[Federal Register Volume 59, Number 144 (Thursday, July 28, 1994)]
[Unknown Section]
[Page ]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17867]


[Federal Register: July 28, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-SW-25-AD; Amendment 39-8943; AD 94-13-03]


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 amendment adopts a new airworthiness directive (AD) that 
is applicable to The Enstrom Helicopter Corporation Model F-28C, F-28C-
2,  F-28F, 280C, 280F, and 280FX series helicopters. This action 
requires a visual inspection for cracks in the tail rotor spindle; a 
repetitive dye penetrant inspection for cracks; and removal and 
replacement of the tail rotor spindle upon reaching 1,200 hours' time-
in-service (TIS). This amendment is prompted by five reports of cracked 
tail rotor spindles. The actions specified in this AD are intended to 
prevent failure of the tail rotor spindle, loss of directional control, 
and subsequent loss of control of the helicopter.

DATES: Effective August 12, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 12, 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-25-AD, 2601 Meacham Boulevard, Room 663, Fort 
Worth, Texas 76137-4298.
    The service information referenced in this AD 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, Airframe Branch, FAA, 2300 East 
Devon Avenue, Room 202, Des Plaines, Illinois 60018, telephone (708) 
294-7136, fax (708) 294-7834.

SUPPLEMENTARY INFORMATION: This amendment adopts a new airworthiness 
directive that is applicable to The Enstrom Helicopter Corporation 
(Enstrom) Model F-28C, F-28C-2,  F-28F, 280C, 280F, and 280FX series 
helicopters equipped with tail rotor spindle (spindle), part number (P/
N) 28-150064-11 or 28-150064-13. The manufacturer advises that there 
have been five reports of cracked spindles that had time-in-service 
(TIS) ranging from 282 to 3,449 hours. Three of the five defects were 
found during a visual preflight inspection. One of the reported 
incidents resulted in an emergency landing due to a tail rotor 
imbalance and the resultant high vibrations as a result of the cracked 
spindle. Based on an analysis and evaluation of the data, the FAA has 
determined that an unsafe condition exists in the spindle. This 
condition, if not corrected, could result in failure of the spindle, 
loss of directional control, and subsequent loss of control of the 
helicopter.
    The FAA has reviewed and approved The Enstrom Helicopter 
Corporation Service Directive Bulletin (SDB) No. 0077, Revision B, 
dated November 16, 1992, that describes procedures for performing a 
visual inspection of the area around the spindle teeter bearing bores 
for cracks prior to the next flight and prior to each subsequent 
flight, and if cracks are found, removal and replacement of the spindle 
with an airworthy spindle; continuing the visual inspection before each 
flight and performing a dye penetrant inspection of the spindle for 
cracks within the next five hours' TIS; securing the spindle bearing 
caps with safety wire following the dye penetrant inspection; and 
removing and replacing spindles with 1,200 hours' or more total TIS.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Enstrom Model F-28C, F-28C-2, F-28F, 280C, 
280F, and 280FX series helicopters of the same type design, this AD is 
being issued to prevent failure of the spindle, loss of directional 
control, and subsequent loss of control of the helicopter. Before 
further flight, this AD requires a visual inspection of the spindle, 
part number (P/N) 28-150064-11 or 28-150064-13, for cracks in 
accordance with paragraph 5.2 of SDB 0077, Revision B, dated November 
16, 1992. A dye penetrant inspection is required whenever track and 
balance procedures are required more than once within a 5 hours' TIS 
period. Additionally, within the next 25 hours' TIS and thereafter, at 
intervals not to exceed 25 hours' TIS, this AD requires an inspection 
of the spindle for cracks (without removing the tail rotor from the 
helicopter) using a visual and dye penetrant inspection in accordance 
with paragraph 5.3 of SDB 0077, Revision B, dated November 16, 1992. 
Also, this AD requires replacement of spindles with cracks or 
scratches, nicks, or surface discontinuities that are in excess of 
certain specified tolerances, or, if the spindle is not required to be 
replaced, returning the helicopter to service in accordance with 
paragraph 5.4 of SDB 0077, Revision B, dated November 16, 1992. 
Replacing a spindle, P/N 28-150064-11 or 28-150064-13, is also required 
within the next 100 hours' TIS, or on or before reaching 1,200 hours' 
TIS, whichever occurs later. Installing a spindle, P/N 28-150074-11, 
constitutes terminating action for the requirements of this AD. Since 
the unsafe condition requires an immediate inspection to ensure safety 
of the fleet, this AD needs to be adopted immediately, without prior 
public comment. The compliance requirements of this AD and take 
precedence over those stated in the Service Directive Bulletin, except 
where specifically referenced in this AD.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-SW-25-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 94-13-03 The Enstrom Helicopter Corporation: Amendment 39-8943. 
Docket Number 93-SW-25-AD.

    Applicability: Model F-28C, F-28C-2,  F-28F, 280C, 280F, and 
280FX series helicopters, equipped with tail rotor spindle 
(spindle), part number (P/N) 28-150064-11 or 28-150064-13, 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the spindle, loss of directional control 
and subsequent loss of control of the helicopter, accomplish the 
following:
    (a) Before further flight, visually inspect the spindle for 
cracks using a 5-power or higher magnifying glass in accordance with 
paragraph 5.2 of The Enstrom Helicopter Corporation Service 
Directive Bulletin (SDB) No. 0077, Revision B, dated November 16, 
1992.
    (b) Before further flight, whenever tail rotor (T/R) vibrations 
occur that cannot be corrected with track and balance procedures or 
track and balance procedures are required more than once within a 5 
hours' TIS period, inspect the spindle teetering bearing bores for 
cracks using a dye penetrant method in accordance with paragraph 5.3 
of SDB 0077, Revision B, dated November 16, 1992.
    (c) Within the next 25 hours' time-in-service (TIS) after the 
effective date of this airworthiness directive (AD) and thereafter 
at intervals not to exceed 25 hours' TIS from the last inspection, 
without removing the tail rotor from the helicopter, inspect the 
spindle teetering bearing bores for cracks using a dye penetrant 
inspection and visually inspect for scratches, nicks, or surface 
discontinuities in accordance with paragraph 5.3 of SDB 0077, 
Revision B, dated November 16, 1992.
    (d) If neither a crack nor any scratches, nicks, or surface 
discontinuities are found that exceed the tolerances specified in 
paragraph 5.3.4 and 5.3.5 of SDB 0077, Revision B, dated November 
16, 1992, during the inspections required by paragraphs (a), (b), or 
(c) of this AD, return the helicopter to service in accordance with 
the procedures contained in paragraph 5.3.5 of the SDB 0077, 
Revision B, dated November 16, 1992, and the applicable maintenance 
manual.
    (e) If a crack is found, or scratches, nicks, or surface 
discontinuities are found that exceed the tolerances specified in 
paragraph 5.3.4 and 5.3.5 of SDB 0077, Revision B, dated November 
16, 1992, remove the spindle before further flight and install an 
airworthy spindle in accordance with the provisions of the 
appropriate maintenance manual.
    (f) Within the next 100 hours' TIS or, on or before reaching 
1,200 hours' TIS, whichever occurs later, remove spindle, P/N 28-
150064-11 or 28-150064-13, from service and replace it with an 
airworthy spindle in accordance with the appropriate maintenance 
manual.
    (g) Installation of a spindle, P/N 28-150074-11, constitutes 
terminating action for the requirements of this AD.
    (h) 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.

    (i) Except for the inspection required by paragraphs (a) and (b) 
of this AD, 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 other requirements of this AD can be accomplished.
    (j) The inspections shall be done in accordance with The Enstrom 
Helicopter Corporation Service Directive Bulletin No. 0077, Revision 
B, dated November 16, 1992. 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.
    (k) This amendment becomes effective on August 12, 1994.

    Issued in Fort Worth, Texas, on June 14, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-17867 Filed 7-27-94; 8:45 am]
BILLING CODE 4910-13-P