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Comments Invited
This AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments prior to it becoming effective. However, we invite you to participate in this rulemaking by submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy, or federalism impacts that resulted from adopting this AD. The most helpful comments reference a specific portion of the AD, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, commenters should send only one copy of written comments, or if comments are filed electronically, commenters should submit them only one time. We will file in the docket all comments that we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this rulemaking during the comment period. We will consider all the comments we receive and may conduct additional rulemaking based on those comments.
Discussion
We are adopting a new AD for MDHI Model MD900 helicopters. This AD requires cleaning the upper hub and performing an eddy current inspection of the upper hub for a crack. If there is a crack, this AD requires replacing the upper hub with an airworthy upper hub before further flight. This AD is prompted by a report that four cracks were found at the blade attach holes on a high-time upper hub. This is the first time a crack has been reported in an upper hub at this location in the MD900 fleet. We are issuing this AD to detect a crack on the upper hub, which if not corrected could result in failure of the upper hub and subsequent loss of control of the helicopter.
FAA's Determination
We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other helicopters of the same type design.
Related Service Information
MDHI has issued Service Bulletin SB900-122, dated April 8, 2014. The service bulletin specifies a one-time visual inspection of the upper hub for a crack and damage. If there is damage, the service bulletin specifies replacing the upper hub with an airworthy upper hub. If there are no visible cracks or damage, the service bulletin specifies performing a one-time eddy current inspection. If there is a crack, the service bulletin specifies removing the upper hub, tagging it as unairworthy and returning it to MDHI, and replacing it with an airworthy upper hub.
AD Requirements
This AD requires, within the next 25 hours time-in-service (TIS) or at the next annual inspection, whichever occurs first, cleaning the upper hub inspection areas and eddy current inspecting the upper hub for a crack. The eddy current inspection must be done by a level II or higher technician with the National Aerospace Standard 410 or equivalent certification who has performed an eddy current inspection in the last 12 months. If there is a crack, before further flight, this AD requires replacing the upper hub with an airworthy upper hub.
Differences Between This AD and the Service Information
This AD does not require you to contact the manufacturer, return a cracked upper hub to the manufacturer, or do a visual inspection of the upper hub, as does the service information.
Interim Action
We consider this AD interim action. If final action is later identified, we might consider further rulemaking then.
Costs of Compliance
We estimate that this AD will affect 23 helicopters of U.S. Registry. We estimate $85 for labor costs. We estimate 1 work hour to do an eddy current inspection for a cost of $85 per helicopter and a total fleet cost of $1,955. We estimate 11 work hours to replace an upper hub with a required parts cost of $15,998 for a total cost of $16,933 per helicopter.
FAA's Justification and Determination of the Effective Date
Providing an opportunity for public comments before adopting these AD requirements would delay implementing the safety actions needed to correct this known unsafe condition. Therefore, we find that the risk to the flying public justifies waiving notice and comment before adopting this rule because the required corrective actions must be done within 25 hours TIS, which will be accumulated in about one month based on the average flight-hour utilization rate of these helicopters that are mostly used for emergency medical service.
Since an unsafe condition exists that requires the immediate adoption of this AD, we determined that notice an opportunity for public comment before issuing this AD are impracticable and contrary to the public interest and that good cause exists for making this amendment effective in less than 30 days.
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 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
We determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on theStates, 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, I certify that this AD:
1. Is not a ``significant regulatory action'' under Executive Order 12866;
2. Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
3. Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory distinction; 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.
We prepared an economic evaluation of the estimated costs to comply with this AD and placed it in the AD docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.