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 duringthe comment period. We will consider all the comments we receive and may conduct additional rulemaking based on those comments.
Discussion
On June 13, 2013, we issued AD 2013-12-06, Amendment 39-17484 (78 FR 40956, July 9, 2013) (AD 2013-12-06), for Eurocopter Deutschland GmbH (now Airbus Helicopters) Model MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, and MBB-BK 117 C-2 helicopters with a Metro vapor-cycle air conditioning kit installed in accordance with Supplemental Type Certificate No. SH3880SW. AD 2013-12-06 required repetitively inspecting the air conditioning drive pulley for looseness and properly installed lockwire, and also required reinstalling the pulley. AD 2013- 12-06 resulted from two reports of the pulley detaching from the rotor brake disk on the T/R driveshaft. We issued AD 2013-12-06 to prevent separation of the pulley, damage to the T/R driveshaft, and subsequent loss of control of the helicopter.
Actions Since AD 2013-12-06 Was Issued
Afterwe issued AD 2013-12-06, Metro developed a procedure to install a tabbed washer underneath the bolt heads securing the pulley to the rotor disc. This procedure was intended to provide a secondary locking feature to the bolts, and to relieve the requirement for repetitive inspections of the safety wire which secures the bolts. On December 20, 2013, Metro requested and we approved this procedure as a global Alternative Method of Compliance (AMOC) for AD 2013-12-06 in lieu of performing the repetitive inspections required by paragraph (e) of that AD.
On March 10, 2014, we received a report that an attaching bolt would not seat on the mating surface of the pulley. Compliance with the AMOC revealed a possible design deficiency and a manufacturing defect in some pulleys. Metro has determined that the pulley, along with two additional pulleys from other helicopters, did not have sufficient thread depth. This condition may allow the attaching bolts to come loose, resulting in the pulley detaching from the rotor brake disc, subsequent damage to the T/R driveshaft, and loss of control of the helicopter.
On March 24, 2014, we issued EAD 2014-06-51, which superseded AD 2013-12-06, for those to whom it was made immediately effective. EAD 2014-06-51 requires inspecting the pulley to determine if there is sufficient depth of the threads and removing the pulley if there is not sufficient depth. EAD 2014-06-51 also requires installing a dual locking tab on each pulley attaching bolt and reporting the inspection findings to the FAA. Finally, EAD 2014-06-51 revises the applicability to helicopters with a pulley, P/N 30001, installed rather than with the air conditioning kit installed because this pulley has been determined to be the unsafe condition. EAD 2014-06-51 was sent previously to all known U.S. owners and operators of these helicopters. The actions in EAD 2014-06-51 are intended to prevent the pulley detaching from the rotor brake disc, subsequent damage to the T/R driveshaft, and 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 products of these same type designs.
Related Service Information
We reviewed Metro Alert Service Bulletin (ASB) No. MA145-21B-003, Revision B, dated December 20, 2013 (ASB MA145-21B-003), which describes procedures for installing a dual-locking tab on the air conditioning drive pulley attachment bolts.
Since we issued EAD 2014-06-51, Metro released ASB No. MA145-21- 004, Revision IR, dated March 24, 2014, which describes procedures for inspecting the air conditioning drive pulley thread depth. This AD continues to reference ASB MA145-21B-003.
AD Requirements
This AD requires, within 5 hours time-in-service, inspecting each pulley attaching bolt hole to determine if there is sufficient depth of the threads. If the depthis less than 0.61 inch, this AD requires removing the pulley. This AD also requires installing dual locking tabs under each pulley attaching bolt by following the Accomplishment Instructions, paragraphs 3.E. through 3.G., of ASB MA145-21B-003. This AD also requires submitting a report of the inspection findings to the FAA.
Differences Between This AD and the Service Information
This AD requires determining the depth of the threaded portion of the pulley attaching bolt holes; the service information does not.
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 work- hour, inspecting the pulley bolt holes, and installing the tabbed washers will require 6 work hours, and required parts will cost $100, for a cost per helicopter of $610 and a total cost of $45,750 for the fleet.
Reviewing instructions, collecting and reviewing information, and submitting a report to the FAA will require 0.5 work-hour, for a cost per helicopter of $43 and a cost of $3,225 for the fleet.
If necessary, replacing a pulley will require about 2 work-hours, and required parts would cost $800, for a total cost per helicopter of $970.
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
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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 AD is 2120- 0056. The paperwork cost associated with this 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 ofinformation. Therefore, all reporting required by this 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.
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 found and continue to find that the risk to the flying public justifies waiving notice and comment prior to adopting this rule because the required corrective actions must be done within 5 hours time-in-service, a very short time period based on the average flight-hour utilization rate of these helicopters.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment before issuingthis AD were impracticable and contrary to the public interest and that good cause existed to make the AD effective immediately by EAD 2014-06-51, issued on March 24, 2014, to all known U.S. owners and operators of these helicopters. These conditions still exist and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
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 makinga 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.