Airworthiness Directives; British Aerospace Model ATP Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-41-AD]

Airworthiness Directives; British Aerospace Model ATP Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain British Aerospace Model

ATP airplanes. This proposal would require modification of the power

supply for the communications system. This proposal is prompted by

reports of loss of power to the communications system due to an

electrical fault in the ground crew jack box or the handset of the

public address (PA) system. The actions specified by the proposed AD

are intended to prevent the inability of the flight crew to communicate

with passengers via the PA system and with air traffic control due to

loss of power to the communication system, which may lead to unsafe

operation of the airplane.

DATES: Comments must be received by July 5, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-41-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 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-41-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-41-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 certain British Aerospace Model ATP

airplanes. The CAA advises that it has received reports of loss of

power to both essential and emergency power supplies for the

communications systems due to a ground fault in the communications jack

box of the ground crew-to-flight crew communications system in the bay

of the nose landing gear or the handset of the public address (PA)

system. This condition, if not corrected, could result in the inability

of the flight crew to communicate with passengers via the PA system and

with air traffic control, which may lead to unsafe operation of the

airplane.

Jetstream has issued Service Bulletin ATP-23-21-35288A, Revision 2,

dated February 15, 1994, that describes procedures for modification of

the power supply for the communications system. This modification

(Modification 35288A) entails installing two diodes on the terminal

block and the associated wiring to ensure that, in the event of an

electrical fault in the jack box for the ground crew-to-flight crew

communications system or the handset of the PA system, the

communications circuits will continue to operate. 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 Section 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

power supply for the communications system. The actions would be

required to be accomplished in accordance with the service bulletin

described previously.

The FAA estimates that 10 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 30 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

$16,500, or $1,650 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:

British Aerospace: Docket 94-NM-41-AD.

Applicability: Model ATP airplanes having constructor's numbers

2002 through 2063 inclusive, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the inability of the flight crew to communicate with

passengers via the public address system and with air traffic

control due to loss of power to the communication system, which may

lead to unsafe operation of the airplane, accomplish the following:

(a) Within 675 hours time-in-service after the effective date of

this AD, modify the power supply of the communications system

(Modification 35288A) in accordance with Jetstream Service Bulletin

ATP-23-21-35288A, Revision 2, dated February 15, 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

Secs. 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 May 5, 1994.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-11352 Filed 5-10-94; 8:45 am]

BILLING CODE 4910-13-U