[Federal Register Volume 65, Number 147 (Monday, July 31, 2000)]
[Proposed Rules]
[Pages 46667-46670]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19264]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-76-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 supersedure of an existing 
airworthiness directive (AD), applicable to certain Saab Model SAAB 
SF340A and SAAB 340B series airplanes, that currently requires 
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 action would 
require repetitive accomplishment of the inspections using improved 
inspection methods; a one-time visual and repetitive general visual and 
detailed visual inspections; new repetitive non-destructive test (NDT) 
inspections; and corrective and follow-on actions, as

[[Page 46668]]

necessary. This action also would provide for terminating action for 
all repetitive inspections and would revise the applicability of the 
existing AD. The actions specified by the proposed AD are intended to 
prevent high bearing stress on the bushings of the flap fittings, 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 August 30, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-76-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-76-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    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: Norman B. Martenson, Manager, 
International Branch, ANM-116, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-
2110; 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 2000-NM-76-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-114, Attention: Rules 
Docket No. 2000-NM-76-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 14, 1997, the FAA issued AD 96-25-06 R1, amendment 39-
9891 (62 FR 3209, January 22, 1997), applicable to certain Saab Model 
SAAB SF340A and SAAB 340B series airplanes, to 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. That action was 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 fitting. 
The requirements of that AD are intended to prevent 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.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the Luftfartsverket (LFV), which is 
the airworthiness authority for Sweden, has advised the FAA that the L-
shaped flap fittings at WS 123.38, where the triangular flap fitting is 
installed, have failed in some cases due to fatigue. Investigation 
revealed that the initial failure occurred in the aft attachment lug 
where the swaged bushing is installed, which led to a failure in the 
bottom radius of the adjacent L-shaped fitting. The LFV further advises 
that the inspection methods specified by Saab Service Bulletin 340-57-
027, Revision 01, dated June 30, 1995, and required in AD 96-25-06 R1, 
are inadequate to detect cracking of the forward and aft attachment 
lugs at WS 123.38. In that inspection, it is possible for small cracks 
to pass by undetected. Over time, these small cracks could cause 
failure of certain components of the flap fittings at WS 123.38.
    The LFV also advises that, bushings with incorrect length may have 
been installed at the forward attachment point to the triangular 
fitting. Bolts and bushings with incorrect lengths also may have been 
installed at the aft attachment point. Consequently, high bearing 
stress can occur to the bushings and on the L-fittings due to short 
bushings and bolts.
    In light of the recent events, the manufacturer has released new 
service information, and the FAA has determined that it is necessary to 
perform a new, one-time visual inspection, repetitive general and 
detailed visual inspections, and repetitive non-destructive test (NDT) 
inspections to enable early detection of discrepancies of the affected 
area.

Explanation of Relevant Service Information

    The manufacturer has issued SAAB Service Bulletins 340-57-035, 340-
57-037, and 340-57-038, each dated January 18, 2000, which describe 
procedures for the following:
     Saab Service Bulletin 340-57-035: One-time visual 
inspection of the flap assemblies to determine the serial numbers. If 
certain flap assemblies (as listed in the service bulletin) are 
installed, the follow-on actions include repetitive visual inspections 
of the affected flap assemblies (forward and aft attachment lugs) of 
the flap fittings at WS 123.38 to detect cracking or damage. The 
service bulletin also references Saab Service Bulletin 340-57-037 for 
performing NDT inspection of the aft attachment lugs of the flap 
fittings at WS 123.38 to detect cracking; and detailed visual 
inspections of the flap fittings to determine the size of the inboard 
and outboard holes (swaged bushings) and to detect loose swaged 
bushings. If no discrepancies (incorrectly sized hole, loose swaged 
bushings, or cracking) are detected, the service bulletin describes 
procedures for installing new fasteners (nuts, bolts, bushings, and 
washers) that attach to

[[Page 46669]]

the flap hinges. If any discrepancy (as described previously) is 
detected during the visual or NDT inspection, the service bulletin 
refers to Saab Service Bulletin 340-57-038 for replacement of all flap 
fittings.
     Saab Service Bulletin 340-57-037: One-time visual 
inspection of the aft attachment lugs (flap assemblies) of the flap 
fittings at WS 123.38 to determine the flap assembly modification 
status. If any flap assembly is installed that has a thinner lug, the 
follow-on actions include repetitive visual inspections of the aft 
attachment lugs of the flap fittings at WS 123.38 to detect cracking or 
damage. If any cracking or damage is detected, the service bulletin 
refers to Saab Service Bulletin 340-57-038 for replacement of all flap 
fittings. The service bulletin also describes procedures for repetitive 
NDT inspections of the aft attachment lugs of the flap fittings at WS 
123.38 to detect cracking. If any cracking is detected, the service 
bulletin refers to Saab Service Bulletin 340-57-038 for replacement of 
the flap fittings.
     Saab Service Bulletin 340-57-038: Replacement of the flap 
fittings at WS 123.38, with new, improved flap fittings. Accomplishment 
of the replacement of all flap fittings would eliminate the need for 
all inspections specified by Service Bulletins 340-57-035 and 340-57-
037, as described previously.
    The LFV classified Saab Service Bulletins 340-57-035 and 340-57-037 
as mandatory and issued Swedish airworthiness directives No. 1-152 and 
No. 1-153, each dated January 19, 2000, 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 is likely to exist or develop on other 
airplanes of the same type design registered in the United States, the 
proposed AD would supersede all requirements of AD 96-25-06 R1. This 
proposed AD would require a new, one-time visual inspection; new 
repetitive general visual and detailed visual inspections; and a new 
repetitive NDT inspection; and corrective and follow-on actions, as 
necessary. The proposed AD also would provide for terminating action 
for the repetitive inspections, would revise the applicability of the 
existing AD to apply only to airplanes on which a certain flap assembly 
is installed, and would add airplanes that may be subject to the unsafe 
condition. The actions would be required to be accomplished in 
accordance with the Saab service bulletins described previously.

Cost Impact

    The FAA estimates that 303 airplanes of U.S. registry would be 
affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed repetitive general visual inspections, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the proposed general visual inspections on U.S. operators is estimated 
to be $18,180, or $60 per airplane, per inspection cycle.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed one-time general visual inspection, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the proposed general visual inspection on U.S. operators is estimated 
to be $18,180, or $60 per airplane.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed repetitive detailed visual inspections, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed detailed visual inspections on U.S. operators is 
estimated to be $18,180, or $60 per airplane, per inspection cycle.
    It would take approximately 2 work hours per airplane to accomplish 
the proposed repetitive NDT inspections, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the 
proposed NDT inspections on U.S. operators is estimated to be $36,360, 
or $120 per airplane, per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    Should an operator be required or elect to accomplish the 
terminating modification, it would take approximately 92 work hours per 
airplane (46 work hours per flap), at an average labor rate of $60 per 
hour. Required parts would cost $7,362 per airplane ($3,681 per flap). 
Based on these figures, the cost impact of the terminating modification 
on U.S. operators is estimated to be $12,882 per airplane.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 removing amendment 39-9891 (62 FR 
3209, January 22, 1997), and by adding a new airworthiness directive 
(AD), to read as follows:

SAAB Aircraft AB: Docket 2000-NM-76-AD. Supersedes AD 96-25-06 R1, 
Amendment 39-9891.


[[Page 46670]]


    Applicability: Model SAAB SF340A series airplanes, 
manufacturer's serial numbers -004 through -159 inclusive; and SAAB 
340B series airplanes, manufacturer's serial numbers -160 through -
459 inclusive; certificated in any category; on which any flap 
assembly having part number (P/N) 7257800-501 through 508 inclusive, 
or 7257800-851 through 7257800-856 inclusive, is installed.

    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 (d) 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:

Visual Inspection for Serial Numbers

    (a) Within 800 flight hours after the effective date of this AD, 
perform a one-time visual inspection of the flap assemblies of the 
flap fittings at wing station (WS) 123.38 to determine the flap 
assembly serial numbers, in accordance with Saab Service Bulletin 
340-57-035, dated January 18, 2000.
    (1) If none of the serial numbers of the flap assemblies are 
listed in the service bulletin, no further action is required by 
this paragraph.
    (2) If the serial number of any flap assembly is listed in the 
service bulletin, prior to further flight, accomplish the 
requirements of paragraph (a)(2)(i) and, at the time specified, 
accomplish the requirements of paragraph (a)(2)(ii) of this AD.

General Visual Inspection, Non-Destructive Test (NDT) Inspection, and 
Replacement of Bolts and Bushings

    (i) Perform a general visual inspection of the affected flap 
fittings at WS 123.38 to detect cracking, in accordance with the 
service bulletin. If no cracking is detected, repeat the visual 
inspection thereafter at intervals not to exceed 800 flight hours, 
until the requirements of paragraph (a)(2)(ii) are accomplished. If 
any cracking is detected, prior to further flight, accomplish the 
terminating action specified by paragraph (c) of this AD.
    (ii) Within 4,800 flight hours after the effective date of this 
AD, perform a one-time detailed visual inspection of the flap 
fittings to determine the size of the inboard and outboard holes 
(swaged bushing) and to detect loose swaged bushings; and perform an 
NDT inspection of the aft attachment lugs of the flap assemblies at 
WS 123.38 to detect cracking, in accordance with the service 
bulletin. Accomplishment of the NDT inspection terminates the 
general visual inspection required by paragraph (a)(2)(i) of this 
AD.

    Note 2: For the purpose of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or drop-light, and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''


    Note 3: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirrors, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (A) If all the hole sizes are within the limits specified by the 
service bulletin, no loose swaged bushings are found, and no 
cracking of the aft attachment lugs is detected: Prior to further 
flight, install new fasteners that attach to the flap hinges (nuts, 
bolts, bushing, and washers), in accordance with the service 
bulletin.
    (B) If any hole size is outside the limits specified by the 
service bulletin, or any loose swaged bushing is found, or any 
cracking is detected on the aft attachment lugs: Prior to further 
flight, accomplish the terminating action specified in paragraph (c) 
of this AD.

Visual Inspection for Modification Status

    (b) Within 800 flight hours after the effective date of this AD, 
perform a one-time visual inspection of the aft attachment lugs 
(flap assemblies) of the flap fittings at wing station (WS) 123.38 
to determine the flap assembly modification status, in accordance 
with Saab Service Bulletin 340-57-037, dated January 18, 2000.
    (1) If the modification status is such that all flap assemblies 
installed have thicker lugs, as specified by Figure 1 of the service 
bulletin, no further action is required by this paragraph.
    (2) If the modification status is such that any flap assembly 
installed has a thinner lug, as specified by Figure 1 of the service 
bulletin, prior to further flight, accomplish the requirements of 
paragraph (b)(2)(i) and, at the time specified, accomplish the 
requirements of paragraph (b)(2)(ii) of this AD.

Visual Inspection and NDT Inspection

    (i) Perform a general visual inspection of the aft attachment 
lugs of the flap fittings at WS 123.38 to detect cracking or damage, 
in accordance with the service bulletin. If no cracking or damage is 
detected during the visual inspection, repeat the inspection 
thereafter at intervals not to exceed 800 flight hours, until the 
requirements of paragraph (b)(2)(ii) of this AD are accomplished. If 
any cracking or damage is detected during any general visual 
inspection required by this paragraph, prior to further flight, 
accomplish the terminating action specified by paragraph (c) of this 
AD.
    (ii) Within 6,000 flight cycles after the effective date of this 
AD, perform an NDT inspection of the aft attachment lug of the flap 
fittings at WS 123.38 to detect cracking, in accordance with the 
service bulletin. Accomplishment of the NDT inspection terminates 
the repetitive visual inspections required by paragraph (b)(2)(i) of 
this AD. If no cracking is detected, repeat the NDT inspection 
thereafter at intervals not to exceed 6,000 flight cycles, until the 
actions specified by paragraph (c) are accomplished. If any cracking 
is detected during any NDT inspection required by this paragraph, 
prior to further flight, accomplish the terminating action specified 
by paragraph (c) of this AD.

Terminating Action

    (c) Replacement of all flap fittings at WS 123.38 with new, 
improved flap fittings in accordance with Saab Service Bulletin 340-
57-038, dated January 18, 2000, terminates all inspections required 
by this AD.

Alternative Methods of Compliance

    (d) 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, International Branch, ANM-116, 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, International 
Branch, ANM-116.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

Special Flight Permits

    (e) 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.

    Note 5: The subject of this AD is addressed in Swedish 
airworthiness directives No. 1-152 and No. 1-153, each dated January 
19, 2000.


    Issued in Renton, Washington, on July 25, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19264 Filed 7-28-00; 8:45 am]
BILLING CODE 4910-13-U