Airworthiness Directives; Saab Model SAAB 340B Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-176-AD]

RIN 2120-AA64

Airworthiness Directives; Saab Model SAAB 340B Series Airplanes

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 340B

series airplanes. This proposal would require a one-time inspection for

moisture or other contamination of a certain wiring harness, electrical

relay, and relay socket; a one-time inspection for electrical damage of

the same electrical relay and socket; corrective actions, if necessary;

and replacement of certain nut plates with new, improved parts. This

proposal is prompted by issuance of mandatory continuing airworthiness

information by a foreign civil airworthiness authority. The actions

specified by the proposed AD are intended to prevent a short circuit

caused by fluid leakage, which could result in inability to extend or

retract the landing gear.

DATES: Comments must be received by August 17, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 98-NM-176-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, Linkping, Sweden. This information may be examined at the FAA,

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager,

International Branch, ANM-116, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)

227-2110; fax (425) 227-1149.

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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 98-NM-176-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-114, Attention: Rules

Docket No. 98-NM-176-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Luftfartsverket (LFV), which is the airworthiness authority for

Sweden, notified the FAA that an unsafe condition may exist on certain

Saab Model SAAB 340B series airplanes. The LFV advises that it has

received a report indicating that circuit breaker 7GA opened while an

airplane was in flight, which resulted in the flightcrew being unable

to extend and lock down the landing gear. In another incident, circuit

breaker 7GA opened shortly after takeoff of an airplane, which resulted

in the flightcrew being unable to retract the landing gear.

Investigation revealed that the design of nut plates installed on the

cockpit floor allowed fluid to leak through carpet attachment holes on

the floor. Such fluid leakage contaminated electrical relay 15GA, which

is located directly below the nut plates, and caused a short circuit

that caused circuit breaker 7GA to open. Fluid leakage also

contaminated related wiring harnesses, which could cause the wiring

insulation to break down and lead to a short circuit. This condition,

if not corrected, could result in inability to extend or retract the

landing gear, or possible collapse of the landing gear if it is not

locked down properly upon landing.

Explanation of Relevant Service Information

The manufacturer has issued Saab Service Bulletin 340-32-115, dated

April 7, 1998. This service bulletin describes procedures for a one-

time detailed visual inspection for moisture or other contamination of

a wiring harness above relay consoles 305VU and 306VU, and cleaning the

wiring harness, if necessary. This service bulletin also describes

procedures for a one-time detailed visual inspection for moisture or

other contamination of electrical relay 15GA and its socket, which

involves removing the relay from its socket; and corrective actions, if

necessary. These corrective actions include removing the socket from

the relay console, disconnecting the wires from the relay socket, and

cleaning the relay socket and relay. This service bulletin also

describes procedures for a one-time detailed visual inspection for

electrical damage (i.e., arcing, discoloration, or charring) of

electrical relay 15GA and its socket; and replacement of the relay and

its socket with new parts, if necessary. The service bulletin also

describes procedures for replacement of certain existing nut plates on

the floor of the cockpit with new, improved parts. Accomplishment of

the actions specified in the service bulletin is intended to adequately

address the identified unsafe condition. The LFV classified this

service bulletin as mandatory and issued Swedish airworthiness

directive SAD 1-125, dated April 7, 1998, in order to assure the

continued airworthiness of these airplanes in Sweden.

FAA's Conclusions

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 (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 require accomplishment of

the actions specified in the service bulletin described previously.

Cost Impact

The FAA estimates that 120 airplanes of U.S. registry would be

affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish

the proposed inspections, at an average labor rate of $60 per work

hour. Based on these figures, the cost impact of the inspections

proposed by this AD on U.S. operators is estimated to be $7,200, or $60

per airplane.

It would take approximately 3 work hours per airplane to accomplish

the proposed replacement, at an average labor rate of $60 per work

hour. Required parts would be provided by the manufacturer at no cost

to operators. Based on these figures, the cost impact of the

replacement proposed by this AD on U.S. operators is estimated to be

$21,600, or $180 per airplane.

The cost impact figures discussed above are 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.

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

[[Page 38355]]

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

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 adding the following new

airworthiness directive:

SAAB Aircraft AB: Docket 98-NM-176-AD.

Applicability: Model SAAB 340B series airplanes, manufacturer

serial numbers 380 through 499 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

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 (b) 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 a short circuit caused by fluid leakage, which could

result in inability to extend or retract the landing gear,

accomplish the following:

(a) Within 400 flight hours after the effective date of this AD,

accomplish the actions required by paragraphs (a)(1), (a)(2),

(a)(3), and (a)(4) of this AD, in accordance with Saab Service

Bulletin 340-32-115, dated April 7, 1998.

(1) Perform a detailed visual inspection to detect moisture or

other contamination of the electrical wiring harness above relay

consoles 305VU and 306VU. If any moisture or other contamination is

found, prior to further flight, clean the wiring harness.

(2) Perform a detailed visual inspection to detect moisture or

other contamination of electrical relay 15GA and its socket. If any

moisture or other contamination is found, prior to further flight,

accomplish corrective actions.

(3) Perform a detailed visual inspection for electrical damage

of electrical relay 15GA and its socket. If any sign of electrical

damage (arcing, discoloration, or charring) is detected, prior to

further flight, replace the existing relay and socket with new

parts.

(4) Replace the existing nut plates on the floor of the cockpit

with new, improved nut plates, on the left and right sides of the

airplane.

(b) 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, International Branch, ANM-116, 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, International

Branch, ANM-116.

Note 2: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the International Branch, ANM-116.

(c) 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.

Note 3: The subject of this AD is addressed in Swedish

airworthiness directive SAD 1-125, dated April 7, 1998.

Issued in Renton, Washington, on July 8, 1998.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 98-18949 Filed 7-15-98; 8:45 am]

BILLING CODE 4910-13-U