DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0322; Product Identifier 2019-NM-039-AD; Amendment
39-19712; AD 2019-16-09]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

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

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Bombardier, Inc., Model DHC-8-400 series airplanes. This AD was
prompted by reports of cracked elevator power control unit (PCU)
brackets on the horizontal stabilizer rear spar and cracking on the
elevator front spar. This AD requires one-time inspections for cracks
and damage of the elevator PCU brackets and surrounding area,
horizontal stabilizer rear spar, and elevator front spar, and related
investigative and corrective actions if necessary. The FAA is issuing
this AD to address the unsafe condition on these products.

DATES: This AD is effective October 9, 2019.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of October 9,
2019.

ADDRESSES: For service information identified in this final rule,
contact De Havilland Aircraft of Canada Ltd., Q-
Series Technical Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K
1Y5, Canada; phone: 416-375-4000; fax: 416-375-4539; email:
thd@dehavilland.com; internet: https://dehavilland.com. You may view
this service information at the FAA, Transport Standards Branch, 2200
South 216th St., Des Moines, WA. For information on the availability of
this material at the FAA, call 206-231-3195. It is also available on
the internet at http://www.regulations.gov by searching for and
locating Docket No. FAA-2019-0322.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2019-
0322; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations is U.S. Department
of Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Andrea Jimenez, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7330; fax 516-
794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding 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, 2019 (84 FR 21268). The NPRM was prompted
by reports of cracked elevator PCU brackets on the horizontal
stabilizer rear spar and cracking on the elevator front spar. The NPRM
proposed to require one-time inspections for cracks and damage of the
elevator PCU brackets and surrounding area, horizontal stabilizer rear
spar, and elevator front spar, and related investigative and corrective
actions if necessary.
The FAA is issuing this AD to address failure of an elevator PCU
bracket or fracture of the front spar into two segments; either
structural failure may cause a jam in one elevator or a loss of
airplane pitch control if both elevators are affected.
Transport Canada Civil Aviation (TCCA), which is the aviation
authority for Canada, has issued Canadian AD CF-2018-34, dated December
17, 2018 (referred to after this as the Mandatory Continuing
Airworthiness Information, or ``the MCAI''), to correct an unsafe
condition for certain Bombardier, Inc., Model DHC-8-400 series
airplanes. The MCAI states:

There have been five in-service reports of cracked elevator
power control unit (PCU) brackets on the horizontal stabilizer rear
spar, and two reports of cracking on the elevator front spar. In one
case, the PCU bracket cracking led to detachment of the bracket
during pushback. An investigation found that the force-fight loads
induced by elevator PCUs not rigged to the required tolerance is the
common factor in cracking of both the elevator PCU bracket and of
the elevator front spar. A secondary contributor to the elevator PCU
bracket cracking is the bracket flange preload that may be induced
during production installation. Failure of an elevator PCU bracket
or progression of the elevator front spar cracking into two segments
may cause the affected elevator to jam. Failure of an elevator
bracket on both elevators, or progression of elevator front spar
cracking into two segments on both elevators, could cause a loss of
aeroplane pitch control.
This [Canadian] AD mandates a one-time inspection of the
elevator PCU brackets, the horizontal stabilizer rear spar and
elevator front spar with reporting of inspection findings. Any
brackets found cracked are to be replaced with new brackets with
improved strength. For any spar found cracked, obtain instructions
to repair the spar from Bombardier and repair the spar accordingly.
Additional corrective action may be considered depending on the
results of the inspections findings.

You may examine the MCAI in the AD docket on the internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2019-0322.

Comments

The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.

Request To Remove Certain Service Information Procedures

Horizon Air requested that the FAA change the language in the
introductory text of paragraph (g) of the proposed AD from mandating
``the Accomplishment Instructions'' in the service information to
mandating only the section that corrects the unsafe condition. Horizon
Air stated that the Accomplishment Instructions, Part A, ``Job Set-
up,'' and Part C, ``Close Out,'' do not directly correct the unsafe
condition. Horizon Air stated that incorporating these two sections as
a requirement in the AD restricts an operator's ability to accomplish
other maintenance in conjunction with the required actions to correct
the unsafe condition.
The FAA agrees with the commenter's request to exclude the ``Job
Set-up'' and ``Close Out'' sections of Bombardier Service Bulletin 84-
55-09, dated June 7, 2018. The FAA has revised the introductory text of
paragraph (g) of this AD to require accomplishment of Section 3.B, Part
A, of the Accomplishment Instructions of Bombardier Service Bulletin
84-55-09, dated June 7, 2018, and the FAA has revised paragraph (g)(1)
of this AD to require accomplishment of Section 3.B, Part B, of the
Accomplishment Instructions of Bombardier Service Bulletin 84-55-09,
dated June 7, 2018.

Request To Revise Company Name and Email Address

Horizon Air requested that the FAA update the contact information
for reporting in the introductory text of paragraph (h) of the proposed
AD. Horizon Air pointed out that De Havilland Aircraft of Canada Ltd is
now the design approval holder (DAH) for the Q400 aircraft.
The FAA agrees with the commenter's request. The FAA has updated
the address information accordingly in this final rule.
As a note, there is a difference between the commercial designation
and the model designation on the U.S. type certificate data sheet
(TCDS). ``Q400'' is the commercial designation, while Bombardier, Inc.,
Model DHC-8-400 is the designation on the TCDS. The FAA uses the model
designation on the TCDS to define the applicability in ADs and, as a
result, have not changed the applicability of this AD. The FAA is in
the process of changing the TCDS to reflect the name change for these
models. The FAA will use the name identified in the current TCDS so as
not to delay issuance of the final rule. Once the TCDS has been
changed, the FAA will use the new name in subsequent ADs.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. The FAA has determined that these minor
changes:

Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Related Service Information Under 1 CFR Part 51

Bombardier has issued Service Bulletin 84-55-09, dated June 7,
2018. This service information describes procedures for one-time
detailed visual and fluorescent penetrant inspections for cracks and
damage of the elevator PCU brackets (including the surrounding area),
horizontal stabilizer rear spar, and elevator front spar, and related
investigative and corrective actions if necessary. The related
investigative action is an eddy current inspection for cracking of
certain mating holes of the horizontal stabilizer rear spar. Corrective
actions include replacement of the elevator PCU brackets and repair of
the horizontal stabilizer rear spar and elevator front spar.
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in the ADDRESSES section.

Costs of Compliance

The FAA estimates that this AD affects 54 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions *

* Table does not include estimated costs for reporting.

The FAA estimates that it would take about 1 work-hour per product
to comply with the reporting requirement in this AD. The average labor
rate is $85 per hour. Based on these figures, the FAA estimates the
cost of reporting the inspection results on U.S. operators to be
$4,590, or $85 per product.
The FAA estimates the following costs to do any necessary on-
condition actions that would be required based on the results of any
required actions. The FAA has no way of determining the number of
aircraft that might need these on-condition actions:

Estimated Costs of On-Condition Actions

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.
The FAA is 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.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to transport category airplanes and
associated appliances to the Director of the System Oversight Division.

Regulatory Findings

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) Will not affect intrastate aviation in Alaska, and
(3) 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.

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 airworthiness
directive (AD):