Airworthiness Directives; Boeing Model 767 Series Airplanes Equipped With Carbon Brakes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-218-AD]

Airworthiness Directives; Boeing Model 767 Series Airplanes

Equipped With Carbon Brakes

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 Boeing Model 767 series

airplanes. This proposal would require inspections to detect cracking,

corrosion, and wear of various components of the main landing gear

(MLG) brake assembly, and correction of discrepancies. This proposal is

prompted by reports indicating that components in the MLG assembly have

been damaged due to the consequences of vibration. The actions

specified by the proposed AD are intended to prevent failure of

components of the MLG, which could severely affect the braking

capability of the airplane while on the ground.

DATES: Comments must be received by May 9, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-218-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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

Washington 98124-2207. This information may be examined at the FAA,

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: Kristin Larson, Aerospace Engineer,

Systems & Equipment Branch, ANM-130S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055-4056; telephone (206) 227-1760; fax (206)

227-1181.

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-218-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-218-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received several reports indicating that Boeing Model

767 series airplanes equipped with carbon brakes have experienced

certain vibratory conditions that have resulted in damage to or failure

of components of the main landing gear (MLG) assembly. Such damage has

included cracked and worn bushings on the brake load path, deformation

of the brake rod lugs, and missing chrome or heat damage of the brake

attach pins. Failure of these components due to the damage caused by

the vibratory phenomenon could result in the loss of one or two brakes,

depending upon the location of the failure. In fact, there have been

reports of at least 14 incidents of single brake failure and 2

incidents of two-brake failure related to these problems. This

condition, if not corrected, could severely affect the braking

capability of the airplane.

The FAA has reviewed and approved Boeing Service Bulletin 767-32-

0128, dated November 11, 1993, that describes procedures for conducting

repetitive visual, fluorescent magnetic particle, and fluorescent

penetrant inspections to detect cracks and corrosion of the pin that

attaches the brake rod to the brake housing, and replacement of the

pin, if necessary. It also contains procedures for conducting visual

inspections to detect cracking and wear of the brake torque arm

bushing, and to detect cracking of the brake rod bushings; and repair

or replacement of parts, if necessary. Also included are procedures for

conducting repetitive visual inspections to detect corrosion or damage

of the bulkhead, keeper pin, and the bore and face of the brake

attachment pin; and replacement of parts, if necessary.

Since an unsafe condition has been identified that is likely to

exist or develop on other products of this same type design, the

proposed AD would require repetitive inspections to detect corrosion

and cracking of the pin that attaches the brake rod to the brake

housing, the brake torque arm bushing, the brake rod bushings, the

keeper pin, and the bore and face of the brake attach pin. Any

discrepant parts would be required to be replaced or repaired, as

applicable. The actions would be required to be accomplished in

accordance with the service bulletin described previously.

There are approximately 289 Model 767 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 71

airplanes of U.S. registry would be affected by this proposed AD, that

it would take approximately 10 work hours per airplane to accomplish

the proposed actions, and that the average labor rate

is $55 per work hour. Based on these figures, the total cost impact of

the proposed AD on U.S. operators is estimated to be $39,050, or $550

per airplane, per inspection cycle.

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. 9.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Boeing: Docket 93-NM-218-AD.

Applicability: Model 767 series airplanes equipped with carbon

brakes, certificated in any category. -

Compliance: Required as indicated, unless accomplished

previously.

To prevent the failure of components of the main landing gear,

which could severely affect the braking capability of the airplane

while on the ground, accomplish the following: -

(a) Within 1,500 hours time-in-service after the effective date

of this AD, and thereafter at intervals not to exceed 1,500 hours

time-in-service, conduct inspections to detect cracking and

corrosion of the pin that attaches the brake rod to the brake

housing; to detect cracking of the brake torque arm bushings; and to

detect wear of the brake rod bushings; in accordance with Part 1 of

Boeing Service Bulletin 767-32-0128, dated November 11, 1993. If any

discrepancy is detected in any part, replace or repair the part in

accordance with the compliance schedule specified in Figure 1 or

Figure 2 of the service bulletin, as applicable.

(b) Within 6 months after the effective date of this AD, and

thereafter at intervals not to exceed 6 months, conduct a visual

inspection to detect corrosion and damage of the bulkhead, the

keeper pin, and the bore and face of the brake attach pin, in

accordance with Part 2 of Boeing Service Bulletin 767-32-0128, dated

November 11, 1993. If any corrosion or damage is found on any part,

prior to further flight, replace the part in accordance with the

service bulletin.

(c) 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, Seattle Aircraft Certification

Office (ACO), 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, Seattle ACO.

Note: Information concerning the existence of approved

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

obtained from the Seattle ACO.

(d) 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 March 9, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-5935 Filed 3-14-94; 8:45 am]

BILLING CODE 4910-13-U