[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]
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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.
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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
