[Federal Register Volume 61, Number 5 (Monday, January 8, 1996)]
[Rules and Regulations]
[Pages 511-513]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-188]
========================================================================
Rules and Regulations
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains regulatory documents
having general applicability and legal effect, most of which are keyed
to and codified in the Code of Federal Regulations, which is published
under 50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by the Superintendent of Documents.
Prices of new books are listed in the first FEDERAL REGISTER issue of each
week.
========================================================================
Federal Register / Vol. 61, No. 5 / Monday, January 8, 1996 / Rules
and Regulations
[[Page 511]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-260-AD; Amendment 39-9480; AD 96-01-04]
Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B
Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
-----------------------------------------------------------------------
SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Saab Model SAAB SF340A and SAAB 340B series
airplanes. This action requires revising the Airplane Flight Manual
(AFM) to require verification that the auto-ignition system is
operational; to define icing conditions at higher ambient temperatures;
and to provide the flight crew with limitations and procedures to aid
in the avoidance of engine power interruptions. This amendment is
prompted by a report of complete power loss of the left engine and
power fluctuations on the right engine as a result of build up of ice
and/or slush in the engine inlet and subsequent ingestion into the
engines; the auto-ignition system of the left engine had failed, which
prevented automatic restart of the engine following power interruption.
The actions specified in this AD are intended to prevent failure of the
auto-ignition system to re-light the engine in the event of power
interruptions due to the ingestion of ice and/or slush into the engine,
which could result in engine flameout and subsequent shutdown, and to
provide the flight crew with guidance to aid in avoidance of such
occurrences.
DATES: Effective January 23, 1996.
Comments for inclusion in the Rules Docket must be received on or
before March 8, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-260-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The information concerning this amendment may be obtained from or
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,
SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Ruth E. Harder, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-1721; fax (206) 227-1149.
SUPPLEMENTARY INFORMATION: The FAA has received a report indicating
that an unsafe condition may exist on certain Saab Model SAAB SF340A
and SAAB 340B series airplanes. Recently, an incident occurred on a
Model SAAB 340B series airplane during which, shortly after exiting
icing conditions, the left engine of the airplane shut down abruptly
and the right engine experienced multiple power interruptions.
Subsequent investigation revealed that shutdown of the left engine
occurred due to ingestion of ice and/or slush into the engine from the
inlet. In addition, the auto-ignition system had failed on that engine;
therefore, engine re-light did not occur. Failure of the auto-ignition
system, which is a component of the engine Digital Electronic
Controller (DEC), was the result of a broken fuse. This fuse failure
also caused the engine turbine (or Np) overspeed protection system to
be inoperative.
The interruptions of power to the right engine also were caused by
ingestion of ice and/or slush into the engine; however, the auto-
ignition system for the right engine was operational and engine re-
light occurred. In addition, failure of the auto-ignition system can
exist concurrently such that engine re-light does not occur. These
conditions, if not corrected, could result in engine flameout and
subsequent shutdown.
Although single event power interruptions have occurred previously
on this airplane type, recent occurrences of multiple power
interruptions demonstrate a need to increase the safety margin for
flight in icing conditions. Activation of the engine anti-icing system
at higher ambient temperatures will reduce the ice/slush build-up
within the engine inlet and will improve the engine surge margin.
In light of the information discussed previously, the FAA finds
that certain limitations and procedures should be included in the FAA-
approved Airplane Flight Manual (AFM) to:
--provide the flight crew with procedures to verify that the auto-
ignition system is operational;
--expand the current definition of icing conditions by increasing the
temperature at which those conditions exist from +5 degrees Celsius to
+10 degrees Celsius; and
--alert the flight crew to certain icing conditions during which power
to an engine may be interrupted, and provide the flight crew with
guidance to aid in avoidance of such occurrences.
The FAA has determined that such limitations and procedures
currently are not defined adequately in the AFM for these airplanes.
This airplane model is manufactured in Sweden 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 Luftfartsverket (LFV), which is
the airworthiness authority for Sweden, has kept the FAA informed of
the situation described above. The FAA has examined the findings of the
LFV, 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.
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, this AD is being issued to prevent failure of the
auto-ignition system to re-light the engine in the event of power
interruptions due to the ingestion of ice and/or slush into the engine,
which could result in engine flameout and subsequent shutdown; and
[[Page 512]]
to provide the flight crew with guidance to aid in avoidance of such
occurrences.
This AD requires the following:
--revising the Limitations Section of the AFM to require verification
that the auto-ignition system is operational;
--revising the Limitations Section of the AFM to define icing
conditions at higher ambient temperatures;
--revising the Normal Procedures Section of the AFM to alert the flight
crew to certain icing conditions during which power to an engine may be
interrupted, and to provide the flight crew with limitations and
procedures to aid in avoidance of interruptions of power to an engine.
For Model SAAB 340B series airplanes having an auto-ignition system
that is found to be inoperative, this AD requires a test of the Np
overspeed system to ensure that it is operative, and repair, if
necessary.
This is considered to be interim action until final action is
identified, at which time the FAA may consider further rulemaking.
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 shall 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 Number 95-NM-260-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, 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 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-01-04 SAAB Aircraft AB: Amendment 39-9480. Docket 95-NM-260-AD.
Applicability: Model SAAB SF340A series airplanes, serial
numbers 004 through 159 inclusive; and Model SAAB 340B series
airplanes, serial numbers 160 and subsequent; certificated in any
category.
Note 1: This AD applies to each airplane 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 airplanes 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 (c) of this AD 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 airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the auto-ignition system to re-light the
engine in the event of power interruptions due to the ingestion of
ice and/or slush into the engine, which could result in engine
flameout and subsequent shutdown; and to provide the flight crew
with guidance to aid in avoidance of such occurrences; accomplish
the following:
(a) Within 10 days after the effective date of this AD, revise
the FAA-approved Airplane Flight Manual (AFM) to include the text
contained in paragraphs (a)(1), (a)(2), (a)(3), and (a)(4) of this
AD, as applicable. This may be accomplished by inserting a copy of
this AD into the AFM.
(1) For Model SAAB SF340A series airplanes: Insert the following
sub-section in the Limitations Section of the AFM:
``IGNITION SYSTEM
Prior to each flight, before engine start, perform a check of
the auto-ignition system.
Select batteries ON (external power ON or OFF).
Check that IGN switches are in NORM position.
Advance PLs above FLT IDLE and verify the IGN lights in
the Flight Status Panel (FSP) illuminate. In bright sunlight, shade
FSP to ensure IGN lights are visible when illuminated.
Retard PLs to GND IDLE. (IGN lights should go out.)
If an IGN light fails to illuminate when PLs are above
FLT IDLE, the auto-ignition system is considered to be inoperative.
If the auto-ignition system is inoperative:
BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT.
Maintain ignition in CONT until touchdown, even if icing conditions
cease to exist.''
[[Page 513]]
(2) For Model SAAB 340B series airplanes: Insert the following
sub-section in the Limitations Section of the AFM:
``IGNITION SYSTEM
After each engine shutdown, perform a check of the auto-ignition
system.
Adjust Ng to approximately 75%-77%; minimum is 75%.
Shut down the engines (CL to FUEL OFF).
Verify the IGN lights in the Flight Status Panel (FSP)
illuminate while Ng is above 62%. In bright sunlight, shade the FSP
to ensure that lights are visible when illuminated.
If an IGN light fails to illuminate, the auto-ignition
system is considered to be inoperative.
Retard PLs to GND IDLE.
If the auto-ignition system is inoperative:
BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT.
Maintain ignition in CONT until touchdown, even if icing conditions
cease to exist.''
(3) For all airplanes: Insert the following in the Limitations
Section of the AFM, under Icing Conditions:
``Icing conditions exist when visible moisture in any form is
present (such as clouds, fog with visibility of one mile or less,
rain, snow, sleet, ice crystals) or standing water, slush, or snow
(hard packed snow excluded) is present on the ramps, taxiways, or
runways and the OAT or SAT is +10 degrees C and below during ground
and flight operation.''
(4) For all airplanes: Insert the following in the Normal
Procedures Section of the AFM, under Operation in Icing Conditions:
``CAUTION
Engine power interruptions may occur at ISA to ISA +20 degrees
Celsius temperature and in light (or undetected) icing conditions,
or shortly after exiting these conditions. Engine function will
normally be recovered by the auto-ignition system before any serious
loss of power. To aid in avoidance of these occurrences:
Engine anti-ice systems must be activated prior to
entering icing conditions, and maintained ON for at least 5 minutes
after exiting icing conditions.''
(b) For Model SAAB 340B series airplanes: If an auto-ignition
system is found to be inoperative, prior to further flight, perform
an Np overspeed test to ensure that the Np overspeed system is
operative, in accordance with the procedures specified in General
Electric Maintenance Manual SEI-576. If the Np overspeed system is
found to be inoperative, prior to further flight, repair in
accordance with the procedures specified in General Electric
Maintenance Manual SEI-576.
(c) 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, Standardization Branch, ANM-113,
FAA, Transport 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,
Standardization Branch, ANM-113.
-Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
(d) 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.
(e) This amendment becomes effective on January 23, 1996.
Issued in Renton, Washington, on January 2, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-188 Filed 1-5-96; 8:45 am]
BILLING CODE 4910-13-U
