[Federal Register Volume 67, Number 171 (Wednesday, September 4, 2002)]
[Proposed Rules]
[Pages 56506-56509]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-22436]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-212-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-90-30 
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 McDonnell Douglas Model 
MD-90-30 airplanes. This proposal would require measuring the length of 
the wear indicator on the brake stack of the main landing gear (MLG) 
brake assembly to determine the degree of wear, and follow-on actions. 
This proposal also would require eventual replacement of the existing 
MLG brake assembly with a new, improved or modified assembly, which 
would constitute terminating action for any repetitive actions being 
performed per this proposed AD. This action is necessary to prevent 
failure of the MLG brakes and consequent loss of braking capability, 
which could result in the airplane overrunning the runway during take-
off or landing. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by October 21, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-212-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-212-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Aircraft Group, Long Beach Division, 
3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data 
and Service Management, Dept. C1-L5A (D800-0024). This information may 
be examined at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT: Technical Information: Ken Sujishi, 
Aerospace Engineer, Systems & Equipment Branch, ANM-130L, FAA, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5353; fax (562) 
627-5210.
    Other Information: Judy Golder, Airworthiness Directive Technical 
Editor/Writer; telephone (425) 687-4241, fax (425) 227-1232. Questions 
or comments may also be sent via the Internet using the following 
address: [email protected]. Questions or comments sent via the 
Internet as attached electronic files must be formatted in Microsoft 
Word 97 for Windows or ASCII text.

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NM-212-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-114, Attention: Rules 
Docket No. 2001-NM-212-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of discrepancies of the carbon brake 
assembly installed on the main landing gear (MLG) of certain McDonnell 
Douglas Model MD-90-30 airplanes. On the discrepant MLG brake 
assemblies, which had wear of 50 percent or more, piston insulators had 
pushed below the surface of the pressure plate. In a few

[[Page 56507]]

cases where the brake assembly was near ``full worn'' condition, the 
piston insulators had broken through the pressure plate and pushed into 
the rotating carbon disk of the brake assembly. This condition, if not 
corrected, could result in failure of the MLG brakes and consequent 
loss of braking capability, which could result in the airplane 
overrunning the runway during take-off or landing.

Explanation of Relevant Service Information

    We have reviewed and approved Boeing Alert Service Bulletin MD90-
32A042, Revision 01, dated August 17, 2000, which recommends 
accomplishment of Aircraft Braking Systems Corporation (ABS) Service 
Bulletin MD90-32-13.
    ABS Service Bulletin MD90-32-13, Revision 2, dated April 28, 2000, 
describes procedures for measuring the wear indicator on the MLG brake 
stack. When the wear indicator on the brake stack measures 1.30 inches 
or less, the ABS service bulletin specifies inspecting the contact area 
between the piston insulators and the pressure plate to find 
discrepancies of the pressure plate (i.e., the surface of the piston 
insulator is flush with or has pushed beyond the surface of the 
counterbore). The follow-on actions are as follows:
    [sbull] If no discrepancy of the pressure plate is found--
repetitive inspections for discrepancies of the pressure plate.
    [sbull] If any discrepancy is found and the length of the wear 
indicator on the MLG brake is within certain limits--overhaul of the 
MLG brake, including replacement of the carbon brake stack.
    [sbull] If any discrepancy is found and the length of the wear 
indicator on the MLG brake is outside certain limits--repair of the 
brake assembly, which involves replacing the swage tube subassembly of 
the brake with a new subassembly, replacing the pressure plate with a 
new, improved pressure plate, shortening the wear indicator tube, 
inspecting to determine the radius of the piston insulators, and 
replacing the piston insulators with reworked insulators if necessary.
    Overhaul or repair of the brake assembly eliminates the need for 
the repetitive inspections.
    The FAA also has reviewed and approved Boeing Service Bulletin 
MD90-32-045, Revision 01, dated December 15, 2000. That service 
bulletin describes procedures for replacement of the MLG brake assembly 
with a brake assembly that has been modified according to ABS Service 
Bulletin MD90-32-14, dated May 9, 2000.
    ABS Service Bulletin MD90-32-14 describes procedures for modifying 
brake assemblies in certain configurations to a new configuration. The 
modification involves replacing certain wear indicator tubes with new 
tubes, measuring the radius of the piston insulators, reworking the 
piston insulators if necessary, installing new or refurbished 
components, and reidentifying the brake assembly.
    Accomplishment of the actions specified in the service bulletins 
described previously is intended to adequately address the identified 
unsafe condition.

Explanation of Requirements of Proposed Rule

    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 accomplishment of the actions specified in 
the service bulletins, described previously, except as discussed below.

Differences Between Service Bulletins and Proposed AD

    ABS Service Bulletin MD90-32-13, Revision 2, specifies that, if the 
wear indicator on the brake stack measures more than 1.30 inches, no 
further action is necessary to comply with the service bulletin. 
However, we find that, as the brake continues in service and the wear 
indicator on the brake stack decreases to 1.30 inches or less, the 
actions in that service bulletin will apply. Therefore, this proposed 
AD would require repetitive measurements of the wear indicator on the 
brake stack every 260 landings, until the wear indicator on the brake 
stack measures 1.30 inches or less, at which time the proposed follow-
on actions would apply.
    As part of the follow-on actions that would be required by the 
proposed AD, Boeing Alert Service Bulletin MD90-32A042, Revision 01; 
and ABS Service Bulletin MD90-32-13, Revision 2; specify performing an 
inspection of the MLG brake assembly. However, neither service bulletin 
specifies what type of inspection is necessary. We have determined that 
a general visual inspection is necessary; therefore, paragraph (b) of 
this proposed AD would require a general visual inspection of the MLG 
brake assembly for discrepancies of the pressure plate (i.e., the 
surface of the piston insulator is flush with or has pushed beyond the 
surface of the counterbore). Note 2 of this proposed AD defines such an 
inspection.
    Also, ABS Service Bulletin MD90-32-13, Revision 2, specifies to use 
the repair procedure in that service bulletin only when the wear 
indicator on the MLG brake is not longer than 2.10 inches. For a wear 
indicator on the MLG brake that is longer than 2.10 inches, the 
pressure plate modification cannot be accomplished per the service 
bulletin, and is not necessary until the MLG brake is worn further. 
Thus, we have clarified in this proposed AD that an MLG brake with a 
wear indicator longer than 2.10 inches may remain installed without 
repair or replacement until the MLG brake assembly is replaced with a 
new, improved or modified MLG brake assembly.
    These issues have been discussed with the airplane manufacturer, 
and the manufacturer concurs with our decision to issue this proposed 
AD with these differences.

Cost Impact

    There are approximately 115 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 21 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed measurement of the brake stack wear indicator, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this proposed action on U.S. operators is estimated to 
be $1,260, or $60 per airplane, per measurement cycle.
    It would also take approximately 1 work hour per airplane to 
accomplish the proposed inspection for discrepancies of the pressure 
plate of the MLG brake, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of this proposed action on U.S. 
operators is estimated to be $1,260, or $60 per airplane, per 
inspection cycle.
    It would take approximately 6 work hours per airplane to accomplish 
the proposed replacement of the MLG brake assembly, at an average labor 
rate of $60 per work hour. Required parts would cost approximately 
$55,000. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $1,162,560, or $55,360 per airplane.
    The cost impact figures discussed above are 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 proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include

[[Page 56508]]

incidental costs, such as the time required to gain access and close 
up, planning time, or time necessitated by other administrative 
actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 2001-NM-212-AD.

    Applicability: Model MD-90-30 airplanes, certificated in any 
category; equipped with a main landing gear (MLG) brake assembly 
having part number (P/N) 5012193R, 5012193-1, 5012193-1-P, 5012193-
2, 5012193-2-P, 5012193-3, or 5012193-3-P.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (h) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the MLG brake and consequent loss of 
braking capability, which could result in the airplane overrunning 
the runway during take-off or landing, accomplish the following:

Measurement of Brake Wear

    (a) Within 120 days after the effective date of this AD, measure 
the length of the wear indicator on the brake stack of the MLG brake 
assembly to determine the degree of wear, according to Boeing Alert 
Service Bulletin MD90-32A042, Revision 01, dated August 17, 2000; 
and Aircraft Braking Systems Corporation Service Bulletin MD90-32-
13, Revision 2, dated April 28, 2000.
    (1) If the wear indicator measures more than 1.30 inches: Repeat 
the measurement of the brake stack wear indicator every 260 
landings, until the wear indicator measures 1.30 inches or less. 
When the wear indicator measures 1.30 inches or less, do paragraph 
(a)(2) of this AD.
    (2) If the wear indicator measures 1.30 inches or less: Before 
further flight, do paragraph (b) of this AD.

Repetitive Inspections for Discrepancies of Pressure Plate

    (b) Perform a general visual inspection of the MLG brake 
assembly for discrepancies of the pressure plate (i.e., the surface 
of the piston insulator is flush with or has pushed beyond the 
surface of the counterbore), according to Boeing Alert Service 
Bulletin MD90-32A042, Revision 01, dated August 17, 2000; and 
Aircraft Braking Systems Corporation Service Bulletin MD90-32-13, 
Revision 2, dated April 28, 2000. If no discrepancy of the pressure 
plate is found, repeat the inspection at intervals not to exceed 260 
landings, until paragraph (c)(1), (c)(2), or (d) of this AD has been 
accomplished.

    Note 2: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made from within 
touching distance unless otherwise specified. A mirror may be 
necessary to enhance visual access to all exposed surfaces in the 
inspection area. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or droplight and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''

Corrective Actions

    (c) If any discrepancy of the pressure plate is found during any 
inspection required by paragraph (b) of this AD: Before further 
flight, do paragraph (c)(1), (c)(2), (c)(3), or (d) of this AD.
    (1) If the length of the wear indicator on the MLG brake is less 
than 0.40 inch: Overhaul the MLG brake assembly (including replacing 
the carbon stack) according to Boeing Alert Service Bulletin MD90-
32A042, Revision 01, dated August 17, 2000; and Aircraft Braking 
Systems Corporation Service Bulletin MD90-32-13, Revision 2, dated 
April 28, 2000. Such overhaul terminates the repetitive inspections 
required by paragraph (b) of this AD.
    (2) If the length of the wear indicator on the MLG brake is 
greater than or equal to 0.40 inch but less than or equal to 2.10 
inches: Repair the MLG brake assembly according to Boeing Alert 
Service Bulletin MD90-32A042, Revision 01, dated August 17, 2000; 
and Aircraft Braking Systems Corporation Service Bulletin MD90-32-
13, Revision 2, dated April 28, 2000. The repair procedures involve 
replacing the swage tube subassemblies of the brake with new 
subassemblies, replacing the pressure plate with a new, improved 
pressure plate, shortening the wear indicator tube, inspecting to 
determine the radius of the piston insulators, and replacing the 
piston insulators with reworked insulators if necessary. Such repair 
terminates the repetitive inspections required by paragraph (b) of 
this AD.
    (3) If the length of the wear indicator on the brake is greater 
than 2.10 inches: No further action is required by this paragraph.

Replacement With Modified Brake Assembly

    (d) Except as provided by paragraph (c) of this AD, at the next 
brake overhaul, or within 36 months after the effective date of this 
AD, whichever is first: Replace any MLG brake assembly having P/N 
5012193R, 5012193-1, 5012193-1-P, 5012193-2, 5012193-2-P, 5012193-3, 
or 5012193-3-P; with a new, improved or modified MLG brake assembly 
having P/N 5012193-4; according to Boeing Service Bulletin MD90-32-
045, Revision 01, dated December 15, 2000; and Aircraft Braking 
Systems Corporation Service Bulletin MD90-32-14, dated May 9, 2000. 
The modification involves replacement of certain wear indicator 
tubes with new tubes, installation of a new, improved pressure 
plate, measurement of the radius of the piston insulators, rework of 
the piston insulators if necessary, and reidentification of the 
brake assembly. Accomplishment of the replacement specified in this 
paragraph terminates the requirements of this AD.

Actions Accomplished Per Previous Revisions of Service Bulletin

    (e) Inspections and corrective actions accomplished before the 
effective date of this AD according to Boeing Alert Service Bulletin 
MD90-32A042, dated April 27, 2000, is acceptable for compliance with 
the corresponding actions required by paragraphs (a), (b), and (c) 
of this AD.
    (f) Replacements accomplished before the effective date of this 
AD according to Boeing

[[Page 56509]]

Service Bulletin MD90-32-045, dated July 21, 2000, are acceptable 
for compliance with paragraph (d) of this AD.

Spares

    (g) As of the effective date of this AD, no person may install a 
MLG brake assembly having P/N 5012193R, 5012193-1, 5012193-2, or 
5012193-3 on any airplane, unless the MLG brake assembly is 
inspected and any applicable corrective action has been accomplished 
according to this AD.

Alternative Methods of Compliance

    (h) 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, Los Angeles Aircraft Certification 
Office (ACO), FAA. Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Los Angeles ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

Special Flight Permits

    (i) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 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 August 27, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-22436 Filed 9-3-02; 8:45 am]
BILLING CODE 4910-13-P