[Federal Register Volume 61, Number 81 (Thursday, April 25, 1996)]
[Rules and Regulations]
[Pages 18242-18245]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-10210]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-74-AD; Amendment 39-9582; AD 96-01-04 R1]


Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment revises an existing airworthiness directive 
(AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series 
airplanes, that currently 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. The actions specified 
by that 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. This amendment 
clarifies certain requirements of the AFM revision. This amendment is 
prompted by communications received from affected operators that 
certain of the current requirements of the AD are unclear.

DATES: Effective May 10, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before June 24, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-74-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

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: On January 2, 1996, the FAA issued 
airworthiness directive (AD) 96-01-04, amendment 39-9480 (61 FR 511, 
January 8, 1996), which is applicable to certain Saab Model SAAB SF340A 
and SAAB 340B series airplanes. That AD requires revising the FAA-
approved Airplane Flight Manual (AFM) to:
    1. Require verification that the auto-ignition system is 
operational;
    2. Define icing conditions at higher ambient temperatures; and
    3. Povide the flight crew with limitations and procedures to aid in 
the avoidance of engine power interruptions.
    That AD action was 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 actions required by that 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.

[[Page 18243]]

    Since the issuance of that AD, the FAA has received communications 
from the Swedish airworthiness authority, Luftfartsverket (LFV), and 
various affected operators indicating that certain text of the AFM 
revision as cited in AD 96-01-04 is not clear.

Request to Clarify Frequency of Checks

    Affected operators specifically request that the frequency of the 
auto-ignition system checks, as specified in the AFM revision contained 
in paragraphs (a)(1) and (a)(2) of AD 96-01-04, be clarified. As AD 96-
01-04 was worded, some operators may have misinterpreted its 
requirements to mean that the engine must be shut down following each 
flight and restarted before the next flight.
    The FAA finds that clarification is necessary to prevent such 
misinterpretation. The FAA did not intend that the AD require shutdown 
of the engine following each flight. The FAA acknowledges that some 
operators may elect not to shut down the engine following each flight. 
In such a case, this AD does not require that a check of the auto-
ignition system be performed. Therefore, the FAA has determined that 
the limitations specified in paragraph (a)(1) and (a)(2) of AD 96-01-04 
must be revised to clarify that the check of the auto-ignition system 
is required prior to each engine start and during each engine shutdown.

Request to Clarify Relationship of AD to MMEL

    The LFV noted that the AFM revision specified in paragraphs (a)(1) 
and (a)(2) of AD 96-01-04 may imply that dispatch may occur 
indefinitely with an inoperative auto-ignition system.
    The FAA finds that clarification of this point is necessary. The 
intent of AD 96-01-04 was that, if the auto-ignition system is found to 
be inoperative, dispatch should be accomplished in accordance with the 
Minimum Master Equipment List (MMEL). The FAA finds that the addition 
of that information to the AFM revision specified in paragraphs (a)(1) 
and (a)(2) of this AD will clarify the dispatch requirements.

Request to Clarify Definition of ``Icing Conditions''

    For systems other than engine anti-ice activation, affected 
operators request that a separate and relieving definition of ``Icing 
Conditions'' of Outside Air Temperature (OAT) or Static Air Temperature 
(SAT) be included in paragraph (a)(3) of the AD, with the OAT or SAT 
criteria to be specified as +5 degrees Centigrade (C).
    The FAA agrees that the definition of ``Icing Conditions'' needs to 
be clarified for systems other than engine anti-ice. The FAA finds that 
paragraph (a)(3) of the AD must be revised to expand the definition of 
``Icing Conditions'' by including a separate definition for all 
airplane operations other than engine anti-ice, which specifies the OAT 
or SAT criteria as +5 degrees C.

Conclusion

    Based on the issues raised by the affected operators and the LFV, 
the FAA finds that AD 96-01-04 must be revised as discussed previously. 
These revisions will ensure that the requirements of the AD are 
understood clearly. Clearer understanding will ensure that the intent 
of the AD is met and that the addressed unsafe condition is prevented.

Explanation of the Revised Rule

    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.
    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 revises AD 96-01-04 to continue to 
require verification that the auto-ignition system is operational; to 
define icing conditions at higher

[[Page 18244]]

ambient temperatures for engine anti-ice systems; and to provide the 
flight crew with limitations and procedures to aid in the avoidance of 
engine power interruptions. For Model SAAB 340B series airplanes having 
an auto-ignition system that is found to be inoperative, this AD also 
continues to require a test of the Np overspeed system to ensure that 
it is operative, and repair, if necessary.
    In addition, this AD revises the AFM revision by:
    1. Clarifying the times at which the auto-ignition checks are to be 
performed;
    2. Specifying that the dispatch with the auto-ignition system 
inoperative shall be done in accordance with the current MMEL; and
    3. Providing a relieving definition of Icing Conditions for systems 
other than engine anti-ice.
    This is to be considered interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Effective Date of the Revised Rule

    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 96-NM-74-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9480 (61 FR 
511, January 8, 1996), and by adding a new airworthiness directive 
(AD), amendment 39-9582, to read as follows:

96-01-04  R1 SAAB Aircraft AB: Amendment 39-9582. Docket 96-NM-74-
AD. Revises AD 96-01-04, Amendment 39-9480.

    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 request approval for an 
alternative method of compliance in accordance with paragraph (c) 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 been 
eliminated, the request should include specific proposed actions to 
address it.

    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 engine start, perform a check of the auto-ignition 
system.
    <bullet> Select batteries ON (external power ON or OFF).
    <bullet> Check that IGN switches are in NORM position.
    <bullet> 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.
    <bullet> Retard PLs to GND IDLE. (IGN lights should go out.)
    <bullet> 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:
    <bullet> BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT. 
Maintain ignition in CONT until touchdown, even if icing conditions 
cease to exist.

[[Page 18245]]

    <bullet> The obligation to comply with the current version of 
the Master Minimum Equipment List (MMEL), Revision 11, or later 
approved revisions is not affected by this limitation.''
    (2) For Model SAAB 340B series airplanes: Insert the following 
sub-section in the Limitations Section of the AFM:

``IGNITION SYSTEM

    During each engine shutdown, perform a check of the auto-
ignition system.
    <bullet> Adjust Ng to approximately 75%-77%; minimum is 75%.
    <bullet> Shut down the engines (CL to FUEL OFF).
    <bullet> 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.
    <bullet> If an IGN light fails to illuminate, the auto-ignition 
system is considered to be inoperative.
    <bullet> Retard PLs to GND IDLE.
    If the auto-ignition system is inoperative:
    <bullet> BEFORE ENTERING ICING CONDITIONS, SET IGNITION TO CONT. 
Maintain ignition in CONT until touchdown, even if icing conditions 
cease to exist.''
    <bullet> The obligation to comply with the current version of 
the Master Minimum Equipment List (MMEL), Revision 11, or later 
approved revisions is not affected by this limitation.
    (3) For all airplanes: Insert the following in the Limitations 
Section of the AFM, under Icing Conditions:
    ``For engine anti-ice system activation, 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.
    For all airplane operations other than engine anti-ice, 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 +5 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:
    <bullet> 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 May 10, 1996.

    Issued in Renton, Washington, on April 19, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-10210 Filed 4-24-96; 8:45 am]
BILLING CODE 4910-13-P