[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]
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