[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]


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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).

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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