AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted
by reports of excessive wear on the lower latch surface of the main
landing gear (MLG) up-lock hook. This AD requires revising the
maintenance program. We are issuing this AD to detect and correct up-
lock hooks worn beyond the wear limit, which could prevent the
successful extension of the MLG using the primary landing gear
extension system, which in combination with an alternate extension
system failure could result in the inability to extend the MLG.

DATES: This AD becomes effective May 8, 2014.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of May 8, 2014.

ADDRESSES: You may examine the AD docket on the Internet at http://www.regulations.gov/#!documentDetail;D=FAA-2013-0419-0002 or in
person at the U.S. Department of Transportation, Docket Operations, M-30,
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC.
For service information identified in this AD, contact Bombardier,
Inc., Q-Series Technical Help Desk, 123 Garratt Boulevard, Toronto,
Ontario M3K 1Y5, Canada; telephone 416-375-4000; fax 416-375-4539;
email thd.qseries@aero.bombardier.com; Internet http://www.bombardier.com.
You may view this referenced service information at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton,
WA. For information on the availability of this material at the FAA,
call 425-227-1221.

FOR FURTHER INFORMATION CONTACT: Cesar Gomez, Aerospace Engineer,
Airframe and Mechanical Systems Branch, ANE-171, FAA, New York Aircraft
Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; telephone (516) 228-7318; fax (516) 794-5531.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 to include an AD that would apply to certain Bombardier, Inc.
Model DHC-8-400 series airplanes. The NPRM published in the Federal
Register on May 14, 2013 (78 FR 28156). The NPRM was prompted by
reports of excessive wear on the lower latch surface of the main
landing gear (MLG) up-lock hook. The NPRM proposed to require revising
the maintenance program. We are issuing this AD to detect and correct
up-lock hooks worn beyond the wear limit, which could prevent the
successful extension of the MLG using the primary landing gear
extension system, which in combination with an alternate extension
system failure could result in the inability to extend the MLG.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian Airworthiness Directive CF-
2012-21, dated June 25, 2012 (referred to after this as ``the MCAI''),
to correct an unsafe condition for the specified products. The MCAI
states:

The main landing gear up-lock assembly part number (P/N) 46500-7
was introduced as the terminating action to AD CF-2002-13R2 [http://www.regulations.gov/#!documentDetail;D=FAA-2013-0419-0002].
The main landing gear up-lock assembly P/N 46500-9 was later introduced
as a product improvement and has the same up-lock hook as P/N 46500-7.
Due to a delay in the release of the new Maintenance Review
Board (MRB) task associated with P/Ns 46500-7 and 46500-9, it is
anticipated that in-service aeroplanes may be operating with up-lock
hooks worn beyond the wear limit. An up-lock hook worn beyond the
wear limit could prevent the successful extension of the main
landing gear using the primary landing gear extension system. In
combination with an alternate extension system failure, this could
result in the inability to extend the main landing gear.
This [Canadian] AD mandates the incorporation of the MRB task
number 323100-202.

MRB Task Number 323100-202 adds a functional check of the main landing
gear up-lock assembly latch to the maintenance program. You may examine
the MCAI in the AD docket on the Internet at http://www.regulations.gov
by searching for and locating it in Docket No. FAA-2013-0419.

Comments

We gave the public the opportunity to participate in developing
this AD. We considered the comments received.

Request for Clarification of Maintenance Program Requirement

Horizon Air requested that we revise paragraph (g) of the NPRM (78
FR 28156, May 14, 2013) to clarify which maintenance program (the
operator or maintenance program in PSM 1-84-7) would require revision.
Horizon Air also asked whether the operators are required to put the
MRB task into their program and revise PSM 1-84-7, or just revise PSM
1-84-7.
We agree to clarify. We have revised the language in paragraph (g)
by replacing the phrase ``revise the maintenance program'' with the
phrase ``revise the maintenance or inspection program as applicable.''
The AD requires revising the maintenance or inspection program, as
applicable, to incorporate the information in Bombardier Temporary
Revision MRB-66, dated December 7, 2011, to Section 1-32, Systems/
Powerplant Maintenance Program of MRB Report Part 1, Bombardier Q400
Dash 8 Maintenance Requirements Manual, PSM 1-84-7. We have revised the
introductory text of paragraph (g) of this final rule to include this
terminology.

Request for Clarification of Procedures

Horizon Air requested clarification of the procedures to be used to
accomplish the actions specified in paragraph (g) of the NPRM (78 FR
28156, May 14, 2013). Horizon Air stated that paragraph (g) would
mandate implementation of Task Number 323100-202 into the maintenance
program, but is silent on which procedures are used to accomplish the
task.
We agree to clarify. This final rule requires incorporating Task
Number 323100-202, as introduced by Temporary Revision (TR) MRB-66 into
the maintenance or inspection program. Bombardier Temporary Revision
MRB-66, dated December 7, 2011, to Section 1-32, Systems/Powerplant
Maintenance Program of MRB Report Part 1, Bombardier Q400 Dash 8
Maintenance Requirements Manual, PSM 1-84-7 provides information on how
to accomplish the task. No change has been made to this final rule in
this regard.

Request for Credit for Actions Done Previously

Horizon Air requested that we allow credit for actions done prior
to the effective date of the AD using airplane maintenance manual (AMM)
Task Number 32-31-21-220-801 for the corresponding actions specified in
paragraphs (g)(1), (g)(2), and (g)(3) of the NPRM (78 FR 28156, May 14,
2013).
We agree to allow credit as requested. The final rule provides an
initial compliance time for the performance of MRB Task Number 323100-
202. If the operator has already performed the initial task using AMM
Task 32-31-21-220-801, then the intent of the final rule is met for the
initial task. No change has been made to this final rule in this
regard.

Request To Allow Replacement of Up-Lock With Serviceable Up-Lock

Horizon Air (the commenter) requested that we revise paragraph (h)
of the NPRM (78 FR 28156, May 14, 2013) to require that replacement up-
locks be ``serviceable'' rather than ``new.'' The commenter stated that
operators are required to purchase zero time ``new'' up-locks to meet
the intent of the final rule, which places an unnecessary financial
burden on operators.
We agree with the commenter that operators should be allowed to use
a serviceable (i.e., reworked) up-lock. Paragraphs (h)(2)(i),
(h)(2)(ii), (h)(2)(iii), and (h)(4)(ii), as stated in the NPRM (78 FR
28156, May 14, 2013), give the option to replace the affected parts
with new or reworked (serviceable) parts, or a new up-lock assembly. No
change has been made to this final rule in this regard.

Request To Change Heading of Paragraph (h) of the NPRM (78 FR 28156,
May 14, 2013)

Horizon Air (the commenter) requested that we change the heading
for paragraph (h) of the NPRM (78 FR 28156, May 14, 2013) to ``Optional
Method of Compliance.'' The commenter stated that the paragraph
provides instructions that may be used in lieu of the initial
functional check required by paragraph (g).
We agree with the commenter. We have changed the heading of
paragraph (h) of this final rule to ``Optional Method of Compliance.''

Request To Allow Operators To Reduce the Repetitive Intervals

Horizon Air (the commenter) requested that the requirements of
paragraph (i) of the NPRM (78 FR 28156, May 14, 2013) be changed to
allow operators to set repetitive intervals at times less than those
required by Bombardier Temporary Revision MRB-66, dated December 7,
2011. The commenter stated the language in paragraph (i) of the NPRM is
too restrictive in regard to the repetitive intervals.
We agree to clarify the repetitive interval that is specified in
Bombardier Temporary Revision MRB-66, dated December 7, 2011. In
paragraph (g) of this final rule, we have added a sentence to specify
that the repetitive interval is not to exceed 6,000 flight hours or 60
months, whichever occurs first. Because the compliance time is
specified as ``not to exceed'' the interval, operators are allowed to
do the actions earlier than the specified interval. We have not changed
paragraph (j) of this final rule (referred to as paragraph (i) of the
NPRM (78 FR 28156, May 14, 2013)), which specifies that no alternative
intervals may be used unless the intervals are approved as an
alternative method of compliance in accordance with the procedures
specified in paragraph (l) of this final rule.

Request To Remove Reporting Requirements

Horizon Air (the commenter) requested that we remove the reporting
requirements from the NPRM (78 FR 28156, May 14, 2013). The commenter
stated that the AMM task and TR MRB-66, dated December 7, 2011, of PSM
1-84-7, do not include a reporting requirement. The commenter stated
that an operator that performed the AMM task or the MRB task prior to
the release of the final rule would not have recorded the wear
dimensions because there was no requirement to record it in either
task. The commenter stated that to force operators who have proactively
accomplished the inspection to go back and perform the task again just
to get a wear measurement to fulfill the requirements of paragraph (j)
of the NPRM places an unnecessary financial burden on the operator, and
provides data that do nothing to enlighten the manufacturer to the
amount of hook wear occurring on high-time up-locks.
We agree that any operator that has performed the AMM task prior to
publication of the NPRM (78 FR 28156, May 14, 2013) would not have
recorded any dimension. However, we disagree with the request to remove
the requirement entirely, because it is beneficial for any operator
that has not performed the required task to submit the report. We have
revised paragraph (j) of this final rule to state: ``For airplanes on
which the requirements of paragraph (g) or (h) of this AD have been
accomplished after the effective date of this AD: Within 30 days after
the functional check, submit a report of the initial functional check
findings using Form No ISETS-03-AOM Q400 in Bombardier Q400 All
Operator Message DHC8-400-AOM-515, Revision 2009-06-24, dated April 4,
2012. Send the report to Bombardier, Inc., Technical Help Desk, phone:
416-375-4000; fax: 416-375-4539; email:
thd.qseries@aero.bombardier.com.''

Other Changes to This Final Rule

We have revised the introductory text to paragraph (g) and
paragraphs (g)(1), (g)(2), and (g)(3) of this final rule to clarify the
requirements regarding the compliance time for doing the initial
functional check. The compliance time has not changed.
We have removed the reference to Bombardier Repair Drawing 8/4-32-
0190, Issue 1, dated April 2, 2012, in paragraph (h)(3) of this final
rule because the introductory text of paragraph (h) already refers to
the service information.
We have also added new paragraph (i) to this final rule to allow
credit for using Bombardier Repair Drawing 8/4-32-0190, Issue 1, dated
April 2, 2012. We have re-designated subsequent paragraphs accordingly.

Conclusion

We reviewed the relevant data, including the comments received, and
determined that air safety and the public interest require adopting
this AD with the changes described previously and minor editorial changes.
We have determined that these changes:
Are consistent with the intent that was proposed in the
NPRM (78 FR 28156, May 14, 2013) for correcting the unsafe condition;
and
Do not add any additional burden upon the public than was
already proposed in the NPRM (78 FR 28156, May 14, 2013).

Costs of Compliance

Based on the service information, we estimate that this AD affects
about 83 products of U.S. registry. We also estimate that it takes
about 1 work-hour per product to comply with the basic requirements of
this AD. The average labor rate is $85 per work-hour. Based on these
figures, we estimate the cost of the AD on U.S. operators to be $7,055,
or $85 per product.

Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a current valid OMB control number. The control
number for the collection of information required by this AD is 2120-
0056. The paperwork cost associated with this AD has been detailed in
the Costs of Compliance section of this document and includes time for
reviewing instructions, as well as completing and reviewing the
collection of information. Therefore, all reporting associated with
this AD is mandatory. Comments concerning the accuracy of this burden
and suggestions for reducing the burden should be directed to the FAA
at 800 Independence Ave. SW., Washington, DC 20591, ATTN: Information
Collection Clearance Officer, AES-200.

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 AD will not have federalism implications
under Executive Order 13132. This AD will 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 above, I certify that this AD:
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; 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.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov/#!documentDetail;D=FAA-2013-0419-0002;
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 AD, the regulatory evaluation, any comments received, and other
information. The street address for the Docket Operations office
(telephone (800) 647-5527) is in the ADDRESSES section.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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 AD: