[Federal Register Volume 59, Number 154 (Thursday, August 11, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-18934] [[Page Unknown]] [Federal Register: August 11, 1994] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 93-SW-24-AD; Amendment 39-8968; AD 93-24-13] Airworthiness Directives; The Enstrom Helicopter Corporation Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX Series Helicopters AGENCY: Federal Aviation Administration, DOT. ACTION: Final rule; request for comments. ----------------------------------------------------------------------- SUMMARY: This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 93-24-13 that was sent previously to all known U.S. owners and operators of The Enstrom Helicopter Corporation Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX series helicopters by individual letters. This AD requires inspecting the trim motor, wiring, and relays (trim system) for failure, rewiring the trim system, and replacing the trim actuator circuit breaker. This amendment is prompted by three reports of trim system failures resulting in inadvertent trim motor operation due to struck relays. A stuck relay could cause the trim motor to deploy to the full trim position, resulting in high cyclic control forces that significantly reduce the controllability of the helicopter. The actions specified by this AD are intended to prevent failure of the trim motor relay that could result in full deployment of the trim system, high cyclic control forces, and loss of control of the helicopter. DATES: Effective August 26, 1994, to all persons except those persons to whom it was made immediately effective by Priority Letter AD 93-24- 13, issued on December 6, 1993, which contained the requirements of this amendment. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of August 26, 1994. Comments for inclusion in the Rules Docket must be received on or before September 26, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Assistant Chief Counsel, Attention: Rules Docket No. 93-SW-24-AD, 2601 Meacham Boulevard, Room 663, Fort Worth, Texas 76137-4298. The applicable service information may be obtained from The Enstrom Helicopter Corporation, Twin County Airport, P.O. Box 490, Menominee, Michigan 49858. This information may be examined at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Boulevard, Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. FOR FURTHER INFORMATION CONTACT: Mr. Joe McGarvey, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, Small Airplane Directorate, 2300 East Devon Avenue, Room 232, Des Plaines, Illinois 60018, telephone (708) 294-7136, fax (708) 294-7834. SUPPLEMENTARY INFORMATION: On December 6, 1993, the FAA issued Priority Letter AD 93-24-13, applicable to The Enstrom Helicopter Corporation Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX series helicopters, which requires inspecting the trim motor, wiring, and relays (trim system) for failure, rewiring the trim system, and replacing the trim actuator circuit breaker. That action was prompted by three reports of trim system failures resulting in inadvertent trim motor operation due to stuck relays. A stuck relay could cause the trim motor to deploy to the full trim position, resulting in high cyclic control forces that significantly reduce the controllability of the helicopter. The cyclic control is a critical part of the rotorcraft flight control system. The cyclic control tilts the tip-path plane of the rotating main rotor in the direction of the desired horizontal movement, either forward, sideward, or backward. Therefore, any uncontrolled trim force applied to the cyclic control creates an unsafe condition. This condition, if not corrected, could result in failure of the trim motor relay that could result in full deployment of the trim system, high cyclic control forces, and loss of control of the helicopter. The FAA has reviewed and approved The Enstrom Helicopter Corporation Service Directive Bulletin No. 0082, Revision A, dated March 18, 1993, that describes procedures for inspecting the trim system for failure; replacing any failed trim system part; rewiring of the trim system to preclude trim overtravel; replacing the trim actuator circuit breaker; and, verifying proper operation of the trim system and the limit switch stop position. Since the unsafe condition described is likely to exist or develop on other helicopters of the same type design, the FAA issued Priority Letter AD 93-24-13 to prevent failure of the trim motor relay that could result in full deployment of the trim system, high cyclic control forces, and loss of control of the helicopter. The AD requires inspecting the trim system for failure; replacing any failed trim system part; rewiring of the trim system to preclude trim overtravel; replacing the trim actuator circuit breaker; and, verifying proper operation of the trim system and the limit switch stop position. The actions are required to be accomplished in accordance with The Enstrom Helicopter Corporation Service Directive Bulletin No. 0082, Revision A, dated March 18, 1993, described previously. Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on December 6, 1993, to all known U.S. owners and operators of The Enstrom Helicopter Corporation Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX series helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of part 39 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons. Comments Invited Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 93-SW-24-AD.'' The postcard will be date stamped and returned to the commenter. The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a ``significant regulatory action'' under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: AD 93-24-13 The Enstrom Helicopter Corporation: Amendment 39-8968. Docket Number 93-SW-24-AD. Applicability: Model F-28C, F-28C-2, F-28F, 280C, 280F, and 280FX series helicopters, equipped with a 24 volt D.C. electrical system, certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent failure of the trim motor relay that could result in full deployment of the trim system, high cyclic control forces, and loss of control of the helicopter, accomplish the following: (a) Within the next 5 hours' time-in-service (TIS) after the effective date of this airworthiness directive (AD), inspect the trim motor, wiring, and relays (trim system) for failure in accordance with the Compliance Section of The Enstrom Helicopter Corporation Service Directive Bulletin No. 0082 (SDB 0082), Revision A, dated March 18, 1993. (1) Rewire the trim system and replace the trim actuator circuit breaker in accordance with paragraph 5.3 of SDB 0082, Revision A, dated March 18, 1993, to preclude trim overtravel. (2) After rewiring the trim system in accordance with paragraph (a)(1) of this AD, verify proper operation of the trim system and the limit switch stop position in accordance with the applicable maintenance manual. (b) When installing a replacement or zero-time relay or circuit breaker, install in accordance with paragraph 5.3 of SDB 0082, Revision A, dated March 18, 1993. After wiring the trim system in accordance with SDB 0082, Revision A, dated March 18, 1993, verify proper operation of the trim system at the limit switch stop position in accordance with the applicable maintenance manual. (c) Inspect the trim system for failure in accordance with the Compliance Section of SDB 0082, Revision A, dated March 18, 1993, at intervals not to exceed 100 hours' TIS from the last inspection or at each annual inspection, whichever occurs first. (d) Replace any unairworthy trim system part with an airworthy part in accordance with the applicable maintenance manual. (e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Chicago Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Chicago Aircraft Certification Office. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Chicago Aircraft Certification Office. (f) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished. (g) The inspection, rewiring, and replacement shall be done in accordance with The Enstrom Helicopter Corporation Service Directive Bulletin No. 0082, Revision A, dated March 18, 1993. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from The Enstrom Helicopter Corporation, Twin County Airport, P.O. Box 490, Menominee, Michigan 49858. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Boulevard, Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (h) This amendment becomes effective on August 26, 1994, to all persons except those persons to whom it was made immediately effective by Priority Letter AD 93-24-13, issued December 6, 1993, which contained the requirements of this amendment. Issued in Fort Worth, Texas, on June 30, 1994. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 94-18934 Filed 8-10-94; 8:45 am] BILLING CODE 4910-13-M