Airworthiness Directives; Israel Aircraft Industries (IAI) Model 1125 Westwind Astra Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-39-AD]

Airworthiness Directives; Israel Aircraft Industries (IAI) Model

1125 Westwind Astra 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 IAI Model 1125 Westwind

Astra airplanes. This proposal would require relocation of the ground

cable in the slat power drive unit. This proposal is prompted by a

report that the drive system for the leading edge slat stopped in

transit during flight on a Model 1125 Westwind Astra airplane. This

incident was caused by an improper ground connection for the electric

motor of the slat drive system, which resulted in arcing and an open

electrical circuit. The actions specified by the proposed AD are

intended to prevent possible fuel vapor fire due to electrical arcing

in an area where fuel vapors might be present and the inability to move

the slats during flight due to an open electrical circuit.

DATES: Comments must be received by June 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-39-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from Astra Jet Corporation, Technical Publications, 77

McCullough Drive, suite 11, New Castle, Delaware 19720-9813. This

information may be examined at the FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone (206)

227-2141; fax (206) 227-1320.

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 94-NM-39-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. 94-NM-39-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Civil Aviation Administration of Israel (CAAI), which is the

airworthiness authority for Israel, recently notified the FAA that an

unsafe condition may exist on certain Israel Aircraft Industries (IAI)

Model 1125 Westwind Astra airplanes. The CAAI advises that it has

received a report that the drive system for the leading edge slat

stopped in transit during flight on a Model 1125 Westwind Astra

airplane. The cause of this incident has been attributed to an improper

ground connection for the electric motor of the leading edge slat drive

system, which resulted in arcing and an open electrical circuit. The

ground connection for the electric motor is located in the area just

forward of the wing spar. Since the fuel system is integrated into the

structure of the wing, the area is subject to fuel leakage. An improper

ground connection for the subject motor, if not corrected, could result

in possible fuel vapor fire due to electrical arcing in an area where

fuel vapors might be present, and the inability to move the slats

during flight due to an open electrical circuit.

Astra Jet Corporation has issued Service Bulletin SB 1125-27-110,

Revision 1, dated February 16, 1994, that describes procedures for

relocation of the ground cable in the slat power drive unit

(Modification 6350). Accomplishment of this modification involves

routing the ground cable for the slat power drive located in the

aircraft secondary structure to the aircraft primary structure.

Relocating the ground cable will improve electrical grounding for the

slat power drive unit. The CAAI classified this service bulletin as

mandatory and issued Airworthiness Directive No. 93-02, dated December

2, 1993, in order to assure the continued airworthiness of these

airplanes in Israel.

This airplane model is manufactured in Israel and is type

certificated for operation in the United States under the provisions of

Sec. 21.29 of the Federal Aviation Regulations and the applicable

bilateral airworthiness agreement. Pursuant to this bilateral

airworthiness agreement, the CAAI has kept the FAA informed of the

situation described above. The FAA has examined the findings of the

CAAI, 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, the proposed AD would require relocation of the

ground cable in the slat power drive unit. The actions would be

required to be accomplished in accordance with the service bulletin

described previously.

The FAA estimates that 52 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 3 work

hours per airplane to accomplish the proposed actions, and that the

average labor rate is $55 per work hour. Required parts would cost

approximately $53 per airplane. Based on these figures, the total cost

impact of the proposed AD on U.S. operators is estimated to be $11,336,

or $218 per airplane.

The total cost impact figure discussed above is 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.

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

Administrator, the Federal Aviation Administration proposes to amend 14

CFR part 39 of the Federal Aviation Regulations 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Israel Aircraft Industries Limited: Docket 94-NM-39-AD.

Applicability: Model 1125 Westwind Astra airplanes; serial

numbers 004 through 066 inclusive, and 068; certificated in any

category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent possible fuel vapor fire due to electrical arcing in

an area where fuel vapors might be present and the inability to move

the slats during flight due to an open electrical circuit,

accomplish the following:

(a) Within 50 hours time-in-service after the effective date of

this AD, relocate the ground cable in the slat power drive unit in

accordance with Astra Jet Service Bulletin SB 1125-27-110, Revision

1, dated February 16, 1994.

(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, 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.

(c) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 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 29, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-10777 Filed 5-4-94; 8:45 am]

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