[Federal Register Volume 59, Number 234 (Wednesday, December 7, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-29437]


[[Page Unknown]]

[Federal Register: December 7, 1994]


-----------------------------------------------------------------------


DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-23-AD; Amendment 39-9083; AD 94-24-10]

 

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: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Saab Model SAAB SF340A and SAAB 340B airplanes, 
that requires 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 amendment also requires repair and identification of the 
modification plate, which would terminate the requirement to inspect 
repetitively. This amendment 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 
this AD are intended to prevent failure of the backrest on these seats, 
which could inhibit emergency egress.

DATES: Effective January 6, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 6, 1995.

ADDRESSES: The service information referenced in this AD 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 
Federal Aviation Administration (FAA), Transport Airplane Directorate, 
Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to Saab Model SAAB SF340A and SAAB 
340B airplanes, equipped with Flight Equipment and Engineering Limited 
Model 121 series seats, was published in the Federal Register on May 3, 
1994 (59 FR 22771). That action proposed to 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. It also proposed to 
require repair and identification of the modification plate, which 
would terminate the requirement to inspect repetitively.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the single comment received.
    The commenter has no objections to the proposal, but questions the 
accuracy of the description of the point of failure, as described in 
the preamble to the notice. The preamble stated, ``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'' (emphasis added). The commenter implies that it is not 
accurate to state that the failure point is where the seat backrests 
attach to the main spar of the airplane. The FAA has reconsidered its 
previous description and concurs that clarification is warranted. The 
FAA finds that the following wording comprises a more accurate 
description:

    Cracking in this area may eventually weaken the seat section 
such that the spindles attaching the table and seat back to the seat 
section may break free during crash loads or normal loads. This 
condition, if not corrected, could result in failure of the backrest 
of these seats, which could inhibit emergency egress.

    This clarification of the description of the failure scenario in no 
way alters the basis for issuance of this AD or the unsafe condition 
addressed by it.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. Under 
these circumstances, at least one operator appears to have incorrectly 
assumed that its airplane was not subject to an AD. On the contrary, 
all airplanes identified in the applicability provision of an AD are 
legally subject to the AD. If an airplane has been altered or repaired 
in the affected area in such a way as to affect compliance with the AD, 
the owner or operator is required to obtain FAA approval for an 
alternative method of compliance with the AD, in accordance with the 
paragraph of each AD that provides for such approvals. A note has been 
added to this final rule to clarify this requirement.
    The FAA has recently reviewed the figures it has used over the past 
several years in calculating the economic impact of AD activity. In 
order to account for various inflationary costs in the airline 
industry, the FAA has determined that it is necessary to increase the 
labor rate used in these calculations from $55 per workhour to $60 per 
workhour. The economic impact information below has been revised to 
reflect this increase in the specified hourly labor rate.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    The FAA estimates that 73 airplanes of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours per 
seat to accomplish the required actions, and that the average labor 
rate is $60 per work hour. There are usually 34 seats per airplane. 
Required parts will be provided by the manufacturer at no cost to the 
operator. Based on these figures, the total cost impact of the AD on 
U.S. operators is estimated to be $297,840, or $4,080 per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


39.13  [Amended]

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

94-24-10  SAAB Aircraft AB: Amendment 39-9083. 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, and FEEL Service Bulletin 25-20-1287, Revision 3, dated March 
1993; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 use the authority 
provided in paragraph (c) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    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 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.
    (e) The inspection shall be done in accordance with FEEL Service 
Bulletin 25-20-1287, Revision 3, dated March 1993. The repair and 
identification shall be done in accordance with FEEL Service 
Bulletin 25-20-1294, Revision 1, dated May 1993, which contains the 
following list of effective pages:

------------------------------------------------------------------------
                                            Revision                    
                Page No.                   level shown    Date shown on 
                                             on page          page      
------------------------------------------------------------------------
1-3, 19.................................  1...........  May 1993.       
4-18....................................  Basic.......  Mar. 1993.      
------------------------------------------------------------------------

This incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Flight Equipment and Engineering 
Limited, Technical Manager, Nissen House, Grovebury Road, Leighton 
Buzzard, Bedfordshire LU7 8TB, United Kingdom. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (f) This amendment becomes effective on January 6, 1995.

    Issued in Renton, Washington, on November 23, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-29437 Filed 12-6-94; 8:45 am]
BILLING CODE 4910-13-U