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,
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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 concerningthis rulemaking during the comment period. We will consider all the comments we receive and may conduct additional rulemaking based on those comments.
Discussion
STC No. SH3880SW approves the installation of the Metro vapor-cycle air conditioning kit on Eurocopter Model MBB-BK117 A-3, MBB-BK117 A-4, MBB-BK117 B-1, and MBB-BK117 C-2 helicopters. The air conditioning compressor is driven by a pulley attached to the rotor brake disc. We received a report of a recent incident where the fasteners attaching the air conditioning compressor pulley to the rotor brake disc lost torque and allowed the pulley to separate. After the helicopter landed without incident, the pulley was discovered loose, rotating freely on, and causing damage to the T/R driveshaft. A prior incident in 2008 occurred where the pulley mount bolts sheared, resulting in the pulley detaching from the rotor brake disc. Separation of the pulley from the rotor brake disc could damage the T/R driveshaft, resulting insubsequent loss of control of the helicopter.
FAA's Determination
We are issuing this AD because we evaluated all information provided by Metro and determined the unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs.
Related Service Information
We reviewed Metro Alert Service Bulletin No. MA145-21A-003, Revision A, dated April 26, 2013 (ASB MA145-21A-003), which describes procedures to inspect the pulley for properly installed lockwire, and for removing, inspecting, and re-installing the pulley.
AD Requirements
This AD requires, before further flight, and thereafter at intervals not exceeding 10 hours time-in-service (TIS), inspecting the pulley for looseness and proper installation of the lockwire on the pulley mount bolts.
Additionally, within 25 hours TIS, this AD requires removing the pulley, inspecting the bolts and mounting holes with a 10X or higher magnifying glass for damage or distortion, and re-installing the pulley. If there is any damage or distortion, this AD requires replacing the damaged pulley.
Differences Between This AD and the Manufacturer's Service Information
This AD requires repetitively inspecting the pulley bolts every 10 hours TIS; the ASB does not require the repetitive inspections after re-installing the pulley.
This AD also applies to Model MBB-BK117 A-3, MBB-BK117 A-4, MBB- BK117 B-1, and MBB-BK117 C-2 helicopters; the ASB only applies to Model MBB-BK C-2 helicopters.
Interim Action
We consider this AD to be an interim action. The design approval holder is currently developing a modification that will address the unsafe condition identified in this AD. Once this modification is developed, approved, and available, we might consider additional rulemaking.
Costs of Compliance
We estimate that this AD will affect 75 helicopters of U.S. Registry. We estimate that operators may incur the following costs in order to comply with this AD. At an average labor rate of $85 per hour, inspecting the pulley will require about .5 work-hour, for a cost per helicopter of $43, and a total cost of $3,225 for the fleet per inspection cycle. Inspecting and re-installing the pulley will require about 2 work-hours, for a cost per helicopter of $170, and a total cost of $12,750 for the fleet.
If necessary, replacing a damaged pulley would require about 2 work-hours, and required parts would cost $525, for a total cost per helicopter of $695.
FAA's Justification and Determination of the Effective Date
Providing an opportunity for public comments prior to 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 prior to the adoption of this rule because the required corrective actions must be accomplished within 25 hours TIS or 30 calendar days, a veryshort time period based on the average flight hour utilization rate of these helicopters in the air ambulance and offshore operations industries.
Since an unsafe condition exists that requires the immediate adoption of this AD, we determined that notice and opportunity for public comment before issuing this AD are impracticable 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 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, 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.