[Federal Register Volume 62, Number 183 (Monday, September 22, 1997)]
[Rules and Regulations]
[Pages 49434-49436]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-25059]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-SW-31-AD; Amendment 39-10142; AD 97-20-04]
RIN 2120-AA64


Airworthiness Directives; Enstrom Helicopter Corporation Model F-
28A, F-28C, 280 and 280C 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 Enstrom Helicopter Corporation (Enstrom) Model F-28A, 
280 and certain serial-numbered F-28C and 280C helicopters. This action 
requires an inspection of the voltage control system and an owner/
operator (pilot) cockpit check of the amperage of the electrical 
system. If certain Prestolite-manufactured components are installed, 
additional tests and actions are required before further flight and at 
each pre-flight run-up and annual inspection thereafter. A terminating 
action is provided by replacing the existing voltage control system 
with a transistorized system. This amendment is prompted by 14 reports 
of voltage control system problems, including one incident in which 
smoke emanated from the radio panel during flight, forcing the pilot to 
make an emergency landing. The actions specified in this AD are 
intended to prevent an electrical overload and a failure of the voltage 
regulator and over-voltage relay, that could result in an inflight 
fire, and subsequent forced landing of the helicopter.

DATES: Effective October 7, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 7, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before November 21, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 96-SW-31-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.
    The service information referenced in this AD may be obtained from 
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 76137; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ms. Brenda S. Ocker, Aerospace 
Engineer, FAA, Systems and Flight Test Branch, Chicago Aircraft 
Certification Office, 2300 East Devon Ave., Des Plaines, Illinois 
60018, telephone (847) 294-7126, fax (847) 294-7834.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to Enstrom Model F-28A, 280 and certain serial-numbered 
Model F-28C and 280C helicopters. This action requires a determination 
of whether a Prestolite-manufactured voltage regulator, part number (P/
N) VSF7203, or a Prestolite-manufactured over-voltage relay, P/N 
X16799, X17621, or FOC-4002A is installed, and if installed, within 5 
hours time-in-service (TIS), an inspection of the alternator output 
voltage system for proper operation and an operational test of the 
over-voltage relay; after the initial inspection, before each flight, a 
pilot check to determine that the amp meter is reading within the 
normal range while the engine is operating at 2,200 revolutions-per-
minute (RPM); and thereafter, at each annual inspection or 100 hour TIS 
inspection, whichever occurs first, a test to determine if the 
alternator output voltage is within normal limits and a test of the 
over-voltage relay. The checks required by this AD may be performed by 
the owner/operator holding at least a private pilot certificate, and 
must be entered into the aircraft records showing compliance with the 
applicable sections of this AD in accordance with sections 43.9 and 
91.417(a)(2)(v) (14 CFR 43.9 and 91.417(a)(2)(v)) of the Federal 
Aviation Regulations. This amendment is prompted by 14 reports of these 
helicopters having electrical system problems, including one incident 
in which smoke came from the radio panel during flight, forcing the 
pilot to make an emergency landing. An investigation conducted by the 
rotorcraft manufacturer, with FAA participation, revealed that the 
Prestolite-manufactured voltage regulator, P/N VSF7203, failed, which 
resulted in a massive voltage increase. A subsequent failure of the 
over-voltage protection device resulted in overheating of the system 
wiring and components. The investigation revealed that at least four of 
the 14 helicopters did not have over-voltage protection installed. This 
condition, if not corrected, could result in an electrical overload and 
a failure of the voltage regulator and over-voltage relay, that could 
result in an inflight fire, and subsequent forced landing of the 
helicopter.
    The FAA has reviewed and approved the technical contents of Enstrom 
Helicopter Corporation Service Directive Bulletin No. 0086, dated March 
31, 1996, which describes procedures for inspecting the voltage control 
system, testing the components, and replacing the voltage regulator and 
over-voltage relay as necessary.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Enstrom Model F-28A, F-28C, 280 and 280C 
helicopters of the same type design, this AD is being issued to prevent 
failure of the voltage regulator and over-voltage relay, resulting in 
an over-voltage and possible fire. This AD requires, within the next 
five hours time-in-service (TIS), an inspection to determine if the 
Prestolite-manufactured voltage regulator, part number (P/N) VSF7203, 
or Prestolite-manufactured over-voltage relays, P/N X16799, X17621, or 
FOC-4002A, are installed, and an inspection of the alternator output 
voltage and an operational test of the over-voltage relay. If any of 
these components are installed, the AD further requires, before each 
flight, a pilot check of the amp meter for readings within the normal 
operating range. Thereafter, at each annual inspection or 100 hour TIS 
inspection (whichever occurs first), a test is required to determine if 
the alternator output voltage is within tolerance, and if the 
alternator output voltage is not within the specified range, an 
adjustment to the voltage regulator, or replacement of the voltage 
regulator with an airworthy voltage regulator if the voltage regulator 
cannot be adjusted within the specified range. An operational test of 
the over-voltage relay is required to determine if the relay operates 
at the correct voltage, and replacement of any over-voltage relay that 
fails the operational test with an airworthy over-voltage relay. Any 
aircraft found without over-voltage relay protection must have an 
airworthy over-voltage relay installed. A terminating action is 
provided for in the AD by modifying the wiring and replacing the 
existing voltage control system with a transistorized voltage 
controller, P/N ECD-069-11, with built-in over-voltage protection. The 
actions are required to be accomplished in accordance with the 
Compliance section of the service bulletin described previously.
    Since a situation exists that requires the immediate adoption of 
this

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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 rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 96-SW-31-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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

97-20-04  Enstrom Helicopter Corporation: Amendment 39-10142. Docket 
No. 96-SW-31-AD.

    Applicability: Model F-28A; 280; F-28C helicopters, with a 
serial number (S/N) less than S/N 745; and Model 280C helicopters, 
with a S/N less than S/N 1502, certificated in any category.

    Note 1: This AD applies to each helicopter identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (e) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an electrical overload and a failure of the voltage 
regulator and over-voltage relay, that could result in an inflight 
fire, and subsequent forced landing of the helicopter:
    (a) Within the next five hours time-in-service (TIS) after the 
effective date of this AD, determine if a Prestolite-manufactured 
voltage regulator, part number (P/N) VSF7203, or Prestolite-
manufactured over-voltage relay,
P/N X16799, P/N X17621, or P/N FOC-4002A, is installed.
    (1) If any of these parts are installed, perform the following:
    (i) Determine if the alternator output is within the proper 
output voltage range (14.2 + .2 to -.4 volts). If the alternator 
output voltage is not within the proper voltage range, adjust or 
replace the voltage regulator.
    (ii) Conduct an operational test of the over-voltage relay, and 
replace any over-voltage relay that fails the operational test with 
an airworthy over-voltage relay. Accomplish both the operational 
test and the over-voltage relay replacement in accordance with 
paragraph 6.3.3 of Enstrom Helicopter Corporation SDB No. 0086, 
dated March 31, 1996.
    (2) If no over-voltage relay is installed, before further 
flight, install an airworthy relay, P/N FOC-4002A, in accordance 
with paragraph 6.3.4. of Enstrom Helicopter Corporation Service 
Directive Bulletin (SDB) No. 0086, dated March 31, 1996, or complete 
the terminating action described in paragraph (c).
    (b) After compliance with paragraph (a) of this AD, thereafter, 
before each flight, check the amp meter for readings within the 
normal operating range while the helicopter engine is operating at 
2,200 revolutions-per-minute (RPM). This check may be performed by 
the owner/operator (pilot) holding at least a private pilot 
certificate, and must be entered into the aircraft records showing 
compliance with this paragraph in accordance with sections 43.9 and 
91.417(a)(2)(v) of the Federal Aviation Regulations (14 C.F.R. 43.9 
and 91.417(a)(2)(v)).
    (c) After compliance with paragraph (a) of this AD, thereafter, 
at each annual inspection or 100 hour time-in-service (TIS) 
inspection, whichever occurs first, perform the following:
    (1) Determine if the alternator output is within the proper 
output voltage range, and if the alternator output voltage is not 
within the proper voltage range, adjust or replace the voltage 
regulator.
    (2) Conduct an operational test of the over-voltage relay, and 
replace any over-voltage relay that fails the operational test with 
an airworthy over-voltage relay in accordance with paragraph 6.3.3 
of Enstrom Helicopter Corporation SDB No. 0086, dated March 31, 
1996.
    (d) Replacement of the existing voltage control system with a 
transistorized voltage controller, P/N ECD-069-11, and modifying the 
wiring in accordance with paragraph 6.4 of Enstrom Helicopter 
Corporation SDB No. 0086, dated March 31, 1996, is considered a 
terminating action for the requirements of this AD.
    (e) An alternative method of compliance or adjustment of the 
compliance time that

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provides an acceptable level of safety may be used if 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 2: 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) The check, test, and replacement, if necessary, shall be 
done in accordance with Enstrom Helicopter Corporation Service 
Directive Bulletin No. 0086, dated March 31, 1996. 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 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 Blvd., Room 663, Fort Worth, Texas; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.
    (g) This amendment becomes effective on October 7, 1997.

    Issued in Fort Worth, Texas, on September 16, 1997.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 97-25059 Filed 9-19-97; 8:45 am]
BILLING CODE 4910-13-P