[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]


 ========================================================================
 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.
 
 ========================================================================
 

  Federal Register / Vol. 64, No. 141 / Friday, July 23, 1999 / 
Proposed Rules  

[[Page 39944]]


=======================================================================
-----------------------------------------------------------------------

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).

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

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.


[[Page 39946]]


    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