[Federal Register Volume 61, Number 177 (Wednesday, September 11, 1996)]
[Proposed Rules]
[Pages 47831-47833]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-23101]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-201-AD]
RIN 2120-AA64
Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B
Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Saab Model SAAB SF340A and
SAAB 340B series airplanes. This proposal would require inspections to
detect damage or cracking of the forward and aft attachment lugs of the
flap fittings at wing station (WS) 123.38; an inspection to verify that
the sizes of the holes of the flap fittings are within specified limits
and to ensure that the swaged bushings are not loose; and modification
of the flap fittings. This proposal is prompted by a report of jamming
of a flap due to incorrect tolerances of the flap-hinge installation,
which caused high bearing stress on the bushings in the flap fittings.
The actions specified by the proposed AD are intended to prevent such
high bearing stress, which could result in wear on the bushings,
cracking of the flap fittings, and breakage of the lugs; these
conditions could result in jamming of the flaps and consequent reduced
controllability of the airplane.
DATES: Comments must be received by October 21, 1996.
[[Page 47832]]
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-201-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 (206)
227-1721; fax (206) 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 95-NM-201-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. 95-NM-201-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Luftfartsverket (LFV), which is the airworthiness authority for
Sweden, recently notified the FAA that an unsafe condition may exist on
certain Saab Model SAAB SF340A and SAAB 340B series airplanes. The LFV
advises that it received a report indicating that one of the flaps on
one airplane jammed because the rear lug of one of the flap fittings at
wing station (WS) 123.38 was broken and the bushing in the lug was
worn. Investigation revealed that the bushings in the flap fittings
were subjected to high bearing stress due to incorrect tolerances in
the initial design of the flap-hinge installation. This condition can
result in wear on the bushings, cracking of the flap fittings, and
breakage of the lugs on the flap fittings. These conditions, if not
corrected, could result in jamming of the flaps and consequent reduced
controllability of the airplane.
Explanation of Relevant Service Information
Saab has issued Service Bulletin SAAB 340-57-027, Revision 01,
dated June 30, 1995, which describes procedures for repetitive visual
inspections to detect damage or cracking of the forward and aft
attachment lugs of the flap fittings at WS 123.38.
For airplanes on which any cracking or damage is found during the
visual inspection, the service bulletin describes procedures for
installation of new improved flap fittings and installation of improved
bushings (Modification 2628--Part 3). This modification involves
replacing the flap fittings and installing the flap hinge to the flap
fittings.
The service bulletin also describes procedures for an eventual
inspection to verify that the sizes of the inboard and outboard holes
(swaged bushings) of the flap fittings are within specified limits, and
to ensure that the swaged bushings are not loose.
For airplanes on which the sizes of the inboard and outboard holes
are within specified limits and on which no loose swaged bushings are
found, the service bulletin describes procedures for installation of
improved bushings (Modification 2628--Part 1). This modification
involves attaching the flap hinge to the flap fittings, torquing the
nuts, and installing new cotter pins.
For airplanes on which the size of any hole is outside specified
limits or on which any loose swaged bushing is found, the service
bulletin describes procedures for installation of oversize bushings in
the flap fittings, and installation of improved bushings (Modification
2628--Part 2). This modification entails removing and replacing the
swaged bushings; increasing the hole for the floating bushings to
oversize dimensions; and performing an eddy current inspection to
detect cracking of the holes.
Installation of improved bushings (with a flange) will prevent
damage and cracking as a result of high bearing stress on the bushings.
The LFV classified this service bulletin as mandatory and issued
Swedish airworthiness directive SAD No. 1-072, dated April 21, 1995, 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, the
proposed AD would require repetitive visual inspections to detect
damage or cracking of the forward and aft attachment lugs of the flap
fittings at WS 123.38; an eventual inspection to verify that the sizes
of the inboard and outboard holes (swaged bushings) of the flap
fittings are within specified limits and to ensure that the swaged
bushings are not loose; and modification of the flap fittings. The
actions would be required to be accomplished in accordance with the
service bulletin described previously.
Cost Impact
The FAA estimates that 224 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 1 work
hour per airplane to accomplish the proposed visual inspection, and
that the average labor rate is $60 per work hour. Based on
[[Page 47833]]
these figures, the cost impact of the proposed visual inspections on
U.S. operators is estimated to be $13,440, or $60 per airplane.
For operators required to accomplish proposed Modification 2628--
Part 1, the FAA estimates that it would take approximately 30 work
hours per airplane to accomplish it, at an average labor rate of $60
per work hour. Required parts would cost $100 per airplane. Based on
these figures, the cost impact of proposed Modification 2628--Part 1 on
U.S. operators is estimated to be $1,900 per airplane.
For operators required to accomplish proposed Modification 2628--
Part 2, the FAA estimates that it would take approximately 60 work
hours per airplane to accomplish it, at an average labor rate of $60
per work hour. Required parts would cost $100 per airplane. Based on
these figures, the cost impact of proposed Modification--Part 2 on U.S.
operators is estimated to be $3,700 per airplane.
For operators required to accomplish proposed Modification 2628--
Part 3, the FAA estimates that it would take approximately 96 work
hours per airplane to accomplish it, at an average labor rate of $60
per work hour. Required parts would cost $1,400 per airplane. Based on
these figures, the cost impact of proposed Modification--Part 3 on U.S.
operators is estimated to be $7,160 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.
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 95-NM-201-AD.
Applicability: Model SAAB SF340A series airplanes, serial
numbers 004 through 159 inclusive; and Model SAAB 340B series
airplanes, serial numbers 160 through 379 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 (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 high bearing stress on the bushings in the flap
fittings, which could result in jamming of the flaps and consequent
reduced controllability of the airplane, accomplish the following:
(a) Within 800 hours time-in-service after the effective date of
this AD: Perform a visual inspection to detect damage or cracking of
the forward and aft attachment lugs of the flap fittings at wing
station (WS) 123.38, in accordance with Saab Service Bulletin SAAB
340-57-027, Revision 01, dated June 30, 1995.
(1) If no cracking or damage is found, and the flap fittings
have not been modified or replaced, repeat the visual inspection
thereafter at intervals not to exceed 800 hours time-in-service.
(2) If any cracking is found, prior to further flight, replace
the flap fittings with new improved flap fittings, and install
improved bushings, in accordance with the Accomplishment
Instructions (Modification 2628 - Part 3) of the service bulletin.
After this modification is accomplished, no further action is
required by this paragraph.
(b) Within 4,500 hours time-in-service after the effective date
of this AD, perform an inspection to determine the size of the
inboard and outboard holes (swaged bushings) of the flap fittings,
and to detect loose swaged bushings, in accordance with Saab Service
Bulletin SAAB 340-57-027, Revision 01, dated June 30, 1995.
(1) If the sizes of the holes are within the limits specified in
the service bulletin, and if no loose swaged bushings are found,
prior to further flight, install improved bushings in accordance
with the Accomplishment Instructions (Modification 2628--Part 1) of
the service bulletin. After this modification is accomplished, no
further action is required by this AD.
(2) If the size of any hole is outside the limits specified in
the service bulletin, or if any loose swaged bushing is found, prior
to further flight, install oversize bushings in the flap fittings,
and install improved bushings, in accordance with the Accomplishment
Instructions (Modification 2628--Part 2) of the service bulletin.
After this modification is accomplished, no further action is
required by this AD.
(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.
Issued in Renton, Washington, on September 4, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-23101 Filed 9-10-96; 8:45 am]
BILLING CODE 4910-13-U
