[Federal Register Volume 62, Number 90 (Friday, May 9, 1997)]
[Proposed Rules]
[Pages 25566-25568]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-12251]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-212-AD]
RIN 2120-AA64
Airworthiness Directives; Saab Model SAAB SF340A, SAAB 340B, and
SAAB 2000 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
[[Page 25567]]
directive (AD) that is applicable to certain Saab Model SAAB SF340A,
SAAB 340B, and SAAB 2000 series airplanes. This proposal would require
repetitive operational tests of the pitch trim system of the elevator
trim-tab of the flight control unit to ensure that the system operates
correctly, and repair, if necessary. This proposal is prompted by a
report of uncommanded movement of the right-hand elevator trim-tab to a
maximum deflection position, which was apparently due to a failure in
the aircraft harness and a fault in the pitch trim synchronizer. The
actions specified by the proposed AD are intended to prevent such
uncommanded movement of the elevator trim-tab, which could lead to
structural overload of the horizontal stabilizers at speeds above 180
knots, and resultant reduced controllability of the airplane.
DATES: Comments must be received by June 20, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-212-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 SAAB Aircraft AB, SAAB Aircraft Product Support, S-
581.88, Linkoping, Sweden. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Ruth Harder, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
227-1721; fax (425) 227-1149.
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 96-NM-212-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. 96-NM-212-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Luftfartsverket (LFV), which is the airworthiness authority for
Sweden, notified the FAA that an unsafe condition may exist on certain
Saab Model SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes. The
LFV advises of a report of uncommanded movement of the right-hand
elevator trim-tab to a position of maximum deflection on a Model SAAB
340 series airplane. Uncommanded movement of the right-hand elevator
trim-tab may be caused by a combination of factors, such as a failure
of the aircraft harness and a fault in the pitch trim synchronizer.
Such uncommanded movement could result in the elevator trim-tab moving
to a maximum deflection position and a split occurring in the elevator
position. Uncommanded movement of the right-hand elevator trim-tab due
to failure of the aircraft harness and a fault in the pitch trim
synchronizer, if not prevented, could lead to a structural overload of
the horizontal stabilizers at speeds above 180 knots, and result in
reduced controllability of the airplane.
Similar Models Subject to the Unsafe Condition
This problem also could occur on certain Model SAAB 2000 series
airplanes that have mechanically controlled elevator control systems,
because the pitch trim system is the same.
Explanation of Relevant Service Information
Saab has issued Service Bulletin 340-27-079 (for certain Model SAAB
SF340A and SAAB 340B series airplanes); and Service Bulletin 2000-27-
018 (for certain Model SAAB 2000 series airplanes); both dated December
22, 1995. These service bulletins describe procedures for repetitive
operational tests of the pitch trim system that moves the elevator
trim-tab of the flight control unit to ensure that the system operates
correctly. Accomplishment of these operational tests will ensure that
the standby trim switch operates correctly when commanded to the
maximum up position, and continues to operate correctly when the reset
button is pushed. A similar operational test ensures that the standby
trim switch also operates correctly in the maximum down position.
The LFV classified the two service bulletins as mandatory and
issued Swedish airworthiness directive (SAD) 1-083, Revision 1, dated
January 2, 1996, in order to assure the continued airworthiness of
these airplanes in Sweden.
FAA's Conclusions
These airplane models are manufactured in Sweden and are 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 LFV 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.
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 repetitive
operational tests of the pitch trim system that moves the elevator
trim-tab of the flight control unit to ensure that the system operates
correctly, and repair, if necessary. The repair would be required to be
accomplished in accordance with a method approved by the FAA. Other
actions would be required to be accomplished in accordance with the
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two service bulletins described previously.
Interim Action
This is considered to be interim action until final action is
identified, at which time the FAA may consider further rulemaking.
Cost Impact
The FAA estimates that 235 Model SAAB SF340A and SAAB 340B series
airplanes of U.S. registry would be affected by this proposed AD.
Currently, there are no Model SAAB 2000 series airplanes of U.S.
registry that would be affected by this proposed AD. It would take
approximately 1 work hour per airplane to accomplish the proposed
actions, at an average labor rate of $60 per work hour. Based on these
figures, the cost impact of the proposed AD on U.S. operators is
estimated to be $14,100, or $60 per airplane, per operational test.
The cost impact figure discussed above is 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.
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:
Saab Aircraft AB: Docket 96-NM-212-AD.
Applicability: Model SAAB SF340A series airplanes, serial
numbers -004 through -159 inclusive; Model SAAB 340B series
airplanes, serial numbers -160 and subsequent; and Model SAAB 2000
series airplanes, serial numbers -005 and -007 through -009
inclusive; 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 (b) 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 uncommanded movement of the right-hand elevator trim-
tab to a maximum deflection position, which could lead to structural
overload of the horizontal stabilizers at speeds above 180 knots,
and resultant reduced controllability of the airplane, accomplish
the following:
(a) Within 150 hours time-in-service after the effective date of
this AD, perform an operational test of the pitch trim system that
moves the elevator trim-tab of the flight control unit to ensure
that the system operates correctly, in accordance with Saab Service
Bulletin 340-27-079 (for Model SAAB SF340A and SF340B series
airplanes); and 2000-27-018 (for Model SAAB 2000 series airplanes);
both dated December 22, 1995; as applicable.
(1) If no discrepancy is found, repeat the operational test of
the pitch trim system thereafter at intervals not to exceed 150
hours time-in-service.
(2) If any discrepancy is found, prior to further flight, repair
the system in accordance with a method approved by the Manager,
Standardization Branch, ANM-113, FAA, Transport Airplane
Directorate.
(b) 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.
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.
(c) 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.
Issued in Renton, Washington, on May 5, 1997.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-12251 Filed 5-8-97; 8:45 am]
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