[Federal Register Volume 59, Number 84 (Tuesday, May 3, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10508]


[[Page Unknown]]

[Federal Register: May 3, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-23-AD]

 

Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B 
Airplanes, Equipped With Flight Equipment and Engineering Limited Model 
121 Series Seats

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 airplanes. This proposal would require repetitive inspections 
to detect cracking of the tray stop spindle and backrest spindle bosses 
on the inboard sections of certain seats; and replacement of the 
inboard sections, if necessary. This proposal would also require repair 
and identification of the modification plate, which would terminate the 
requirement to inspect repetitively. This proposal is prompted by 
reports of fatigue cracking in the vicinity of the tray stop spindle 
and backrest spindle bosses, which could lead to excessive movement and 
eventual failure of the backrest on these seats during aft loading. The 
actions specified by the proposed AD are intended to prevent failure of 
the backrest on these seats, which could inhibit emergency egress.

DATES: Comments must be received by June 27, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-23-AD, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule may be 
obtained from Flight Equipment and Engineering Limited, Technical 
Manager, Nissen House, Grovebury Road, Leighton Buzzard, Bedfordshire, 
LU7 8TB, United Kingdom. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2145; fax (206) 227-1320.

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 94-NM-23-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. 94-NM-23-AD, 1601 Lind Avenue SW., Renton, Washington 98055-
4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, recently notified the FAA that an 
unsafe condition may exist on certain Flight Equipment and Engineering 
Limited (FEEL) Model 121 series seats that are installed on Saab Model 
SAAB SF340A and SAAB 340B airplanes. The CAA advises that several 
operators of Saab Model SAAB SF340A and SAAB SF340B airplanes found 
fatigue cracking in the vicinity of the tray stop spindle and backrest 
spindle bosses. Cracking in this area may weaken the machined component 
that attaches the backrest of the seats to the main spars of the 
airplane and may lead to excessive movement and eventual failure of the 
backrest on these seats during aft loading. This condition, if not 
corrected, could result in failure of the backrest of these seats, 
which could inhibit emergency egress.
    FEEL has issued Service Bulletin 25-20-1287, Revision 3, dated 
March 1993, that describes procedures for a detailed visual inspection 
to detect cracking of the tray stop spindle and backrest spindle bosses 
on the inboard section of certain Model 121 series seats; replacement 
of the inboard section with a section having the same part number, if 
necessary, and repetitively inspecting; and identification of the newly 
installed section.
    FEEL has also issued Service Bulletin 25-20-1294, Revision 1, dated 
May 1993, that describes procedures for repair by replacing the inboard 
section of certain Model 121 series seats with a newly designed, 
stronger inboard section, and replacing the front beam with a 
serviceable beam, if necessary; and identification of the newly 
installed section. This repair and identification procedure would 
eliminate the need to inspect the inboard sections repetitively.
    The CAA classified these service bulletins as mandatory and issued 
CAA Airworthiness Directives 006-03-93 and 017-03-93 in order to assure 
the continued airworthiness of these airplanes in the United Kingdom.
    This airplane model is manufactured in Sweden and is type 
certificated for operation in the United States under the provisions of 
Sec. 21.29 of the Federal Aviation Regulations and the applicable 
bilateral airworthiness agreement. Pursuant to this bilateral 
airworthiness agreement, the CAA has kept the FAA informed of the 
situation described above. The FAA has examined the findings of the 
CAA, 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.
    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 a detailed visual 
inspection to detect cracking of the tray stop spindle and backrest 
spindle bosses on the inboard section of certain Model 121 series 
seats; replacement of the inboard sections with sections having the 
same part number and repetitively inspecting, if necessary; and 
identification of the newly installed section. This proposal would 
require repair (including the installation of stronger inboard 
sections) and identification of the stronger inboard sections 
(accomplishment of the actions specified in FEEL Service Bulletin 25-
20-1294), which would terminate the requirement to inspect 
repetitively. The actions would be required to be accomplished in 
accordance with the service bulletins described previously.
    The FAA estimates that 73 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 2 work 
hours (1 work hour per seat to inspect and 1 work hour per seat to 
replace, with 34 seats per airplane) to accomplish the proposed 
actions, and that the average labor rate is $55 per work hour. Required 
parts would be provided by the manufacturer at no cost to the operator. 
Based on these figures, the total cost impact of the proposed AD on 
U.S. operators is estimated to be $273,020, or $3,740 per airplane.
    The total 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.
    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 14 
CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES-

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

SAAB Aircraft AB: Docket 94-NM-23-AD.

    Applicability: Model SAAB SF340A airplanes having serial numbers 
004 through 159 inclusive, and Model SAAB 340B airplanes having 
serial numbers 160 through 330 inclusive; equipped with Flight 
Equipment and Engineering Limited (FEEL) Model 121 series seats 
listed in FEEL Service Bulletin 25-20-1294, Revision 1, dated May 
1993, or FEEL Service Bulletin 25-20-1287, Revision 3, dated March 
1993; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the backrest on these seats, which could 
inhibit emergency egress, accomplish the following:
    (a) Within 28 days after the effective date of this AD, perform 
a detailed visual inspection to detect cracking of the tray stop 
spindle and backrest spindle bosses of the inboard section of the 
seat, in accordance with FEEL Service Bulletin 25-20-1287, Revision 
3, dated March 1993.
    (1) If no cracking is found, or if cracking is found that does 
not penetrate the shear web, repeat the inspection of that seat 
thereafter at intervals not to exceed 150 hours time-in-service 
until the requirements or paragraph (b) of this AD are accomplished.
    (2) If any cracking is found that penetrates the shear web, 
prior to further flight, replace the inboard section (up to issue 
12), and identify the modification plate with ``25-20-1287A,'' in 
accordance with the service bulletin. Thereafter, repeat the 
inspection at intervals not to exceed 150 hours time-in-service 
until the requirements of paragraph (b) of the AD are accomplished.
    (b) Within 6 months after the effective date of this AD, repair 
and identify the modification plate with ``25-20-1294,'' in 
accordance with FEEL Service Bulletin 25-20-1294, Revision 1, dated 
May 1993. Accomplishment of the actions required by this paragraph 
constitutes terminating action for the requirements of 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: 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 April 26, 1994.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-10508 Filed 5-2-94; 8:45 am]
BILLING CODE 4910-13-U