[Federal Register Volume 59, Number 23 (Thursday, February 3, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2336]
[[Page Unknown]]
[Federal Register: February 3, 1994]
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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
