[Federal Register Volume 59, Number 176 (Tuesday, September 13, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22627]


[[Page Unknown]]

[Federal Register: September 13, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-SW-27-AD]

 

Airworthiness Directives; The Enstrom Helicopter Corporation 
Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F, and 280FX 
Series Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to The Enstrom Helicopter 
Corporation Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F, 
and 280FX series helicopters, that currently requires initial and 
repetitive inspections of a certain main rotor transmission clutch 
assembly (clutch assembly) for bearing roughness, noise, lock-up, or 
improper oil level and, if necessary, replacement of the clutch 
assembly. The current AD also requires replacement of the clutch 
assembly at certain time-in-service intervals. This action would 
require the same inspections and replacements as required by the 
current AD, but would provide an additional approved replacement part 
number and provide a reference to three additional manufacturer service 
documents. The actions specified by the proposed AD are intended to 
prevent failure of the clutch assembly, loss of control of the main 
rotor system, and subsequent loss of control of the helicopter.

DATES: Comments must be received by October 28, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 93-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137-4298. Comments may be inspected at this location between 
9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule 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 Blvd., Room 663, Fort Worth, Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Joe McGarvey, Aerospace Engineer, 
Chicago Aircraft Certification Office, Airframe Branch, FAA, Small 
Airplane Directorate, 2300 East Devon Avenue, Room 202, Des Plaines, 
Illinois 60018, telephone (708) 294-7136, fax (708) 294-7834.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-SW-27-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Office of the Assistant Chief Counsel, Attention: Rules 
Docket No. 93-SW-27-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137-4298.

Discussion

    On January 23, 1989, the FAA issued AD 89-04-09, Amendment 39-6138 
(54 FR 6391, February 10, 1989), to require initial and repetitive 
inspections of certain main rotor transmission clutch assemblies for 
bearing roughness, noise, lock-up, and improper oil levels. AD 89-04-09 
also requires replacement of the main rotor transmission clutch 
assembly (clutch assembly) when unairworthy, and establishes a 1,200 
hours time-in-service retirement life on the clutch assembly. That 
action was prompted by several failures of the clutch assembly. Based 
on an analysis of the clutch assembly failure data, the FAA, in 
conjunction with The Enstrom Helicopter Corporation and Formsprag, the 
clutch assembly manufacturer, determined that the clutch assembly, P/N 
28-13401-1 (Formsprag CL 40526-1 through -7), could not be safely 
overhauled and returned to service. The FAA has determined that 
premature failure of the clutch assembly due to a loss of lubricant 
creates an unsafe condition. The requirements of that AD are intended 
to prevent failure of the clutch assembly, loss of control of the main 
rotor system, and subsequent loss of control of the helicopter.
    Since the issuance of that AD, the FAA has approved the use of 
clutch assembly, part number (P/N) 28-13401-4 (Formsprag CL 40526-10), 
in addition to the earlier clutch assembly, P/N 28-13401-2 (Formsprag 
CL 40526-8) as replacement clutch assemblies. Additionally, subsequent 
to the issuance of AD 89-04-09, The Enstrom Helicopter Corporation 
(Enstrom) issued Service Directive Bulletin (SDB) No. 0069, Revision A, 
dated July 9, 1990, that contains an overhaul time interval for clutch 
assemblies, P/N 28-13401-2 (Formsprag CL 40526-8) and P/N 28-13401-4 
(Formsprag CL 40526-10). Also, AD 89-04-09 referenced neither Enstrom 
Service Information Letter (SIL) No. 0084, dated December 19, 1978, 
pertaining to checking the run-out of the main rotor pinion shaft nor 
Enstrom SDB No. 0068, dated May 8, 1986, subsequently reissued July 9, 
1990, pertaining to the retirement life of the clutch assembly. 
Finally, a note contained in AD 89-04-09 incorrectly referenced SIL 
``0038A''; the reference should have been SIL ``No. 0088, Revision A, 
dated August 6, 1980.''
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 89-04-09 to require initial and 
repetitive inspections of certain clutch assemblies for bearing 
roughness, noise, lock-up, or improper oil levels and, if necessary, 
immediate replacement of the clutch assembly. Owner/operator checks are 
proposed after engine start and rotor engagement to verify proper 
operation of the clutch assembly and, after each engine shutdown, while 
the main rotor is still turning down, to check for abnormal noise (such 
as a clicking or racheting sound) from the upper pulley that houses the 
clutch assembly. These proposed owner/operator checks do not require 
the use of tools, precision measuring equipment, training, pilot 
logbook endorsements, or the use of technical data not contained in the 
AD. Additionally, these owner/operator checks are considered part of 
the normal pilot ``Before Takeoff'' and ``After Landing'' checks and 
were allowed by the existing AD. These owner/operator checks are 
additional measures to ensure, between 25 hours TIS inspections, that 
sufficient lubricants are maintained in the clutch assembly and not 
lost through a leaking seal. These checks may be performed by an owner/
operator holding at least a private pilot certificate and must be 
entered into the aircraft records showing compliance with this AD in 
accordance with sections 43.11 and 91.417(a)(2)(v) of the Federal 
Aviation Regulations. The proposed AD would also require replacement of 
the clutch assembly at certain TIS intervals.
    The FAA estimates that 162 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 2 work 
hours per helicopter to accomplish the proposed actions, and that the 
average labor rate is $55 per work hour. Required parts would cost 
approximately $2,800 to overhaul or $10,500 for a zero-time clutch 
assembly per helicopter. Based on these figures, the total cost impact 
of the proposed AD on U.S. operators is estimated to be from $471,420, 
if only overhauled clutch assemblies are installed, to $1,718,820, if 
only zero-time clutch assemblies are used.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 removing Amendment 39-6138 (54 FR 
6391, February 10, 1989), and by adding a new airworthiness directive 
(AD), to read as follows:

The Enstrom Helicopter Corporation (Enstrom): Docket No. 93-SW-27-
AD. Supersedes AD 89-04-09, Amendment 39-6138.

    Applicability: Model F-28, F-28A, F-28C, F-28C-2, F-28F, 280, 
280C, 280F, and 280FX series helicopters, certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the main rotor transmission clutch 
assembly (clutch assembly), loss of control of the main rotor 
system, and subsequent loss of control of the helicopter, accomplish 
the following:
    (a) For Model F-28, F-28A, F-28C, F-28C-2, 280, and 280C series 
helicopters, equipped with clutch assembly part number (P/N) 28-
13401-1 (Formsprag CL 40526-1 through-7) perform the following:
    (1) Before the first flight of each day, before takeoff, gently 
close the throttle, splitting the tachometer needles to verify 
proper operation of the clutch assembly. If the tachometer needles 
do not split, before further flight, inspect the clutch assembly in 
accordance with paragraph (a)(4).
    (2) At the conclusion of the last flight of each day, after 
engine shutdown, while the main rotor is still running down, listen 
for any abnormal noise (such as a clicking or racheting sound) from 
the area of the upper pulley that houses the clutch assembly. If any 
abnormal noise is heard from the clutch assembly, inspect the clutch 
assembly in accordance with paragraph (a)(4).
    (3) The operational checks required by paragraphs (a)(1) and 
(a)(2) may be performed by an owner/operator holding at least a 
private pilot certificate and must be entered into the aircraft 
records showing compliance with this AD in accordance with 14 CFR 
43.11 and 91.417(a)(2)(v).
    (4) If any irregularities are noted while performing the 
procedures required by paragraph (1) or (2), inspect the clutch 
assembly to determine if it is locked-up, or if the upper pulley 
will rotate. Rotate it in both directions while feeling for any 
bearing roughness and listening for any bearing noise. The upper 
pulley should free-wheel if rotated in a clockwise direction and 
engage if rotated in a counterclockwise direction.
    (5) Within the next 25 hours time-in-service (TIS) after the 
effective date of this airworthiness directive (AD), make an entry 
in the aircraft log book documenting the clutch assembly part 
number, the number of hours TIS, and the date.
    (6) Within the next 25 hours TIS after the effective date of 
this AD, and thereafter at intervals not to exceed 100 hours TIS, 
inspect the clutch assembly for proper oil level in accordance with 
the appropriate maintenance manual. If there has been less than a 
complete loss of oil, replenish the oil and service the clutch 
assembly in accordance with The Enstrom Helicopter Corporation 
Service Information Letter No. 0079A, dated February 14, 1980.
    (7) If there has been a complete oil loss, or lock-up, noise, or 
roughness are detected from the clutch assembly as a result of the 
inspections required by this AD, before further flight, replace the 
clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 through-7), 
with an airworthy clutch assembly, P/N 28-13401-2 (Formsprag CL 
40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10).
    (8) For a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 
through-7), that has 1,175 or more hours TIS on the effective date 
of this AD, within the next 25 hours TIS, replace the clutch 
assembly with an airworthy clutch assembly, P/N 28-13401-2 
(Formsprag CL 40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10).
    (9) For a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 
through-7), that has less than 1,175 hours TIS on the effective date 
of this AD, replace the clutch assembly with an airworthy clutch 
assembly, P/N 28-13401-2 (Formsprag CL 40526-8) or P/N 28-13401-4 
(Formsprag CL 40526-10), prior to the clutch assembly accumulating 
1,200 hours TIS.

    Note: The clutch service information published in The Enstrom 
Helicopter Corporation (Enstrom) Service Note No. 0027, dated 
December 9, 1975; Enstrom Service Information Letter No. 0084, dated 
December 19, 1978; Enstrom Service Information Letter No. 0079A, 
dated February 14, 1980; Service Information Letter No. 0088, 
Revision A, dated August 6, 1980, Enstrom Service Directive Bulletin 
No. 0068, Revision A, dated July 9, 1990; and Enstrom Service 
Directive Bulletin No. 0069, Revision A, dated July 9, 1990; 
pertains to this AD.

    (b) For Model F-28F, 280F, and 280FX series helicopters, 
accomplish the following:
    (1) Within the next 25 hours TIS after the effective date of 
this AD, determine the part number of the clutch assembly.
    (2) If a clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 
through-7), is found, before further flight, replace it with an 
airworthy clutch assembly, P/N 28-13401-2 (Formsprag CL 40526-8) or 
P/N 28-13401-4 (Formsprag CL 40526-10). The clutch assembly, P/N 28-
13401-1 (Formsprag CL 40526-1 through-7), is not approved for use on 
Enstrom Model F-28F, 280F, or 280FX series helicopters.
    (c) Installation of a clutch assembly, P/N 28-13401-2 (Formsprag 
CL 40526-8) or P/N 28-13401-4 (Formsprag CL 40526-10), on Model F-
28, F-28A, F-28C, F-28C-2, F-28F, 280, 280C, 280F, and 280FX series 
helicopters constitutes a terminating action for the requirements of 
this AD.
    (d) This AD establishes a retirement life of 1,200 hours TIS for 
the clutch assembly, P/N 28-13401-1 (Formsprag CL 40526-1 through-
7). However, for clutch assemblies with 1,175 or more hours TIS on 
the effective date of this AD, those clutch assemblies need not be 
retired until on or before the accumulation of an additional 25 
hours TIS.
    (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.

    Issued in Fort Worth, Texas, on September 6, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-22627 Filed 9-12-94; 8:45 am]
BILLING CODE 4910-13-P