[Federal Register Volume 64, Number 75 (Tuesday, April 20, 1999)]
[Rules and Regulations]
[Pages 19254-19255]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9825]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-48-AD; Amendment 39-11137; AD 99-09-05]
RIN 2120-AA64


Airworthiness Directives; Bell Helicopter Textron Canada (BHTC) 
Model 230 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 BHTC Model 230 helicopters. This action requires 
initial and repetitive visual inspections and verification of the 
torque of the bolts on the main rotor hub. This amendment is prompted 
by a report of fatigue cracks around the bolt holes of the main rotor 
pitch horn (pitch horn) and a cracked main rotor flapping bearing 
assembly (flapping bearing assembly) on a similar model helicopter. 
This condition, if not corrected, could result in fretting-induced 
fatigue cracking of the flapping bearing assembly and around the bolt 
holes of the pitch horn, loss of the rotor system, and subsequent loss 
of control of the helicopter.

DATES: Effective May 5, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before June 21, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 98-SW-48-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Harry Edmiston, Aerospace Engineer, 
Rotorcraft Certification Office, Rotorcraft Directorate, FAA, 2601 
Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5158, fax 
(817) 222-5783.

SUPPLEMENTARY INFORMATION: Transport Canada, which is the airworthiness 
authority for Canada, recently notified the FAA that an unsafe 
condition may exist on BHTC Model 230 helicopters. Transport Canada 
advises that fatigue cracks at the bolt holes of the pitch horn and in 
the flapping bearing assembly can lead to loss of control of the 
helicopter.
    BHTC issued Alert Service Bulletin No. 230-98-13, dated April 23, 
1998 (ASB), which specifies inspecting the main rotor hub in the areas 
between the pitch horn and main rotor grip tangs (grip tangs) and 
between the flapping bearing assembly and the main rotor yoke assembly 
for fretting. The ASB also specifies torque verification procedures for 
the main rotor grip retaining bolts and the flapping bearing assembly 
retaining bolts. Transport Canada classified this ASB as mandatory and 
issued Transport Canada AD CF-98-17, dated July 15, 1998, to ensure the 
continued airworthiness of these helicopters in Canada.
    This helicopter model is manufactured in Canada and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, Transport Canada has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of Transport Canada, reviewed all available information, and 
determined that AD action is necessary for products of this type design 
that are certificated for operation in the United States.
    The FAA estimates that 17 helicopters will be affected by this AD, 
that it will take approximately 1 work hour to accomplish the 
inspection and retorque of bolts, if necessary, 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 $3,060 per year, 
assuming three inspections and retorques per year and assuming that no 
parts will need to be replaced.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other BHTC Model 230 helicopters of the same type 
design registered in the United States, this AD is being issued to 
prevent fretting induced fatigue cracking of the flapping bearing 
assembly and around the bolt holes of the pitch horn, loss of the rotor 
system, and subsequent loss of control of the helicopter. This AD 
requires recurring inspections of the main rotor hub in the areas 
between the pitch horn and grip tangs and between the flapping bearing 
assembly and the main rotor yoke assembly for fretting. If fretting is 
found on any part, replacing that part with an airworthy part is 
required. This AD also requires verifying the torque on the main rotor 
grip retaining bolts and the flapping bearing assembly retaining bolts. 
The short compliance time involved is required because the previously 
described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, a visual inspection of 
the main rotor hub between the pitch horn and grip tangs and the 
flapping bearing assembly and the main rotor yoke assembly for fretting 
is required. A torque check of the main rotor grip retaining bolts and 
the flapping bearing assembly retaining bolts is also required. These 
actions are required within 10 hours TIS and 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.

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

[[Page 19255]]

postcard on which the following statement is made: ``Comments to Docket 
No. 98-SW-48-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. 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 99-09-05  Bell Helicopter Textron Canada: Amendment 39-11137. 
Docket No. 98-SW-48-AD.

    Applicability: Model 230 helicopters, serial numbers 23001 
through 23038, 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 as indicated, unless accomplished 
previously.
    To prevent fretting induced fatigue cracking of the main rotor 
flapping bearing assembly (flapping bearing assembly) and around the 
bolt holes of the main rotor pitch horn (pitch horn), loss of the 
rotor system, and subsequent loss of control of the helicopter, 
accomplish the following:
    (a) Within 10 hours time-in-service (TIS), and thereafter at 
intervals not to exceed 150 hours TIS:
    (1) Perform a visual inspection of the main rotor hub for 
fretting between the pitch horn and main rotor grip tangs (grip 
tangs) and between the flapping bearing assembly and the main rotor 
yoke assembly. If fretting is found on any part, replace it with an 
airworthy part.
    (2) Verify the torque of the main rotor grip retaining bolts and 
the flapping bearing assembly bolts in the tightening direction, 
minimum 100 foot-pounds. If 100 foot-pounds torque is reached 
without movement of the bolts, torque bolts to 125 foot-pounds.
    (3) If any bolt moves before 100 foot-pounds torque is reached, 
remove the pitch horn or the flapping bearing assembly, as 
applicable, from the main rotor hub assembly for further inspection. 
Inspect the pitch horn or flapping bearing assembly, as applicable, 
and all faying surfaces of the pitch horn, flapping bearing 
assembly, buffers, main rotor yoke assembly, and the grip tangs for 
fretting. If fretting is found on any part, replace it with an 
airworthy part.
    (4) Apply corrosion preventive compound to the exposed portions 
of the bolts and nuts.

    Note 2: Bell Helicopter Textron Alert Service Bulletin No. 230-
98-13, dated April 23, 1998, pertains to the subject of this AD.

    (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 3: 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 
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.
    (d) This amendment becomes effective on May 5, 1999.

    Note 4: The subject of this AD is addressed in Transport Canada 
(Canada) AD CF-98-17, dated July 15, 1998.

    Issued in Fort Worth, Texas, on April 13, 1999.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-9825 Filed 4-19-99; 8:45 am]
BILLING CODE 4910-13-U