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 December 14, 2011, we issued AD 2011-26-10, amendment 39-16900 (77 FR 729, January 6, 2012) for Enstrom Model F-28C, F-28C-2, F-28F, 280C, 280F, 280FX, TH-28, 480, and 480B helicopters with a trim relay, part-number (P/N) KUP14D55-472, M83536/10-015M, or M83536/10-024M. That AD requires modifying the lateral and longitudinal trim actuator assemblies by replacing the actuator and limit switch bracket to provide a positive stop for the trim actuator. In the event of a trim actuator runaway, the new bracket will stop the actuator, causing the circuit breaker to trip before any significant loss of control occurs. After the trim actuator assemblies are modified, that AD requires performing operational (ground) and flight tests to determine that the trim relay is working correctly. That AD was prompted by reports of 4 failures in the cyclictrim system in the field, 2 that occurred on the Enstrom Model 480B helicopter and 2 that occurred on the Enstrom Model F28 helicopter. These failures resulted in reduced controllability of the helicopter. We issued that AD to prevent failure of the cyclic trim system and subsequent loss of control of the helicopter.
Comments
Since we issued immediately adopted AD 2011-26-10, we received one comment from Enstrom, the manufacturer, and Revision 4 to Enstrom Service Directive Bulletin No. 0110, dated January 23, 2012 (SDB 0110), for Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX helicopters. In its comment, the manufacturer stated that the list of affected part numbers for the F-28 series and 280 series helicopter should include P/ N KUP14D55-24 and that this P/N was erroneously left off of Enstrom's original Service Directive Bulletin. It stated that the same safety concerns also exist with this relay and that adding this P/N will not affect the cost analysis or fleet size as these aircraft were included in the initial calculations.
We agree with the commenter that the additional part numbered relay contained in Enstrom SDB 0110 should be added to the applicability section of the AD because it may contain the same unsafe condition. Also, we agree that the revised compliance instructions contained in SDB 0110 should be required.
FAA's Determination
We are issuing this AD because we evaluated all the relevant information, including the comment received and the revised service information, and determined the unsafe condition described previously is likely to exist or develop in other helicopters of these same type designs.
Related Service Information
We reviewed Enstrom SDB No. T-039, Revision 3, dated July 6, 2011 (SDB T-039), for Model TH-28, 480, and 480B helicopters and Enstrom SDB 0110, for Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX helicopters. SDB T-039 specifies, for helicopters with a trim relay, P/ N M83536/10-024M, procedures for modifying the lateral and longitudinal trim actuator assembly using the cyclic trim assembly kit (modification kit), P/N 4230045-1, and specifies performing an operational check and flight test to determine if the trim is operating correctly after the modification. SDB 0110 specifies, for helicopters with a trim relay, P/ N KUP14D55-24, KUP14D55-472, M83536/10-015M, or M83536/10-024M, procedures for modifying the lateral and longitudinal trim actuator assembly using the modification kit, P/N 28-01063-1, and specifies performing an operational check and flight test to determine if the trim is operating correctly after the modification. The SDBs state that the modification kits contain the upgraded bracket.
AD Requirements
In addition to those part-numbered trim relays contained in the applicability section of the current AD 2011-26-10, this AD adds trim relay P/N KUP14D55-24. Also, this AD adopts the revised modification instructions for the Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX helicopters contained in SDB 0110. Otherwise, this AD retains most of the requirements of AD 2011-26-10, which requires modifying the lateral and longitudinal trim actuator assembly, using modification kit, P/N 28-01063-1, for the Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX helicopters and modification kit, P/N 4230045-1, for the Model TH-28, 480, and 480B helicopters, and verifying that the modification has been completed properly by performing an operational and flight test after the modification is complete.
The actions required by this AD are to be accomplished by following specified
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portions of the SDBs described previously.
Differences Between This AD and the Service Information
The SDBs specify, before further flight, to insert a special addendum into the Emergency Procedures section of the Flight Manual, and this AD does not require this action.
Costs of Compliance
We estimate that thisAD will affect 207 helicopters of U.S. Registry. We estimate that operators may incur the following costs in order to comply with this AD. For Model 480, 480B, and TH-28, modifying the actuator assemblies will require 8 work hours at a cost of $85 per hour and parts will cost $327; the cost per helicopter will be $1,007. For Model 280C, 280F, 280FX, F-28C, F-28C-2, and F-28F, modifying the actuator assemblies will require 8 work hours at a cost of $85 per hour; parts will cost $383; and the cost per helicopter will be $1,063.
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 5 hours time-in-service, avery short time period based on the average flight-hour utilization rate of these helicopters.
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 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 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.