[Federal Register Volume 64, Number 220 (Tuesday, November 16, 1999)]
[Rules and Regulations]
[Pages 62105-62106]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-29612]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-55-AD; Amendment 39-11419; AD 99-23-23]
RIN 2120-AA64


Airworthiness Directives; Bell Helicopter Textron, Inc. Model 
412, 412EP and 412CF 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) 
applicable to Bell Helicopter Textron, Inc. (BHTI) Model 412, 412EP, 
and 412CF helicopters. This action requires inspecting and measuring 
the thickness of certain main rotor yoke assemblies. This AD also 
requires adding 500 hours time-in-service (TIS) to the total time for 
main rotor yoke assemblies that measure below 0.478-inch thickness and 
noting the measurement and added TIS on the component history card or 
equivalent record. This amendment is prompted by a report of an 
emergency landing due to severe main rotor vibration on a BHTI Model 
412 helicopter. Subsequent fatigue analysis indicates that the main 
rotor yoke assembly (yoke) does not have the anticipated service life 
when manufactured below 0.478-inch thickness. The actions specified in 
this AD are intended to prevent a fatigue failure of the yoke, loss of 
a main rotor blade, and subsequent loss of control of the helicopter.

DATES: Effective December 1, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 1, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before January 18, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-55-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.
    The service information referenced in this AD may be obtained from 
Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101, 
telephone (817) 280-3391, fax (817) 280-6466. This information may be 
examined at the FAA, Office of the Regional Counsel, Southwest Region, 
2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137; or at the Office 
of the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Michael Kohner, FAA, Rotorcraft 
Directorate, Rotorcraft Certification Office, 2601 Meacham Blvd., Fort 
Worth, Texas 76137, telephone (817) 222-5447, fax (817) 222-5783.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD applicable to 
BHTI Model 412, 412EP, and 412CF helicopters. This action requires 
inspecting and measuring each yoke, part number (P/N) 412-010-101-123 
or -127, installed on Model 412 and 412EP helicopters, serial numbers 
(S/N) 33001 through 33213, 34001 through 34036, and 36001 through 
36204; and on Model 412CF helicopters, S/N 46400 through 46499. If a 
yoke measures less than 0.478-inch thickness, this AD requires adding 
500 hours TIS to the total time for the component and noting the 
measurement and the increase in hours TIS on the component history card 
or equivalent record. This amendment is prompted by a report of an 
emergency landing due to severe main rotor vibration on a BHTI Model 
412 helicopter. Subsequent fatigue analysis indicates that a yoke does 
not have the anticipated service life when manufactured to less than a 
0.478-inch thickness. This condition, if not corrected could result in 
a fatigue failure of the yoke, loss of a main rotor blade, and 
subsequent loss of control of the helicopter.
    The FAA has reviewed BHTI Service Bulletins 412-98-93 and 412CF-98-
5, both dated March 2, 1998 (ASB), which describe procedures for 
inspecting and measuring certain yokes and imposing a flight-hour 
penalty of 500 hours TIS for yokes measuring less than 0.478-inch 
thickness.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other BHTI Model 412, 412EP, and 412CF helicopters 
of the same type design, this AD is being issued to prevent a fatigue 
failure of a yoke, loss of a main rotor blade, and subsequent loss of 
control of the helicopter. This AD requires inspecting and measuring 
each yoke, P/N 412-010-101-123 and -127, for thickness. The AD also 
requires noting on the component history card or equivalent record the 
thickness measurement and adding 500 hours TIS to the total time of any 
yoke that measures under 0.478-inch thickness. The actions are required 
to be accomplished in accordance with the applicable ASB described 
previously. The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, to prevent a fatigue 
failure of the yoke, this AD must be issued immediately.
    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.
    The FAA estimates that 149 helicopters will be affected by this AD, 
that it will take approximately 8 work hours to accomplish the 
measurement of the yoke thickness and to annotate the history card or 
equivalent component record, 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 $71,520.

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

[[Page 62106]]

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. 99-SW-55.'' 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, 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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

AD 99-23-23 Bell Helicopter Textron, Inc. Amendment 39-11419. Docket 
No. 99-SW-55-AD.

    Applicability: Model 412 or 412EP helicopters, serial numbers 
(S/N) 33001 through 33213, 34001 through 34036, and 36001 through 
36204, or Model 412CF helicopter, S/N 46400 through 46499, with main 
rotor yoke assembly (yoke), part number 412-010-101-123 or -127, 
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 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required within 10 hours time-in-service (TIS) for a 
yoke with 4,500 or more hours TIS or required within 90 days for a 
yoke with less than 4,500 hours TIS but prior to the accumulation of 
4,500 hours TIS, unless accomplished previously.
    To prevent a fatigue failure of a yoke, loss of a main rotor 
blade, and subsequent loss of control of the helicopter, accomplish 
the following:
    (a) Inspect and measure each yoke in accordance with the 
Accomplishment Instructions, paragraphs 1 through 6, of Bell 
Helicopter Textron, Inc. (BHTI), Alert Service Bulletin (ASB) 412-
98-93, applicable to the Model 412 and 412EP helicopters, or BHTI 
ASB 412CF-98-5, applicable to the Model 412CF helicopters, both 
dated March 2, 1998. If any measurement for a yoke is less than 
0.478-inch thickness, add 500 hours to the TIS indicated on the 
component history card or equivalent record.
    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if 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.

    (c) Special flight permits may be issued in accordance with 
Secs. 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.
    (d) The inspection shall be done in accordance with Bell 
Helicopter Textron, Inc. Alert Service Bulletins 412-98-93 or 412CF-
98-5, both dated March 2, 1998, as applicable. This incorportion 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 Bell Helicopter Textron, Inc., P.O. Box 482, Fort 
Worth, Texas 76101, telephone (817) 280-3391, fax (817) 280-6466. 
Copies may be inspected at the FAA, Office of the Regional Counsel, 
Southwest Region, 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.
    (e) This amendment becomes effective on December 1, 1999.

    Issued in Fort Worth, Texas, on November 4, 1999.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-29612 Filed 11-15-99; 8:45 am]
BILLING CODE 4910-13-P