[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
