[Federal Register Volume 62, Number 229 (Friday, November 28, 1997)]
[Proposed Rules]
[Pages 63288-63290]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31156]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-231-AD]
RIN 2120-AA64
Airworthiness Directives; Empresa Brasileira de Aeronautica, S.A.
(EMBRAER), Model
EMB-120 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain EMBRAER Model EMB-120
series airplanes. This proposal would require deactivation of certain
circuit breakers, and a revision to the Airplane Flight Manual (AFM) to
provide operational procedures to prevent loss of electrical power
following an engine flameout. This proposal also would require
modifications of the electrical system, which would terminate the
requirement for the AFM revision and allow reactivation of the circuit
breakers. This proposal is prompted by the issuance of mandatory
continued airworthiness information by a foreign civil airworthiness
authority. The actions specified by the proposed AD are intended to
prevent generator overload conditions that could result in loss of
electrical power and failure of certain flight and landing control
systems, and to prevent power interruption to the attitude heading
reference system (AHRS) that could result in the display of erroneous
heading information.
DATES: Comments must be received by December 29, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 97-NM-231-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. 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 Empresa Brasileira de Aeronautica S/A, Sao Jose dos
Campos, Brazil. This information may be examined at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at
the FAA, Small Airplane Directorate, Atlanta Aircraft Certification
Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta,
Georgia.
FOR FURTHER INFORMATION CONTACT: John W. McGraw, Aerospace Engineer,
Systems and Flight Test Branch, ACE-116A, FAA, Atlanta Aircraft
Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite
450, Atlanta, Georgia 30349; telephone (770) 703-6098; fax (770) 703-
6097.
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 shall 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 97-NM-231-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, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 97-NM-231-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Departamento de Aviacao Civil (DAC), which is the airworthiness
authority for Brazil, notified the FAA that an unsafe condition may
exist on certain EMBRAER Model EMB-120 series airplanes. The DAC
advises that it received a report of one instance of substantial
electrical power loss after flameout of the number 1 engine. The power
loss was caused by activation of the system overload protection due to
excessive loads on the remaining number 2 engine generator, which led
to loss of certain flight and landing control systems. The DAC also
advises that, due to power interruption for a few milliseconds to the
attitude heading reference system (AHRS), erroneous heading information
in both electronic horizontal situation indicators (EHSI) may be
provided, without warning to the pilots, during an electrical emergency
or when the electrical emergency switch is set to the ``EMERGENCY''
position. This condition, if not corrected, could result in generator
overload conditions that could result in loss of electrical power and
failure of certain flight and landing control systems, and power
interruption to the AHRS that could result in display of erroneous
heading information.
Explanation of Relevant Service Information
EMBRAER has issued Service Bulletin 120-24-0008, Change 04, dated
October 3, 1995, which describes procedures for modification of the
electrical system.
This modification involves revising the electrical connections and
wiring in the relay boxes and circuit breaker panels.
EMBRAER has also issued Service Bulletin 120-24-0051, Change 04,
dated March 8, 1995, which also describes procedures for modification
of the electrical system. This modification involves electrical load
redistribution and introduction of a contactor to connect a direct
current (DC) bus to the emergency bus.
Accomplishment of the actions specified in these service bulletins
is
[[Page 63289]]
intended to adequately address the identified unsafe condition.
The DAC classified these service bulletins as mandatory and issued
Brazilian airworthiness directives (DAE) 93-24-01, dated December 31,
1993; 94-03-01R1, dated December 10, 1994, and 93-12-01R1, dated
December 12, 1994, in order to assure the continued airworthiness of
these airplanes in Brazil.
FAA's Conclusions
This airplane model is manufactured in Brazil and is type
certificated for operation in the United States under the provisions of
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and
the applicable bilateral airworthiness agreement. Pursuant to this
bilateral airworthiness agreement, the DAC has kept the FAA informed of
the situation described above. The FAA has examined the findings of the
DAC, reviewed all available information, and determined that AD action
is necessary for products of this type design that are certificated for
operation in the United States.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design registered
in the United States, the proposed AD would require accomplishment of
the actions specified in the service bulletins described previously.
The proposed AD also would require a revision to the FAA-approved
Airplane Flight Manual (AFM) to provide operational procedures in the
event of loss of electrical power following an engine flameout.
Differences Between the Proposal and Related Brazilian AD
This proposed AD differs from the parallel Brazilian airworthiness
directives in the following four respects:
1. It would not require (as DAE 93-24-01 and DAE 93-12-01R1
require) that the electrical emergency switch be set to the
``EMERGENCY'' position prior to takeoff for operations without
auxiliary power units (APU); rather, it would require electrical loads
to be reduced to below 400 amps. The FAA has determined that reduction
of loads to below 400 amps prevents the unsafe generator overload
condition.
2. It would require that the APU be operational for all flights
into known or forecast icing conditions and during takeoff and landing.
DAE 93-12-01R1 makes no limitation with respect to such icing
conditions. The FAA has determined that the APU must be operational for
flights into known or forecast icing conditions to ensure adequate
electrical power for systems that are necessary for operation in such
conditions.
3. It would extend the proposed compliance time for accomplishment
of the modifications beyond that specified by DAE 93-12-01R1 and DAE
94-03-01R1. The FAA has determined that the compliance time specified
in this proposed AD would allow the modifications to be accomplished
during regularly scheduled maintenance.
4. It would not require the accomplishment of PART C of DAE 94-03-
01R1, which requires revision of Section 4 (``Normal Procedures'') of
the AFM. The FAA has determined that Part C has been incorporated by a
previously approved change to the AFM and need not be mandated.
Cost Impact
The FAA estimates that 227 airplanes of U.S. registry would be
affected by this proposed AD.
It would take approximately 1 work hour per airplane to accomplish
the proposed AFM revisions, at an average labor rate of $60 per work
hour. Based on these figures, the cost impact of the AFM revisions
proposed by this AD on U.S. operators is estimated to be $13,620, or
$60 per airplane.
It would take approximately 90 work hours per airplane to
accomplish the proposed modifications at an average labor rate of $60
per work hour. Required parts would cost approximately $4,150 per
airplane. Based on these figures, the cost impact of the modifications
proposed by this AD on U.S. operators is estimated to be $2,167,850, or
$9,550 per airplane.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the proposed requirements
of this AD action, and that no operator would accomplish those actions
in the future if this AD were not adopted. However, the FAA has been
advised that 43 U.S.-registered airplanes are in compliance in
accordance with the requirements of this proposed AD. Therefore, the
future economic cost impact of this rule on U.S. operators is now
$11,040 for accomplishment of the AFM revisions, and $1,757,200 for
accomplishment of the modifications.
Regulatory Impact
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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Empresa Brasileira de Aeronautica, S.A. (EMBRAER): Docket 97-NM-231-
AD.
Applicability: Model EMB-120, EMB-120RT, and EMB-120ER series
airplanes; up to and including serial number 120291; certificated in
any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (d) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not
[[Page 63290]]
been eliminated, the request should include specific proposed
actions to address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent generator overload conditions that could result in
loss of electrical power and failure of certain flight and landing
control systems, and to prevent power interruption to the attitude
heading reference system (AHRS) that could result in the display of
erroneous heading information, accomplish the following:
(a) For airplanes not equipped with an auxiliary power unit
(APU); except serial numbers 120004, 120006 through 120024
inclusive, 120026 through 120030 inclusive, 120033 through 120035
inclusive, 120037, and 120040; on which Part I, II, or III of
EMBRAER Service Bulletin 120-24-0008, Change 03, dated August 19,
1994, or Change 04, dated October 3, 1995, has not been
accomplished: Within 3 days after the effective date of this AD,
accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD.
(1) Trip (pull open) circuit breakers (CB) 534 (auxiliary
generator 2 bus control) and CB 535 (auxiliary generator 1 bus
control) located in the right-hand direct current (DC) relay box and
left-hand DC relay box, respectively.
(2) Install circuit breaker collars to prevent the circuit
breakers from closing.
(3) Install, near CB 534 and CB 535, a placard or tag with the
following wording: ``Do not close CB 534 or CB 535.''
(b) For all airplanes: Within 30 days after the effective date
of this AD, accomplish paragraphs (b)(1), (b)(2), and (b)(3) of this
AD.
(1) Revise the Abnormal Procedures section of the FAA-approved
Airplanese Gen Flight Manual (AFM) to include the following. This
may be accomplished by inserting a copy of this AD into the AFM.
``Section III--Abnormal Procedures:
Engine Failure
One Engine Inoperative Approach and Landing
If auxiliary power unit (APU) is not available
Electrical Load--Reduce to Below 400 Amps
At least the following systems should be turned off: windshield
heating, propeller de-ice, gasper fans, recirculation fans, logotype
lights, and taxi lights.
Caution
Should an unexpected electrical power loss occur during a
rejected takeoff or landing run, remember:
--Emergency brake will be available
--Below 45 knots (KT), turn anti-skid off to recover one normal
brake pair (inboard or outboard).
Electrical Failure
Short Circuit in the Relay Box Direct Current (DC) Bus 1
--Gen 1 off Bus, Bus 1 off. Emerg Bus off, Central Bus off, Batt off
Bus and inverter 2 INOP lights illuminated on the electrical panel.
Note: In some cases, the Central Bus off light may not
illuminate.
--ELEC light illuminated on the multiple alarm panel.
--CAUTION light flashing.
Caution: Do not try to Reset the Electrical System.
Electrical Emergency Switch--Emerg
Altitude--At or Below 25,000 FT
Airplane is limited to 25,000 ft since the left engine bleed is
closed due to loss of the electrical power.
The engines or APU airstart and electrical crossfeed are not
possible.
The equipment connected to the relay box DC BUS 1, DC BUS 1,
radio master DC buses 1B and 1C are out. Land as soon as practical.
Note:
For airplanes Pre-Mod SB 120-24-0008, the AHRS 1 and
the equipment connected to the radio master DC BUS 1A are out too.
For airplanes Post-Mod SB 120-33-0033 or S/N 120.273
and on:
--The emergency lights will be automatically turned on when the
electrical system is in emergency operating mode.
--The emergency lights must be turned off, in order to save the
emergency light batteries.
--The emergency lights must be turned on during approach or when
necessary.''
(2) Revise the Normal Procedures section of the FAA-approved AFM
to include the following. This may be accomplished by inserting a
copy of this AD into the AFM.
``Section IV--Normal Procedures: Before Takeoff
If APU is available:
APU Generator........................................................ON
Takeoff must be carried out with APU generator connected to the
central DC bus, thus providing another source to avoid overload
should one engine flame out.
If APU is not available:
Electrical Load................................Reduce to Below 400 Amps
At least the following systems should be turned off: windshield
heating, propeller de-ice, gasper fans, recirculation fans, logotype
lights, and taxi lights.
After Takeoff
If APU is available:
APU.........................................................As Required
If APU is not available:
Electrical load--RESTORE
Windshield heating--AS REQUIRED
Emergency lights switch--OFF, then ARM
Approach
If APU is available:
APU Generator........................................................ON
Approach and landing must be carried out with APU generator
connected to the central DC bus.
Before Landing
If APU is not available:
Electrical Load................................Reduce to Below 400 Amps
At least the following systems should be turned off: windshield
heating, propeller de-ice, gasper fans, recirculation fans, logotype
lights, and taxi lights.
Caution:
Do not set electrical emergency switch to emergency position
during approach or landing.''
(3) Revise the Limitations section (Section II) of the FAA-
approved AFM to include the following. This may be accomplished by
inserting a copy of this AD into the AFM.
``Both starter/generators must operate normally prior to flight.
The APU generator must operate normally prior to flight in known or
forecast icing conditions. [Note: This supersedes any relief
provided by the Master Minimum Equipment List (MMEL).]''
(c) Within 12 months after the effective date of this AD,
accomplish paragraph (c)(1) and (c)(2) of this AD, as applicable.
(1) For all airplanes except serial numbers 120004, 120006
through 120024 inclusive, 120026 through 120030 inclusive, 120033
through 120035 inclusive, 120037, and 120040; on which Part I, II,
or III of EMBRAER Service Bulletin 120-24-0008, Change 03, dated
August 19, 1994, or Change 04, dated October 3, 1995; has not been
accomplished: Modify the electrical system in accordance with Part
IV of EMBRAER Service Bulletin 120-24-0008, Change 04, dated October
3, 1995. After this modification is accomplished, the modification
required by paragraph (a) of this AD may be removed and the affected
circuit breakers reactivated.
(2) For all airplanes: Modify the electrical system in
accordance with EMBRAER Service Bulletin 120-24-0051, Change 04,
dated March 8, 1995. After this modification is accomplished, the
AFM revisions required by paragraph (b) of this AD may be removed
from the AFM.
(d) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Atlanta Aircraft Certification
Office (ACO), FAA, Small Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Atlanta ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
(e) 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 airplane to a location where
the requirements of this AD can be accomplished.
Note 3: The subject of this AD is addressed in Brazilian
airworthiness directives 93-24-01, dated December 31, 1993; 94-03-
01R1, dated December 10, 1994; and 93-12-01R1, dated December 12,
1994.
Issued in Renton, Washington, on November 20, 1997.
Stewart R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-31156 Filed 11-26-97; 8:45 am]
BILLING CODE 4910-13-U
