DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-0337; Directorate Identifier 2010-SW-090-AD]
RIN 2120-AA64

Airworthiness Directives; Bell Helicopter Textron Canada
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for the
Bell Helicopter Textron Canada Limited (BHTC) Model 407 helicopters.
This proposed AD is prompted by a review of the tailboom-attachment
installation, which revealed that the torque value of the bolts
specified in the BHTC Model 407 Maintenance Manual and applied during
manufacturing was incorrect and exceeded the torque range recommended
for the bolts. This proposed AD would require you to replace tailboom-
attachment hardware (attachment hardware), and perform initial and
recurring determinations of
the torque on the nuts of the tailboom-attachment bolts (bolts) at all
four attachment locations. The actions required by this proposed AD are
intended to prevent an over-torque of a bolt, bolt failure, loss of the
tailboom, and subsequent loss of control of the helicopter.

DATES: We must receive comments on this proposed AD by May 29, 2012.

ADDRESSES: You may send comments by any of the following methods:

Federal eRulemaking Docket: Go to http://www.regulations.gov. Follow the
online instructions for sending your comments electronically.

Fax: 202-493-2251.

Mail: Send comments to the U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001.

Hand Delivery: Deliver to the "Mail" address between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Examining the AD Docket: You may examine the AD docket on the
Internet at http://www.regulations.gov or in person at the Docket
Operations Office between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this proposed AD, the
economic evaluation, any comments received, and other information. The
street address for the Docket Operations Office (telephone 800-647-
5527) is in the ADDRESSES section. Comments will be available in the AD
docket shortly after receipt.

For service information identified in this proposed AD, contact
Bell Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir,
Mirabel, Quebec J7J1R4, telephone (450) 437-2862 or (800) 363-8023, fax
(450) 433-0272, or at http://www.bellcustomer.com/files/. You may
review copies of the referenced service information at the FAA, Office
of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room
663, Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Sharon Miles, Aerospace Engineer, FAA,
Regulations and Policy Group, 2601 Meacham Blvd., Fort Worth, Texas
76137; telephone: (817) 222-5122; fax: (817) 222-5961; email:
sharon.y.miles@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to participate in this rulemaking by submitting
written comments, data, or views. We also invite comments relating to
the economic, environmental, energy, or federalism impacts that might
result from adopting the proposals in this document. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. To
ensure the docket does not contain duplicate comments, commenters
should send only one copy of written comments, or if comments are filed
electronically, commenters should submit only one time.

We will file in the docket all comments that we receive, as well as
a report summarizing each substantive public contact with FAA personnel
concerning this proposed rulemaking. Before acting on this proposal, we
will consider all comments we receive on or before the closing date for
comments. We will consider comments filed after the comment period has
closed if it is possible to do so without incurring expense or delay.
We may change this proposal in light of the comments we receive.

Discussion

Transport Canada, which is the aviation authority for Canada, has
issued AD No. CF-2010-33, dated September 30, 2010 (AD CF-2010-33), to
correct an unsafe condition for the BHTC Model 407 helicopter, serial
numbers (S/Ns) 53000 through 53990. Transport Canada advises that a
review of the tailboom-attachment installation determined that the
torque value of the bolts specified in the BHTC Model 407 Maintenance
Manual and applied during manufacturing exceeded the torque range
recommended for the bolts. Transport Canada states that this situation,
if not corrected, could lead to a bolt failure, detachment of the
tailboom, and subsequent loss of control of the helicopter.

These helicopters have been approved by the aviation authority of
Canada and are approved for operation in the United States. Pursuant to
our bilateral agreement with Canada, Transport Canada, its technical
representative, has notified us of the unsafe condition described in
its AD.

FAA's Determination

We are proposing this AD because we evaluated all known relevant
information and determined that an unsafe condition exists and is
likely to exist or develop on other products of the same type design.

Related Service Information

BHTC has issued Alert Service Bulletin No. 407-10-93, Revision A,
dated August 30, 2010 (ASB), which specifies installing new attachment
hardware with a reduced torque value. This ASB specifies performing a
torque check of the newly installed bolts and nuts every one to five
flight hours until torque stabilizes at all locations, and thereafter
at intervals not to exceed 300 flight hours. Transport Canada
classified this ASB as mandatory and issued AD CF-2010-33 to ensure the
continued airworthiness of these helicopters.

Proposed AD Requirements

This proposed AD would require for helicopters with 7000 hours or
less time-in-service (TIS), at the next 600 hours scheduled inspection,
or 90 days, whichever comes first; and for helicopters with more than
7000 hours TIS, within 150 hours TIS or 90 days, whichever comes first,
the following actions:

Remove the left upper bolt, washers, and nut. Install a
new bolt, part number (P/N) NAS627-30; washers, P/N 140-007-29S25E6 and
P/N NAS1149G0732P; and new nut, P/N 42FLW-720. Repeat this action for
the opposite right upper attachment hardware.

Remove the left lower bolt, washers, and nut. Install a
new bolt, P/N NAS626-26; washer, P/N 140-007-25S22E6, washer(s), P/N
NAS1149G0663P; and new nut, P/N 42FLW-624. Repeat this action for the
opposite right lower attachment hardware.

After installation of the new attachment hardware, at
intervals of not less than 1 hour TIS but not exceeding 5 hours TIS,
determine the torque of each nut until torque stabilizes at each
attachment location. Thereafter, determine the torque of each nut at
recurring intervals not to exceed 300 hours TIS. If the proper torque
has not been retained since the last torquing, remove and inspect the
tailboom assembly for damage, corrosion, improper assembly, and
condition. If the tailboom assembly is airworthy, replace the
attachment hardware and determine that the torque has stabilized at
each attachment location. Replace any unairworthy tailboom assembly
with an airworthy tailboom assembly before further flight.

Differences Between This Proposed AD and the Transport Canada AD

The differences between this proposed AD and the Transport Canada
AD are as follows:

This proposed AD uses the term "hours time-in-service"
to describe compliance times, and the Transport Canada AD uses the term
"air time";

For helicopters with 7000 hours or less TIS, the Transport
Canada AD requires accomplishing the actions in the AD at the next
scheduled 600-hour inspection or by December 31, 2010, whichever occurs
first. This proposed AD requires accomplishing the actions at the next
scheduled 600-hour inspection or 90 days, whichever occurs first.

This proposed AD uses the term "determine the torque"
when referring to the torque on a nut, and the Transport Canada AD uses
the term "perform a torque check."

Costs of Compliance

We estimate that this proposed AD would affect 552 helicopters of
U.S. registry. We estimate it would take about 2.0 work-hours per
helicopter to replace the hardware and 1.0 work-hour per helicopter to
determine the recurring torque value at an average labor rate of $85
per work hour. Required parts would cost about $498 per helicopter.
Based on these figures, we estimate for the first year the total cost
per helicopter to be $923, and the total cost impact on U.S. operators
to be $509,496. This estimated total cost assumes attachment hardware
will be replaced on all affected helicopters, the torque will be
considered stabilized after determining the torque value once, and the
300-hour TIS recurring torque determination will be accomplished twice
a year.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. "Subtitle VII: Aviation
Programs," describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in
"Subtitle VII, Part A, Subpart III, Section 44701: General
requirements." Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect 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.

For the reasons discussed, I certify this proposed regulation:

1. Is not a "significant regulatory action" under Executive Order 12866;

2. Is not a "significant rule" under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979);

3. Will not affect intrastate aviation in Alaska to the extent that
it justifies making a regulatory distinction; and

4. Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

We prepared an economic evaluation of the estimated costs to comply
with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. The FAA amends Sec. 39.13 by adding the following new
Airworthiness Directive (AD):