Airworthiness Directives; Jetstream Model 4101 Airplanes

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

is applicable to certain Jetstream Model 4101 airplanes. This action

requires repetitive removal of the spoiler actuators, purging the

hydraulic system, and installation of an actuator that has been

previously certified. This amendment is prompted by a report of damage

to the locking mechanisms on some pistons of the spoiler actuators. The

actions specified in this AD are intended to prevent uncommanded

extension of the lift spoiler in the event of loss of hydraulic

pressure in the spoiler actuator.

DATES: Effective September 6, 1994.

The incorporation by reference of certain publications listed in

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

of September 6, 1994. -

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

before October 21, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-124-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

The service information referenced in this AD 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; or at the Office of the Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

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: 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 certain Jetstream Model

4101 airplanes. The CAA advises that, during routine maintenance, the

locking mechanisms on the pistons of the spoiler actuators were found

to be damaged. The cause of this damage has been attributed to

inadequate bleeding of the spoiler hydraulic system. In some instances,

the spoiler operation was out of sequence and may have caused damage to

the locking mechanisms on the pistons of the spoiler actuators. This

condition, if not corrected, could result in uncommanded extension of

the lift spoiler in the event of loss of hydraulic pressure in the

spoiler actuator.

Jetstream has issued Alert Service Bulletin J41-A27-034, dated June

9, 1994, which describes procedures for removal of the left and right

spoiler actuators, purging the hydraulic system, and installation of a

previously certified spoiler actuator. The CAA classified this alert

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 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 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, this AD is being issued to prevent uncommanded

extension of the lift spoiler. This AD requires repetitively removing

the spoiler actuators, purging the hydraulic system, and installing an

actuator that has been previously certified. The actions are required

to be accomplished in accordance with the alert service bulletin

described previously.

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

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 rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-124-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 that it 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 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. 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:

94-17-12 Jetstream Aircraft Limited: Amendment 39-9007. Docket 94-

NM-124-AD.

Applicability: Model 4101 airplanes having airplane constructors

numbers 41004 through 41033 inclusive, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent uncommanded extension of the lift spoiler in the

event of loss of hydraulic pressure in the spoiler actuator,

accomplish the following:

(a) Within 21 days after the effective date of this AD, remove

the spoiler actuators in accordance with Jetstream Alert Service

Bulletin J41-A27-034, dated June 9, 1994. Following removal of the

actuators, accomplish the requirements of paragraphs (a)(1) and

(a)(2) of this AD, in accordance with the service bulletin.

(1) Prior to further flight, purge the hydraulic system to

ensure that there is no contamination.

(2) Prior to further flight, install a spoiler actuator that has

been previously certified and marked with an ``R'' after the serial

number on the nameplate of the actuator.

(b) Thereafter, repeat the requirements of paragraph (a) of this

AD at intervals not to exceed 500 landings.

(c) As of 21 days after the effective date of this AD, all

spoiler actuators installed on any airplane shall be previously

certified and bear an ``R'' after the serial number on the nameplate

of the actuator, in accordance with Jetstream Alert Service Bulletin

J41-A27-034, dated June 9, 1994.

(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: 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.

(f) The actions shall be done in accordance with Jetstream Alert

Service Bulletin J41-A27-034, dated June 9, 1994. 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 Jetstream Aircraft, Incorporated, P.O. Box 16029,

Dulles International Airport, Washington, DC 20041-6029. 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.

(g) This amendment becomes effective on September 6, 1994.

Issued in Renton, Washington, on August 12, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-20286 Filed 8-19-94; 8:45 am]

BILLING CODE 4910-13-U