Airworthiness Directives; British Aerospace Model BAC 1-11-200 and -400 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-167-AD]

Airworthiness Directives; British Aerospace Model BAC 1-11-200

and -400 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 all British Aerospace Model BAC 1-

11-200 and -400 series airplanes. This proposal would require that

certain landing gear brakes be inspected for wear and replaced if the

wear limits prescribed in this proposal are not met, and that the

specified wear limits be incorporated into the FAA-approved maintenance

inspection program. This proposal is prompted by an accident in which a

transport category airplane executed a rejected takeoff (RTO) and was

unable to stop on the runway due to worn brakes; and the subsequent

review of allowable brake wear limits for all transport category

airplanes. The actions specified by the proposed AD are intended to

prevent the loss of brake effectiveness during a high energy RTO.

DATES: Comments must be received by March 23, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-167-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.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer,

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

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

227-2145; 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 93-NM-167-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. 93-NM-167-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

In 1988, a McDonnell Douglas Model DC-10 series airplane was

involved in an aborted takeoff accident in which eight of the ten

brakes failed and the airplane ran off the end of the runway.

Investigation revealed that there were failed pistons on each of the

eight brakes, with O-rings damaged by over-extension due to extensive

wear. Fluid leaking from the damaged pistons caused the hydraulic fuses

to close, releasing all brake pressure.

This accident prompted a review of allowable wear limits for all

brakes installed on transport category airplanes. The FAA and the

Aerospace Industries Association (AIA) jointly developed a set of

dynamometer test guidelines that could be used to validate appropriate

wear limits for all airplane brakes. It should be noted that this worn

brake accountability determination validates brake wear limits with

respect to brake energy capacity only and is not meant to account for

any reduction in brake force due solely to the wear state of the brake.

The guidelines for validating brake wear limits allow credit for use of

reverse thrust with a critical engine inoperative to determine the

energy level absorbed by the brake during the dynamometer test.

The FAA has requested that airframe manufacturers of transport

category airplanes: (1) Determine required adjustments in allowable

wear limits for all of its brakes in use; (2) schedule dynamometer

testing to validate wear limits as necessary; and (3) submit

information from items (1) and (2) to the FAA so that appropriate

rulemaking action(s) can be initiated.

British Aerospace has conducted worn brake rejected takeoff (RTO)

dynamometer testing and analyses on various brakes installed on Model

BAC 1-11-200 and -400 series airplanes. Based on the results of that

testing and analyses, the FAA has determined that the maximum brake

wear limits currently recommended in the Component Maintenance Manual

for Model BAC 1-11-200 series airplanes equipped with brakes

manufactured by Allied Signal Aerospace Company (Bendix) are acceptable

as they relate to the effectiveness of the brakes during a high energy

RTO. The FAA also finds that the maximum brake wear limits currently

recommended in the Component Maintenance Manual for Model BAC 1-11-400

series airplanes equipped with Bendix brakes are not acceptable as they

relate to the effectiveness of the brakes during a high energy RTO.

Consequently, the FAA has determined that the brake wear limits for

Model BAC 1-11-200 series airplanes and the new brake wear limits for

Model BAC 1-11-400 series airplanes must be incorporated into the FAA-

approved maintenance inspection program.

The FAA has determined that, in order to prevent loss of brake

effectiveness during a high energy RTO, the following maximum brake

wear limits are necessary for Model BAC 1-11-200 and -400 series

airplanes equipped with Bendix brakes:

British Aerospace Model Bac 1-11-200 and -400 Series Airplanes Equipped

With Bendix Brakes

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Brake part

Airplane Model No. Maximum brake wear limit (inch/mm)

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BAC 1-11-200.... 2601225-1 0.75 inch (19.1 mm).

BAC 1-11-400.... 2601240-1 1.0 inch (25.4 mm).

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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. The FAA has 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 that certain

landing gear brakes be inspected for wear and replaced if the wear

limits prescribed in this proposal are not met, and that the specified

wear limits be incorporated into the FAA-approved maintenance

inspection program.

There are approximately 100 Model BAC 1-11-200 and -400 series

airplanes of the affected design in the worldwide fleet.

The FAA estimates that 10 Model BAC 1-11-200 series airplanes of

U.S. registry and 2 U.S. operators would be affected by this proposed

AD. For these airplanes and operators, although the proposed rule would

require the incorporation of maximum brake wear limits into the FAA-

approved maintenance inspection program, no other specific additional

action, inspection, or part replacement costs relative to that

requirement would be involved; such actions are currently a part of the

current maintenance program. However, it is estimated that it would

take approximately 1 work hour, at an average labor rate of $55 per

work hour, for each operator to incorporate the requirement into its

FAA-approved maintenance inspection program. Based on these figures,

the total cost impact of the proposed requirement to revise the FAA-

approved maintenance inspection program on U.S. operators of Model BAC

1-11-200 series airplanes is estimated to be $110, or $55 per operator.

The FAA estimates that 20 Model BAC 1-11-400 series airplanes of

U.S. registry and 19 U.S. operators would be affected by this proposed

AD. It is estimated that it would take approximately 1 work hour, at an

average labor rate of $55 per work hour, for each operator to

incorporate the proposed revision of its FAA-approved maintenance

inspection program. Based on these figures, the total cost impact of

that proposed requirement on U.S. operators of Model BAC 1-11-400

series airplanes is estimated to be $1,045, or $55 per operator.

Additionally, the FAA estimates that for operators of Model BAC 1-

11-400 series airplanes, it would take approximately 2 work hours per

airplane to shorten the wear pins for replacement brakes, and 8 work

hours per airplane to change the brakes, at an average labor rate of

$55 per work hour. The cost of required parts to accomplish the change

in wear limits for these airplanes (that is, the cost resulting from

the requirement to change the brakes before they are worn to their

previously approved limits for a one-time change) would be

approximately $912 per airplane. Based on these figures, the total cost

impact of these proposed requirements on U.S. operators of Model BAC 1-

11-400 series airplanes is estimated to be $29,240, or $1,462 per

airplane.

These total cost figures are based on the assumption that no

operator has yet accomplished the proposed requirements of this AD.

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 93-NM-167-AD.

Applicability: All Model BAC 1-11-200 and -400 series airplanes,

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the loss of brake effectiveness during a high energy

rejected takeoff (RTO), accomplish the following:

(a) Within 180 days after the effective date of this AD, accomplish

paragraphs (a)(1) and (a)(2) of this AD.

(1) Inspect main landing gear brakes having the brake part

numbers listed below for wear. Any brake worn more than the maximum

wear limit specified below must be replaced, prior to further

flight, with a brake within that limit.

British Aerospace Model BAC 1-11-200 and -400 Series Airplanes Equipped

With Bendix Brakes

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

Brake part

Airplane model No. Maximum brake wear limit (inch/mm)

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

BAC 1-11-200.... 2601225-1 0.75 inch (19.1 mm).

BAC 1-11-400.... 2601240-1 1.0 inch (25.4 mm).

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

Note 1: Measuring instructions for Bendix brakes can be found in

Revision 4 of the Allied Signal Component Maintenance Manual.

Note 2: Revision 4 of the Allied Signal Component Maintenance

Manual specifies a brake wear limit of 1.06 inch for brake part

number 2601240-1. That brake wear limit is superseded by the brake

wear limit of 1.0 inch specified above for that brake part number.

Revision 5 of the Allied Signal Component Maintenance Manual will

reflect the revised brake wear limit of 1.0 inch. Brake units having

wear indicators set at 1.06 inch will be considered to be fully worn

when either wear indicator pin is 1.0 inch or less above the surface

of the carrier, provided the wear pin has not been shortened on that

brake unit.

Note 3: Each operator should provide a method of identifying

modified brakes until Revision 5 of the Allied Signal Component

Maintenance Manual has been issued. Revision 5 of the manual will

define a method of brake identification and reflect the brake wear

limits specified above. A paint scheme similar to that used to

differentiate between new and refurbished brakes could be used, for

example, if a different color is used.

(2) Incorporate into the FAA-approved maintenance inspection

program the maximum brake wear limits specified in paragraph (a)(1)

of this AD.

(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 4: 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 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 January 21, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-1690 Filed 1-26-94; 8:45 am]

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