Airworthiness Directives; Raytheon Corporate Jets Model BAe 125- 1000A Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-35-AD]

Airworthiness Directives; Raytheon Corporate Jets Model BAe 125-

1000A Series 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 Raytheon Corporate Jets

Model BAe 125-1000A series airplanes. This proposal would require

modification of the control circuit wiring for the engine thrust

reversers and of the wiring for annunciation of rudder bias status.

This proposal is prompted by a report that a single dormant electrical

fault in the control circuit of the thrust reversers could cause a

thrust reverser to deploy if the pilot selects reverse thrust during

the approach phase of flight; and by reports that if an asymmetric

thrust reverser condition occurs, the correct rudder bias may not be

annunciated before the flight crew applies high reverse thrust. The

actions specified by the proposed AD are intended to prevent adversely

affected controllability of the airplane.

DATES: Comments must be received by June 22, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-35-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 Raytheon Corporate Jets Inc., 3 Bishops Square, St.

Albans Road West, Hatfield, Hertfordshire, AL109NE, United Kingdom.

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-35-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-35-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 Raytheon Corporate Jets Model BAe

125-1000A series airplanes. The CAA advises that a single dormant

electrical fault in the control circuit of the thrust reversers could

cause a thrust reverser to deploy if the pilot selects reverse thrust

during the approach phase of flight. The CAA also advises that,

currently, a 4-second time delay occurs in the rudder bias annunciation

system. This annunciation system provides a warning to the flight crew

that an asymmetric thrust reverser condition may exist. If an

asymmetric thrust reverser condition occurs, and the flight crew does

not receive sufficient warning from the annunciation system, the flight

crew may apply high reverse thrust.

These conditions, if not corrected, could adversely affect the

controllability of the airplane.

Raytheon Corporate Jets has issued Service Bulletin SB.78-9-3662B,

dated January 7, 1994, that describes procedures for modification of

the control circuit wiring of the left and right engine thrust

reversers and of the wiring for annunciation of rudder bias status. The

modification involves grounding the normally closed contacts of the

deploy microswitch to remove possible dormant shorts, wiring new

independently signalled contacts in series with the power supply to the

deploy valve solenoid, separating the wiring for the rudder bias not

inhibited annunciation (warning) from the wiring for the uncommanded

hydraulic pressure warning to bypass the 4-second time delay, and other

miscellaneous wiring changes to the thrust reverser wiring system.

Accomplishment of the modification will improve the integrity of the

electrical control circuits of the thrust reversers by eliminating the

possibility of single dormant failures in the thrust reverser system.

Accomplishment of the modification will also correct the status

annunciation of the rudder bias by ensuring that, when an asymmetric

thrust reverser condition occurs, the status of the rudder bias system

is annunciated to the flight crew before the power settings for high

reverse thrust are applied. 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

control circuit wiring for the engine thrust reversers and of the

wiring for annunciation of rudder bias status. The actions would be

required to be accomplished in accordance with the service bulletin

described previously.

The FAA estimates that 19 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 60 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 $1,000 per airplane. Based on these figures, the total

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

$81,700, or $4,300 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:

Raytheon Corporate Jets, Inc.: Docket 94-NM-35-AD.

Applicability: Model BAe 125-1000A series airplanes; serial

numbers 258151, 258159, and 259003 through 259044 inclusive;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent in-flight deployment of a thrust reverser, which

could adversely affect the controllability of the airplane,

accomplish the following:

(a) Within 8 months after the effective date of this AD, modify

the control circuit wiring for the left and right engine thrust

reversers and rudder bias status annunciation, in accordance with

Raytheon Corporate Jets Service Bulletin SB.78-9-3662B, dated

January 7, 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 22, 1994.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-10231 Filed 4-28-94; 8:45 am]

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