AD 2000-15-17

[Federal Register Volume 65, Number 153 (Tuesday, August 8, 2000)]
[Rules and Regulations]
[Pages 48368-48371]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-19816]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-227-AD; Amendment 39-11849; AD 2000-15-17]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9-81 (MD-
81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87); Model MD-88 
Airplanes; and Model MD-90-30 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain McDonnell Douglas Model DC-9-81 (MD-81), DC-9-82 
(MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87); Model MD-88 airplanes; 
and Model MD-90-30 series airplanes; that requires installation of a 
pipe support and clamps on the hydraulic lines in the aft fuselage; 
replacement of the hydraulic pipe assembly in the aft fuselage with a 
new pipe assembly; and installation of drain tube assemblies and 
diverter assemblies in the area of the auxiliary power unit (APU) 
inlet; as applicable. This amendment is prompted by reports of smoke 
and odor in the passenger cabin and cockpit due to hydraulic fluid 
leaking into the APU inlet, and subsequently, into the air conditioning 
system. The actions specified by this AD are intended to prevent such 
hydraulic fluid leakage due to fatigue vibration and cracking in the 
flared radius of a hydraulic pipe in the aft fuselage, which could 
result in smoke and odors in the passenger cabin or cockpit.

DATES: Effective September 12, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 12, 2000.

ADDRESSES: The service information referenced in this AD 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 Federal Aviation Administration 
(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, 
SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, 
Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87); 
Model MD-88 airplanes; and Model MD-90-30 series airplanes; was 
published in the Federal Register on January 18, 2000 (65 FR 2555). 
That action proposed to require installation of a pipe support and 
clamps on the hydraulic lines in the aft fuselage; replacement of the 
hydraulic pipe assembly in the aft fuselage with a new pipe assembly; 
and installation of drain tube assemblies and diverter assemblies in 
the area of the auxiliary power unit (APU) inlet; as applicable.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Requests for Alternative Methods of Compliance (AMOC)

    One commenter requests that operators be allowed to install NAS 
1252-10H washers in lieu of the NAS1149D0363H washers specified in 
McDonnell Douglas Service Bulletin MD80-29-056, dated June 18, 1996 
[which was referenced in paragraph (a) of the proposed AD as the 
appropriate source of service information for accomplishing the 
required installation]. The commenter states that NAS 1252-10H washers 
are manufactured from 7075-T6 aluminum alloy and are more wear 
resistant than NAS1149D0363H washers manufactured from 2024-T3 aluminum 
alloy.
    The FAA partially concurs. The FAA acknowledges that 7075-T6 
aluminum alloy material is more durable than 2024-T3 aluminum alloy 
material. However, the commenter did not provide any data, such as the 
size or thickness of a NAS 1252-10H washer, to substantiate that this 
alternative washer would provide an acceptable level of safety. 
However, under the provisions of paragraph (e) of the final rule, the 
FAA may consider requests for approval of an AMOC if sufficient data 
are submitted to substantiate that such a design change would provide 
an acceptable level of safety.
    One commenter requests that, in lieu of replacing the hydraulic 
pipe assembly in the aft fuselage with a new pipe assembly having a 
greater wall thickness [required by paragraph (b) of the proposed AD], 
operators be allowed to manufacture and install this tube assembly with 
flares in order to minimize preload. The commenter states that the 
failure rate of the hydraulic pipe assembly is compounded due to a 
preload situation at the flanges. Flange failure will consequently 
occur more often when a pre-assembled tube is installed. The commenter 
also states that this configuration will improve the reliability of the 
tube assembly, which would reduce the possibility of smoke/odor in the 
cabin.
    The FAA does not concur. The FAA has received no reports of failure 
of the new pipe assembly having a greater wall thickness. The FAA has 
determined that replacement of the hydraulic pipe assembly in the aft 
fuselage with a new pipe assembly having a greater wall thickness will 
adequately address the identified unsafe condition. In addition, the 
commenter did not provide any data to support its request. However, the 
FAA may consider requests for approval of an AMOC under the provisions 
of paragraph (e) of this AD if sufficient data are submitted to 
substantiate that such a design change would provide an acceptable 
level of safety.
    One commenter requests that operators be allowed to install the 
drain tubes and diverter assemblies, as required by paragraph (c) of 
the proposed AD, using blind rivets rather than solid rivets. The 
commenter states that blind rivets provide a structurally

[[Page 48369]]

sound installation and an equivalent level of safety as the solid 
rivets.
    The FAA does not concur. The FAA finds that blind rivets in the 
tail area of airplanes are highly susceptible to vibration from the 
engine and APU, which, over time, could loosen the blind rivets. 
However, under the provisions of paragraph (e) of the final rule, the 
FAA may consider requests for approval of an AMOC if sufficient data 
are submitted to substantiate that such a design change would provide 
an acceptable level of safety.

Requests To Revise Certain Compliance Times

    Four commenters request that the 18-month compliance time for 
accomplishing the installation of drain tube assemblies and diverter 
assemblies required by paragraph (c) of the proposed AD be extended. 
Each commenter suggested different times (i.e, 3, 4, and 5 years). 
Three of the commenters state that such an extension would allow the 
subject installation to be accomplished during a regularly scheduled 
heavy ``C'' check where trained personnel will be available, if 
necessary, and will allow time for procurement of additional parts. One 
commenter states that the airplane manufacturer is currently quoting a 
10-month lead time for the availability of all parts needed for 
accomplishing the required installation.
    One of the commenters also requests that the 18-month compliance 
time for accomplishing the replacement of the hydraulic pipe assembly 
required by paragraph (c) of the proposed AD be extended to 3 years. 
The commenter states that a 3-year compliance time would provide 
operators with more time to investigate the true cause of smoke/odor in 
the cabin.
    The FAA concurs that the compliance time can be extended somewhat. 
In developing an appropriate compliance time for this AD action, the 
FAA considered not only the degree of urgency associated with 
addressing the subject unsafe condition, but the practical aspect of 
incorporating the required modification into affected operators' 
maintenance schedules in a timely manner. Based on the information 
supplied by the commenters, the FAA now recognizes that 24 months 
corresponds more closely to the interval representative of most of the 
affected operators' normal maintenance schedules for accomplishing the 
requirements of paragraph (c) of this AD. The FAA has reviewed data 
submitted by the manufacturer regarding parts availability and finds 
that there is approximately a 10-month lead time for procuring certain 
parts. Therefore, the FAA has revised paragraph (c) of the final rule 
to reflect a compliance time of 36 months. The FAA does not consider 
that these extensions will adversely affect safety.

Requests That the Installation of Drain Tube and Diverter 
Assemblies Be Optional

    Two commenters request that the requirements (i.e., installation of 
drain tube assemblies and diverter assemblies) of paragraph (c) of the 
proposed AD be optional. One commenter states that the installation of 
the drainage tubing does nothing to increase safety. Another commenter 
states that it is pursuing the installation of center diverters, and 
that it does not see the advantage of side diverters. The commenter 
also states that, based on data collected from cabin smoke/odor events, 
the occurrences caused by APU engine oil ingestion outnumber those 
caused by skydrol (hydraulic fluid) ingestion at a ratio of four to one 
(4:1). The side diverters appear to be focused mainly on the skydrol 
ingestion. The commenter further states that these instances are the 
exception rather than the rule and do not warrant the increase in cost 
and maintenance time.
    The FAA does not concur. As discussed in the preamble of the NPRM, 
the FAA has received several reports of smoke and odor in the passenger 
cabin and cockpit due to hydraulic fluid leaking into the APU inlet, 
and subsequently, into the air conditioning system. The FAA is also 
aware of a similar event that resulted in an emergency evacuation of an 
airplane and consequent injury to several passengers. Further, the 
results of drain tests, conducted by the airplane manufacturer, 
indicate that installation of drain tubes and diverter assemblies 
prevent fluid from being ingested into the APU when hydraulic fluids 
leak into the bilge area of the tailcone. The FAA acknowledges that the 
required installation is mainly focused on preventing skydrol ingestion 
into the APU inlet and does not prevent any fluid from leaking within 
the APU or environmental control system of the airplane. However, the 
FAA has identified an unsafe condition that must be corrected. If any 
other unsafe condition is identified subsequent to the release of this 
AD, the FAA may consider further rulemaking. Therefore, in light of 
these findings, the FAA finds the installation of drain tube assemblies 
and diverter assemblies in the area of the APU inlet required by 
paragraph (c) of this AD is warranted.

Request To Devise a Certain Work Hour Estimate

    One commenter notes that the FAA estimates 14 work hours per 
airplane for accomplishing the proposed installation of drain tube 
assemblies and diverter assemblies, whereas the referenced service 
bulletins estimate 44.8 work hours per airplane. However, the commenter 
states that it would take 60 work hours per airplane to accomplish the 
proposed installation.
    From this comment, the FAA infers that the commenter is requesting 
that the work hour estimate for accomplishing the proposed installation 
be revised from 14 work hours per airplane to 60 work hours per 
airplane. The FAA does not concur. The cost impact information, below, 
describes only the ``direct'' costs of the specific actions required by 
this AD. The number of work hours necessary to accomplish the required 
installation of drain tube assemblies and diverter assemblies, 
specified as 14 in the cost impact information, below, was provided to 
the FAA by the manufacturer based on the best data available to date. 
This number represents the time necessary to perform only the actions 
actually required by this AD. The FAA recognizes that, in accomplishing 
the requirements of any AD, operators may incur ``incidental'' costs in 
addition to the ``direct'' costs. The cost analysis in AD rulemaking 
actions, however, typically does not include incidental costs, such as 
the time required to gain access and close up; planning time; or time 
necessitated by other administrative actions. Because incidental costs 
may vary significantly from operator to operator, they are almost 
impossible to calculate.

Explanation of Change to Cost Impact

    The FAA's estimate of the number of affected airplanes of U.S. 
registry (i.e., 634 airplanes) in the Cost Impact section of the 
proposed AD is incorrect. The correct figure is 656. Also, the FAA 
inadvertently omitted some of the affected airplanes [i.e., 634 Model 
DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) 
series airplanes; Model MD-88 airplanes] from the cost figures for 
accomplishing the required installation of the drain tube assemblies 
and diverter assemblies. Therefore, the FAA has revised the final rule 
accordingly.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the

[[Page 48370]]

adoption of the rule with the changes previously described. The FAA has 
determined that these changes will neither increase the economic burden 
on any operator nor increase the scope of the AD.

Cost Impact

    There are approximately 1,126 Model DC-9-81 (MD-81), DC-9-82 (MD-
82), DC-9-83 (MD-83), and DC-987 (MD-87); Model MD-88 airplanes; and 
Model MD-90-30 series airplanes of the affected design in the worldwide 
fleet. The FAA estimates that 656 airplanes of U.S. registry will be 
affected by this AD.
    It will take approximately 2 work hours per airplane [for 512 Model 
DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) 
series airplanes] to accomplish the required installation of the pipe 
support and clamps, at an average labor rate of $60 per work hour. 
Required parts will cost approximately $226 per airplane. Based on 
these figures, the cost impact of this installation required by AD on 
U.S. operators is estimated to be $177,152, or $346 per airplane.
    It will take approximately 2 work hours per airplane [for 634 Model 
DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) 
series airplanes, and Model MD-88 airplanes] to accomplish the required 
replacement of the hydraulic pipe assembly, at an average labor rate of 
$60 per work hour. Required parts will cost approximately $520 per 
airplane. Based on these figures, the cost impact of this replacement 
required by this AD on U.S. operators is estimated to be $405,760, or 
$640 per airplane.
    It will take approximately 14 work hours per airplane [for 656 
Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 
(MD-87) series airplanes; Model MD-88 airplanes; and Model MD-90-30 
series airplanes] to accomplish the required installation of drain tube 
assemblies and diverter assemblies, at an average labor rate of $60 per 
work hour. Required parts will cost approximately $4,503 per airplane. 
Based on these figures, the cost impact of this installation required 
by this AD on U.S. operators is estimated to be $3,505,008, or $5,343 
per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the 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 adopted herein will 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 final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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 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:

2000-15-17  McDonnell Douglas: Amendment 39-11849. Docket 99-NM-227-
AD.

    Applicability: Models and series of airplanes as listed in the 
applicable McDonnell Douglas service bulletin(s) specified in Table 
1 of this AD, certificated in any category.

                                 Table 1
------------------------------------------------------------------------
                                            McDonnell Douglas Service
           Model of airplane                       Bulletin(s)
------------------------------------------------------------------------
DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-  MD80-29-056, dated June 18,
 83 (MD-83), and DC-9-87 (MD-87) series   1996; MD80-29-062, Revision
 airplanes.                               01, dated August 3, 1999; and
                                          MD80-53-286, dated September
                                          3, 1999.
MD-88 airplanes........................  MD80-29-062, Revision 01, dated
                                          August 3, 1999; and MD80-53-
                                          286, dated September 3, 1999.
MD-90-30 series airplanes..............  MD90-53-018, dated September 3,
                                          1999.
------------------------------------------------------------------------


    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 (e) 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 hydraulic fluid leakage into the auxiliary power unit 
(APU) inlet due to fatigue vibration and cracking in the flared 
radius of a hydraulic pipe in the aft fuselage, which could result 
in smoke and odors in the passenger cabin or cockpit; accomplish the 
following:

Installation of a Pipe Support and Clamps

    (a) For Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), 
and DC-9-87 (MD-87) series airplanes, as listed in McDonnell Douglas 
Service Bulletin MD80-29-056, dated June 18, 1996: Within 18 months 
after the effective date of this AD, install a pipe support and 
clamps on the hydraulic lines in the aft fuselage in accordance with 
the service bulletin.

Replacement of the Hydraulic Pipe Assembly

    (b) For Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), 
and DC-9-87 (MD-87) series airplanes, and Model MD-88 airplanes, as 
listed McDonnell Douglas Service Bulletin MD80-29-062, Revision 01,

[[Page 48371]]

dated August 3, 1999: Within 18 months after the effective date of 
this AD, replace the hydraulic pipe assembly in the aft fuselage 
with a new pipe assembly having a greater wall thickness, in 
accordance with the service bulletin. Except for Model MD-88 
airplanes that have been modified in accordance with McDonnell 
Douglas MD-80 Service Bulletin 29-54, dated February 2, 1993, or 
Revision 2, dated December 17, 1993, the requirements of this 
paragraph must be accomplished concurrently with the requirements of 
paragraph (a) of this AD.

Installation of Drain Tube Assemblies and Diverter Assemblies

    (c) For Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), 
and DC-9-87 (MD-87) series airplanes, as listed in McDonnell Douglas 
Service Bulletin MD80-53-286, dated September 3, 1999; and Model MD-
90-30 series airplanes, as listed in McDonnell Douglas Service 
Bulletin MD90-53-018, dated September 3, 1999: Within 36 months 
after the effective date of this AD, install drain tube assemblies 
and diverter assemblies in the area of the APU inlet, in accordance 
with the applicable service bulletin.

Spares

    (d) As of the effective date of this AD, no person shall install 
a hydraulic pipe assembly, part number 7936907-603, on any airplane.

Alternative Methods of Compliance

    (e) 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 2: 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

    (f) Special flight permits may be issued in accordance with 
Secs. 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.

Incorporation by Reference

    (g) The actions shall be done in accordance with McDonnell 
Douglas Service Bulletin MD80-29-056, dated June 18, 1996; McDonnell 
Douglas Service Bulletin MD80-29-062, Revision 01, dated August 3, 
1999; McDonnell Douglas Service Bulletin MD80-53-286, dated 
September 3, 1999; or McDonnell Douglas Service Bulletin MD90-53-
018, dated September 3, 1999; as applicable. 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 Aircraft Group, Long Beach Division, 
3855 Lakewood Boulevard, Long Beach, California 90846, Attention: 
Technical Publications Business Administration, Dept. C1-L51 (2-60). 
Copies may be inspected 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; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

Effective Date

    (h) This amendment becomes effective on September 12, 2000.

    Issued in Renton, Washington, on July 31, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19816 Filed 8-7-00; 8:45 am]
BILLING CODE 4910-13-U