Airworthiness Directives; Jetstream Aircraft Limited Model 4101 Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-15-AD]

Airworthiness Directives; Jetstream Aircraft Limited Model 4101

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 all Jetstream Model 4101

airplanes. This proposal would require modification of the mounting

structure of the elevator controls on the rear pressure bulkhead. This

proposal is prompted by the results of a structural analysis which

indicate that certain structure in the elevator control system may be

subject to deformation when maximum load is exerted by the pilot(s) in

the event of a jam in the elevator control cables. The actions

specified by the proposed AD are intended to prevent reduced

controllability of the airplane due to structural deformation in the

elevator control system.

DATES: Comments must be received by April 25, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-15-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 Jetstream Aircraft, Incorporated, P.O. Box 16029, Dulles

International Airport, Washington, DC 20041-6029. This information may

be examined at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,

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

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

227-2148; 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 changed 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-15-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-15-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Civil Aviation Authority (CAA), which is the airworthiness

authority for the United Kingdom, recently notified the FAA that an

unsafe condition may exist on all Jetstream Model 4101 airplanes. The

CAA advises that the results of a structural analysis revealed that the

mounting structure on the elevator controls may be subject to

deformation when maximum load is exerted by the pilot(s) in the event

of a jam in the elevator control cables. This condition, if not

corrected, could result in reduced controllability of the airplane due

to structural deformation in the elevator control system. -

Jetstream has issued Service Bulletin J41-53-012, dated November

30, 1993, that describes procedures for modification of the mounting

structure of the elevator controls on the rear pressure bulkhead. This

modification entails installing thicker support brackets and additional

stiffening to the mounting structure of the upper and lower pulley

installations of the elevator and rudder cables aft of the rear

pressure bulkhead. The CAA classified this service bulletin as

mandatory in order to assure the continued airworthiness of these

airplanes in the United Kingdom. -

This airplane model is manufactured in the United Kingdom 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 CAA has kept the FAA informed of

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

CAA, 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 modification of the

mounting structure of the elevator control components on the rear

pressure bulkhead. The actions would be required to be accomplished in

accordance with the service bulletin described previously. -

The FAA estimates that 8 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 16.5

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

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

provided at no cost to the operator. Based on these figures, the total

cost impact of the proposed AD on U.S. operators is estimated to be

$7,260, or $907.50 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:

Jetstream Aircraft Limited: Docket 94-NM-15-AD.

-Applicability: All Model 4101 airplanes, certificated in any

category. -

Compliance: Required as indicated, unless accomplished

previously. -

To prevent reduced controllability of the airplane due to

structural deformation in the elevator control system, accomplish

the following: -

(a) Within 6 months after the effective date of this AD, modify

the mounting structure of the elevator controls on the rear pressure

bulkhead in accordance with Jetstream Service Bulletin J41-53-012,

dated November 30, 1993. -

(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.

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 March 9, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-5934 Filed 3-14-94; 8:45 am]

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