Airworthiness Directives; Jetstream Model 4101 Airplanes

DEPARTMENT OF AGRICULTURE

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 96-NM-49-AD]

RIN 2120-AA64

Airworthiness Directives; Jetstream Model 4101 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Jetstream Model

4101 airplanes, that currently requires inspection to determine the

number of hours time-in-service on the landing gear control unit, and

modification of the cable (electrical wiring circuit) of the landing

gear control unit. That AD was prompted by a report of failure of a

micro-switch in the landing gear control unit. This action would

require installation of a new landing gear control unit. This action

also would expand the applicability of the existing AD to include

additional airplanes. The actions specified by the proposed AD are

intended to prevent uncommanded retraction of a landing gear, which

could adversely affect airplane controllability.

DATES: Comments must be received by June 10, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 96-NM-49-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 Jetstream Aircraft, Inc., 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,

[[Page 18708]]

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

227-2148; fax (206) 227-1149.

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 96-NM-49-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. 96-NM-49-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On May 18, 1995, the FAA issued AD 95-09-03, amendment 39-9241 (60

FR 28035, May 30, 1995), applicable to certain Jetstream Model 4101

airplanes, to require inspection to determine the number of hours time-

in-service on the landing gear control unit, and modification of the

cable (electrical wiring circuit) of the landing gear control unit.

That action was prompted by a report of failure of a micro-switch in

the landing gear control unit. The requirements of that AD are intended

to prevent uncommanded retraction of a landing gear, which could

adversely affect airplane controllability.

In the preamble to AD 95-09-03, the FAA indicated that modification

(Jetstream Modification JM41490) of the cable (electrical wiring

circuit) of the landing gear control unit was considered ``interim

action'' and that further rulemaking action was being considered. As a

follow-on action from that determination, the FAA is now proposing

additional, final action.

Explanation of Relevant Service Information

Since the issuance of AD 95-09-03, Jetstream has issued Service

Bulletin J41-32-044, dated September 22, 1995, which describes

procedures for installation of a new improved landing gear control

unit, identified as Modification JM41501. The procedures involve

installing a new landing gear control unit that has revised switching.

The new switching will prevent uncommanded landing gear retractions

caused by spurious signals from single switch failures.

The installation also involves revising certain wiring, which

includes removing cables installed in accordance with Jetstream

Modification JM41490. Additionally, the installation involves

reallocating a spare pin in the airplane connector to prevent the

operation of the old landing gear control unit in the event that one is

inadvertently installed.

Accomplishment of Modification JM41501 will positively address the

unsafe condition identified as uncommanded retraction of a main landing

gear.

In addition, the effectivity listing of this service bulletin

includes additional airplanes that were not previously affected by AD

95-09-03, and removes certain others.

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

authority for the United Kingdom, classified this service bulletin as

mandatory in order to assure the continued airworthiness of these

airplanes in the United Kingdom.

FAA's Conclusions

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.

Explanation of the Requirements of the 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 supersede AD 95-09-03. For

those airplanes subject to AD 95-09-03, it would continue to require an

inspection to determine the number of hours time-in-service on the

landing gear control unit, and modification of the cable (electrical

wiring circuit) of the landing gear control unit. For those airplanes

and certain others, it would require installation of a new improved

landing gear control unit. The actions would be required to be

accomplished in accordance with the Jetstream service bulletin

described previously.

The applicability of the proposed AD would include additional

airplanes that have been identified to be subject to the same unsafe

condition (an included in the effectivity listing of the Jetstream

service bulletin).

Cost Impact

There are approximately 44 Jetstream Model 4101 airplanes of U.S.

registry that would be affected by this proposed AD.

The actions that are currently required by AD 95-09-03, and

retained in this proposed AD, take approximately 7 work hours per

airplane to accomplish, at an average labor rate of $60 per work hour.

The required parts are provided by the manufacturer at no cost to the

operator. Based on these figures, the cost impact on U.S. operators of

the actions currently required is estimated to be $18,480, or $420 per

airplane. The FAA has been advised that all affected U.S. operators

have accomplished these requirements; therefore, there is no future

cost impact of these requirements on current U.S. operators of these

airplanes.

The new installation that would be required by this proposed AD

would take approximately 6 work hours per airplane to accomplish, at an

average labor rate of $60 per work hour. Required parts would be

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

impact on U.S. operators of the proposed requirements of this AD is

estimated to be $15,840, or $360 per airplane. This cost impact figure

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.

[[Page 18709]]

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

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 removing amendment 39-9241 (60 FR

28035, May 30, 1995), and by adding a new airworthiness directive (AD),

to read as follows:

Jetstream Aircraft Limited: Docket 96-NM-49-AD. Supersedes AD 95-09-

03, Amendment 39-9241.

Applicability: Model 4101 airplanes, constructor numbers 41001

through 41073 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

otherwise 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 (d) 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 uncommanded retraction of the landing gear, which can

adversely affect airplane controllability, accomplish the following:

-

(a) For airplanes having constructor numbers 41001 through 41046

inclusive, and 41048 through 41052 inclusive; equipped with either

landing gear control unit part number 717701-1 or 717701-1 Mod A:

Within 8 hours time-in-service after June 14, 1995 (the effective

date of AD 95-09-03, amendment 39-9241), perform an inspection to

determine the number of hours time-in-service on the landing gear

control unit, in accordance with Jetstream Alert Service Bulletin

J41-A32-042, dated April 13, 1995. -

(1) For those airplanes on which the control unit has

accumulated less than 200 hours time-in-service: Prior to further

flight, modify the cable (electrical wiring circuit) of the landing

gear control unit in accordance with the alert service bulletin. -

(2) For those airplanes on which the control unit has

accumulated 200 hours or more time-in-service: Within 50 hours time-

in-service or within 7 days after June 14, 1995 (the effective date

of AD 95-09-03, amendment 39-9241), whichever occurs earlier, modify

the cable (electrical wiring circuit) of the landing gear control

unit in accordance with the alert service bulletin. -

(b) For airplanes having constructor numbers 41001 through 41073

inclusive: Within 6 months after the effective date of this AD,

install a new improved landing gear control unit and modify the

wiring, in accordance with Jetstream Service Bulletin J41-32-044,

dated September 22, 1995. -

(c) As of the effective date of this AD, no person shall install

a landing gear control unit having part number 717701-1 or 717701-1

Mod A, on any airplane. -

(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 2: Information concerning the existence of approved

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

obtained from the Manager, 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.

Issued in Renton, Washington, on April 23, 1996.

S. R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 96-10505 Filed 4-26-96; 8:45 am]

BILLING CODE 4910-13-P