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
We are adopting a new AD for the 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. This AD does not apply to the specified helicopters with a reversible trim motor, P/N 28-16621 (Ford Motor Company C1AZ-14553A) or P/N AD1R-10 (Signal Electric). This 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, this AD requires performing operational (ground) and flight tests to determine that the trim relay is working correctly. This AD was prompted by reports of 4 failures in the cyclic trim 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 are issuing this AD to prevent failure of the cyclic trim system 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 products of the same type design.
[[Page 730]]
Related Service Information
We reviewed Enstrom Service Directive Bulletin (SDB) No. 0110, Revision 3, dated July 6, 2011 (SDB 0110), for Model F-28C, F-28C-2, F- 28F, 280C, 280F, and 280FX helicopters; and Enstrom SDB No. T-039, Revision 3, dated July 6, 2011 (SDB T-039), for Model TH-28, 480, and 480B helicopters. SDB 0110 specifies, for helicopters with a trim relay, P/N KUP14D55-472, M83536/10-015M, or M83536/10-024M, procedures for modifying the lateral and longitudinal trim actuator assembly using the cyclic trim assembly kit (modification kit), P/N 28-01063-1, and specifies performing an operational check and flight test to determine the trim is operating correctly after the modification. 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 modification kit, P/N 4230045-1, and specifies performing an operational check and flight test to determine the trim is operating correctly after the modification. The SDBs state that the modification kits contain the upgraded bracket.
AD Requirements
This AD requires, within 5 hours time-in-service (TIS) or at the next annual or 100 hour time-in-service inspection, whichever occurs first, the following actions:
For the Enstrom Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX helicopters with a trim relay, P/N KUP14D55-472, M83536/10- 015M, or M83536/10-024M, modify the lateral and longitudinal trim actuator assembly using the modification kit, P/N 28-01063-1.
For the Enstrom Model TH-28, 480, and 480B helicopter with a trim relay, P/N M83536/10-024M, modify the lateral and longitudinal trim actuator assembly using the modification kit, P/N 4230045-1.
For all affected helicopters, after accomplishing the modification of the lateral and longitudinal trim actuator assemblies and before further flight, perform an operational test and flight test to determine the trim is operating correctly.
The actions required by this AD are to be accomplished by following specified 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 this AD 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 assembly will require 4 work hours at a cost of $85 per hour and parts will cost $327; the cost per helicopter will be $667. For Model 280C, 280F, 280FX, F-28C, F-28C-2, and F-28F, modifying the actuator assembly will require 4 work hours at a cost of $85 per hour; parts will cost $383; and the cost per helicopter will be $723.
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 becausethe required corrective actions must be accomplished within 5 hours time-in-service, a very 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.