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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-209-AD; Amendment 39-8814; AD 94-03-07]

Airworthiness Directives; Boeing Model 767 Series Airplanes

Equipped With Carbon Brakes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain Boeing Model 767 series airplanes. This action

requires inspections of the brake rod inner cylinder bolts on the main

landing gear (MLG) wheels and brakes; inspections of certain MLG

bushings; installation of retainer plates at each MLG brake disconnect;

inspection and modification of the brake rod pin assembly at each MLG

wheel; repair or replacement of discrepant parts; and revision of the

Airplane Flight Manual (AFM), as necessary. This amendment is prompted

by numerous reports of brake failure during landing and during a low

energy rejected takeoff. The actions specified in this AD are intended

to prevent failure of two or more MLG brakes, which could adversely

affect the stopping performance of the airplane.

DATES: Effective February 18, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of February 18, 1994.

Comments for inclusion in the Rules Docket must be received on or

before April 4, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-209-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

The service information referenced in this AD 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; or at

the Office of the Federal Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Kristin Larson, Aerospace Engineer,

Systems and 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: The FAA has received reports from Boeing

that certain Model 767 series airplanes, equipped with carbon brakes,

have experienced vibratory conditions, which resulted in damage or

failure of the brake torque rod cross bolts and pins. Recently, one

operator experienced a two-brake failure on a low energy rejected

takeoff, whereas previously, there had been reports of two-brake

failures occurring only during landings. To date, there have been 13

reported incidents of one-brake failure and 5 incidents of a two-brake

failure, all due to the vibratory phenomenon. This type of failure

could result in the loss of one or two brakes (out of eight total

brakes), depending upon the location of the failure. The possibility

exists that more than one brake-couple pair could experience

simultaneous failure of the cross bolts or pins, which could result in

the loss of more than two brakes.

Boeing has advised the FAA that heat damage resulting from high

vibrational loads could lead to fracture of the brake rod inner

cylinder bolts. If this should occur, the adjacent brake rods would

disconnect from the inner cylinder, causing the brakes not to operate

at two MLG wheels. As a result, secondary damage to the hydraulic lines

and damage to wiring and the airframe could occur.

Boeing has also advised the FAA that vibrations during braking can

lead to separation of the brake disconnect. Separation of brake hoses

from the brakes would increase braking distances, which is of greatest

concern if this should happen during a rejected takeoff.

Additionally, Boeing has advised the FAA that the development of a

fracture in a cross bolt in the brake rod pin assembly could cause the

brake not to operate at that MLG wheel. The brake rod could separate

from the brake housing, permitting the brake housing to turn on the

axle. Under such conditions, while the wheel turns and brake pressure

is applied, rotation of the brake housing would cut the hydraulic line

and electrical wires attached to the brake.

These conditions, if not corrected, could adversely affect the

stopping performance of the airplane.

The FAA has reviewed and approved Boeing Service Bulletin 767-

32A0116, Revision 1, dated January 13, 1994, that describes procedures

for repetitive surface temper etch inspections and fluorescent magnetic

particle inspections to detect cracks or thermal damage of the existing

brake rod inner cylinder bolts on the MLG wheels and brakes, and

replacement of cracked or damaged bolts with new or serviceable bolts.

The service bulletin also describes procedures for performing

repetitive visual inspections to detect cracking of the inner cylinder

fork lug bushings, and the brake rod bushings at the inner cylinder

fork lug end, and repair of cracked bushings. Accomplishment of the

repetitive inspections, and replacement or repair as necessary, will

help prevent the possibility of a fracture developing in the brake rod

inner cylinder bolts. (The service bulletin limits the effectivity to

Model 767 series airplanes equipped with carbon brakes.)

The FAA has also reviewed and approved Boeing Alert Service

Bulletin 767-32A0125, dated November 11, 1993, that describes

procedures for installation of retainer plates at each MLG brake

disconnect. The alert service bulletin also describes procedures for

adjustment of the torque of the ``B''-nut on the hydraulic line

connection to the disconnect fitting. Accomplishment of the

installation of retainer plates at each MLG brake disconnect will

provide an improved installation of the brake disconnect, which keeps

the brake hose connected to the brake. (The alert service bulletin

limits the effectivity to Model 767 series airplanes equipped with

carbon brakes, line positions 132 through 518, inclusive.)

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

32A0126, Revision 1, dated January 13, 1994, that describes procedures

for performing a visual inspection of the brake rod pin assembly at

each MLG wheel to detect cracks, bronze transfer, corrosion, chrome

discoloration, and areas of missing chrome plate; replacement of any

damaged brake rod pin assembly; modification of the brake rod pin

assembly; installation of the modified brake rod pin into the brake

housing and brake rod; and installation of a new brake attach pin

retainer configuration. The service bulletin also describes a visual

inspection to detect cracking, deformation, and/or missing pieces of

material in the brake housing, and the bushings in the end of the brake

rod; and repair or replacement as necessary. Accomplishment of this

inspection and modification of the brake rod pin assembly at each MLG

wheel, inspection of certain MLG bushings, and replacement or repair as

necessary, will help prevent the possibility of a fracture developing

in a cross bolt. The manufacturer has installed this modification on

airplanes (equipped with carbon brakes) in production, starting at line

number 519 and subsequent. (The service bulletin limits the effectivity

to Model 767 series airplanes equipped with carbon brakes, line

positions 132 through 518, inclusive.)

Since an unsafe condition has been identified that is likely to

exist or develop on other Model 767 series airplanes of the same type

design, this AD is being issued to prevent failure of two or more MLG

brakes, which could adversely affect the stopping performance of the

airplane. This AD requires the following actions:

1. Repetitive surface temper etch inspections and fluorescent

magnetic particle inspections to detect cracks or thermal damage of the

existing brake rod inner cylinder bolts on the MLG wheels and brakes,

and replacement of cracked or damaged bolts with new or serviceable

bolts;

2. Repetitive visual inspections to detect cracking of the inner

cylinder fork lug bushings and the brake rod bushings at the inner

cylinder fork lug end;

3. Installation of retainer plates at each MLG brake disconnect and

adjustment of the torque of the ``B''-nut on the hydraulic line

connection to the disconnect fitting;

4. A one-time visual inspection of the brake rod pin assembly at

each MLG wheel to detect cracks, bronze transfer, corrosion, chrome

discoloration, and areas of missing chrome plate; replacement of any

damaged brake rod pin assembly with a new or serviceable assembly;

modification of the brake rod pin assembly; installation of the

modified brake rod pin into the brake housing and brake rod; and

installation of a new brake attach pin retainer configuration;

5. A one-time visual inspection to detect cracking, deformation,

and/or missing pieces in the bushings in the brake housing, and the

bushings in the end of the brake rod; and

6. Subsequent repair or replacement of any cracked and/or deformed

bushings, and/or any bushings having missing pieces of material.

The actions are required to be accomplished in accordance with the

service bulletins described previously.

This AD allows operation with one-brake-deactivated performance

decrements for cracked or broken bushings, for operators who comply

with the requirements of paragraphs (a) through (b)(3) of this AD

within the acceptable compliance timeframe.

This AD allows operation with two-brake-deactivated performance

decrements, for operators who have not accomplished the requirements of

paragraphs (a) through (b)(3) of this AD within the acceptable

compliance timeframe. For those operators, this AD requires revising

the Limitations and Flight Performance Sections of the Airplane Flight

Manual (AFM) to include two-brake-deactivated performance decrements.

Three options are provided: the first and second options are simple,

conservative corrections; the third option, while more complicated, can

provide a less penalizing correction, depending upon the conditions.

The effect of this AD is to ensure that flight crews are advised of the

potential hazard and of the procedures to address it.

The applicability of this AD is limited to only Model 767 series

airplanes equipped with carbon brakes.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ``ADDRESSES.''

All communications received on or before the closing date for comments

will be considered, and this rule may be amended in light of the

comments received. Factual information that supports the commenter's

ideas and suggestions is extremely helpful in evaluating the

effectiveness of the AD action and determining whether additional

rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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-209-AD.'' The postcard will be date stamped and

returned to the commenter.

The regulations adopted herein will 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 final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, may

be obtained from the Rules Docket at the location provided under the

caption ``ADDRESSES.''

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 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:

94-03-07 Boeing: Amendment 39-8814. Docket 93-NM-209-AD.

Applicability: Model 767 series airplanes equipped with carbon

brakes, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of two or more MLG brakes, which could

adversely affect the stopping performance of the airplane,

accomplish the following:

(a) Except as provided in paragraph (f) of this AD, within 60

days after the effective date of this AD, accomplish paragraphs

(a)(1) and (a)(2) of this AD in accordance with Boeing Service

Bulletin 767-32A0116, Revision 1, dated January 13, 1994:

(1) Perform a surface temper etch inspection and a fluorescent

magnetic particle inspection to detect cracks or thermal damage of

the brake rod inner cylinder bolts on the main landing gear (MLG)

wheels and brakes in accordance with the service bulletin. As a

result of these inspections, accomplish either paragraph (a)(1)(i)

or (a)(1)(ii) of this AD, as applicable:

(i) If cracking or thermal damage is found on any bolt: Prior to

further flight, replace the existing bolt with a new or serviceable

bolt in accordance with the service bulletin. Repeat the inspections

thereafter at intervals not to exceed 800 flight cycles.

(ii) If cracking or thermal damage is not found on any bolt:

Apply finish and reinstall the bolt in accordance with the service

bulletin. Repeat the inspections thereafter at intervals not to

exceed 800 flight cycles.

(2) Perform a visual inspection to detect cracking of the inner

cylinder fork lug bushings and the brake rod bushings at the inner

cylinder fork lug end in accordance with the service bulletin.

Repeat that inspection thereafter at intervals not to exceed 800

flight cycles.

(b) For airplanes having line positions 132 through 518,

inclusive: Except as provided in paragraph (f) of this AD, within 60

days after the effective date of this AD, accomplish paragraphs

(b)(1), (b)(2), and (b)(3), as follows:

(1) Install the retainer plates at each MLG brake disconnect;

and adjust the torque of the ``B''-nut on the hydraulic line

connection to the disconnect fitting; in accordance with Boeing

Alert Service Bulletin 767-32A0125, dated November 11, 1993.

(2) Remove the cross bolt from the brake housing and brake rod

pin assembly at each MLG wheel; remove the brake rod pin assembly;

perform a visual inspection of the brake rod pin assembly to detect

cracks, bronze transfer, corrosion, chrome discoloration, and areas

of missing chrome plate; prior to further flight, replace any

damaged brake rod pin assembly with a new or serviceable assembly;

modify the brake rod pin assembly; install the modified brake rod

pin into the brake housing and brake rod; and install a new brake

attach pin retainer configuration; in accordance with Boeing Service

Bulletin 767-32A0126, Revision 1, dated January 13, 1994.

(3) Perform a one-time visual inspection to detect cracking,

deformation, and/or a missing piece in the bushings in the brake

housing, and the bushings in the end of the brake rod, in accordance

with Boeing Service Bulletin 767-32A0126, Revision 1, dated January

13, 1994.

(c) For any bushing that is found broken and/or any bushing that

is found having a piece missing during the inspection(s) required by

paragraphs (a)(2) and/or (b)(3) of this AD, accomplish the

requirements of either paragraph (c)(1) or (c)(2), as follows:

(1) Within 10 flight cycles after detection, repair or replace

the bushing in accordance with the appropriate service bulletin. No

performance decrements are required within the first 10 flight

cycles since detection. Or

(2) If the affected bushing has not been replaced within 10

flight cycles after detection, observe one-brake-deactivated

performance decrements in accordance with the FAA-approved Airplane

Flight Manual (AFM) until replacement of the affected bushing is

accomplished. Operation must be performed with all brakes and the

antiskid system fully functional, while operating with one-brake-

deactivated performance decrements for broken bushings and/or a

bushing with a missing piece.

(d) For any bushing that is found to be cracked or deformed

during the inspection(s) required by paragraphs (a)(2) and/or (b)(3)

of this AD, accomplish the requirements of either paragraph (d)(1)

or (d)(2), as follows:

(1) Within 100 flight cycles since detection, repair or replace

the bushing in accordance with the appropriate service bulletin. No

performance decrements are required within the first 100 flight

cycles since detection. Or

(2) If the affected bushing(s) has not been replaced within 100

flight cycles since detection, observe one-brake-deactivated

performance decrements in accordance with the FAA-approved AFM until

replacement of the affected bushing is accomplished. Operation must

be performed with all brakes and the antiskid system fully

functional, while operating with one-brake-deactivated performance

decrements for cracked bushings.

(e) Operators may operate beyond 60 days after the effective

date of this AD with one-brake-deactivated performance decrements

for cracked or broken bushings, provided that the actions required

by paragraphs (a) through (b)(3) of this AD have been accomplished.

(f) Revise the Limitations and Flight Performance sections of

the FAA-approved AFM (or computer generated takeoff weight tables)

to include the following information. (This may be accomplished by

inserting a copy of this AD in the AFM.) If the actions required by

paragraphs (a) through (b)(3) of this AD have not been accomplished

within 60 days after the effective date of this AD, the following

two-brake-deactivated performance decrements must be observed until

the actions required by paragraphs (a) through (b)(3) of this AD

have been accomplished. The following adjustments reflect takeoff

and landing performance, assuming failure of two brakes. Operation

must be performed with all brakes operative and the anti-skid system

operative.

``Option 1

(1) Subtract 70,000 LB ( 31,750 KG) from the takeoff limited

weight (the most limiting (lowest) of maximum certified, obstacle

clearance, tire speed, brake energy, climb, or field length limited

weight). No adjustment to the takeoff speeds for the resulting

weight is required.

(2) Landing Field Length--Section 4.13 of the Airplane Flight

Manual: Multiply `all brakes operative' FAR landing field length by

a factor of 1.20.

(3) Maximum Quick Turnaround Weight--Section 4.13 of the

Airplane Flight Manual: No change from the 'all brakes operative'

value.

Option 2

(1) Field Length Limited Weight--Section 4.4 of the Airplane

Flight Manual: Reduce the `all brakes operative' field length

limited weight by 10,500 LB (4,750 KG). The maximum allowable

takeoff weight is the most limiting (lowest) of maximum certified,

climb, obstacle clearance, tire speed, or this adjusted field length

limited weight.

(2) Reference V1(mcg) Limited Accelerate-Stop Distance--

Section 4.8 of the Airplane Flight Manual: Increase the reference

V1(mcg) limited accelerate-stop distance by 1000 FT.

(3) Takeoff Decision Speed, V1--Section 4.7 of the Airplane

Flight Manual: Reduce V1 by the following:

Weights below 330,000 LB (150,000 KG):

Subtract 4 knots

Weights at or above 330,000 LB (150,000 KG):

Subtract 3 knots

If the resulting V1 is less than V1(mcg), takeoff is

permitted with V1 set equal to V1(mcg) provided the

corrected accelerate-stop distance available exceeds the adjusted

reference V1(mcg) limited accelerate-stop distance from Step 2.

(4) Brake Energy Limits--Section 4.7 of the Airplane Flight

Manual: Reduce the maximum brake energy speed allowed with all

brakes operative by 30 knots. Verify the scheduled V1 is less

than the reduced VMBE. If not, then takeoff weight must be

reduced.

(5) Landing Field Length--Section 4.13 of the Airplane Flight

Manual: Multiply `all brakes operative' FAR landing field length by

a factor of 1.20.

(6) Maximum Quick Turnaround Weight--Section 4.13 of the

Airplane Flight Manual: No change from the `all brakes operative'

value.

Option 3

Once the following adjustments to corrected accelerate-stop

distance and VMBE are determined, the takeoff weights should be

calculated in the normal fashion (using these adjusted data) to

determine the maximum allowable takeoff weight.

(1) Corrected Accelerate Stop Distance--Section 4.3 of the

Airplane Flight Manual: Use the following table to adjust the

corrected accelerate-stop distance.

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

Adjusted Adjusted

Corrected accel- corrected accel- corrected accel- Corrected accel-

stop distance stop distance stop distance stop distance

(feet) (feet) (feet) (feet)

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

4,000............ 3,420 13,000 11,552

5,000............ 4,312 14,000 12,470

6,000............ 5,206 15,000 13,391

7,000............ 6,104 16,000 14,315

8,000............ 7,005 17,000 15,241

9,000............ 7,908 18,000 16,171

10,000........... 8,815 19,000 17,104

11,000........... 9,724 20,000 18,039

12,000........... 10,637 ................ ................

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

Linearly interpolate for accelerate-stop distance values between

those shown.

(2) Reference V1(mcg) Limited Accelerate-Stop Distance--

Section 4.8 of the Airplane Flight Manual: Increase the reference

V1(mcg) limited accelerate-stop distance by 500 FT.

If V1 is less than V1(mcg), takeoff is permitted with

V1 set equal to V1(mcg) provided the corrected accelerate-

stop distance available exceeds this adjusted reference V1(mcg)

limited accelerate-stop distance.

(3) Brake Energy Limits--Section 4.7 of the Airplane Flight

Manual: Use the following table to adjust the maximum brake energy

speed allowed with all brakes operative after correcting for runway

slope and wind.

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

All brake op Adjusted VMBE-- All brake op Adjusted VMBE--

VMBE--KIAS KIAS VMBE--KIAS KIAS

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

100.............. 84.2 170 141.4

110.............. 92.4 180 149.6

120.............. 100.6 190 157.8

130.............. 108.7 200 166.0

140.............. 116.9 210 174.2

150.............. 125.1 220 182.3

160.............. 133.3 ................ ................

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

Linearly interpolate for VMBE values between those shown.

(4) Landing Field Length--Section 4.13 of the Airplane Flight

Manual: Multiply `all brakes operative' FAR landing field length by

a factor of 1.20.

(5) Maximum Quick Turnaround Weight--Section 4.13 of the

Airplane Flight Manual: No change from the `all brakes operative'

value.''

(g) 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.

(h) 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.

(i) The actions shall be done in accordance with Boeing Service

Bulletin 767-32A0116, Revision 1, dated January 13, 1994; Boeing

Alert Service Bulletin 767-32A0125, dated November 11, 1993; and

Boeing Service Bulletin 767-32A0126, Revision 1, dated January 13,

1994. This incorporation by reference was approved by the Director

of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR

part 51. Copies may be obtained from Boeing Commercial Airplane

Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be

inspected at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the Office of the Federal

Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(j) This amendment becomes effective on Febriary 18, 1994.

Issued in Renton, Washington, on January 27, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-2336 Filed 2-2-94; 8:45 am]

BILLING CODE 4910-13-U