visually inspect the following for cracks--
(i) The root fittings around the blade attachment lugs; and,
(ii) The M/R blade doubler and blade skin adjacent to the root fittings.

(3) Mark the root fittings and bushings with slippage marks in accordance with paragraph (e) of Part I of the SIN, dated January 27, 1993, if the slippage marks are degraded or missing.

(4) Replace any M/R blades or links found to be cracked or to have loose bushings withairworthy parts before further flight.

(b) Within 25 hours TIS after compliance with the requirements of paragraph (a) of this AD, and thereafter at intervals not to exceed 25 hours TIS from the last inspection, accomplish the following without removing the M/R blade:

(1) Visually inspect the root fittings and links for cracks or loose bushings in accordance with Part II of the SIN, dated January 27, 1993.

(2) Replace any M/R blades or links found to be cracked or to have loose bushings with airworthy parts before further flight.

(c) 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 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: 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.

(d) 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.

(e) The inspections and replacements, if necessary, shall be done in accordance with McDonnell Douglas Helicopter Company Service Information Notice No. HN-211.4, DN-51.6, EN-42.4, FN-31.4, dated January 27, 1993. 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 McDonnell Douglas Helicopter Systems, Technical Publications, Bldg. 530/B111, 5000 E. McDowell Road, Mesa, Arizona 85205-9797. 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.

(f) This amendment becomes effective on March 21, 1995.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 91-17-04, Amendment 39-8003 (56 FR 42230, August 27, 1991), which is applicable to McDonnell Douglas Helicopter Systems and Hughes Helicopters, Inc. Model 369 and OH-6A series helicopters with certain main rotor (M/R) blade assemblies or certain M/R hub lead-lag assemblies installed, was published in the Federal Register on July 21, 1994 (59 FR 37185). That action proposed to require application of a slippage mark on each M/R blade root fitting lug and related bushings to detect movement within 25 hours time-in-service (TIS). In addition, that action proposed to require, within 25 hours TIS after the effective date of the AD and thereafter at intervals not to exceed 100 hours TIS from the last inspection, that the M/R blade assembly be removed and that the M/R blade root fittings (root fittings), root fitting lugs, lead-lag lugs, the M/R blade skin, andthe doublers adjacent to the root fittings be inspected for cracks. That action also proposed that the lug bushings be inspected for looseness and slippage, and that slippage marks be applied if not already present. Visual inspections of the root fittings and M/R lead-lag links for cracks and inspection of the bushing slippage marks for movement, without removing the M/R blade, were also proposed at intervals not to exceed 25 hours TIS.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for editorial changes and a change in the manufacturer's name from McDonnell Douglas Helicopter Company to McDonnell Douglas Helicopter Systems. Additionally, the FAA has revised the average labor rate from $55 per work hour to $60 per work hour, which raises the estimated total cost impact of the AD to $1,320,000. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 1,000 helicopters of U.S. registry will be affected by this AD, that it will take approximately 22 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,320,000.

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 FederalismAssessment.

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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [Amended]
2. Section 39.13 is amended by removing Amendment 39-8003 (56 FR 42230, August 27, 1991), and by adding a new airworthiness directive (AD), Amendment 39-9149, to read as follows: