AD 2004-06-04

[Federal Register Volume 69, Number 62 (Wednesday, March 31, 2004)]
[Rules and Regulations]
[Pages 16778-16780]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 04-6777]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-SW-45-AD; Amendment 39-13530; AD 2004-06-04]
RIN 2120-AA64


Airworthiness Directives; Sikorsky Aircraft Corporation Model S-
76 A, B, and C Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD) for 
Sikorsky Aircraft Corporation (Sikorsky) Model S-76 A, B, and C 
helicopters with dual channel autopilot and dual inverters installed. 
This action requires a test to determine if the No. 1 inverter is wired 
to the DC essential bus, and if so, it requires modifying the wiring so 
that the No. 1 inverter is wired to the No. 2 DC primary bus and the 
No. 2 inverter is wired to the DC essential bus. If the wiring 
modification is required and is not performed before further flight, 
then revising the Rotorcraft Flight Manual (RFM) before further flight 
to limit the maximum instrument meteorological conditions (IMC) 
airspeed and installing a placard near the airspeed indicator is also 
required. The wiring modification is required within 30 days. This 
amendment is prompted by three incidents in which a No. 2 generator 
intermittent malfunction occurred and both autopilots disengaged. The 
actions specified in this AD are intended to prevent both autopilots 
from disengaging following a No. 2 DC generator failure, and subsequent 
loss of control of the helicopter during IMC operations.

DATES: Effective April 15, 2004.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 15, 2004.
    Comments for inclusion in the Rules Docket must be received on or 
before June 1, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 2003-SW-45-AD, 2601 Meacham Blvd., Room 
663, Fort Worth, Texas 76137. You may also send comments electronically 
to the Rules Docket at the following address: <a href="/cdn-cgi/l/email-protection#122b3f7361653f7376717d7f7f777c6661527473733c757d64"><span class="__cf_email__" data-cfemail="51687c3022267c3035323e3c3c343f2522113730307f363e27">[email&#160;protected]</span></a>.
    The service information referenced in this AD may be obtained from 
Sikorsky Aircraft Corporation, Attn: Manager, Commercial Tech Support, 
6900 Main Street, Stratford, Connecticut 06614, phone (203) 386-3001, 
fax (203) 386-5983. This information may be examined at the FAA, Office 
of the Regional Counsel, Southwest Region, 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.

FOR FURTHER INFORMATION CONTACT: Solomon Hecht, Aviation Safety 
Engineer, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, MA 01803, telephone (781) 238-7159, fax 
(781) 238-7170.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD for Sikorsky 
Model S-76 A, B, and C helicopters with dual channel autopilot and dual 
inverters installed. This action requires, before further flight, 
determining if the No. 1 inverter is wired to the DC essential bus, and 
if it is, modifying the wiring or installing a placard that limits the 
maximum IMC airspeed to 120 knots indicated airspeed (KIAS) as well as 
annotating the Operating Limitations section of the RFM to reflect this 
limit. Also, this action requires, within 30 days, for those 
helicopters with the No. 1 inverter wired to the DC essential bus, 
modifying the electrical wiring so that the No. 1 inverter, which 
powers the co-pilot's Automatic Flight Control System (AFCS) computer, 
is wired to the No. 2 DC primary bus and also modifying the electrical 
wiring so that the No. 2 inverter, which powers the pilot's AFCS 
computer, is wired to the DC essential bus. If installed, removing the 
placard and the RFM annotation is allowed after modifying the 
electrical wiring. This amendment is prompted by three incidents in 
which a No. 2 generator had an intermittent malfunction and both 
autopilots disengaged. The actions specified in this AD are intended to 
prevent both autopilots from disengaging following a No. 2 DC generator 
failure, and subsequent loss of control of the helicopter during IMC 
operations.
    The FAA has reviewed Sikorsky Alert Service Bulletin (ASB) No. 76-
24-14A, Revision A, dated October 9, 2003, which describes procedures 
for performing a test to determine if the No. 1 inverter is wired to 
the DC essential bus, and provides the required wiring modification to 
relocate the source for the No. 2 Inverter to the DC essential bus and 
to relocate the No. 1 Inverter to the No. 2 DC bus, if required. The 
ASB also provides for a temporary airspeed limitation of 120 knots 
indicated airspeed during IMC operations until the required wiring 
modification is completed.
    This unsafe condition is likely to exist or develop on other 
helicopters of the same type design. Therefore, this AD is being issued 
to prevent both autopilots from disengaging following a No. 2 DC 
generator failure, and subsequent loss of control of the helicopter 
during IMC operations. This action requires, before further flight, 
determining if the No. 1 inverter is wired to the DC essential bus, and 
if it is, modifying the wiring or installing a placard that limits the 
maximum IMC airspeed to 120 KIAS as well as annotating the Operating 
Limitations section of the RFM to reflect this limit. Also, this action 
requires, within 30 days, for those helicopters with the No. 1 inverter 
wired to the DC essential bus, modifying the electrical wiring so that 
the No. 1 inverter, which powers the co-pilot's AFCS computer, is wired 
to the No. 2 DC primary bus and also modifying the electrical wiring so 
that the No. 2 inverter, which powers the pilot's AFCS computer, is 
wired to the DC essential bus. If installed, removing the placard and 
the RFM annotation is allowed after modifying the electrical wiring. 
The short compliance time involved is required because the previously 
described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, the previously described 
airspeed limitation reduction is required before further flight, and 
this AD must be issued immediately.
    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.
    The FAA estimates that this AD will affect 105 helicopters. The 
operational test will take approximately 1 work hour to accomplish and 
the wiring modification will take approximately 2 work hours to 
accomplish at an average labor rate of $65 per work hour. The

[[Page 16779]]

materials required to perform the modification consists of 2 wire 
sleeve markers whose cost is negligible. Based on these figures, we 
estimate the total cost impact of the AD on U.S. operators to be 
$18,525 assuming that all 105 helicopters will be tested and about 90 
helicopters will need the modification.

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 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. 2003-SW-45-AD.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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

0
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

0
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]

0
2. Section 39.13 is amended by adding a new airworthiness directive to 
read as follows:

2004-06-04 Sikorsky Aircraft Corporation: Amendment 39-13530. Docket 
No. 2003-SW-45-AD.

    Applicability: Model S-76 A, B, and C helicopters, with a dual 
channel autopilot and with dual inverters installed, certificated in 
any category.

    Note: The following serial-numbered helicopters were 
manufactured with the dual channel autopilots and dual inverters 
installed:

    S-76 A Serial Numbers: 760267, 760268, 760270 through 760298, 
760300 through 760302, 760304 through 760309, 760364, 760366, 760369 
through 760371, 760373 through 760378;
    S-76 B Serial Numbers: 760262, 760269, 760299, 760303, 760310 
through 760363, 760365, 760367, 760368, 760372, 760379 through 
760382, 760387, 760391, 760393, 760395, 760399, 760403, 760404, 
760409, 760410, 760413, 760414, 760416, 760425, 760427 through 
760430, 762976 (760433), 760437, 760439, 760441 through 760445, 
760447 through 760452, 760454, 760455, 760458, 760462, 760465, and 
760507; and
    S-76 C Serial Numbers: 760383 through 760386, 760388 through 
760390, 760392, 760394, 760396 through 760398, 760400 through 
760402, 760405 through 760408, 760411, 760412, 760415, 760417 
through 760424, 760426, 760431, 760432, 760434 through 760436, 
760438, 760440, 760446, 760453, 760456, 760457, 760459 through 
760461, 760463, 760464, 760466 through 760506, and 760508 through 
760526.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent both autopilots from disengaging following a No. 2 DC 
generator failure, and subsequent loss of control of the helicopter 
during instrument meteorological conditions (IMC) flight, do the 
following:
    (a) Before further flight:
    (1) Determine if the No. 1 inverter is wired to the DC essential 
bus by following the Accomplishment Instructions, paragraph 3.B. of 
Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-24-14A, 
Revision A, dated October 9, 2003 (ASB).
    (2) If the No. 1 inverter is wired to the DC essential bus, and 
the wiring modification is not accomplished as described in 
paragraph (b) of this AD, then before further flight, install a 
placard near the airspeed indicator that contains the limitation 
``Maximum IMC Airspeed 120 KIAS'' and annotate this airspeed 
limitation in the Operating Limitation section of the Rotorcraft 
Flight Manual (RFM).
    (b) Within 30 days, for those helicopters with the No.1 inverter 
wired to the DC essential bus, modify the electrical wiring so that 
the No.1 inverter, which powers the co-pilot's Automatic Flight 
Control System (AFCS) computer, is wired to the No. 2 DC primary bus 
and the No. 2 inverter, which powers the pilot's AFCS computer, is 
wired to the DC essential bus by following the Accomplishment 
Instructions, paragraph 3.C. of the ASB.
    (c) After modifying the electrical wiring as required in 
paragraph (b) of this AD, remove the placard and RFM annotation.
    (d) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Contact the Boston Aircraft Certification Office, Engine and 
Propeller Directorate, FAA, for information about previously 
approved alternative methods of compliance.
    (e) The test, modification, revision and placard installation 
shall be done in accordance with Sikorsky Aircraft Corporation Alert 
Service Bulletin No. 76-24-14A, Revision A, dated October 9, 2003. 
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 Sikorsky Aircraft Corporation, Attn: 
Manager, Commercial Tech Support, 6900 Main Street, Stratford, 
Connecticut 06614, phone (203) 386-3001, fax (203) 386-5983. Copies 
may be inspected at the FAA, Office of the Regional Counsel, 
Southwest Region, 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.
    (f) This amendment becomes effective on April 15, 2004.


[[Page 16780]]


    Issued in Fort Worth, Texas, on March 10, 2004.
Scott A. Horn,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 04-6777 Filed 3-30-04; 8:45 am]
BILLING CODE 4910-13-P