[Federal Register Volume 66, Number 63 (Monday, April 2, 2001)]
[Rules and Regulations]
[Pages 17499-17506]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-7732]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-326-AD; Amendment 39-12163; AD 2001-06-16]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series 
Airplanes and Model MD-88 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to all McDonnell Douglas Model DC-9-80 series 
airplanes and Model MD-88 airplanes, that currently requires revisions 
to the Airplane Flight Manual (AFM) and installation of inspection aids 
on the wing upper surfaces. This amendment requires, among other 
actions, installation of an overwing heater blanket system or primary 
upper wing ice detection system, and installation of a heater 
protection panel or an equipment protection device on certain overwing 
heater blanket systems. This amendment is prompted by incidents in 
which ice accumulation on the wing upper surfaces shed into the engines 
during takeoff. The actions specified by this AD are intended to 
prevent ice accumulation on the wing upper surfaces, which could result 
in ingestion of ice into one or both engines and consequent loss of 
thrust from one or both engines.

DATES: Effective May 7, 2001.
    The incorporation by reference of McDonnell Douglas Service 
Bulletin 30-59, dated September 18, 1989, and McDonnell Douglas Service 
Bulletin 30-59, Revision 1, dated January 5, 1990, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of January 17, 1992 (57 FR 2014, November 12, 1998).
    The incorporation by reference of certain other publications, as 
listed in the regulations, is approved by the Director of the Federal 
Register as of May 7, 2001.

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, 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, 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) by superseding AD 92-03-02, 
amendment 39-8156 (57 FR 2014, January 17, 1992), which is applicable 
to all McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 
airplanes, was published as a supplemental notice of proposed 
rulemaking (NPRM) in the Federal Register on April 28, 2000 (65 FR 
24882). The action proposed to continue to require a revision to the 
Airplane Flight Manual (AFM) to specify restrictions on operations 
during icing conditions, installation of inspection aids on the inboard 
side of the wing upper surfaces, and a revision to the AFM to specify 
restrictions on operations when such inspection aids are missing. That 
action also proposed to add a requirement for installation of an 
overwing heater blanket system or a primary upper wing ice detection 
system, and a new revision to the AFM to advise the flight crew of the 
hazards associated with ice accumulation on wing surfaces.

Comments Received

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

Support for Supplemental NPRM

    Several commenters support the supplemental NPRM.

Request To Allow a Certain Installation After the Effective Date of 
the AD

    One commenter requests that installation of an operational overwing 
heater blanket system per TDG Aerospace, Inc., Supplemental Type 
Certificate (STC) SA6042NM without an equipment protective device (EPD) 
be allowed after the effective date of this AD until an EPD becomes 
available, provided that the inspection and test requirements of 
paragraph (d)(2) of the supplemental NPRM are done. As currently 
worded, paragraph (d) of the supplemental NPRM requires inspection and 
test requirements for airplanes on which an overwing heater blanket 
system was installed without a heater protection panel (HPP) or an EPD 
prior to the effective date of this AD. The commenter states that it 
interprets this paragraph to mean that any overwing heater blanket 
system installed after the effective date of the AD must include an HPP 
or EPD as part of the installation. The commenter notes that there are 
no EPD's available to date.
    The FAA does not agree and finds that clarification is necessary. 
The commenter is correct that this AD (paragraph (f)) requires 
installation of an overwing heater blanket system with an HPP or EPD. 
Since issuance of the supplemental NPRM, we have reviewed and approved 
the design of an EPD (reference TDG Master Drawing List (MDL) E93-104, 
Revision R, dated October 25, 2000), which provides a circuit 
protection function to the overwing heater blanket, for installation on 
certain affected airplanes. We have revised paragraph (f)(2)(i) of the 
final rule to reference this MDL as an acceptable method of compliance. 
We find that the 3-year compliance time specified in paragraph (f) of 
this AD for installation of an EPD will accommodate the time necessary 
for affected operators to order, obtain, and install an EPD in 
conjunction with an

[[Page 17500]]

overwing heater blanket system, without adversely affecting safety.

Request To Revise Repetitive Test Intervals

    One commenter requests that the repetitive test interval specified 
in paragraph (d)(2)(ii)(A) of the supplemental NPRM be extended from 
150 days to 180 days. The commenter states that it currently does the 
tests during base maintenance visits every 1,300 flight hours. The 
commenters notes that, based on its average airplane utilization rate, 
1,300 flight hours can be as much as 180 days.
    The FAA does not agree. In developing an appropriate compliance 
time, the FAA considered the safety implications of potential arcing of 
an overwing heater blanket, and normal maintenance schedules for timely 
accomplishment of the tests. In light of these items, we have 
determined that 150 days for compliance is appropriate. However, 
paragraph (i)(1) of the final rule does provide affected operators the 
opportunity to apply for an adjustment of the compliance time if data 
are presented to justify such an adjustment.

Request To Allow Deactivation of the Heater Blanket System

    One commenter requests that a statement be added to paragraph (e) 
of the supplemental NPRM to allow the heater blanket system to be 
deactivated per the Master Minimum Equipment List (MMEL) until the 
repair or replacement can be done.
    The FAA agrees. As discussed below under the heading ``Request to 
Allow An Inoperative Overwing Heater Blanket System,'' we find that an 
overwing heater blanket or ice detection system may be inoperative for 
10 days per the MMEL, so that the affected airplane may be rerouted to 
a suitable repair station. We have included a new paragraph (h) in the 
final rule that provides for such an option. We have also revised 
paragraph (e) of the final rule to reference that option in paragraph 
(h) of the final rule.

Requests To Revise 3-Year Compliance Time

    Several commenters request that the 3-year compliance time 
specified in paragraph (f) of the supplemental NPRM be revised. Some of 
the commenters suggest 2 years, and another suggests 18 months. One 
commenter suggests that the FAA determine and define a compliance time 
that is consistent with the flight safety risk implications, parts 
availability, and ability of operators to incorporate the modification.
    Three commenters, one acting as a consultant to the others, state 
that a shorter compliance time would enhance public safety and reduce 
exposure to current manual tactile inspection procedures as the primary 
means of determining whether wings are free of ice. The commenters also 
state that an 18-month or 24-month compliance time should not cost 
operators any more to comply with than a 3-year compliance time. The 
commenters further state that one of the heater blanket manufacturers 
can provide sufficient quantities of heater blanket kits within an 18-
month or 24-month compliance time. One of the commenters states that a 
3-year compliance time seems unduly long given the potential severity 
of the problem and that the solution is already well established.
    The FAA does not agree. As discussed under the heading 
``Explanation of Differences Between Service Bulletins and Supplemental 
NPRM'' in the preamble of the supplemental NPRM, we find installation 
of both an overwing heater blanket system and HPP or EPD within 3 years 
after the effective date of this AD to be appropriate. In developing an 
appropriate compliance time, the FAA considered the interim 
requirements (i.e., repetitive inspections of the overwing heater 
blanket); development, approval, and manufacturing schedule of EPD's; 
scope of an EPD installation; and safety impact of the existing TDG 
overwing heater blanket without an EPD. Because the installation of an 
EPD or HPP is relatively simple and may be done during a light 
maintenance check, we find that a 3-year compliance time for fielding 
an EPD to affected operators will not impose an unreasonable burden on 
operators. Also, we find that an overwing heater blanket system should 
be installed during a heavy maintenance check (i.e., 3 years). An 18-
month compliance time would require operators to schedule special times 
for installation of an overwing heater blanket system or primary upper 
wing ice detection system, at additional expense and downtime.
    Operators are always permitted to accomplish the requirements of an 
AD at a time earlier than that specified as the compliance time; 
therefore, if an operator elects to accomplish the installation 
required by paragraph (f) of this AD before 3 years after the effective 
date of this AD, it is that operator's prerogative to do so. If 
additional data are presented that would justify a shorter compliance 
time, the FAA may consider further rulemaking on this issue. Therefore, 
no change to the compliance time of paragraph (f) of the final rule is 
necessary.
    One commenter requests that the 3-year compliance time specified in 
paragraph (f) of the supplemental NPRM begin from the date when an 
approved EPD becomes available. The commenter states that, to date, 
there are no EPD's available. The FAA does not agree. As discussed 
above under the heading ``Request to Allow a Certain Installation After 
the Effective Date of the AD,'' we have approved the design for an EPD 
and find that the 3-year compliance time for installation of an EPD 
will accommodate the time necessary for affected operators to order, 
obtain, and install an EPD in conjunction with an overwing heater 
blanket system, without adversely affecting safety.

Request To Only Require Installation of an Overwing Heater Blanket 
System

    One commenter requests that paragraph (f) of the proposed AD only 
require installation of an overwing heater blanket. The commenter 
states that installation of a primary upper wing ice detection system 
(the proposed alternative to installation of an overwing heater 
blanket) may detect the occurrence of ice, but will not remove ice. The 
commenter provides the following safety/operational issues concerning 
ice detectors:
    1. Ice can form on the ``cold corner'' of Model DC-9-80 series 
airplanes at an outside air temperature as high as 50 deg. Fahrenheit 
(10 deg. Celsius). Under these non-winter conditions, de-icing 
equipment may not be available.
    2. Most types of ice detectors are ``point detectors,'' so ice may 
form undetected away from the sensor head. The commenter concludes that 
installation of an overwing heater blanket provides both the required 
level of safety and airline operational benefit (no de-icing from 
``cold corner'' ice).
    Another commenter states that it is concerned about the 
availability of technology related to primary upper wing ice detection 
systems, which may not be adequate to provide a reliable ice detection 
system. However, in contradiction to this statement, the commenter also 
states the remote system ice detection technology may prove to be more 
adequate; however, current airport environments may preclude their use.
    The FAA does not agree with the commenter's request to only require 
installation of an overwing heater blanket system. The requirements of 
this AD are intended to prevent ``ice accumulation on the wing upper 
surfaces, which could result in ingestion of ice into one or both 
engines and

[[Page 17501]]

consequent loss of thrust from one or both engines.'' We have 
determined that installation of an FAA-approved primary upper wing ice 
detection system will detect ice on the ``cold corner'' of Model DC-9-
80 series airplanes and is a reliable ice detection system. In 
addition, all Model MD-90-30 and 717 series airplanes are equipped with 
primary upper wing ice detection systems. We have not received any 
report of failures or malfunctions of the primary upper wing ice 
detection systems that resulted in an unsafe condition on those 
airplanes. Furthermore, airplane-mounted ice detection systems have 
been fully developed and are being widely used on different areas and 
on different types of airplane models. We find that both the overwing 
heater blanket and primary upper wing ice detection systems perform 
their intended functions and provide an acceptable level of safety. As 
a result, the AD allows operators the flexibility to choose an 
appropriate system that suits their operational requirements.

Request To Revise Applicability of Certain Paragraphs

    One commenter requests clarification of the applicability of 
paragraph (f)(1)(iii) of the supplemental NPRM. The commenter states 
that the wording is vague and should clearly state that airplanes 
identified, but not modified, per paragraph (f)(1)(i) or (f)(1)(ii) of 
the supplemental NPRM must do the requirements of paragraph 
(f)(1)(iii)(B) or (f)(1)(iii)(C) of the supplemental NPRM. The 
commenter states that its airplanes are identified in the effectivity 
of McDonnell Douglas Service Bulletin MD80-30-090, but opted to install 
the AlliedSignal system.
    The FAA agrees that clarification is necessary. Paragraph (f) of 
the supplemental NPRM states ``accomplish the requirements of either 
paragraph (f)(1) or (f)(2) of this AD.'' Our intent was that operators 
could do any of the actions specified in those paragraphs (including 
the sub-paragraphs), regardless of whether an airplane was identified 
in paragraph (f)(1)(i) or (f)(1)(ii) of the supplemental NPRM (Group 1 
and Group 2 airplanes listed in McDonnell Douglas Service Bulletin 
MD80-30-090, dated October 19, 1999). For airplanes not identified in 
paragraph (f)(1)(i) or (f)(1)(ii) of the supplemental NPRM, it was also 
our intent that operators be able to do the requirements of paragraph 
(f)(1)(i) or (f)(1)(ii) of this AD if approved per paragraph (i)(1) of 
this AD. Because some operators may misinterpret paragraph (f) of the 
supplemental NPRM as it is currently worded, we have revised paragraph 
(f) of the final rule to clarify these points by deleting paragraph 
(f)(1)(iii) of the supplemental NPRM, adding a new note, and 
redesignating other sub-paragraphs of paragraph (f) of the supplemental 
NPRM.

Request To Revise AFM

    One commenter requests that the AFM be revised to include 
additional foreign object damage (FOD) information for the flight crew. 
The commenter suggests the following:
    1. Airplanes operated with an overwing heater blanket system can 
still encounter possible FOD danger in certain weather conditions, and 
in this case, a hands-on inspection to detect ice in the flap and 
spoiler areas must be performed. The heaters should remain OFF until 
completion of that inspection and de-icing.
    2. In the case of an inoperative overwing heater blanket system, a 
hands-on inspection, as required by AD 92-03-02, must be performed 
until the system is repaired.
    The commenter notes that there were incidents of FOD to an engine 
on airplanes equipped with an overwing heater blanket system, which 
apparently originated from ice being ingested into the engine during 
takeoff. Investigation revealed that, if an overwing heater blanket 
system is left ON for several hours when an airplane is on the ground 
during a snow or ice storm, frozen precipitation over the heated area 
of the wing melts and runs off into the flap trailing edge or spoiler 
cavity areas. De-icing crews cleared the remainder of the airframe, but 
failed to detect the ice remaining in the flap or spoiler areas. If the 
airplane is dispatched in that condition, the ice may be ingested into 
the engine during takeoff.
    The FAA does not agree. Overwing heater blanket systems are only 
designed and certified as anti-icing systems and should not be used as 
a de-icing device. We have determined that the runoff flows into the 
flap or spoiler cavity areas are no different for airplanes equipped 
with or without an overwing heater blanket system. Therefore, ice could 
form on any airplane area where runoff flows are not cleared by a de-
icing crew. As discussed previously, the requirements of this AD are 
intended to prevent ice accumulation on the wing upper surfaces, which 
does not relieve operators and flight crews from complying with 14 CFR 
parts 91.527 and 121.629 requirements to properly operate an airplane 
in icing conditions. Subsequent to the incidents cited by the 
commenter, Boeing issued All Operators Letter, FO-AOL-9-061, dated 
September 25, 1996, which informs operators and flightcrews of proper 
de-icing and inspection procedures.

Request To Revise Description of Tufts and Triangular Decals

    One commenter requests that the FAA revise the term ``tufts and 
triangular decals'' throughout the supplemental NPRM to ``inspection 
aids.'' The commenter states that this revision would provide one term 
to describe the various inspection aids (i.e., tufts, decals, mount 
pads, painted symbols, and paint stripes.) The FAA agrees and has 
revised the final rule accordingly.

Request To Continue To Require Inspection Aids After Certain 
Actions

    One commenter requests that inspection aids required by paragraph 
(c) of the supplemental NPRM remain required after installation of 
either an overwing heater blanket system or primary upper wing ice 
detector system, and incorporation of the AFM revision required by 
paragraphs (f) and (g) of the supplemental NPRM, respectively. The 
commenter states that this is required for MMEL relief. The commenter 
also states that the inspection aids are part of the MD-90 production 
configuration, even though the wing clear ice issue was eliminated by a 
return-to-tank heating system. The commenter further states that a 
certain operator incorporated the grid strips inspection aids, along 
with the heater blanket installation, on its fleet.
    The FAA partially agrees. We do not agree that the inspection aids 
required by paragraph (c) of the AD are necessary after installation of 
either an overwing heater or primary upper ice detector system, and 
incorporation of the AFM revision, required by paragraphs (f) and (g) 
of the AD, respectively. However, as discussed below under the heading 
``Request to Allow An Inoperative Overwing Heater Blanket System,'' we 
do agree that an airplane may be operated with an inoperative overwing 
heater blanket or primary upper ice detection system for 10 days per 
the MMEL, provided that the actions specified in paragraphs (h)(1), 
(h)(2), and (h)(3) of this final rule are done before further flight. 
As indicated below, we have included a new paragraph (h) to provide 
this exception. Therefore, no change to paragraph (c) is necessary.

Request To Allow an Inoperative Overwing Heater Blanket System

    One commenter requests that dispatch with an inoperative overwing 
heater

[[Page 17502]]

blanket system per the MMEL be permitted in paragraph (g) of the 
supplemental NPRM. The commenter notes the AFM revision required by 
paragraph (g) of the supplemental NPRM is the same as that required by 
AD 92-03-02 (paragraph (a) of the supplemental NPRM), except the 
requirement for the visual and physical checks of the wing upper 
surfaces for ice has been removed. The commenter also notes that 
requirements of paragraph (g) of the supplemental NPRM allow for the 
removal of the AFM revisions required by paragraphs (a) and (b) of the 
supplemental NPRM, as well as the tuft and triangular decal 
installation required by paragraph (c) of the supplemental NPRM (all of 
which were requirements of AD 92-03-02 that were retained in the 
supplemental NPRM).
    The commenter states that its affected airplanes are equipped with 
an overwing heater blanket system and operated per the AFM Supplement 
for TDG Aerospace, Inc., STC SA6042NM. This STC, which was approved as 
an alternative method of compliance (AMOC) for AD 92-03-02, allows an 
overwing heater blanket system to be inoperative per the MMEL for 120 
days, provided that the visual and physical checks of the wing upper 
surfaces for ice are performed as indicated in the AFM revision 
required by paragraph (a) of the supplemental NPRM. As paragraph (g) of 
the supplemental NPRM is currently worded, the commenter states that it 
will no longer be able to operate with an inoperative overwing heater 
blanket system per the MMEL, and that the overwing heater blanket 
system must be operational for every flight.
    The FAA partially agrees with the commenter's request. The FAA 
acknowledges that it issued AMOC's for AD 92-03-02 (i.e., Boeing TDG 
overwing heater blankets without an HPP installed, and TDG Aerospace, 
Inc., STC SA6042NM without an EPD installed) that reverted to the 
physical and visual checks to detect ice required by that AD in the 
event that the overwing heater blanket became inoperative. As discussed 
in the preamble of the NPRM, we found that the physical and visual 
checks to detect ice accumulation, as specified by the AFM revision 
required by AD 92-03-02, may not be adequate to ensure the safety of 
the affected transport airplane fleet.
    However, we find that, for 10 days (not the 120 days currently 
specified in the MMEL), an overwing heater blanket or primary upper 
wing ice detection system may be inoperative per the MMEL, provided 
that the physical and visual checks to detect ice are performed. This 
would allow the affected airplanes with an inoperative overwing heater 
blanket system to be rerouted to a suitable repair station and would 
still maintain an adequate level of safety. It should be noted that the 
10-day MMEL relief does not relieve operators and flight crews from 
complying with the requirements of 14 CFR parts 91.527 and 121.69 for 
properly operating an airplane in icing conditions.
    Therefore, the FAA has added a new paragraph (h) to include 
instructions for operating an airplane with an overwing heater blanket 
system that is inoperative and revised paragraph (g) to reference that 
paragraph as an exception.

Request To Include Previously Approved AMOC's

    One commenter notes that paragraph (h)(2) of the supplemental NPRM 
states that ``Alternative methods of compliance, approved previously in 
accordance with AD 92-03-02, amendment 39-8156, are NOT approved as 
alternative methods of compliance with this AD.'' The commenter states 
that it has received AMOC's for the requirements of paragraphs (b) and 
(c) of the supplemental NPRM and provides an explanation of those 
AMOC's. Therefore, the commenter requests that the requirements of 
paragraphs (b) and (c) of the supplemental NPRM be revised to address 
those AMOC's.
    The FAA partially agrees. We acknowledge that we approved an AMOC, 
which installed a non-skid, striped triangular symbol per Option 5 of 
McDonnell Douglas Service Bulletin MD80-30-059, Revision 4 through 
Revision 7, for the requirements of paragraph (b) of AD 92-03-02. We 
also acknowledge that we approved an AMOC, which revises the 
Configuration Deviation List (CDL) Appendix of the AFM by inserting a 
copy of CDL Appendix, Section I, Page 2A, dated March 10, 1993, into 
the AFM, for the requirements of paragraph (c) of AD 92-03-02.
    We find that these AMOC's are still acceptable for compliance with 
the requirements of paragraphs (b) and (c) of this AD, respectively. We 
have revised paragraph (i)(2) of the final rule accordingly. However, 
for the reasons identified in the preamble of the supplemental NPRM, 
AMOC's approved previously per AD 92-03-02 for Boeing TDG overwing 
heater blankets without an HPP installed, or TDG Aerospace, Inc. STC 
SA6042NM without an EPD installed are NOT approved as AMOC's with this 
AD.

Explanation of Change to Certain STC References

    The FAA has revised paragraphs (f)(2)(i) and (f)(2)(ii) of the 
final rule to: (1) Remove the reference to TDG Aerospace, Inc., STC 
SA6042NM and AlliedSignal STC SA6061NM and, instead, include a 
reference to a method approved by the FAA; and (2) add new notes to 
reference those STC's as approved means of compliance with the 
requirements of paragraphs (f)(2)(i) and (f)(2)(ii) of this AD, 
respectively. We find these STC's should not be incorporated by 
reference in the final rule, because they contain proprietary 
information.

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 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 1,153 Model DC-9-80 series airplanes and 
Model MD-88 airplanes of the affected design in the worldwide fleet. 
The FAA estimates that 643 airplanes of U.S. registry will be affected 
by this AD.
    The AFM revision that is currently required by AD 92-03-02 takes 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the currently required AFM revision on U.S. operators is 
estimated to be $38,580, or $60 per airplane.
    The revision of the CDL that is currently required by AD 92-03-02 
takes approximately 1 work hour per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the CDL revision on U.S. operators is estimated to be 
$38,580, or $60 per airplane.
    The installation of tufts and decals that is currently required by 
AD 92-03-02 takes approximately 3 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts cost approximately $25 per airplane. Based on these figures, the 
cost impact of the currently required installation of tufts and decals 
on U.S. operators is estimated to be $131,815, or $205 per airplane.
    The installation of the wing heater system that is provided as one 
option

[[Page 17503]]

for compliance with this AD action will take approximately 200 to 350 
work hours per airplane to accomplish, at an average labor rate of $60 
per work hour. Required parts will cost approximately $76,000 to 
$130,000 per airplane, depending on suppliers, airplane fleet size, and 
configuration. Based on these figures, the cost impact of the 
installation required by this AD on U.S. operators is estimated to 
range from $88,000 to $151,000 per airplane.
    In lieu of installation of a wing heater system, this AD provides 
for installation of a primary upper wing ice detector system. Because 
the manufacturer has not issued service information that describes the 
procedures for such an installation, the FAA is unable at this time to 
provide specific information as to the number of work hours or cost of 
parts that will be required to do that installation. However, based on 
estimated costs provided by the manufacturer, we can reasonably 
estimate that the required installation will require 290 work hours to 
do, at an average labor rate of $60 per work hour. The cost of required 
parts is estimated to range from $30,000 to $70,000 per airplane, 
depending on fleet size and airplane configuration. Based on these 
figures, the cost impact of the installation of a primary upper wing 
ice detector system required by this AD on U.S. operators is estimated 
to range from $47,400 to $87,400 per airplane.
    The new AFM revision that is required in this AD action will take 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the new AFM revision required by this AD on U.S. operators is 
estimated to be $38,580, or $60 per airplane.
    For affected airplanes, the new repetitive tests required in this 
AD action will take approximately 3 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the repetitive tests required by this 
AD on U.S. operators is estimated to be $180 per airplane, per test 
cycle.
    For affected airplanes, the one-time detailed visual inspection 
required in this AD action will take approximately 3 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the detailed visual 
inspection required by this AD on U.S. operators is estimated to be 
$180 per airplane.
    For airplanes listed in Group 1 of McDonnell Douglas Alert Service 
Bulletin MD80-30-090, the modification of the existing HPP will take 
approximately 5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. The manufacturer has committed 
previously to its customers that it will bear the cost of necessary 
parts. As a result, the cost of those parts is not attributable to this 
AD. Based on these figures, the cost impact of the AD on U.S. operators 
is estimated to be $300 per airplane.
    For airplanes listed in Group 2 of McDonnell Douglas Alert Service 
Bulletin MD80-30-090, the installation of the HPP and associated wiring 
will take approximately 3 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. The manufacturer has committed 
previously to its customers that it will bear the cost of necessary 
parts. As a result, the cost of those parts is not attributable to this 
AD. Based on these figures, the cost impact of the AD on U.S. operators 
is estimated to be $180 per airplane.
    The installation of an EPD will take approximately 1 work per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
The required EPD will cost approximately $5,475 per airplane. Based on 
these figures, the cost impact of this action required by this AD on 
U.S. operators is estimated to be $5,535 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. 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 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 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 removing amendment 39-8156 (57 FR 
2014, January 17, 1992), and by adding a new airworthiness directive 
(AD), amendment 39-, to read as follows:

2001-06-16  McDonnell Douglas: Amendment 39-12163. Docket 98-NM-326-
AD. Supersedes AD 92-03-02, Amendment 39-8156.

    Applicability: All Model DC-9-81, -82, -83, and -87 series 
airplanes; and Model MD-88 airplanes; 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 (i)(1) 
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 ice accumulation on the wing upper surfaces, which 
could result in ingestion of ice into one or both engines and 
consequent loss of thrust from one or both engines, accomplish the 
following:

[[Page 17504]]

Restatement of Requirements of AD 92-03-02

Airplane Flight Manual Revision

    (a) Within 10 days after January 17, 1992 (the effective date of 
AD 92-03-02, amendment 39-8156), revise the Limitations Section of 
the FAA-approved Airplane Flight Manual (AFM) to include the 
following. This may be accomplished by inserting a copy of this AD 
in the AFM.

``Ice on Wing Upper Surfaces

CAUTION

    Ice shedding from the wing upper surface during takeoff can 
cause severe damage to one or both engines, leading to surge, 
vibration, and complete thrust loss. The formation of ice can occur 
on wing surfaces during exposure of the airplane to normal icing 
conditions. Clear ice can also occur on the wing upper surfaces when 
cold-soaked fuel is in the main wing fuel tanks, and the airplane is 
exposed to conditions of high humidity, rain, drizzle, or fog at 
ambient temperatures well above freezing. Often, the ice 
accumulation is clear and difficult to detect visually. The ice 
forms most frequently on the inboard, aft corner of the main wing 
tanks. [END OF CAUTIONARY NOTE]
    The wing upper surfaces must be physically checked for ice when 
the airplane has been exposed to conditions conducive to ice 
formation. Takeoff may not be initiated unless the flight crew 
verifies that a visual check and a physical (hands-on) check of the 
wing upper surfaces have been accomplished, and that the wing is 
clear of ice accumulation when any of the following conditions 
occur:
    (1) When the ambient temperature is less than 50 degrees F and 
high humidity or visible moisture (rain, drizzle, sleet, snow, fog, 
etc.) is present;
    (2) When frost or ice is present on the lower surface of either 
wing;
    (3) After completion of de-icing.
    When inspection aids (i.e. tufts, decals, mount pads, painted 
symbols, and paint stripes) are installed in accordance with 
McDonnell Douglas MD-80 Service Bulletin 30-59, the physical check 
may be made by assuring that all installed tufts move freely.

NOTE

    This limitation does not relieve the requirement that aircraft 
surfaces are free of frost, snow, and ice accumulation, as required 
by Federal Aviation Regulations Sections 91.527 and 121.629. [END OF 
NOTE]''

AFM Configuration Deviation List Revision

    (b) Within 10 days after January 17, 1992, revise the 
Configuration Deviation List (CDL) Appendix of the FAA-approved AFM 
to include the following. This may be accomplished by inserting a 
copy of this AD in the AFM.

``30-80-01  Triangular Decal and Tuft Assemblies

    Up to two (2) decals or tufts per side may be missing, provided:
    (a) At least one decal and tuft on each side is located along 
the aft spar line; and
    (b) The tufts are used for performing the physical check to 
determine that the upper wing is free of ice by observing that the 
tufts move freely.
    Up to eight (8) decals and/or tufts may be missing, provided:
    (a) Takeoff may not be initiated unless the flight crew verifies 
that a physical (hands-on) check is made of the upper wing in the 
location of the missing decals and/or tufts to assure that there is 
no ice on the wing when icing conditions exist;
      OR
    (b) When the ambient temperature is more than 50 degrees F.''

Installation of Inspection Aids

    (c) Within 30 days after January 17, 1992, install inspection 
aids (i.e., tufts, decals, mount pads, painted symbols, and paint 
stripes) on the inboard side of the wings' upper surfaces, in 
accordance with McDonnell Douglas Service Bulletin 30-59, dated 
September 18, 1989; Revision 1, dated January 5, 1990; or Revision 
2, dated August 15, 1990.

New Requirements of This AD

Repetitive Tests and One-Time Inspection

    (d) For airplanes on which an overwing heater blanket system was 
installed without installation of a heater protection panel (HPP) or 
an equipment protection device (EPD) prior to the effective date of 
this AD: Within 60 days after the effective date of this AD, 
accomplish the actions specified in paragraph (d)(1) or (d)(2) of 
this AD, as applicable.
    (1) For airplanes on which the overwing heater blanket system 
was installed in accordance with McDonnell Douglas Service Bulletin 
MD80-30-071, Revision 02, dated February 6, 1996; or McDonnell 
Douglas Service Bulletin MD80-30-078, Revision 01, dated April 8, 
1997: Accomplish paragraphs (d)(1)(i) and (d)(1)(ii) of this AD.
    (i) Remove secondary access covers, and perform a one-time 
detailed visual inspection to detect discrepancies (mechanical 
damage or punctures in the upper skin of the blanket, prying damage 
on the panel, and fuel leakage) of the overwing heater blanket, in 
accordance with McDonnell Douglas Alert Service Bulletin MD80-
30A087, dated September 22, 1997. And,
    (ii) Accomplish paragraph (d)(1)(ii)(A) or (d)(1)(ii)(B) of this 
AD.
    (A) Perform dielectric withstanding voltage and resistance tests 
in accordance with McDonnell Douglas Alert Service Bulletin MD80-
30A087, dated September 22, 1997. Repeat the tests thereafter at 
intervals not to exceed 150 days, until installation of an HPP in 
accordance with paragraph (f)(1)(i) or (f)(1)(ii) of this AD, as 
applicable.
    (B) Deactivate the overwing heater blanket system until 
accomplishment of dielectric withstanding voltage and resistance 
tests specified in paragraph (d)(1)(ii)(A). If the overwing heater 
blanket system is deactivated as provided by this paragraph, 
continue to accomplish the requirements of paragraphs (a), (b), and 
(c) of this AD.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (2) For airplanes on which the overwing heater blanket system 
was installed in accordance with TDG Aerospace, Inc., STC SA6042NM: 
Accomplish paragraphs (d)(2)(i) and (d)(2)(ii) of this AD.
    (i) Remove secondary access covers, and perform a one-time 
detailed visual inspection to detect discrepancies (mechanical 
damage or punctures in the upper skin of the blanket, prying damage 
on the panel, and fuel leakage) of the overwing heater blanket, in 
accordance with McDonnell Douglas Alert Service Bulletin MD80-
30A087, dated September 22, 1997. And,
    (ii) Accomplish paragraph (d)(2)(ii)(A) or (d)(2)(ii)(B) of this 
AD.
    (A) Perform dielectric withstanding voltage and resistance tests 
in accordance with McDonnell Douglas Alert Service Bulletin MD80-
30A087, dated September 22, 1997. Repeat the tests thereafter at 
intervals not to exceed 150 days, until installation of an EPD in 
accordance with paragraph (f)(1)(iii)(B) of this AD.
    (B) Deactivate overwing heater blanket system until 
accomplishment of dielectric withstanding voltage and resistance 
tests specified in paragraph (d)(2)(ii)(A). If the overwing heater 
blanket system is deactivated as provided by this paragraph, 
continue to accomplish the requirements of paragraphs (a), (b), and 
(c) of this AD.

Corrective Action

    (e) If any discrepancy is detected during any inspection or test 
performed in accordance with paragraph (d) of this AD, prior to 
further flight, repair or replace the affected heater blanket, in 
accordance with McDonnell Douglas Alert Service Bulletin MD80-
30A087, dated September 22, 1997; except as provided in paragraph 
(h) of this AD.

    Note 3: McDonnell Douglas Alert Service Bulletin MD80-30A087, 
dated September 22, 1997, references TDG Aerospace Document E95-451, 
Revision B, dated January 31, 1996, as an additional source of 
service information for accomplishment of repair or replacement of 
the overwing heater blanket.

Installation of Overwing Heater Blanket or Primary Upper Wing Ice 
Detection System

    (f) Within 3 years after the effective date of this AD, do the 
requirements of either paragraph (f)(1) or (f)(2) of this AD.
    (1) Do the actions specified in paragraph (f)(1)(i) or 
(f)(1)(ii) of this AD, as applicable.
    (i) For airplanes listed in Group 1 in McDonnell Douglas Service 
Bulletin MD80-30-090, dated October 19, 1999: Install an overwing 
heater blanket system in accordance with McDonnell Douglas Service 
Bulletin MD80-30-071, Revision 02, dated February 6, 1996; and 
modify and reidentify the existing HPP in accordance with McDonnell 
Douglas Service Bulletin MD80-

[[Page 17505]]

30-090. Modification of the existing HPP in accordance with this 
paragraph constitutes terminating action for the repetitive 
inspections required by (d)(1)(ii)(A) of this AD.
    (ii) For airplanes listed in Group 2 in McDonnell Douglas 
Service Bulletin MD80-30-090, dated October 19, 1999: Install an 
overwing heater blanket system in accordance with McDonnell Douglas 
Service Bulletin MD80-30-078, Revision 01, dated April 8, 1997; and 
install an HPP and associated wiring in accordance with McDonnell 
Douglas Service Bulletin MD80-30-090. Installation of an HPP and 
associated wiring in accordance with this paragraph constitutes 
terminating action for the repetitive inspections required by 
(d)(1)(ii)(A) of this AD.

    Note 4: For other airplanes, accomplishment of the requirements 
of paragraph (f)(1)(i) or (f)(1)(ii) of this AD may be acceptable 
per paragraph (i)(1) of this AD.

    (2) Accomplish the actions specified in either paragraph 
(f)(2)(i), (f)(2)(ii), or (f)(2)(iii) of this AD.
    (i) Install an overwing heater blanket system, and install an 
EPD that provides a circuit protection function to the overwing 
heater blanket, in accordance with a method approved by the Manager, 
Los Angeles Aircraft Certification Office (ACO), FAA. Installation 
of an EPD in accordance with this paragraph constitutes terminating 
action for the repetitive inspections required by (d)(2)(ii)(A) of 
this AD.

    Note 5: Installation of an overwing heater blanket system and 
installation of an EPD that provides a circuit protection function 
to the overwing heater blanket, in accordance with TDG Aerospace, 
Inc., SA6042NM, or TDG Master Drawing List (MDL) E93-104, Revision 
R, dated October 25, 2000; is an approved means of compliance with 
the requirements of paragraph (f)(2)(i) of this AD.

    (ii) Install an overwing heater blanket system in accordance 
with a method approved by the Manager, Los Angeles ACO.

    Note 6: Installation of an overwing heater blanket system in 
accordance with AlliedSignal STC SA6061NM, is an approved means of 
compliance with the requirements of paragraph (f)(2)(ii) of this AD.

    (iii) Install an FAA-approved primary upper wing ice detection 
system in accordance with a method approved by the Manager, Los 
Angeles ACO.

    Note 7: Boeing (McDonnell Douglas) has received FAA approval of 
an acceptable primary upper wing ice detection system. This 
modification has been assigned a Boeing (McDonnell Douglas) service 
bulletin number but, at this time, no service bulletin is available.

AFM Revision

    (g) Except as provided by paragraph (h) of this AD, prior to 
further flight after accomplishment of the installation required by 
paragraph (f)(1) or (f)(2) of this AD, revise the Limitations 
Section of the FAA-approved AFM to include the following. This may 
be accomplished by inserting a copy of this AD in the AFM. After 
accomplishment of the installation required by paragraph (f)(1) or 
(f)(2) of this AD and this AFM revision, the AFM revisions required 
by paragraphs (a) and (b) of this AD may be removed from the AFM, 
and the inspection aids required by paragraph (c) of this AD may be 
removed from the airplane.

``Ice on Wing Upper Surfaces

CAUTION

    Ice shedding from the wing upper surface during takeoff can 
cause severe damage to one or both engines, leading to surge, 
vibration, and complete thrust loss. The formation of ice can occur 
on wing surfaces during exposure of the airplane to normal icing 
conditions. Clear ice can also occur on the wing upper surfaces when 
cold-soaked fuel is in the main wing fuel tanks, and the airplane is 
exposed to conditions of high humidity, rain, drizzle, or fog at 
ambient temperatures well above freezing. Often, the ice 
accumulation is clear and difficult to detect visually. The ice 
forms most frequently on the inboard, aft corner of the main wing 
tanks. [END OF CAUTIONARY NOTE]''

    (h) An airplane may be operated with an inoperative overwing 
heater blanket or primary upper wing ice detection system for 10 
days per the Master Minimum Equipment List (MMEL), provided that the 
actions specified in paragraphs (h)(1), (h)(2), and (h)(3) of this 
AD are done before further flight.
    (1) Revise the Limitations Section of the FAA-approved AFM to 
include the following. This may be accomplished by inserting a copy 
of this AD in the AFM.

``Ice on Wing Upper Surfaces

CAUTION

    The wing upper surfaces must be physically checked for ice when 
the airplane has been exposed to conditions conducive to ice 
formation. Takeoff may not be initiated unless the flight crew 
verifies that a visual check and a physical (hands-on) check of the 
wing upper surfaces have been accomplished, and that the wing is 
clear of ice accumulation when any of the following conditions 
occur:
    (1) When the ambient temperature is less than 50 degrees F and 
high humidity or visible moisture (rain, drizzle, sleet, snow, fog, 
etc.) is present;
    (2) When frost or ice is present on the lower surface of either 
wing;
    (3) After completion of de-icing.
    When inspection aids (i.e. tufts, decals, mount pads, painted 
symbols, and paint stripes) are installed in accordance with 
McDonnell Douglas MD-80 Service Bulletin 30-59, the physical check 
may be made by assuring that all installed tufts move freely.

NOTE

    This limitation does not relieve the requirement that aircraft 
surfaces are free of frost, snow, and ice accumulation, as required 
by Federal Aviation Regulations Sections 91.527 and 121.629. [END OF 
NOTE]''

    (2) Revise the CDL Appendix of the FAA-approved AFM to include 
the following. This may be accomplished by inserting a copy of this 
AD in the AFM.

``30-80-01 Triangular Decal and Tuft Assemblies

    Up to two (2) decals or tufts per side may be missing, provided:
    (a) At least one decal and tuft on each side is located along 
the aft spar line; and
    (b) The tufts are used for performing the physical check to 
determine that the upper wing is free of ice by observing that the 
tufts move freely.
    Up to eight (8) decals and/or tufts may be missing, provided:
    (a) Takeoff may not be initiated unless the flight crew verifies 
that a physical (hands-on) check is made of the upper wing in the 
location of the missing decals and/or tufts to assure that there is 
no ice on the wing when icing conditions exist;
        OR
    (b) When the ambient temperature is more than 50 degrees F.''

    (3) Install inspection aids (i.e., tufts, decals, mount pads, 
painted symbols, and paint stripes) on the inboard side of the 
wings' upper surfaces, in accordance with McDonnell Douglas Service 
Bulletin 30-59, dated September 18, 1989; Revision 1, dated January 
5, 1990; or Revision 2, dated August 15, 1990.

Alternative Methods of Compliance

    (i)(1) 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 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.
    (2) The following alternative methods of compliance (AMOC) were 
approved previously per AD 92-03-02, amendment 39-8156, and are 
approved as AMOC's with the indicated paragraphs of this AD:
    (i) Installation of a non-skid, striped triangular symbol per 
Option 5 of McDonnell Douglas Service bulletin MD80-30-059, Revision 
4 though Revision 7, is approved as an AMOC with paragraph (b) of 
this AD.
    (ii) Revision of the Configuration Deviation List (CDL) Appendix 
of the AFM by inserting a copy of CDL Appendix, Section I, Page 2A, 
dated March 10, 1993, into the AFM, is approved as an AMOC with 
paragraph (c) of this AD.

    Note 8: 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

    (j) 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.

Incorporation by Reference

    (k) The actions required by paragraphs (c), (d), (e), (f)(1), 
and (h)(3) of this AD shall be done in accordance with the 
applicable service document identified in Table 1 of this AD.

[[Page 17506]]



                                     Table 1.--Referenced Service Documents
----------------------------------------------------------------------------------------------------------------
             Service document                     Revision level                           Date
----------------------------------------------------------------------------------------------------------------
McDonnell Douglas Service Bulletin 30-59.  Original....................  September 18, 1989.
McDonnell Douglas Service Bulletin 30-59.  1...........................  January 5, 1990.
McDonnell Douglas Service Bulletin 30-59.  2...........................  August 15, 1990.
McDonnell Douglas Alert Service Bulletin   Original....................  September 22, 1997.
 MD80-30A087.
McDonnell Douglas Service Bulletin MD80-   Original....................  October 19, 1999.
 30-090.
McDonnell Douglas Service Bulletin MD80-   01..........................  April 8, 1997.
 30-078.
McDonnell Douglas Service Bulletin MD80-   02..........................  February 6, 1996.
 30-071.
----------------------------------------------------------------------------------------------------------------

    (1) The incorporation by reference of McDonnell Douglas Service 
Bulletin 30-59, dated September 18, 1989; McDonnell Douglas Service 
Bulletin 30-59, Revision 1, dated January 5, 1990; and McDonnell 
Douglas Service Bulletin 30-59, Revision 2, dated August 15, 1990; 
was approved previously by the Director of the Federal Register as 
of January 17, 1992 (57 FR 2014, January 17, 1992).
    (2) The incorporation by reference of the remaining service 
bulletins listed in Table 1 of this AD, is approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51.
    (3) 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, 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

    (l) This amendment becomes effective on May 7, 2001.

    Issued in Renton, Washington, on March 23, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-7732 Filed 3-30-01; 8:45 am]
BILLING CODE 4910-13-P