[Federal Register Volume 59, Number 139 (Thursday, July 21, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17797]


[[Page Unknown]]

[Federal Register: July 21, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-SW-05-AD]

 

Airworthiness Directives: McDonnell Douglas Helicopter Company 
and Hughes Helicopters, Inc. Model 369 and OH-6A Series Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to McDonnell Douglas 
Helicopter Company and Hughes Helicopters, Inc. Model 369 and OH-6A 
series helicopters equipped with certain main rotor (M/R) blade 
assemblies or certain M/R hub lead-lag assemblies, that currently 
requires repetitive inspections and checks for cracks. This action 
would require the same inspections as the superseded AD, but would 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 to detect movement. This proposal 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 the proposed 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.

DATES: Comments must be received by September 6, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 94-SW-05-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137-4298. Comments may be inspected at this location between 
9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule may be 
obtained from McDonnell Douglas Helicopter Company, Technical 
Publications, Bldg 530/B111, 5000 E. McDowell Road, Mesa, Arizona 
85205-9797. This information may be examined at the FAA, Office of the 
Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Brent Bandley, Aerospace Engineer, 
Airframe Branch, ANM-123L, Northwest Mountain Region, Los Angeles 
Aircraft Certification Office, 3229 E. Spring Street, Long Beach, 
California 90806-2425, telephone (310) 988-5237, fax (310) 988-5210.

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 Number 94-SW-05-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. 94-SW-05-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137-4298.

Discussion

    On August 8, 1991, the FAA issued AD 91-17-04, Amendment 39-8003 
(56 FR 42230, August 27, 1991), to require initial and repetitive 
inspections and checks of certain main rotor (M/R) blade assemblies and 
M/R hub lead-lag link assemblies for fatigue cracks and for loose 
bushings in the M/R blade lead-lag link lugs (lead-lag lugs). That 
action was prompted by two incidents involving a cracked M/R blade root 
fitting lug (root fitting lug). Bushing movement in the M/R blade lead-
lag link lugs may have caused fatigue cracks in the lead lag link 
assemblies. The lead lag link assembly attaches to the M/R blade. Any 
cracks in the lead lag link assembly, the M/R blade, the MR blade root 
fitting, or any movement of the bushing, could create an unsafe 
condition. That condition, if not corrected, could result in 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.
    Since the issuance of that AD, additional incidents of cracks in 
the M/R blade root fitting (root fitting), and M/R blade skin have been 
reported. Additionally, the manufacturer has discovered that in some M/
R blade assemblies, the M/R blade root fitting bushing (bushing) can 
loosen and contribute to fretting-induced fatigue cracking in the root 
fitting lug. The root fittings and M/R blade skins are parts of the M/R 
blade assembly. Therefore, McDonnell Douglas Helicopter Company issued 
a revised Service Information Notice No. HN-211.4, DN-51.6, EN-42.4, 
and FN-31.4 (SIN), dated January 27, 1993, that requested operators 
mark each root fitting lug and bushing with a slippage mark and 
thereafter inspect for slippage on each root fitting lug and bushing. 
The revised SIN, dated January 27, 1993, includes the M/R blade 
assembly and M/R hub lead-lag link assembly inspections contained in 
the preceding versions of the SIN, dated August 5, 1991.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 91-17-04 to require application of a 
slippage mark on each root fitting lug and bushing within 25 hours' 
time-in-service (TIS). In addition, this proposal would require, within 
25 hours' TIS after the effective date of this AD and thereafter at 
intervals not to exceed 100 hours' TIS, that the M/R blade assembly be 
removed and that the root fittings, root fitting lugs, lead-lag lugs, 
the M/R blade skin, and the doublers adjacent to the root fitting be 
inspected for cracks. This AD proposal also requires that the bushings 
be inspected for looseness and slippage, and that slippage marks be 
applied if not already present. Visual inspections of the exposed M/R 
blade skin, root fittings, root fitting lugs, and lead-lag lugs for 
cracks and inspection of the bushing slippage marks for movement are 
also required at intervals not to exceed 25 hours' TIS. The FAA no 
longer allows pilots to perform checks such as those contained in AD 
91-17-04, paragraph (b). Therefore, a pilot would not be permitted to 
perform any of the proposed inspections in this AD.
    The FAA estimates that 1,000 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 22 work 
hours per helicopter to accomplish the proposed actions, and that the 
average labor rate is $55 per work hour. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be Sec. 1,210,000.
    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 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.


Sec. 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), to read as follows:

Mcdonnell Douglas Helicopter Company and Hughes Helicopters, Inc.: 
Docket No. 94-SW-05-AD. Supersedes AD 91-17-04, Amendment 39-8003.

    Applicability: Model 369 and OH-6A series helicopters, 
certificated in any category, equipped with any of the following 
parts: (1) Main rotor 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) Main rotor hub lead-lag link assembly (lead-lag link 
assembly), P/N 369A1203-BSC, -3, or -11; 369H1203-BSC, -11, -21, or 
-31.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent the failure of a main rotor blade assembly or a main 
rotor hub lead-lag link assembly, loss of a 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, 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 main rotor (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 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 with airworthy 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.

    Issued in Fort Worth, Texas, on June 14, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-17797 Filed 7-20-94; 8:45 am]
BILLING CODE 4910-13-P