[Federal Register Volume 86, Number 213 (Monday, November 8, 2021)]
[Proposed Rules]
[Pages 61719-61722]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-24102]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0960; Project Identifier 2019-CE-021-AD]
RIN 2120-AA64


Airworthiness Directives; Viking Air Limited (Type Certificate 
Previously Held by Bombardier, Inc., de Havilland, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 80-
13-10, AD 80-13-12 R1, and AD 2008-03-01, which apply to certain de 
Havilland (type certificate now held by Viking Air Limited) Model DHC-
6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes. AD 80-13-10 
requires repetitively inspecting the main landing gear (MLG) legs for 
cracks and corrosion. AD 80-13-12 R1 requires repetitively inspecting 
each engine nacelle lower longeron for cracks and buckling. AD 2008-03-
01 requires incorporating inspections, modifications, and life limits 
of certain structural components into the aircraft maintenance program. 
Since the FAA issued those ADs, new and more restrictive airworthiness 
limitations have been issued for certain structural components. This 
proposed AD would require incorporating into maintenance records new or 
revised life limits, modification limits, and inspection or overhaul 
intervals. The FAA is proposing this AD to address the unsafe condition 
on these products.

DATES: The FAA must receive comments on this proposed AD by December 
23, 2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12 140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this NPRM, contact Viking Air 
Limited Technical Support, 1959 De Havilland Way, Sidney, British 
Columbia, Canada, V8L 5V5; phone: (North America) (800) 663-8444; fax: 
(250) 656-0673; email: [email protected]; website: 
https://www.vikingair.com/support/service-bulletins. You may view this 
service information at the Airworthiness Products Section, Operational 
Safety Branch, FAA, 901 Locust, Kansas City, MO 64106. For information 
on the availability of this material at the FAA, call (816) 329-4148.

[[Page 61720]]

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0960; 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 NPRM, the MCAI, 
any comments received, and other information. The street address for 
Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Aziz Ahmed, Aviation Safety Engineer, 
New York ACO Branch, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 
11590; phone: (516) 228-7329; fax: (516) 794-5531; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2021-0960; 
Project Identifier 2019-CE-021-AD'' at the beginning of your comments. 
The most helpful comments reference a specific portion of the proposal, 
explain the reason for any recommended change, and include supporting 
data. The FAA will consider all comments received by the closing date 
and may amend the proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this proposed AD.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to Aziz 
Ahmed, Aviation Safety Engineer, New York ACO Branch, FAA, 1600 Stewart 
Avenue, Suite 410, Westbury, NY 11590. Any commentary that the FAA 
receives which is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    The FAA issued AD 80-13-10, Amendment 39-3812 (45 FR 43155, June 
26, 1980) (AD 80-13-10) for de Havilland (type certificate now held by 
Viking Air Limited) Model ``DHC-6 type'' airplanes with certain MLG 
legs. AD 80-13-10 was prompted by several incidents involving collapse 
of the MLG. AD 80-13-10 requires repetitively inspecting the weld 
juncture at the Y-joint of the MLG legs for cracks and corrosion. The 
FAA issued AD 80-13-10 to prevent failure of the MLG legs at the Y-
joint weld, which could result in wing damage during taxiing 
operations.
    The FAA issued AD 80-13-12 R1, Amendment 39-4135 (46 FR 31251, June 
15, 1981) (AD 80-13-12 R1) for certain serial-numbered de Havilland 
(now Viking Air Limited) Model ``DHC-6 type'' airplanes with 
intermediate or high floatation tires, skis, or floats. AD 80-13-12 R1 
was prompted by reports of cracks or buckling on the engine nacelle 
lower longerons. AD 80-13-12 R1 requires repetitively inspecting each 
engine nacelle lower longeron for cracks and buckling. The FAA issued 
AD 80-13-12 R1 to prevent possible failure of the engine nacelle lower 
longerons due to cracking or buckling.
    The FAA issued AD 2008-03-01, Amendment 39-15350 (73 FR 5729, 
January 31, 2008) (AD 2008-03-01), for all Viking Air Limited Model 
DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes. AD 2008-03-01 
was prompted by structural evaluations of the DHC-6 series airplanes 
that showed the service life limits and inspection schedules needed to 
be revised. AD 2008-03-01 was based on Canadian AD CF-2000-14, dated 
May 25, 2000 (AD CF-2000-14), issued by Transport Canada, which is the 
aviation authority for Canada. AD 2008-03-01 requires incorporating the 
inspections, modifications, and life limits (retirement) of certain 
structural components, as contained in Revision 5 of the DHC-6 Product 
Support Manual (PSM) 1-6-11, into the aircraft maintenance program. The 
FAA issued AD 2008-03-01 to maintain the structural integrity of the 
airplane.

Actions Since AD 2008-03-01 Was Issued

    Since the FAA issued AD 2008-03-01, Transport Canada has superseded 
AD CF-2000-14 and issued Canadian AD CF-2019-02, dated January 9, 2019 
(referred to after this as ``the MCAI''). The MCAI applies to all 
Viking Air Limited (formerly de Havilland) Model DHC-6 series 1, DHC-6 
series 100, DHC-6 series 110, DHC-6 series 200, DHC-6 series 210, DHC-6 
series 300, DHC-6 series 310, DHC-6 series 320, and DHC-6 series 400 
airplanes. The MCAI states:

    The airworthiness limitations for DHC-6 aeroplanes are defined 
and published in the Viking Air Ltd. (Viking) Airframe Airworthiness 
Limitations Manual, Product Support Manual (PSM) 1-6-11, approved by 
Transport Canada. The instructions contained in PSM 1-6-11 have been 
identified as mandatory actions for continued airworthiness. Failure 
to comply with those instructions could result in an unsafe 
condition.
    Viking Air Ltd. published Revision 9 of PSM 1-6-11 earlier in 
2018. Revision 9 of PSM 1-6-11, dated 30 April 2018, includes some 
new and/or more restrictive limitations than those contained in 
Revision 5. For the reason described above, this [Transport Canada] 
AD requires implementation of the actions specified in PSM 1-6-11 
Revision 9.
    The compliance requirements for several of the tasks in PSM 1-6-
11 were previously a range of flight hours and flight cycles. With 
Revision 9 of PSM 1-6-11, the range-based requirements have been 
changed to specific flight hours and flight cycle limits. This 
[Transport Canada] AD provides a phase-in allowance for those 
limitations so that operators will have the opportunity to schedule 
the modifications and inspections required by the limitations. The 
phase-in allowances are intended to mitigate the impact of changing 
from compliance ranges to compliance limits for aeroplanes that are 
approaching or have exceeded the limits on the effective date of the 
[Transport Canada] AD.
    Revision 9 of PSM 1-6-11 also includes some airworthiness 
limitations that were previously contained in service bulletins (SB) 
or other PSMs. Some of those limitations were mandated by [Transport 
Canada] ADs, specifically AD CF-80-06, CF-81-07R4 and CF-95-12. 
Because the affected limitations will now be controlled in PSM 1-6-
11, the above mentioned [Transport Canada] ADs are superseded by 
this [Transport Canada] AD.
    The following are new tasks in PSM 1-6-11 Revision 9:
    1. Task 27-007 Replacement of flight control pulleys at Fuselage 
Station (FS) 270.
    2. Tasks 32-001 and 32-002 Overhaul of main landing gear leg. 
There is an associated requirement to ensure that each affected part 
has been assigned a unique serial number.
    3. Task 53-006 Inspection of the skin flange of machined frame 
at FS 239.
    4. Tasks 54-003 to 54-010 Inspection of nacelle longerons.

[[Page 61721]]

    5. Tasks 57-039 to 57-041 Inspection for wing upper skin 
disbond.
    Task 27-004 Replacement of flight control cables after spillage 
of corrosive materials in PSM 1-6-11 was limited to landplane 
configurations in previous revisions of PSM 1-6-11 but is now 
applicable to all configurations.
    The intent of the word ``airframe'' in PSM 1-6-11 Revision 9 is 
to include fuselage, nacelles, struts, interiors, cowlings, 
fairings, airfoils, landing gear and their controls. The airframe 
life limitation in PSM 1-6-11 Revision 9 is not intended to apply to 
components such as those in the fuel, electrical and hydraulic 
systems that are occasionally transferred from one aeroplane to 
another and may be salvaged from an aeroplane that is retired from 
service for use on an in-service aeroplane. PSM 1-6-13 defines 
current airworthiness limitations for DHC-6 avionics that are not 
addressed in this [Transport Canada] AD.

    Model DHC-6-400 airplanes were type certificated after AD CF-2000-
14 was issued and are subject to the same unsafe condition. You may 
examine the MCAI in the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0960.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed DHC-6 Twin Otter PSM 1-6-11, Airframe 
Airworthiness Limitations Manual, Revision 9, dated April 30, 2018. The 
service information contains airworthiness limitations for certain 
structural components. 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.

FAA's Determination

    This product has been approved by the aviation authority of another 
country and is approved for operation in the United States. Pursuant to 
the FAA's bilateral agreement with this State of Design Authority, it 
has notified the FAA of the unsafe condition described in the MCAI and 
service information referenced above. The FAA is issuing this NPRM 
after determining the unsafe condition described previously is likely 
to exist or develop on other products of the same type design.

Proposed AD Requirements

    This proposed AD would require incorporating into maintenance 
records new or revised life limits, modification limits, and inspection 
or overhaul intervals. This proposed AD would also allow a ``phase-in'' 
compliance period for the initial completion of certain tasks.

ADs Mandating Airworthiness Limitations

    The FAA has previously mandated airworthiness limitations by 
issuing ADs that require revising the airworthiness limitation section 
(ALS) of the existing maintenance manual or instructions for continued 
airworthiness to incorporate new or revised inspections and life 
limits. This proposed AD, however, would require incorporating new or 
revised inspections and life limits into the maintenance records 
required by 14 CFR 91.417(a)(2) or 135.439(a)(2) for your airplane. The 
FAA does not intend this as a substantive change. Requiring 
incorporation of the new ALS requirements into the maintenance records, 
rather than requiring individual repetitive inspections and 
replacements, allows operators to record AD compliance once after 
updating the maintenance records, rather than recording compliance 
after every inspection and part replacement.

Differences Between This Proposed AD and the MCAI

    The MCAI applies to Viking Air Limited Model DHC-6 series 110, DHC-
6 series 210, DHC-6 series 310, and DHC-6 series 320, and this proposed 
AD would not because these models do not have an FAA type certificate. 
Transport Canada Models DHC-6 series 1, DHC-6 series 100, DHC-6 series 
200, DHC-6 series 300, and DHC-6 series 400 airplanes correspond to FAA 
Model DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 
airplanes, respectively.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 33 airplanes of U.S. registry.
    The FAA also estimates that it would take about 1 work-hour per 
airplane to incorporate life limits, modification limits, and 
inspection or overhaul intervals, into maintenance records. The average 
labor rate is $85 per work-hour.
    Based on these figures, the FAA estimates the cost of the proposed 
AD on U.S. operators to be $2,805 or $85 per airplane.

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.

Regulatory Findings

    The FAA 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 above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would 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.

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

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:
0
a. Removing Airworthiness Directive 80-13-10, Amendment 39-3812 (45 FR 
43155, June 26, 1980); Airworthiness Directive 80-13-12 R1, Amendment 
39-4135 (46 FR 31251, June 15, 1981); and Airworthiness Directive 2008-
03-01, Amendment 39-15350 (73 FR 5729, January 31, 2008); and
0
b. Adding the following new airworthiness directive:

Viking Air Limited (Type Certificate Previously Held by Bombardier, 
Inc., de

[[Page 61722]]

Havilland, Inc.): Docket No. FAA-2021-0960; Project Identifier 2019-
CE-021-AD.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by December 23, 2021.

(b) Affected ADs

    This AD replaces the ADs specified in paragraphs (b)(1) through 
(3) of this AD.
    (1) AD 80-13-10, Amendment 39-3812 (45 FR 43155, June 26, 1980).
    (2) AD 80-13-12 R1, Amendment 39-4135 (46 FR 31251, June 15, 
1981).
    (3) AD 2008-03-01 Amendment 39-15350 (73 FR 5729, January 31, 
2008).

(c) Applicability

    This AD applies to Viking Air Limited (type certificate 
previously held by Bombardier, Inc., de Havilland, Inc.) Model DHC-
6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 airplanes, all 
serial numbers, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) Code 0500, Time Limits.

(e) Unsafe Condition

    This AD was prompted by mandatory continuing airworthiness 
information (MCAI) originated by an aviation authority of another 
country to identify and address an unsafe condition on an aviation 
product. The MCAI identifies the unsafe condition as failure to 
comply with new and more restrictive airworthiness limitations, 
including tasks where range-based requirements have been changed to 
specific hours time-in-service (TIS) and flight cycle limits. The 
FAA is issuing this AD to prevent loss of structural integrity of 
certain parts. The unsafe condition, if not addressed, could result 
in loss of control of the airplane.

(f) Compliance

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

(g) Maintenance and Life Limits

    (1) Within 30 days after the effective date of this AD, 
incorporate into the maintenance records required by 14 CFR 
91.417(a)(2) or 135.439(a)(2) for your airplane the life limits, 
modification limits, and inspection or overhaul intervals in DHC-6 
Twin Otter PSM 1-6-11, Airframe Airworthiness Limitations Manual, 
Revision 9, dated April 30, 2018 (PSM 1-6-11 Rev9).
    (2) Before further flight after revising the maintenance records 
as required by paragraph (g)(1) of this AD, except as allowed under 
paragraph (h) of this AD, remove from service each part that has 
reached or exceeded its life limit and modify each part that has 
reached or exceeded its modification limit.
    (3) Before further flight after revising the maintenance records 
as required by paragraph (g)(1) of this AD, except as allowed under 
paragraph (h) of this AD, inspect or overhaul each part that has 
reached or exceeded its inspection or overhaul interval.

(h) Phase-In Period

    The following phase-in periods are allowed to comply with the 
initial tasks in PSM 1-6-11 Rev9.
    (1) Task 27-007: For any pulley that has been in service for 48 
or more months on the effective date of this AD, replace the pulley 
within 12 months after the effective date of this AD.
    (2) Tasks 32-001 and 32-002:
    (i) For any main landing gear (MLG) leg that, on the effective 
date of this AD, has not been marked with a new serial number as 
specified in Viking DHC-6 Twin Otter Technical Bulletin V6/00063: 
Within 6 months after the effective date of this AD, inspect and 
serialize the MLG leg. The absence of a serial number indicates that 
the initial inspection of the landing gear leg has not previously 
been accomplished.
    (ii) For all other MLG legs, overhaul the MLG leg within 60 
months after the last overhaul.
    (3) Tasks 57-006, 57-007, 57-010, 57-011, 57-013, and 57-014:
    (i) For any wing that on the effective date of this AD has 
accumulated more than 16,000 hours total TIS or 32,000 total flight 
cycles but less than 17,000 hours total TIS or less than 34,000 
total flight cycles, accomplish the task within 1,000 hours TIS or 
2,000 flight cycles, whichever occurs first after the effective date 
of this AD.
    (ii) For any wing that on the effective date of this AD has 
accumulated 17,000 or more hours total TIS or 34,000 or more total 
flight cycles, accomplish the task before accumulating 18,000 hours 
total TIS or 36,000 total flight cycles, or within 60 months after 
the effective date of this AD, whichever occurs first.
    (4) Tasks 57-018, 57-019, 57-022, 57-023, 57-026, 57-027, 57-
030, and 57-031:
    (i) For any wing that on the effective date of this AD has 
accumulated more than 11,000 hours total TIS or 22,000 total flight 
cycles but less than 12,000 hours total TIS or less than 24,000 
total flight cycles, accomplish the task within 1,000 hours TIS or 
2,000 flight cycles, whichever occurs first after the effective date 
of this AD.
    (ii) For any wing that on the effective date of this AD has 
accumulated 12,000 or more hours total TIS or 24,000 or more total 
flight cycles, accomplish the task before accumulating 13,000 hours 
total TIS or 26,000 total flight cycles or within 60 months after 
the effective date of this AD, whichever occurs first.
    (5) Tasks 57-039 to 57-041 inclusive: For any wing that on the 
effective date of this AD has more than 20 years since the date of 
manufacture and has not previously been inspected in accordance with 
Viking Service Bulletin V6/0018, inspect the wing upper surface 
within 120 days after the effective date of this AD.

(i) No Alternative Actions or Intervals

    After the maintenance records have been revised as required by 
paragraph (g) of this AD, no alternative actions (e.g., inspections) 
or intervals may be used unless the actions or intervals are 
approved as an alternative method of compliance (AMOC) in accordance 
with the procedures specified in paragraph (j)(1) of this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) 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 ACO Branch, send it to the attention of the person 
identified in paragraph (k)(1) of this AD.
    (2) 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.

(k) Related Information

    (1) For more information about this AD, contact Aziz Ahmed, 
Aviation Safety Engineer, New York ACO Branch, FAA,1600 Stewart 
Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7329; fax: 
(516) 794-5531; email: [email protected].
    (2) Refer to Transport Canada AD CF-2019-02, dated January 9, 
2019, for more information. You may examine the Transport Canada AD 
in the AD docket at https://www.regulations.gov by searching for and 
locating it in Docket No. FAA-2021-0960.
    (3) For service information identified in this AD, contact 
Viking Air Limited Technical Support, 1959 De Havilland Way, Sidney, 
British Columbia, Canada, V8L 5V5; phone: (North America) (800) 663-
8444; fax: (250) 656-0673; email: [email protected]; 
website: https://www.vikingair.com/support/service-bulletins. You 
may view this service information at the Airworthiness Products 
Section, Operational Safety Branch, FAA, 901 Locust, Kansas City, MO 
64106. For information on the availability of this material at the 
FAA, call (816) 329-4148.

    Issued on November 1, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-24102 Filed 11-5-21; 8:45 am]
BILLING CODE 4910-13-P