[Federal Register Volume 64, Number 141 (Friday, July 23, 1999)]
[Proposed Rules]
[Pages 39944-39946]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18627]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 64, No. 141 / Friday, July 23, 1999 /
Proposed Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-268-AD]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80,
and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of two existing
airworthiness directives (AD), applicable to certain McDonnell Douglas
Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-
88 airplanes, that currently require installation of hydraulic line
restrictors in the main landing gear (MLG), and modification or
replacement of the left and right MLG hydraulic damper assemblies. This
action would require an additional modification of the MLG hydraulic
damper assemblies, or replacement of the MLG hydraulic damper
assemblies with modified and reidentified hydraulic damper assemblies.
This proposal is prompted by reports indicating that MLG hydraulic
damper assemblies removed for overhaul had failed or damaged spring
retainers, due to insufficient material thickness of the spring
retainers. The actions specified by the proposed AD are intended to
prevent failure of the hydraulic damper assemblies of the MLG, which
could result in vibration damage and collapse of the MLG.
DATES: Comments must be received by August 23, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-268-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except
Federal holidays.
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:
Technical Publications Business Administration, Dept. C1-L51 (2-60).
This information may be examined at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington or at the FAA,
Transport Airplane Directorate, Los Angeles Aircraft Certification
Office, 3960 Paramount Boulevard, Lakewood, California.
FOR FURTHER INFORMATION CONTACT: Albert Lam, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount
Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5346;
fax (562) 627-5210.
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 98-NM-268-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. 98-NM-268-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On January 5, 1996, the FAA issued AD 96-01-09, amendment 39-9485
(61 FR 2407, January 26, 1996), applicable to certain McDonnell Douglas
Model DC-9-80 series airplanes and Model MD-88 airplanes, to require
installation of hydraulic line restrictors in the main landing gear
(MLG), and modification of the hydraulic damper assembly of the MLG.
That action was prompted by reports of vibration occurring in the MLG
during landing; in some cases, such vibration has led to the collapse
of the MLG. The requirements of that AD are intended to prevent
incidents of vibration in the MLG, which can adversely affect the
integrity of the MLG.
On September 30, 1996, the FAA issued AD 96-21-01, amendment 39-
9777 (61 FR 53042, October 10, 1996), applicable to certain McDonnell
Douglas Model DC-9 series airplanes. That AD is similar to AD 96-01-09
in that it requires either replacement or modification of the hydraulic
damper assembly. That action was prompted by reports indicating that
insufficient damping of the hydraulic shimmy damper in the MLG can
allow high torsional vibration to occur. The requirements of that AD
are intended to prevent such vibration, which can damage the MLG
assembly and lead to its collapse.
Actions Since Issuance of Previous Rule
Since the issuance of those AD's, the FAA has received reports
indicating that, during overhaul, 30 percent of the latest
configuration of the MLG hydraulic damper assemblies installed on
McDonnell Douglas Model DC-9 series airplanes had failed or damaged
spring retainers in the assemblies. Investigation revealed that the
cause of the failed or damaged spring retainers
[[Page 39945]]
may be insufficient material thickness of the spring retainers. Such
failure of the spring retainers, if not corrected, could result in
failure of the hydraulic damper assemblies of the MLG, which could
result in vibration damage and collapse of the MLG.
Explanation of Relevant Service Information
The FAA has reviewed and approved McDonnell Douglas Service
Bulletin DC9-32-311, dated July 6, 1998, and McDonnell Douglas Alert
Service Bulletin DC9-32A311, Revision 01, dated March 8, 1999, which
describe procedures for modification of the hydraulic damper assemblies
of the MLG, or replacement of the MLG hydraulic damper assemblies with
modified and reidentified hydraulic damper assemblies. The modification
involves removal and disassembly of the damper assembly, removal of the
spring retainers in the damper assembly, and replacement with new
spring retainers. Accomplishment of the actions specified in the
service bulletins 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, this
proposed AD would supersede AD 96-01-09 and AD 96-21-01 to continue to
require replacement or modification of the left and right MLG hydraulic
damper assemblies and installation of hydraulic line restrictors in the
MLG. This proposed AD would add an additional modification of the
hydraulic damper assemblies of the MLG, or replacement of the MLG
hydraulic damper assemblies with modified and reidentified hydraulic
damper assemblies. The actions would be required to be accomplished in
accordance with the service bulletins described previously.
Cost Impact
There are approximately 2,015 airplanes of the affected design in
the worldwide fleet. The FAA estimates that 1,145 airplanes of U.S.
registry would be affected by this proposed AD.
The installation that is currently required by AD 96-01-09, and
retained in this proposal, takes approximately 4 work hours per
airplane to accomplish, at an average labor rate of $60 per work hour.
Required parts cost approximately $928 per airplane. Based on these
figures, the cost impact of the currently required installation on U.S.
operators is estimated to be $1,168 per airplane.
The modification that is currently required by AD 96-01-09, and
retained in this proposal, takes approximately 6 work hours per
airplane to accomplish, at an average labor rate of $60 per work hour.
Required parts cost approximately $4,000 per airplane. Based on these
figures, the cost impact of the currently required modification on U.S.
operators is estimated to be $4,360 per airplane.
The replacement that is currently required by AD 96-21-01, and
retained in this proposal, takes approximately 6 work hours per
airplane to accomplish, at an average labor rate of $60 per work hour.
Required parts cost approximately $11,139 per airplane (two assemblies
at $5,569 each). Based on these figures, the cost impact of the
currently required replacement on U.S. operators is estimated to be
$11,499 per airplane.
The modification that is currently required by AD 96-21-01, and
retained in this proposal, takes approximately 11 work hours per
airplane to accomplish, at an average labor rate of $60 per work hour.
Required parts cost approximately $2,907 per airplane. Based on these
figures, the cost impact of the currently required modification on U.S.
operators is estimated to be $3,567 per airplane.
The modification or replacement that is proposed in this AD action
would take approximately 18 work hours per airplane to accomplish, at
an average labor rate of $60 per work hour. Required parts would cost
approximately $608 per airplane. Based on these figures, the cost
impact of the modification proposed by this AD on U.S. operators is
estimated to be $1,932,760, or $1,688 per airplane.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the current or proposed
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
Regulatory Impact
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
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 removing amendment 39-9485 (61 FR
2407, January 26, 1996), and amendment 39-9777 (61 FR 53042, October
10, 1996), and by adding a new airworthiness directive (AD), to read as
follows:
McDonnell Douglas: Docket 98-NM-268-AD. Supersedes AD 96-01-09,
Amendment 39-9485; and AD 96-21-01, Amendment 39-9777.
Applicability: Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83),
and -87 (MD-87) series airplanes, and Model MD-88 airplanes; as
listed in McDonnell Douglas Service Bulletins MD80-32-276 and MD80-
32-278, both dated March 31, 1995; and Model DC-9-10, -20, -30, -40,
and -50; and C-9 (military) series airplanes, as listed in McDonnell
Douglas Service Bulletin DC9-32-289, dated March 7, 1996;
certificated in any category.
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.
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Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the hydraulic damper assemblies of the
MLG, which could result in vibration damage and collapse of the MLG,
accomplish the following:
Restatement of Requirements of AD 96-01-09
Modifications
(a) For airplanes listed in McDonnell Douglas MD-80 Service
Bulletin MD80-32-276, dated March 31, 1995, that have not been
previously modified (installation of brake line restrictors) in
accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-
246: Within 9 months after February 26, 1996 (the effective date of
AD 96-01-09, amendment 39-9485), install filtered brake line
restrictors in the MLG hydraulic brake system in accordance with
McDonnell Douglas MD-80 Service Bulletin MD80-32-276, dated March
31, 1995, or Revision 1, dated October 17, 1995.
Note 2: Installation of filtered restrictors in accordance with
the instructions specified in McDonnell Douglas MD-80 Alert Service
Bulletin, MD80-A32-286, dated September 11, 1995, is considered
acceptable for compliance with paragraph (a) of this AD.
(b) For airplanes listed in McDonnell Douglas MD-80 Service
Bulletin MD80-32-278, dated March 31, 1995: Within 36 months after
February 26, 1996, modify the hydraulic damper assembly (by removing
shims, increasing bolt torque, and incorporating changes to increase
the volume of fluid passing between the two damper chambers) in
accordance with McDonnell Douglas MD-80 Service Bulletin MD80-32-
278, dated March 31, 1995, or Revision 1, dated September 6, 1995.
Restatement of Requirements of AD 96-21-01
Replacement or Modification
(c) For airplanes listed in McDonnell Douglas Service Bulletin
DC9-32-289, dated March 7, 1996: Within 24 months after November 14,
1996 (the effective date of AD 96-21-01, amendment 39-9777), either
replace or modify the MLG hydraulic damper assembly, in accordance
with the procedures specified as either ``Option 1'' or ``Option
2,'' respectively, of the service bulletin.
New Requirements of this AD
Replacement or Modification
(d) For McDonnell Douglas Model DC-9 series airplanes, and C-9
(military) series airplanes (as listed in McDonnell Douglas Alert
Service Bulletin DC9-32A311, Revision 01): Within 18 months after
the effective date of this AD, accomplish the requirements specified
in either paragraph (d)(1) or (d)(2) of this AD in accordance with
McDonnell Douglas Service Bulletin DC9-32-311, dated July 6, 1998,
or McDonnell Douglas Alert Service Bulletin DC9-32A311, Revision 01,
dated March 8, 1999.
(1) Modify the left and right MLG hydraulic damper assemblies.
(2) Replace the left and right MLG hydraulic damper assemblies
with modified and reidentified hydraulic damper assemblies having
part number (P/N) SR09320057-7005, SR09320057-7007, SR09320057-7009,
or 5923142-5513.
(e) For McDonnell Douglas Model DC-9-80 series airplanes, and
MD-88 airplanes (as listed in McDonnell Douglas Alert Service
Bulletin DC9-32A311, Revision 01): Within 3,000 flight cycles after
incorporation of the latest configuration of the left and right MLG
hydraulic damper assemblies, or within 9 months after the effective
date of this AD, whichever occurs later; accomplish the requirements
specified in either paragraph (d)(1) or (d)(2) of this AD in
accordance with McDonnell Douglas Service Bulletin DC9-32-311, dated
July 6, 1998, or McDonnell Douglas Alert Service Bulletin DC9-
32A311, Revision 01, dated March 8, 1999.
(f) Paragraph (b) or (c) of this AD, as applicable, must be
accomplished prior to or concurrent with the accomplishment of
either paragraph (d) or (e) of this AD, as applicable.
Spares
(g) As of the effective date of this AD, no person shall install
on any airplane a damper sub assembly having P/N SR09320057-9,
SR09320057-17, or 5923142-5017; or a damper assembly having P/N
SR09320057-7001, SR09320057-7003, or 5923142-5511, unless the part
has been modified and reidentified in accordance with paragraph
(d)(2) of 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, 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, 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
Secs. 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 July 15, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-18627 Filed 7-22-99; 8:45 am]
BILLING CODE 4910-13-P
