[Federal Register Volume 60, Number 91 (Thursday, May 11, 1995)]
[Rules and Regulations]
[Pages 25124-25125]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11540]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-SW-03-AD; Amendment 39-9225; AD 95-10-08]
Airworthiness Directives; Bell Helicopter Textron, Inc.-
Manufactured Restricted Category Model UH-1A, UH-1B, UH-1E, UH-1F, UH-
1H, UH-1L, UH-1P, TH-1F, and TH-1L Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
-----------------------------------------------------------------------
SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to Bell Helicopter Textron, Inc. (BHTI)-manufactured
restricted category Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, UH-
1P, TH-1F, and TH-1L helicopters. This action requires verification
that the tail rotor control system is rigged in accordance with the
applicable maintenance manual; a fluorescent penetrant inspection for
cracks at the roots of the gear teeth on the pinion and gear of
affected 42-degree tail rotor drive gearbox assemblies (42-degree
gearboxes), and replacement of the 42-degree gearbox pinion or gear if
cracks are found; and, creation of a component history card to track
numbers of torque events. A torque event is defined as a takeoff or a
lift (internal or external). This amendment is prompted by 14 accidents
reported since 1979 in the United States and Canada related to failure
of the 42-degree gearbox. The actions specified in this AD are intended
to prevent failure of the 42-degree gearbox, loss of tail rotor
control, and subsequent loss of control of the helicopter.
DATES: Effective May 26, 1995.
Comments for inclusion in the Rules Docket must be received on or
before July 10, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Assistant Chief Counsel, Attention:
Rules Docket No. 95-SW-03-AD, 2601 Meacham Blvd., Room 663, Fort Worth,
Texas 76137.
FOR FURTHER INFORMATION CONTACT: Mr. Uday Garadi, Aerospace Engineer,
FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 2601
Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5157, fax
(817) 222-5959.
SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is
applicable to BHTI-manufactured restricted category Model UH-1A, UH-1B,
UH-1E, UH-1F, UH-1H, UH-1L, UH-1P, TH-1F, and TH-1L helicopters. There
have been 14 accidents reported since 1979 in the United States and
Canada, with the most recent accident occurring on August 31, 1994,
related to failure of the 42-degree gearbox. In operation, these
helicopters endure many more torque events than were originally
anticipated during the certification and fatigue-life substantiation
processes. This was confirmed by BHTI after bench test results
indicated that gear life is reduced when the helicopter is subjected to
repeated torque events. Obviously, operations at power and load levels
outside the gross weight and/or external cargo hook weight limits
specified in the flight manual (i.e., operations at power and load
levels in excess of those allowed by the operating limitations) will
accelerate drivetrain and/or structural component failure. The National
Transportation Safety Board (NTSB) has investigated these accidents and
issued a recommendation that operators should not exceed the
limitations stated in the rotorcraft flight manual. Obviously, the FAA
concurs with this recommendation. The 42-degree gearbox is an integral
part of the tail rotor drivetrain. Failure of the 42-degree gearbox
could lead to a complete loss of directional control. Due to the
criticality of the drivetrain and structural components in maintaining
control of the helicopter, and the short compliance time required, this
AD is being issued immediately to correct an unsafe condition. This
condition, if not corrected, could result in failure of the 42-degree
gearbox, loss of tail rotor control, and subsequent loss of control of
the helicopter.
Since an unsafe condition has been identified that is likely to
exist or develop on other BHTI-manufactured restricted category Model
UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, UH-1P, TH-1F, and TH-1L
helicopters of the same type design, this AD is being issued to prevent
failure of the 42-degree gearbox, loss of tail rotor control, and
subsequent loss of control of the helicopter. This AD requires, before
further flight, and thereafter, at intervals not to exceed 400 torque
events, disassembly of the affected 42-degree gearbox, part number (P/
N) 204-040-003-023 or -037, a fluorescent penetrant inspection for
cracks at the roots of the gear teeth on the pinion, P/N 204-040-500-
007 or -009, and gear, P/N 204-040-500-008 or -010, and replacement of
any unairworthy pinions or gears as necessary. This AD also requires
creation of a component history card to track the number of torque
events.
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
[[Page 25125]] 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, 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-03-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, 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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
to read as follows:
95-10-08 CALIFORNIA DEPARTMENT OF FORESTRY; ERICKSON AIR-CRANE CO.;
GARLICK HELICOPTERS; HAWKINS AND POWERS AVIATION, INC.;
INTERNATIONAL HELICOPTERS, INC.; SMITH HELICOPTERS; SOUTHWEST
FLORIDA AVIATION; WEST COAST FABRICATIONS; WESTERN INTERNATIONAL
AVIATION, INC.; WILLIAMS HELICOPTER TECHNOLOGY, INC.; AND, UNC
HELICOPTERS: Amendment 39-9225. Docket No. 95-SW-03-AD.
Applicability: Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L,
UH-1P, TH-1F, and TH-1L helicopters, with a 42-degree tail rotor
drive gearbox assembly (42-degree gearbox), part number (P/N) 204-
040-003-023, or -037, installed, certificated in the restricted
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 failure of the 42-degree gearbox, loss of tail rotor
control, and subsequent loss of control of the helicopter,
accomplish the following:
(a) Before further flight, after the effective date of this AD,
verify that the tail rotor control system is rigged in accordance
with the applicable maintenance manual.
(b) Before further flight, and thereafter at intervals not to
exceed 400 torque events, disassemble the affected 42-degree gearbox
and inspect for cracks at the roots of the gear teeth on the pinion,
P/N 204-040-500-007 or -009, and gear, P/N 204-040-500-008 or -010,
using a fluorescent penetrant inspection method in accordance with
the applicable maintenance manual. Only post emulsified fluorescent
penetrant inspection materials (Type I, Method B or D, Sensitivity
Level 3 or greater) are approved for use. A torque event is defined
as a takeoff or a lift (internal or external).
(c) If any crack is found at the roots of the gear teeth on the
pinion or gear, replace the pinion or gear with an airworthy pinion
or gear in accordance with the applicable maintenance manual.
(d) Create a component history card for the 42-degree gearbox.
Record the number of torque events on a daily basis.
(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, Rotorcraft Certification Office,
FAA, Rotorcraft Directorate. Operators shall submit their requests
through an FAA Principal Maintenance Inspector, who may concur or
comment and then send it to the Manager, Rotorcraft Certification
Office.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Rotorcraft 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) This amendment becomes effective on May 26, 1995.
Issued in Fort Worth, Texas, on May 4, 1995.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-11540 Filed 5-10-95; 8:45 am]
BILLING CODE 4910-13-P
