[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would require the same inspections as the superseded AD, but would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