[Federal Register Volume 86, Number 106 (Friday, June 4, 2021)]
[Rules and Regulations]
[Pages 29939-29942]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11674]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0975; Project Identifier 2020-NM-061-AD; Amendment 
39-21566; AD 2021-11-04]
RIN 2120-AA64


Airworthiness Directives; De Havilland Aircraft of Canada Limited 
(Type Certificate Previously Held by 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 De Havilland Aircraft of Canada Limited Model DHC-8-400, -401, 
and -402 airplanes. This AD was prompted by a report of main landing 
gear (MLG) retractions after striking an obstacle or severe wheel 
imbalance after a tire failure. This AD requires inspections for 
correct height of the lock link over-center stop pin and for correct 
gaps of the left-hand and right-hand MLG downlock proximity sensors, 
replacement of the shim if necessary, corrective actions, and 
installation of a new, improved proximity sensor electronic unit (PSEU) 
with software changes. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective July 9, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of July 9, 2021.

ADDRESSES: For service information identified in this final rule, 
contact De Havilland Aircraft of Canada Limited, Q-Series Technical 
Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; 
telephone 416-375-4000; fax 416-375-4539; email thd@dehavilland.com; 
internet https://dehavilland.com. You may view this service information 
at the FAA, Airworthiness Products Section, Operational Safety 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 https://www.regulations.gov by searching 
for and locating Docket No. FAA-2020-0975.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0975; 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, 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: Darren Gassetto, Aerospace Engineer, 
Mechanical Systems and Administrative Services Section, FAA, New York 
ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
telephone 516-228-7323; fax 516-794-5531; email 9-avs-nyacocos@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    Transport Canada Civil Aviation (TCCA), which is the aviation 
authority for Canada, has issued TCCA AD CF-2016-31R1, dated March 24, 
2017 (TCCA AD CF-2016-31R1) (also referred to as the Mandatory 
Continuing Airworthiness Information, or the MCAI), to correct an 
unsafe condition for certain De Havilland Aircraft of Canada Limited 
Model DHC-8-400, -401, and -402 airplanes. You may examine the MCAI in 
the AD docket on the internet at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2020-0975.
    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain De Havilland 
Aircraft of Canada Limited Model DHC-8-400, -401, and -402 airplanes. 
The NPRM published in the Federal Register on November 2, 2020 (85 FR 
69276). The NPRM was prompted by a report of MLG retractions after 
striking an obstacle or severe wheel imbalance after a tire failure. 
The NPRM proposed to require inspections for correct height of the lock 
link over-center stop pin and for correct gaps of the left-hand and 
right-hand MLG downlock proximity sensors, replacement of the shim if 
necessary, corrective actions, and installation of a new improved PSEU 
with software changes. The FAA is issuing this AD to address loss of 
MLG downlock signal caused by the vibrations from those events, which 
leads to de-energizing the MLG solenoid sequence valve (SSV) and 
subsequent removal of hydraulic pressure from the MLG downlock 
actuator. Loss of the hydraulic pressure in the downlock actuator, 
combined with the vibrations, can cause the stabilizer brace to unlock 
and the MLG to subsequently retract. See the MCAI for additional 
background information.

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 Exclude Certain Steps of the Accomplishment Instructions of 
Service Information

    Horizon Air requested that paragraphs (g), (h), and (i) of the 
proposed AD be revised to require only paragraph 3.B. of the 
Accomplishment Instructions of the service bulletins referenced in 
those paragraphs. Horizon Air stated that the Job Set-up section 
(paragraph 3.A.) of the Accomplishment Instructions do not directly 
address the unsafe condition. Horizon Air also asserted that retaining 
the Job Set-up sections restricts an operator's ability to do other 
maintenance in conjunction with the required service bulletins.
    The FAA disagrees with the request to exclude paragraph 3.A., Job 
Set-up, of

[[Page 29940]]

the Accomplishment Instructions from this AD's requirements. The Job 
Set-up sections of the required service bulletins include specific 
procedures for the electrical power and proper configurations of the 
nose landing gear (NLG) and MLG, which are necessary for accomplishing 
the applicable corrective actions on the PSEUs and proximity detectors 
and to prevent possible damage to that equipment. Requiring the Job 
Set-up instructions should not, in general, restrict the ability to 
schedule other maintenance actions in conjunction with the required 
actions. The FAA has not changed this AD in this regard.

Request To Allow Use of Alternative Service Information When Installing 
a Certain Part

    Horizon Air requested that paragraph (i) of the proposed AD be 
revised to also allow installation of PSEU part number (P/N) 30145-0602 
in accordance with Bombardier Service Bulletin 84-32-143, Revision B, 
dated November 16, 2016. Horizon Air pointed out that both documents 
stated that operators may receive a PSEU with P/N 30145-0601 or 30145-
0602. Further, Horizon Air noted that PSEU P/N 30145-0602 is ``two-way 
interchangeable'' with P/N 30145-0601, and that the installation 
instructions are the same in both service bulletins.
    The FAA disagrees with the request to revise paragraph (i) of this 
AD. The FAA agrees that the service information does state a two-way 
interchangeability of PSEU P/N 30145-0601 with PSEU P/N 30145-0602 and 
that operators may receive either PSEU P/N due to component 
availability. However, the service information also states that those 
in receipt of a PSEU must declare the appropriate service information 
specific to the PSEU P/N. In addition, while most of the Accomplishment 
Instructions between Bombardier Service Bulletin 84-32-143, Revision B, 
dated November 16, 2016, and Bombardier Service Bulletin 84-32-149, 
dated November 16, 2016, are the same, they are not identical. 
Therefore, recording compliance with another service bulletin would not 
be in compliance with the applicable corrective actions for the PSEU P/
N. The FAA has not changed the AD in this regard.

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 as proposed, except for 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.

Related Service Information Under 1 CFR Part 51

    De Havilland Aircraft of Canada Limited has issued Bombardier 
Service Bulletin 84-32-140, Revision B, dated January 30, 2018. This 
service information describes set-up procedures for proper 
configuration of the MLG prior to performing subsequent procedures for 
inspections for correct height of the lock link over-center stop pin 
and for correct gaps of the left-hand and right-hand MLG downlock 
proximity sensors, and replacement of the shim.
    De Havilland Aircraft of Canada Limited has also issued Bombardier 
Service Bulletin 84-32-143, Revision B, dated November 16, 2016, which 
describes procedures for installation of a new, improved PSEU, P/N 
30145-0601, with software changes.
    De Havilland Aircraft of Canada Limited has also issued Bombardier 
Service Bulletin 84-32-149, dated November 16, 2016, which describes 
procedures for installation of a new, improved PSEU, P/N 30145-0602, 
with software changes.
    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 57 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
              Labor cost                      Parts cost            Cost per product     Cost on U.S.  operators
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Up to 12 work-hours x $85 per hour =   Up to $4,750...........  Up to $5,770...........  Up to $328,890.
 Up to $1,020.
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    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
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                                                             Cost per
              Labor cost                   Parts cost        product
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1 work-hour x $85 per hour = $85......            $374             $459
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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

[[Page 29941]]

develop on products identified in this rulemaking action.

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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2021-11-04 De Havilland Aircraft of Canada Limited (Type Certificate 
Previously Held by Bombardier, Inc.): Amendment 39-21566; Docket No. 
FAA-2020-0975; Project Identifier 2020-NM-061-AD.

(a) Effective Date

    This airworthiness directive (AD) is effective July 9, 2021.

(b) Affected Airworthiness Directives (ADs)

    None.

(c) Applicability

    This AD applies to De Havilland Aircraft of Canada Limited (type 
certificate previously held by Bombardier, Inc.) Model DHC-8-400, -
401, and -402 airplanes, certificated in any category, having serial 
numbers 4001, and 4003 through 4534 inclusive.

(d) Subject

    Air Transport Association (ATA) of America Code 32, Landing 
Gear.

(e) Reason

    This AD was prompted by a report of main landing gear (MLG) 
retractions after striking an obstacle or severe wheel imbalance 
after a tire failure. The FAA is issuing this AD to address loss of 
MLG downlock signal caused by the vibrations from those events, 
which leads to de-energizing the MLG solenoid sequence valve and 
subsequent removal of hydraulic pressure from the MLG downlock 
actuator. Loss of the hydraulic pressure in the downlock actuator, 
combined with the vibrations, can cause the stabilizer brace to 
unlock and the MLG to subsequently retract.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Downlock Sensor Rigging and Reduced Lock Link Over-Center

    Within 9 months after the effective date of this AD: Verify both 
the height of the lock link over-center stop pin and the gap of the 
left-hand and right-hand MLG downlock proximity sensors, and perform 
corrective actions as required, in accordance with paragraphs 3.A. 
and 3.B. of the Accomplishment Instructions of Bombardier Service 
Bulletin 84-32-140, Revision B, dated January 30, 2018. Do all 
applicable corrective actions before further flight.

(h) Installation of Proximity Sensor Electronic Unit (PSEU) Part Number 
(P/N) 30145-0601

    Within 18 months after the effective date of this AD, install 
PSEU P/N 30145-0601 in accordance with paragraphs 3.A. and 3.B. of 
the Accomplishment Instructions of Bombardier Service Bulletin 84-
32-143, Revision B, dated November 16, 2016.

(i) Installation of PSEU P/N 30145-0602

    Installing PSEU P/N 30145-0602 in accordance with paragraphs 
3.A. and 3.B. of the Accomplishment Instructions of Bombardier 
Service Bulletin 84-32-149, dated November 16, 2016, also 
accomplishes the requirements of paragraphs (g) and (h) of this AD.

(j) Credit for Previous Actions

    (1) This paragraph provides credit for actions required by 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using the service information as specified 
in paragraphs (j)(1)(i) or (ii) of this AD.
    (i) Bombardier Service Bulletin 84-32-140, dated August 5, 2016.
    (ii) Bombardier Service Bulletin 84-32-140, Revision A, dated 
June 12, 2017.
    (2) This paragraph provides credit for actions required by 
paragraphs (g) and (h) of this AD, if PSEU P/N 30145-0601 was 
installed before the effective date of this AD using the service 
information as specified in paragraphs (j)(2)(i) or (ii) of this AD.
    (i) Bombardier Service Bulletin 84-32-143, dated June 30, 2016.
    (ii) Bombardier Service Bulletin 84-32-143, Revision A, dated 
August 5, 2016.

(k) Other FAA AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, New 
York ACO Branch, FAA, has the authority to approve AMOCs for this 
AD, if requested using the procedures found in 14 CFR 39.19. In 
accordance with 14 CFR 39.19, send your request to your principal 
inspector or local Flight Standards District Office, as appropriate. 
If sending information directly to the manager of the certification 
office, send it to ATTN: Program Manager, Continuing Operational 
Safety, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; telephone 516-228-7300; fax 516-794-5531. Before 
using any approved AMOC, notify your appropriate principal 
inspector, or lacking a principal inspector, the manager of the 
local flight standards district office/certificate holding district 
office.
    (2) Contacting the Manufacturer: For any requirement in this AD 
to obtain instructions from a manufacturer, the instructions must be 
accomplished using a method approved by the Manager, New York ACO 
Branch, FAA; or Transport Canada Civil Aviation (TCCA); or De 
Havilland Aircraft of Canada Limited's TCCA Design Approval 
Organization (DAO). If approved by the DAO, the approval must 
include the DAO-authorized signature.

(l) Related Information

    (1) Refer to Mandatory Continuing Airworthiness Information 
(MCAI) TCCA AD CF-2016-31R1, dated March 24, 2017, for related 
information. This MCAI may be found in the AD docket on the internet 
at https://www.regulations.gov by searching for and locating Docket 
No. FAA-2020-0975.
    (2) For more information about this AD, contact Darren Gassetto, 
Aerospace Engineer, Mechanical Systems and Administrative Services 
Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; telephone 516-228-7323; fax 516-794-5531; email 
9-avs-nyacocos@faa.gov.
    (3) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (m)(3) and (4) of this AD.

(m) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless this AD specifies otherwise.
    (i) Bombardier Service Bulletin 84-32-140, Revision B, dated 
January 30, 2018.
    (ii) Bombardier Service Bulletin 84-32-143, Revision B, dated 
November 16, 2016.
    (iii) Bombardier Service Bulletin 84-32-149, dated November 16, 
2016.
    (3) For service information identified in this AD, contact De 
Havilland Aircraft of Canada Limited, Q-Series Technical Help

[[Page 29942]]

Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; 
telephone 416-375-4000; fax 416-375-4539; email thd@dehavilland.com; 
internet https://dehavilland.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability 
of this material at the FAA, call 206-231-3195.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email fedreg.legal@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on May 27, 2021.
Ross Landes,
Deputy Director for Regulatory Operations, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-11674 Filed 6-3-21; 8:45 am]
BILLING CODE 4910-13-P


