[Federal Register Volume 60, Number 91 (Thursday, May 11, 1995)]
[Rules and Regulations]
[Pages 25122-25124]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11541]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-SW-02-AD; Amendment 39-9224; AD 95-10-07]


Airworthiness Directives; Bell Helicopter Textron, Inc. Model 
205A, 205A-1, and 204B Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Bell Helicopter Textron, Inc. (BHTI) Model 205A, 205A-
1, and 204B 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 the 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 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-02-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 Model 205A, 205A-1, and 204B helicopters. There have 
been 14 accidents reported since 1979 in the United States and Canada, 
with [[Page 25123]] the most recent accident occurring on August 31, 
1994, related to failure of the 42-degree gearbox. In operation, these 
helicopters undergo 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 
also accelerate drivetrain 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 Model 205A, 205A-1, and 204B 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 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-02-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:

95-10-07  Bell Helicopter Textron, Inc.: Amendment 39-9224. Docket 
No. 95-SW-02-AD.

    Applicability: Model 205A, 205A-1, and 204B 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 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 failure of the 42-degree gearbox, loss of tail rotor 
control, and subsequent loss [[Page 25124]] 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. 95-11541 Filed 5-10-95; 8:45 am]
BILLING CODE 4910-13-P