Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-192-AD; Amendment 39-8813; AD 94-03-06]

Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B

Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain Saab Model SAAB SF340A and SAAB 340B series

airplanes. This action requires inspections to detect improper

connections of the wire harness installation to the nacelle fire

extinguisher, correction of any discrepancy found, and modification of

the wiring. This amendment is prompted by a report of improperly routed

control wiring to the nacelle fire extinguishers on a Model SAAB 340B

series airplane. The actions specified in this AD are intended to

prevent failure of the fire extinguishing agent to reach the correct

engine in the event of an engine fire.

DATES: Effective on February 16, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of February 16, 1994.

Comments for inclusion in the Rules Docket must be received on or

before April 4, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 93-NM-192-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

The service information referenced in this AD 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; 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: The Luftfartsverket (LFV), which is the

airworthiness authority for Sweden, recently notified the FAA that an

unsafe condition may exist on certain Saab Model SAAB SF340A and SAAB

340B series airplanes. The LFV advises that improperly routed control

wiring to the nacelle fire extinguishers was found during a ``C check''

inspection on a Model SAAB 340B series airplane. Further investigation

revealed that some airplanes have an excessively long wire harness,

which allows the possibility to incorrectly connect the wire harness to

the nacelle fire extinguisher cartridge. When the fire extinguisher

discharges, fire extinguishant transfers to the opposite nacelle fire

zone if a wire harness is incorrectly routed or connected. In such a

case, only one extinguisher, rather than two (as under normal

conditions), is available to extinguish a fire in the nacelle fire

zone. This condition, if not corrected, could result in failure of the

fire extinguishing agent to reach the correct engine in the event of an

engine fire.

Saab has issued Service Bulletin 340-26-012, Revision 1, dated

October 5, 1993, that describes procedures for an inspection to detect

improper connections of the wire harness installation to the nacelle

fire extinguisher, correction of any discrepancy found, and

modification of the wiring. The modification involves shortening the

wires by making a loop and securing with wax string, as necessary. The

LFV classified this service bulletin as mandatory and issued Swedish

Airworthiness Directive SAD No. 1-059, dated September 13, 1993, in

order to assure the continued airworthiness of these airplanes in

Sweden.

This airplane model is manufactured in Sweden and is type

certificated for operation in the United States under the provisions of

Section 21.29 of the Federal Aviation Regulations 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.

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, this AD is being issued to prevent failure of the

fire extinguishing agent to reach the correct engine in the event of an

engine fire. This AD requires an inspection to detect improper

connections of the wire harness installation to the nacelle fire

extinguisher, correction of any discrepancy found, and modification of

the wiring. The actions are required to be accomplished in accordance

with the service bulletin described previously.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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 93-NM-192-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, 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 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

I. 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:

94-03-06 SAAB AIRCRAFT AB: Amendment 39-8813. Docket 93-NM-192-AD.

Applicability: Model SAAB SF340A series airplanes, serial

numbers 004 through 159 inclusive; and Model SAAB 340B, serial

numbers 160 through 345 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To preclude cross-connection of the wire harness installation to

the engine nacelle fire extinguisher, accomplish the following:

(a) Within 25 days after the effective date of this AD, perform

an inspection to ensure proper connections of the wire harness

installation to the nacelle fire extinguisher, in accordance with

Saab Service Bulletin 340-26-012, Revision 1, dated October 5, 1993.

Prior to further flight, correct any discrepancy found and modify

the wiring, in accordance with the service bulletin.

(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) 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 FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

(e) The inspections shall be done in accordance with Saab

Service Bulletin 340-26-012, Revision 1, dated October 5, 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 Saab Aircraft AB, SAAB Aircraft

Product Support, S-581.88, Linkoping, Sweden. 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 February 16, 1994.

Issued in Renton, Washington, on January 26, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-2179 Filed 1-31-94; 8:45 am]

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