[Federal Register Volume 62, Number 68 (Wednesday, April 9, 1997)]
[Proposed Rules]
[Pages 17127-17129]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-9012]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-130-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 improper connections of the wire harness 
installation to the cartridges of the fire extinguishers in the engine 
nacelles, correction of any discrepancy, and modification of the 
wiring. This action would add a revised modification of that wiring, 
which, if accomplished, would terminate the inspections currently 
required by the existing AD. This proposal is prompted by reports 
indicating that, due to the removal of a certain clamp during 
maintenance, these fire extinguisher cartridges still could be 
connected incorrectly after the modification required by the existing 
AD has been accomplished. The actions specified by the proposed AD are 
intended to prevent incorrect wiring of these cartridges, which would 
result in inability of the fire extinguishers to jointly discharge 
extinguishing agent into a nacelle in the event of an engine fire.

DATES: Comments must be received by May 19, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-130-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 96-NM-130-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. 96-NM-130-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On January 26, 1994, the FAA issued AD 94-03-06, amendment 39-8813 
(59 FR 4575, February 1, 1994), applicable to certain Saab Model SAAB 
SF340A and SAAB 340B series airplanes, to require repetitive 
inspections to detect improper connections of the harness installation 
to the cartridges of the fire extinguishers in the engine nacelles. If 
an improper connection is found, the AD requires that it be corrected. 
This inspection is to be accomplished on all airplanes immediately 
after any maintenance action that requires

[[Page 17128]]

disconnection of the electrical connectors to the cartridges of either 
fire extinguisher. In addition, if the wiring to one of the electrical 
connectors exceeds a certain length, it is to be shortened by making a 
loop in the wiring and securing the loop with wax string.
    That action was prompted by a report of improperly routed control 
wiring to the nacelle fire extinguisher cartridges on a Model SAAB 340B 
series airplane. An investigation revealed that certain wiring of the 
electrical connectors to these extinguisher cartridges on some 
airplanes is excessively long; this contributes to the possibility of 
incorrectly connecting these cartridges.
    There is one fire extinguisher in each nacelle, and each 
extinguisher has a forward and aft cartridge. When the electrical 
connectors to the forward and aft cartridges of both extinguishers are 
connected correctly, extinguishing agent from both extinguishers can be 
discharged on a fire in either nacelle. Should these connectors be 
reversed, however, the fire extinguishers cannot jointly discharge 
extinguishing agent into a nacelle in the event of an engine fire.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has received reports 
indicating that the wiring of some of these electrical connectors still 
could be connected incorrectly to the fire extinguisher cartridges, in 
spite of accomplishment of the modification mandated by that AD. This 
can occur when the clamp on the modified wiring is removed during 
maintenance. Should an incorrect connection occur, extinguishing agent 
from only one extinguisher, instead of both extinguishers, can be 
discharged into a nacelle in the event of a fire.

Explanation of Relevant Service Information

    Saab has issued Service Bulletin SAAB 340-26-015, Revision 1, dated 
December 8, 1995, which describes procedures for conducting an 
inspection of the wiring of the electrical connectors to the cartridges 
of each fire extinguisher to detect if they are incorrectly connected; 
and correction of any discrepancy. (The inspection procedures differ 
slightly from the procedures for inspection specified in Saab Service 
Bulletin SAAB 340-26-012, Revision 1, dated October 5, 1993. That 
service bulletin is referenced as the appropriate source of service 
information in AD 94-03-06.)
    This service bulletin also describes procedures for a modification 
that is revised from the modification required by the existing AD. This 
revised modification entails cutting the wiring to one of the 
connectors when it exceeds a certain length. This revised modification 
prevents this wiring from being connected to the wrong cartridge of the 
fire extinguisher, and eliminates the need for repetitive inspections 
of this wiring.
    The Luftfartsverket (LFV), which is the airworthiness authority for 
Sweden, classified this service bulletin as mandatory and issued 
Swedish airworthiness directive SAD No. 1-079, dated November 24, 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 
Sec. 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 registered 
in the United States, the proposed AD would supersede AD 94-03-06 to 
continue to require repetitive inspections to detect improper 
connections of the wire harness installation to the cartridges of the 
fire extinguishers in the engine nacelles, and correction of any 
discrepancies.
    The proposed AD also would require a revised modification of the 
wiring to one of the electrical connectors if it exceeds a certain 
length. Accomplishment of this modification would terminate the 
repetitive inspections of the wiring currently required by AD 94-03-06.
    The actions would be required to be accomplished in accordance with 
the service bulletin described previously.

Cost Impact

    There are approximately 235 Saab Model SAAB SF340A and SAAB 340B 
series airplanes of U.S. registry that would be affected by this 
proposed AD.
    The actions that are currently required by AD 94-03-06 take 
approximately 6 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. The cost for required parts would be 
minimal. Based on these figures, the cost impact on U.S. operators of 
the actions currently required is estimated to be $77,760, or $360 per 
airplane. (At the time AD 94-03-06 went into effect, it was estimated 
that 216 airplanes would be affected.)
    The new actions that are proposed in this AD action would take 
approximately 6 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would be provided at no 
cost to operators. Based on these figures, the cost impact on U.S. 
operators of the proposed requirements of this AD is estimated to be 
$84,600, or $360 per airplane.
    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.

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

[[Page 17129]]

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 39-8813 (59 FR 
4575, February 1, 1994), and by adding a new airworthiness directive 
(AD), to read as follows:

SAAB Aircraft AB: Docket 96-NM-130-AD. Supersedes AD 94-03-06, 
Amendment 39-8813.

    Applicability: Model SAAB SF340A series airplanes having serial 
numbers 004 through 159 inclusive; and Model SAAB 340B series 
airplanes having serial numbers 160 through 345 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 (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 the incorrect wiring of the wire harness installation 
to the fire extinguisher cartridges in the engine nacelles, which 
would result in the inability of the fire extinguishers to jointly 
discharge agent into a nacelle in the event of a fire:
    (a) Within 25 days after February 16, 1994 (the effective date 
of AD 94-03-06, amendment 39-8813), perform an inspection to ensure 
proper connections of the wire harness installation to the engine 
nacelle fire extinguisher, in accordance with Saab Service Bulletin 
SAAB 340-26-012, Revision 1, dated October 5, 1993, or Saab Service 
Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. Prior 
to further flight, correct any discrepancy found and modify the 
wiring, in accordance with the service bulletin. After the effective 
date of this AD, perform this inspection and correct any discrepancy 
found, in accordance with Saab Service Bulletin SAAB 340-26-015, 
Revision 1, dated December 8, 1995.
    (b) Repeat the inspection specified in paragraph (a) of this AD 
immediately following any maintenance action during which both 
electric connectors to either of the fire extinguishers in the 
nacelle electrical bays are disconnected.
    (c) Prior to the accumulation of 4,000 hours time-in-service 
after the effective date of this AD, or at the next scheduled 
maintenance inspection after the effective date of this AD, 
whichever occurs earlier:
    (1) Conduct an inspection to ensure proper connection of the 
wire harness installation to the fire extinguisher cartridges in 
both engine nacelles, in accordance with Saab Service Bulletin SAAB 
340-26-015, Revision 1, dated December 8, 1995. If any discrepancy 
is detected, prior to further flight, correct this discrepancy in 
accordance with the service bulletin.
    (2) After the inspection required by paragraph (c)(1) of this AD 
has been accomplished, measure the total length of the wiring 
harness from the clamp to connector 9WB-P2/10WB-P2, in accordance 
with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated 
December 8, 1995. If the wiring harness has been modified with a 
loop in accordance with the requirements of paragraph (a) of this 
AD, or in accordance with Saab Service Bulletin SAAB 340-26-012, 
Revision 1, dated October 5, 1993, before measuring, remove the loop 
in the wire harness in accordance with Saab Service Bulletin SAAB 
340-26-015, Revision 1, dated December 8, 1995.
    (i) If the total length is 7 inches (180mm) or less, no further 
action is required by this AD.
    (ii) If the total length exceeds 7 inches (180mm), modify this 
wiring in accordance with Saab Service Bulletin SAAB 340-26-015, 
Revision 1, dated December 8, 1995. Accomplishment of this 
modification constitutes terminating action for the repetitive 
inspections required by paragraph (b) of this AD, and no further 
action is required by this AD.

    Note 2: Accomplishment of this modification in accordance with 
Saab Service Bulletin SAAB 340-26-015, dated November 23, 1995, 
prior to the effective date of this AD, is considered acceptable for 
compliance with the requirements of paragraph (c)(2)(ii) of this AD.

    (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, 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (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.

    Issued in Renton, Washington, on April 2, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-9012 Filed 4-8-97; 8:45 am]
BILLING CODE 4910-13-U