Discussion
On March 24, 2015, at 80 FR 15530, the Federal Register published our notice of proposed rulemaking (NPRM), which proposed to amend 14 CFR part 39 by adding an AD that would apply to AHD Model MBB-BK 117 A- 1, A-3, A-4, B-1, B-2, C-1, and C-2 helicopters. The NPRM proposed to require repetitive visual inspections of the N2 control arm for corrosion, a crack, and a scratch. The NPRM also proposed to require repairing any N2 control arm with corrosion or a scratch less than 0.020 inch in depth and replacing any N2 control arm with exfoliation corrosion, a crack, or with corrosion or a scratch 0.020 inch or greater in depth. The proposed requirements were intended to detect corrosion, a crack, or a scratch in the N2 control arm, which could lead to failure of the N2 control arm, a drop in rotor
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speed, and subsequent loss of control of the helicopter.
The NPRM was prompted by AD No. 2013-0154, dated July 22, 2013, issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for the Eurocopter Deutschland GmbH (now AHD) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, C- 1, and C-2 helicopters. EASA advises of an incident with a Model MBB- BK117 C-2 helicopter that dropped rotor speed (RPM) within the green range and could not be recovered to nominal value because of a heavily corroded and broken N2 control arm. EASA advises that under certain flight conditions and power demands, a broken N2 control arm can cause a significant and non-recoverable drop in RPM. As a result, EASA AD No. 2013-0154 requires an initial and repetitive inspection of the N2 control arm for corrosion, damage, and scratches, and depending on the outcome of the inspection, repairing or replacing the N2 control arm.
Since the NPRM was issued, the FAA Southwest Regional Office has relocated and a group email address has been established for requesting an FAA alternative method of compliance for a helicopter of foreign design. We have revised the contact information throughout this final rule to reflect the new address and new email address.
Comments
We gave the public the opportunity to participate in developing this AD, but we did not receive any comments on the NPRM (80 FR 15530, March 24, 2015).
FAA's Determination
These helicopters have been approved by the aviation authority of Germany and are approved for operation in the United States. Pursuant to our bilateral agreement with Germany, EASA, its technical representative, has notified us of the unsafe condition described in the EASA AD. We are issuing this AD because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs and that air safety and the public interest require adopting the AD requirements as proposed except for the minor editorial changes described above. These changes are consistent with the intent of the proposals in the NPRM (80 FR 15530, March 24, 2015) and will not increase the economic burden on any operator nor increase the scope of this AD.
Differences Between This AD and the EASA AD
The EASA AD allows a noncumulative tolerance of 3 months in the compliance time for the initial inspection on helicopters with less than 2 years from the date of first flight and for the repetitive inspections, and this AD does not.
Related Service Information Under 1 CFR Part 51
Eurocopter issued ASB MBB-BK117-60A-126 for Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, and ASB MBB-BK117 C-2-76A-005 for Model MBB-BK 117 C-2 helicopters, both Revision 0, and both dated June 24, 2013. The Eurocopter ASBs specify inspecting the N2 control arm for corrosion, damage, and scratches and, depending on the outcome of the inspection, either repairing or replacing the affected parts. The Eurocopter ASBs also specify performing the inspection with each 12 month inspection until the N2 inspection requirements are incorporated into the aircraft maintenance manual.
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.
Costs of Compliance
We estimate that this AD affects 441 helicopters of U.S. Registry. We estimate that operators may incur the following costs in order to comply with this AD. Labor costs are estimated at $85 per work-hour. Inspecting the N2 control arm requires about one work-hour for an estimated cost of $85 per helicopter and $37,485 for the U.S. fleet per inspection cycle. Repairing the N2 control arm requires about four work-hours for an estimated labor cost of $340. Replacing the N2 control arm requires about three work-hours for an estimated labor cost of $255. Parts to replace the N2 control arm for Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters cost about $2,743 for a total estimated cost of $2,998. Parts to replace the N2 control arm for a Model MBB-BK 117 C-2 helicopter cost about $4,500 for a total estimated cost of $4,755.
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 thatis likely to exist or develop on helicopters 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;
(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 evaluationof 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.