[Federal Register Volume 88, Number 57 (Friday, March 24, 2023)]
[Rules and Regulations]
[Pages 17685-17688]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-05987]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0814; Project Identifier AD-2022-00205-A; 
Amendment 39-22397; AD 2023-06-11]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
Viking Air Limited (type certificate previously held by Bombardier Inc. 
and de Havilland Inc.) Model DHC-2 Mk. I airplanes with Supplemental 
Type Certificate (STC) No. SA01324CH installed. This AD was prompted by 
a report of damage in the main wing spar. This AD requires inspecting 
the wing structure for damage (drill starts, corrosion, cracks, and 
improperly installed fasteners), repairing damage, and reporting the 
inspection results if necessary. The FAA is issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective April 28, 2023.

ADDRESSES: AD Docket: You may examine the AD docket at regulations.gov 
by searching for and locating Docket No. FAA-2022-0814; 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: Tim Eichor, Aviation Safety Engineer, 
Chicago ACO Branch, FAA, 2300 E Devon Avenue, Des Plaines, IL 60018; 
phone: (847) 294-7141; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to Viking Air Limited 
(type certificate previously held by Bombardier Inc. and de Havilland 
Inc.) Model DHC-2 Mk. I airplanes with STC No. SA01324CH installed. The 
NPRM published in the Federal Register on July 8, 2022 (87 FR 40749). 
The NPRM was prompted by a report that during an annual inspection of a 
Viking Air Limited Model DHC-2 Mk. I airplane, a gap was noted between 
the doubler and wing near station 42.5, requiring partial removal of 
the doubler and removal of the sealant between the doubler and the wing 
skin. Further inspection of the internal wing structure of that area 
with a borescope found damage in the forward spar caused by a drill 
during initial installation of the doubler. The doubler was installed 
as part of Wipaire, Inc. (Wipaire), STC No. SA01324CH. Inspection of 
the rest of the operator's fleet of airplanes with STC No. SA01324CH 
installed found a total of 7 out of 28 wings with drill start damage in 
the same area. Later inspections on these same airplanes on the 
outboard end of the doubler installation revealed improperly installed 
fasteners. As only a small fraction of the affected fleet has been 
inspected, the possible extent of damage in the field is unknown. 
Accordingly, the FAA determined that in addition to inspecting for 
drill starts and improperly installed fasteners, inspecting for 
corrosion and cracks is necessary. Damage of the main structural 
members of the wing could adversely affect the structural integrity of 
the airplane and could result in loss of control of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from Wipaire. The following presents the 
comments received on the NPRM and the FAA's response to each comment.

Request Regarding Changing the Unsafe Condition

    Wipaire requested that the unsafe condition statement in the 
Background section and paragraph (e) of the proposed AD be changed from 
``Damage of the main structural members of the wing could adversely 
affect the structural integrity of the airplane and could result in 
loss of control of the airplane'' and suggested the wording ``This 
condition, if not addressed, could have a slight adverse effect on the 
structural integrity of the airplane.'' Wipaire stated that although 
the unsafe condition statement in the NPRM is technically correct, it 
is misleading to operators affected by the proposed AD. Wipaire noted 
that a structural analysis performed and approved by an FAA Designated 
Engineering Representative (DER) showed that this type of damage at 
this location had no appreciable effect on the overall strength of the 
spar. Wipaire explained that the doubler is installed inboard of the 
wing strut on the upper section of the wing and in this configuration 
the spar is predominately loaded compression so crack growth would be 
slow and detectable.
    The FAA disagrees with the commenter's request. As only a small 
fraction of the affected fleet has been inspected, the extent of damage 
in the field is unknown. Accordingly, it is not accurate to say that 
the damage of the main structural members of the wing will not 
adversely affect the structural integrity of the wing, resulting in 
both the loss of the wing and loss of control of the airplane. No 
change was made to this AD regarding this issue.

[[Page 17686]]

Request Regarding Background Section

    Wipaire requested the Background section of the NPRM be changed 
from ``6 out of 14 wings with drill start damage,'' which is based off 
of inspection results of a single operator to the broader inspection 
results of ``7 out of 28 wings with drill start damage,'' because these 
results are based on Wipaire's record of inspections performed by 
multiple operators. Wipaire stated that, while still a statistically 
small sample size, the rewording to specify 28 wings provides a more 
accurate representation of the potential for damage existing fleet 
wide. Wipaire also mentioned that it hoped the FAA did not issue the 
NPRM using calculations based on ``6 out of 14 wings.''
    The FAA agrees with the commenter's statement that, in total, 7 
wings were found to be damaged based on inspection results provided by 
Wipaire on January 26, 2022. The FAA has revised the Background section 
of this final rule to read ``Inspection of the rest of the operator's 
fleet of airplanes with STC No. SA01324CH installed found a total of 7 
out of 28 wings with drill start damage in the same area.''
    Regarding issuing the AD based on the data of ``6 out of 14 
wings,'' the FAA clarifies that under 14 CFR 39.5, issuance of an AD is 
based on the finding that an unsafe condition exists in a product and 
that condition is likely to exist or develop in other products of the 
same type design. The FAA does not issue an AD based upon a sample size 
of airplanes. The unsafe condition addressed in this AD is based on a 
report of damage in the main wing spar. This condition, if not 
addressed, could adversely affect the structural integrity of the 
airplane and result in loss of control of the airplane. Inspections and 
repair are therefore necessary to detect and correct damage in the main 
wing spar before it leads to structural failure.

Request Regarding Costs of Compliance: Increase Estimated Work Hours

    Wipaire requested that the work-hours for doing the inspection be 
increased from 6 work-hours for a single side of the wing (left or 
right) to 12 work-hours for both sides of the wing. Wipaire justified 
the request by stating that due to the inspection requirement including 
the complete area under the doubler, the estimate should be increased.
    The FAA agrees with the commenter's request and has increased the 
estimated work-hours for the inspection from 6 to 12 in the Costs of 
Compliance section in this AD.

Request Regarding Costs of Compliance: Add Costs for Developing and 
Approving Repair Scheme

    Wipaire requested that estimated costs for developing a repair 
scheme and obtaining repair scheme approval be included in the Costs of 
Compliance section. Wipaire stated that these are additional costs on 
operators that were not accounted for in the NPRM.
    The FAA acknowledges the commenter's concerns. The FAA recognizes 
that in accomplishing the requirements of any AD, operators might incur 
``incidental'' costs in addition to the ``direct'' costs that are 
reflected in the cost analysis presented in the AD. However, the cost 
analysis in ADs typically does not include incidental costs. No change 
was made to this AD regarding this issue.

Request Regarding Reducing the Inspection Areas

    Wipaire requested that the FAA understand the feasibility of 
inspecting every bay (both forward and aft the spar) across the entire 
area and adjust the inspection requirements accordingly. Wipaire stated 
that the requirement to visually inspect the aircraft structure 
underneath the entire doubler between wing stations 30.26 and 126.36 
may not be able to be accomplished without removal of the wing skins 
and that there are bays, especially on the forward side of the spar, 
that have very limited access through a combination of existing access 
panels and lightening holes in structural members. Wipaire recommended 
focusing the inspection only on areas where data and prior inspections 
support that damage have been found (fastener locations near the spar) 
because a smaller area of focus will lead to more thorough inspections 
and easier compliance for operators in the field. Wipaire further 
stated that the Background section of the NPRM indicated damage was 
found on the inboard side of the doubler and improperly installed 
fasteners on the outboard side of the doubler and recommended focusing 
on those areas for inspection.
    The FAA disagrees with the commenter's request because there is 
other airplane structure under the doublers that could be damaged by 
the installation of STC No. SA01324CH. No change was made to this AD 
regarding this issue.

Comment Regarding the Visual Inspection

    Wipaire stated that a borescope is needed to comply with the visual 
inspection requirement specified in the proposed AD. Wipaire explained 
that a borescope would be needed in order to view the area of 
inspection because there are multiple 90-degree bends due to access 
bays and lightening holes. Wipaire further stated that based on its 
experience, operators in Alaska might not have borescope equipment and 
personnel able to use that equipment readily available, which could 
lead to the inability to comply with the proposed AD as written.
    The FAA acknowledges the commenter's concern. While a borescope 
inspection is acceptable, paragraph (g) of this AD states that a 
borescope, flashlight and mirror, or equivalent, may be used to do the 
visual inspection. The FAA's intent is that any inspection method that 
allows for visual inspection of 100 percent of the airplane structure 
complies with the visual inspection requirement. This AD also provides 
time to transport the airplane to a location with the resources and 
personnel to appropriately inspect the airplane. No change was made to 
this AD regarding this issue.

Request Regarding Required Actions

    Wipaire requested that the FAA reword the proposed inspection 
requirement to ``. . . visually inspect for drill starts, improperly 
installed fasteners, and corrosion or cracks related to the damage 
caused by any drill starts or improperly installed fasteners'' because 
the wording for the proposed requirement to inspect for corrosion and 
cracks could be interpreted broadly and could be extended beyond the 
scope of the proposed AD. Wipaire stated that the proposed requirement 
to inspect generally for corrosion and cracks may lead to operators 
being less likely to comply with the requirements specified in the 
proposed AD in a timely manner.
    The FAA disagrees with the commenter's request. Any crack or 
corrosion that is found, regardless if it is related to damage caused 
by any drill start or improperly installed fastener, must be addressed 
to keep the airplane in an airworthy condition. No change was made to 
this AD regarding this issue.

Request Regarding Special Flight Permit

    Wipaire requested that, if no cracks are found during the visual 
inspection specified in paragraph (g) of the

[[Page 17687]]

proposed AD, special flight permits be allowed so an airplane can fly 
to a maintenance facility for repair work. Wipaire stated that the 
language in paragraph (g) of the proposed AD and the special flight 
permit prohibition in paragraph (i) of the proposed AD are not 
supported by the data it gathered during its investigation into this 
issue.
    The FAA disagrees with the commenter's request to allow a special 
flight permit to repair the aircraft as long as cracks are not found. 
Drill starts, corrosion, and improperly installed fasteners contribute 
to the unsafe condition as well as cracks, and if any of these are 
found during the inspection, then they must be corrected before further 
flight after the inspection. The compliance time of this AD is 12 
months and was established to coincide with the next annual inspection. 
Therefore, at the time of the inspection, the airplane should already 
be at a facility where the repair could be done. Thus, a special flight 
permit is not justified. No change was made to this AD regarding this 
issue.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, and 
any other changes described previously, this AD is adopted as proposed 
in the NPRM. None of the changes will increase the economic burden on 
any operator.

Related Service Information

    The FAA reviewed a Wipaire letter, dated September 7, 2021. This 
letter requests that operators inspect the front wing spar (strap) and 
front (forward) spar aft flange for drill holes due to the installation 
of the top wing strap installed using Wipaire Drawing 5D1-790, which is 
an attachment to the letter. This letter also requests reporting all 
findings of damage to Wipaire.

Differences Between This AD and the Service Information

    The Wipaire letter, dated September 7, 2021, specifies inspecting 
the front spar and front spar aft flange between wing stations 42.5 and 
56. This AD requires inspecting all airplane structure under the 
installed doubler between wing stations 30.26 and 126.36.

Impact on Intrastate Aviation in Alaska

    Airplanes modified by Wipaire STC No. SA01324CH are often used to 
transport cargo and supplies to remote areas of Alaska. The FAA 
estimates that roughly half of the U.S.-registered airplanes modified 
by STC No. SA01324CH are operating in Alaska. Since damage to the main 
structural members of the wing could result in loss of the airplane 
wing and therefore, loss of control of the airplane, the FAA has 
determined that the need to correct the unsafe conditions outweighs any 
impact on aviation in Alaska.

Costs of Compliance

    The FAA estimates that this AD affects 96 airplanes of U.S. 
registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
             Action                    Labor cost              Parts cost             product        operators
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Inspection......................  12 work-hours x $85  Not Applicable...........          $1,020         $97,920
                                   per hour = $1,020.
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    The FAA estimates the following costs to do any necessary repairs 
that would be required based on the results of the inspection. The 
agency has no way of determining the number of airplanes that might 
need these repairs.

                                               On-Condition Costs
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                                                                                                     Cost per
                Action                        Labor cost                    Parts cost                product
----------------------------------------------------------------------------------------------------------------
Repair damage........................  100 work-hours x $85 per  $35,000........................         $43,500
                                        hour = $8,500.
Report inspection results............  1 work-hour x $85 per     Not Applicable.................              85
                                        hour = $85.
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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 a 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 currently valid OMB Control Number. The OMB 
Control Number for this information collection is 2120-0056. Public 
reporting for this collection of information is estimated to take 
approximately 1 hour per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information. All responses to this collection of 
information are mandatory. Send comments regarding this burden estimate 
or any other aspect of this collection of information, including 
suggestions for reducing this burden to: Information Collection 
Clearance Officer, Federal Aviation Administration, 10101 Hillwood 
Parkway, Fort Worth, TX 76177-1524.

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 17688]]

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, and
    (2) 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.

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:

2023-06-11 Viking Air Limited (Type Certificate Previously Held by 
Bombardier Inc. and de Havilland Inc.): Amendment 39-22397; Docket 
No. FAA-2022-0814; Project Identifier AD-2022-00205-A.

(a) Effective Date

    This airworthiness directive (AD) is effective April 28, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Viking Air Limited (type certificate 
previously held by Bombardier Inc. and de Havilland Inc.) Model DHC-
2 Mk. I airplanes, all serial numbers, certificated in any category, 
with Supplemental Type Certificate (STC) No. SA01324CH installed.

(d) Subject

    Joint Aircraft System Component (JASC) Code 5711, Wing Spar.

(e) Unsafe Condition

    This AD was prompted by a report of damage in the main wing 
spar. The FAA is issuing this AD to detect and address damage (drill 
starts, corrosion, cracks, and improperly installed fasteners) to 
the main structural members of the wing. This condition, if not 
addressed, could adversely affect the structural integrity of the 
airplane and result in loss of control of the airplane.

(f) Compliance

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

(g) Required Actions

    Within 12 months after the effective date of this AD, using a 
borescope, flashlight and mirror, or equivalent, visually inspect 
the aircraft structure under the installed doubler between wing 
stations 30.26 and 126.36 for drill starts, corrosion, cracks, and 
improperly installed fasteners. Pay particular attention to the spar 
cap, spar flange, and stringers, and include all structural items in 
the wing. If there is a drill start, any corrosion, a crack, or an 
improperly installed fastener, before further flight, repair using a 
method approved by the Manager, Chicago ACO Branch, FAA. For a 
repair method to be approved by the Manager, Chicago ACO Branch, as 
required by this paragraph, the Manager's approval letter must 
specifically refer to this AD.
    Note 1 to paragraph (g): Wipaire, Inc., letter, dated September 
7, 2021, provides additional information on this subject, including 
examples of damage.

(h) Reporting Requirement

    If, during the inspection required by paragraph (g) of this AD, 
any damage is found, within 30 days after doing the inspection or 
within 30 days after the effective date of this AD, whichever occurs 
later, report the following information to the person identified in 
paragraph (k)(1) of this AD:
    (1) Name and address of owner.
    (2) Date of the inspection.
    (3) Name, address, telephone number, and email address of person 
submitting the report.
    (4) Airplane serial number, registration number, STC 
installation date, and total hours time-in-service on the airplane 
at the time of the inspection.
    (5) Description of damage. Include affected structure, location, 
dimensions, and photos of damage (or sketches, if photos are not 
possible).

(i) Special Flight Permit

    Special flight permits are prohibited.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Chicago 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 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 Tim Eichor, 
Aviation Safety Engineer, Chicago ACO Branch, FAA, 2300 E Devon 
Avenue, Des Plaines, IL 60018; phone: (847) 294-7141; email: 
[email protected].
    (2) For service information identified in this AD that is not 
incorporated by reference, contact Wipaire, Inc., 1700 Henry Avenue, 
Fleming Field (KSGS), South St. Paul, MN 55075; phone: (651) 451-
1205; fax: (651) 457-7858; email: wipaire.com">switte@wipaire.com; website: 
wipaire.com. You may view this referenced service information at the 
FAA, Airworthiness Products Section, Operational Safety Branch, 901 
Locust, Kansas City, MO 64106. For information on the availability 
of this material at the FAA, call (817) 222-5110.

(l) Material Incorporated by Reference

    None.

    Issued on March 20, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-05987 Filed 3-23-23; 8:45 am]
BILLING CODE 4910-13-P