Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to Viking Air Limited Models DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 airplanes. The NPRM was published in the Federal Register on November 6, 2017 (82 FR 51367). The NPRM proposed to correct an unsafe condition for the specified products and was based on mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country.
The MCAI states:
There have been reports of accelerated aileron cable wear because of contact with the fuselage skin cut-out or the wing root rib. Wear that is not detected can lead to failure of the aileron cable and loss of control of the aeroplane.
The root cause of this problem has not yet been identified. This [Transport Canada] AD requires inspection of the aeroplane and reporting of the inspection results to Viking Air Ltd. This [TransportCanada] AD is considered an interim action and further AD action may follow.
Aileron cables are typically replaced at intervals of 60 months in accordance with the DHC-6 maintenance schedule.
The MCAI can be found in the AD docket on the internet at: https://www.regulations.gov/document?D=FAA-2017-1038-0002.
Comments
We gave the public the opportunity to participate in developing this AD. The following presents the comment received on the proposal and the FAA's response to the comment.
Request a Change to the Corrective Actions
Mathew Carlson stated the proposed actions are not necessary. Although the root cause has not yet been determined, the cause appears obvious and the appropriate actions to take are obvious as well. The commenter stated they believe the corrective actions proposed are unnecessary, and the root cause is an alignment issue between pulleys and the fuselage cutout. The commenter believes the corrective action should be to trim the fuselage cutout for better clearance and to not require the repetitive inspections.
We do not agree with the commenter. While it is possible the commenter's root cause/solution is correct, we disagree that the cable inspection and/or replacement has no benefit. Until enough information is gathered and analyzed to accurately determine the root cause of the issue, the repetitive inspection (and replacement if necessary) is the action necessary to address the unsafe condition and provide a safe method to continue airplane operation.
We have not changed this AD based on this comment.
Conclusion
We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the publicthan was already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
Viking Air Limited issued DHC-6 Twin Otter Service Bulletin Number: V6/0022, Revision B, dated June 13, 2014. The service information describes
[[Page 7108]]
procedures for initial and repetitive inspections of the aileron cable for aileron cable wear; fouling at the wing root rib, fuselage skin, and wing root rib fairlead; and/or fraying of the cable from the root rib fairlead; and replacement of the aileron cables as necessary. 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 of the AD.
Costs of Compliance
We estimate that this AD will affect 141 products of U.S. registry. We also estimate that it would take about 20 work-hours 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 this AD on U.S. operators to be $239,700, or $1,700 per product.
In addition, the following is an estimate of possible necessary follow-on replacement actions. We have no way of determining the number of products that may need these actions.
----------------------------------------------------------------------------------------------------------------
Labor cost Cost per
Action Work-hours * ($85/hour) Parts cost product ---------------------------------------------------------------------------------------------------------------- Replace 1 cable................................. 6 $510 $244 $754 Replace 2 cables (on the same wing)............. 8 680 458 1,138 Replace 2 cables (one on each wing)............. 12 1,020 4881,508 Replace all 4 cables (2 per wing)............... 16 1,360 916 2,336 ----------------------------------------------------------------------------------------------------------------
* Work-hours includes access, testing, and close-up.
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 proposed AD is 2120-0056. The paperwork cost associated with this proposed 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 proposed 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 thescope 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 small airplanes, gliders, balloons, airships, domestic business jet transport airplanes, and associated appliances to the Director of the Policy and Innovation Division.
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 andresponsibilities among the various levels of government.
For the reasons discussed above, I certify 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 by searching for and locating Docket No. FAA-2017- 1038; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for Docket Operations (telephone (800) 647-5527) is in theADDRESSES section. Comments will be available in the AD docket shortly after receipt.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.