AD 2020-26-08

[Federal Register Volume 85, Number 247 (Wednesday, December 23, 2020)]
[Rules and Regulations]
[Pages 83755-83759]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2020-28268]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0465; Product Identifier 2020-NM-074-AD; Amendment 
39-21363; AD 2020-26-08]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for The 
Boeing Company Model 787-8, 787-9, and 787-10 airplanes powered by 
Rolls Royce Trent 1000 engines. This AD was prompted by reports of 
damage to the inner fixed structure (IFS) forward upper fire seal and 
damage to thermal insulation blankets in the forward upper area of the 
thrust reverser (TR). This AD requires repetitive inspections of the 
IFS forward upper fire seal and thermal insulation blankets in the 
forward upper area of the TR for damage and applicable on-condition 
actions. The FAA is issuing this AD to address the unsafe condition on 
these products.

DATES: This AD is effective January 27, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of January 27, 
2021.

ADDRESSES: For service information identified in this final rule, 
contact Boeing Commercial Airplanes, Attention: Contractual & Data 
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 
90740-5600; telephone 562-797-1717; internet <a href="https://www.myboeingfleet.com">https://www.myboeingfleet.com</a>. You may view this service information at the 
FAA, Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability of 
this material at the FAA, call 206-231-3195. It is also available on 
the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> by searching for and 
locating Docket No. FAA-2020-0465.

Examining the AD Docket

    You may examine the AD docket on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> by searching for and locating Docket No. FAA-2020-
0465; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this final rule, any comments received, and other information. The 
address for Docket Operations is U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Tak Kobayashi, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA; phone: 206-231-3553; email: <a href="/cdn-cgi/l/email-protection#7420151f151c1d07155a3f1b16150d15071c1d341215155a131b02"><span class="__cf_email__" data-cfemail="095d68626861607a682742666b6870687a6160496f6868276e667f">[email&#160;protected]</span></a>.

SUPPLEMENTARY INFORMATION:

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to The Boeing Company 
Model 787-8, 787-9, and 787-10 airplanes powered by Rolls Royce Trent 
1000 engines. The NPRM published in the Federal Register on June 16, 
2020 (85 FR 36352). The NPRM was prompted by reports of damage to the 
IFS forward upper fire seal and damage to thermal insulation blankets 
in the forward upper area of the TR. The NPRM proposed to require 
repetitive inspections of the IFS forward upper fire seal and thermal 
insulation blankets in the forward upper area of the TR for damage and 
applicable on-condition actions.
    The FAA is issuing this AD to address damage to the IFS forward 
upper fire seal and the thermal insulation blankets of the TR due to 
airflow through structural gapping that could occur at the interface 
between the leading edge of the IFS and the engine splitter structure 
during flight. Failure of the IFS forward upper fire seal could cause 
the loss of seal pressurization and degrade the ability to detect and 
extinguish an engine fire, resulting in an uncontrolled fire. Damage to 
the TR insulation blanket could result in thermal damage to the TR 
inner wall, the subsequent release of engine exhaust components, and 
consequent damage to critical areas of the airplane. Furthermore, 
damage to the TR inner wall and IFS forward upper fire seal could 
compromise the integrity of the firewall and its ability to contain an 
engine fire, resulting in an uncontrolled fire.

[[Page 83756]]

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Request for Clarification on Whether the Unsafe Condition is Likely To 
Exist on Other New Products

    An individual commenter asked how likely it is that the same unsafe 
condition addressed in the proposed AD is to occur on other new 
products that are currently being evaluated for certification by the 
FAA, including the Boeing Model 777X. The commenter stated that the use 
of an electric thruster instead of a hydraulically-driven thrust 
reverser actuator would reduce the maintenance of a hydraulic system, 
and eliminate potential corrosion and fire risk.
    The FAA agrees to clarify. As required by 14 CFR 21.21(b)(2), to 
certify an aircraft, the FAA must find that no feature or 
characteristic makes the aircraft unsafe. If the unsafe condition 
identified in this AD is determined to exist on any product that has 
not been certified by the FAA, the unsafe condition must be adequately 
addressed prior to FAA certification of that product. No change to this 
final rule is necessary in this regard.

Request for Explanation Regarding Timing of AD Action

    The individual commenter asked why there was a 36 month period 
after August 27, 2018 (the effective date of AD 2018-15-03 Amendment 
39-19335 (83 FR 34753, July 23, 2018) (AD 2018-15-03)), to take action 
on Boeing Alert Service Bulletin B787-81205-SB780033-00, Issue 001, 
dated November 1, 2017, which is required by AD 2018-15-03. The FAA 
infers that the commenter is referring to the 36-month compliance time 
for accomplishing the actions described in Boeing Alert Service 
Bulletin B787-81205-SB780033-00, Issue 001, dated November 1, 2017. The 
FAA also infers that the commenter is concerned regarding the time it 
took the FAA to take AD action to address the unsafe condition.
    The FAA agrees to provide clarification regarding the timing of the 
publication of AD 2018-15-03 and the relationship between AD 2018-15-03 
and this final rule. In the preamble of the NPRM preceding this final 
rule, the FAA stated that the proposed AD would not supersede or 
terminate any requirement of AD 2018-15-03. AD 2018-15-03 and this 
final rule both address damage to the IFS forward upper fire seal and 
damage to the thrust reverser thermal blanket. However, the damage to 
these areas is the result of two different causes. When the FAA 
developed AD 2018-15-03, that AD addressed the cause of damage that was 
identified at that time. The FAA assessed the level of risk and the 
compliance time, so that mandatory actions would be accomplished as 
soon as reasonably practical while maintaining an acceptable level of 
safety during the compliance period. The FAA determined that a 
compliance time of 36 months was adequate to address the unsafe 
condition identified in AD 2018-15-03.
    After AD 2018-15-03 was issued, Boeing identified an additional 
cause of the unsafe condition that was different from the one specified 
in AD 2018-15-03. This newly identified cause could similarly result in 
damage to the IFS forward upper fire seal and the thrust reverser 
thermal blanket. This final rule addresses the newly identified cause 
of the unsafe condition that was identified after AD 2018-15-03 was 
issued. As discussed in the preamble of the NPRM and the preamble of 
this final rule, the actions required by this final rule are interim 
action and the FAA may consider further rulemaking when a final 
corrective action becomes available.
    No change to this final rule is necessary in regard to this 
comment.

Request for Clarification Regarding Inspection Personnel

    The individual commenter also asked for clarification regarding 
what type of inspector would perform the inspections of the IFS forward 
upper fire seal and thermal blanket specified in the proposed AD. The 
commenter asked if the inspections would be performed by flight line 
inspectors or FAA inspectors.
    The FAA agrees to provide clarification. The inspections required 
by this AD will be performed by qualified and certified maintenance 
personnel employed by airlines and airplane operators. No change to 
this final rule is necessary in this regard.

Request To Clarify the Unsafe Condition

    Boeing requested that the Discussion section and paragraph (e) of 
the proposed AD be revised to clarify the unsafe condition. The 
commenter stated that the unsafe condition statement in the proposed AD 
was not accurate. However, the commenter did not provide an explanation 
as to why the unsafe condition statement was not accurate.
    The commenter indicated that in both the Discussion section and 
paragraph (e) of the proposed AD the explanation of the unsafe 
condition should be changed by removing the phrase ``the loss of seal 
pressurization'' from ``Failure of the IFS forward upper fire seal 
could cause the loss of seal pressurization and degrade the ability to 
detect and extinguish an engine fire, resulting in an uncontrolled 
fire,'' and replace it with the phrase ``excessive airflow into the 
core compartment firezone.''
    The commenter also requested that in both the Discussion section 
and paragraph (e) of the proposed AD the explanation of the unsafe 
condition be changed by removing the phrase ``the subsequent release of 
engine exhaust components, and consequent damage to critical areas of 
the airplane'' from ``Damage to the TR insulation blanket could result 
in thermal damage to the TR inner wall, the subsequent release of 
engine exhaust components, and consequent damage to critical areas of 
the airplane,'' and replace it with the phrase ``compromising the 
integrity of the firewall barrier which would increase the risk of an 
uncontained fire.''
    The FAA agrees with the commenter's request to clarify that damage 
to the TR inner wall could increase the risk of an uncontained fire. 
The FAA concurs that, depending on the level of damage to the TR inner 
wall and IFS forward upper fire seal, the capability of the firewall to 
contain an engine fire could be compromised, and therefore, it could 
result in an uncontrolled fire. The FAA also considers that damage to 
the IFS forward upper fire seal has the same effect. Although the FAA 
has already identified the potential for an uncontrolled fire as part 
of the unsafe condition addressed by this AD, the FAA has revised the 
Discussion section and paragraph (e) of this AD to provide additional 
clarification on this point.
    The FAA disagrees with the commenter's request to remove the 
reference to ``loss of seal pressurization and'' from the description 
of the unsafe condition. This final rule addresses structural gapping 
that could occur between the leading edge of the IFS and the engine 
splitter structure during flight. Airflow through this structural 
gapping could damage the IFS forward upper fire seal and the thrust 
reverser thermal blanket. When the IFS forward fire seal is damaged, 
airflow can pass through the damaged areas of the IFS forward fire seal 
in addition to airflow through structural gapping, and this condition 
could further degrade the

[[Page 83757]]

ability to detect and extinguish an engine fire, and also damage the TR 
thermal blanket. The FAA's intent was to explain the effect of airflow 
through the damaged IFS forward fire seal due to loss of seal 
pressurization caused by the failure of the IFS forward upper fire 
seal. The FAA has not revised this AD in this regard.
    The FAA also disagrees with the commenter's request to remove ``the 
subsequent release of engine exhaust components, and consequent damage 
to critical areas of the airplane'' from the description of the unsafe 
condition. The FAA has identified the potential of engine components 
departing the airplane due to damage to the TR inner wall as part of 
the unsafe condition addressed in this AD. This failure effect has been 
similarly discussed and addressed in a number of previously issued ADs 
including AD 2018-15-03, which is related to this AD. This AD has not 
been revised in this regard.

Request To Revise the Proposed Cost Estimates

    Boeing requested that the cost estimate in the NPRM be revised. 
Boeing stated that it initially communicated to the FAA that the 
manpower estimate of 0.5 man-hour for fire seal inspection and 0.5 man-
hour for thermal blanket inspection was meant to be per engine, instead 
of per thrust reverser half as the FAA considered under the estimated 
cost provided in the NPRM. Boeing explained that the corrected manpower 
estimate for the fire seal inspection should be 0.25 man-hour per 
thrust reverser half, and the corrected manpower estimate for the 
thermal blanket inspection should be 0.25 man-hour per thrust reverser 
half. Boeing recommended that instead of 4 work-hours x $85 per hour = 
$340 per inspection cycle, the FAA update the labor cost for the 
inspection to 2 work-hours for a cost of $170 per inspection cycle. 
Boeing asserted that this would change the cost on U.S. operators to 
$2,380 per inspection cycle, based on 14 U.S. airplanes.
    The FAA agrees with Boeing's observation that the cost estimate in 
the NPRM was incorrect based upon information that was incorrectly 
communicated from Boeing to the FAA. The FAA has revised the Costs of 
Compliance in this final rule.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule with the changes described previously 
and minor editorial changes. The FAA has determined that these minor 
changes:
    <bullet> Are consistent with the intent that was proposed in the 
NPRM for addressing the unsafe condition; and
    <bullet> Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    The FAA also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin B787-81205-
SB780041-00 RB, Issue 001, dated March 31, 2020. The service 
information describes procedures for repetitive inspections of the IFS 
forward upper fire seal and thermal insulation blankets of the TR for 
damage and applicable on-condition actions. Damage to a forward upper 
fire seal includes cuts, splits, nicks, punctures, and missing 
sections. Damage to an upper thermal blanket includes tears, cuts, 
missing metal skin, missing insulation, and over-temperature conditions 
shown by discoloration or scorching. The on-condition actions include 
replacing any damaged forward upper fire seal with a new fire seal 
having an appropriate part number, and replacing any damaged forward 
upper thermal blanket with a new thermal blanket. This service 
information is reasonably available because the interested parties have 
access to it through their normal course of business or by the means 
identified in the ADDRESSES section.

Interim Action

    The FAA considers this AD interim action. If final action is later 
identified, the FAA might consider further rulemaking then.

Costs of Compliance

    The FAA estimates that this AD affects 14 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
             Action                     Labor cost          Parts cost     Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspection.....................  2 work-hours x $85 per               $0  $170 per            $2,380 per
                                  hour = $170 per                          inspection cycle.   inspection cycle.
                                  inspection cycle.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary on-
condition actions that would be required. The FAA has no way of 
determining the number of aircraft that might need these on-condition 
actions:

                                     Estimated Costs of On-Condition Actions
----------------------------------------------------------------------------------------------------------------
              Action                        Labor cost                Parts cost            Cost per product
----------------------------------------------------------------------------------------------------------------
Fire seal replacement.............  2 work-hours x $85 per      $1,365 per TR half...  $1,535 per TR half (4 TR
                                     hour = $170 per TR half.                           halves per airplane).
Thermal blanket replacement.......  1 work-hour x $85 per hour  $17,855 per TR half..  $17,940 per TR half (4 TR
                                     = $85 per TR half.                                 halves per airplane).
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some or all of the costs of this AD 
may be covered under warranty by Goodrich, thereby reducing the cost 
impact on affected individuals. The FAA does not control warranty 
coverage for affected individuals. As a result, the FAA has included 
all known costs in the cost estimate.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of

[[Page 83758]]

the FAA Administrator. Subtitle VII: Aviation Programs, describes in 
more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2020-26-08 The Boeing Company: Amendment 39-21363; Docket No. FAA-
2020-0465; Product Identifier 2020-NM-074-AD.

(a) Effective Date

    This AD is effective January 27, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 787-8, 787-9, and 
787-10 airplanes, certificated in any category, powered by Rolls 
Royce Trent 1000 engines.

(d) Subject

    Air Transport Association (ATA) of America Code 78, Engine 
Exhaust.

(e) Unsafe Condition

    This AD was prompted by reports of damage to the inner fixed 
structure (IFS) forward upper fire seal and damage to thermal 
insulation blankets in the forward upper area of the thrust reverser 
(TR). The FAA is issuing this AD to address the damage to the IFS 
forward upper fire seal and the thermal insulation blankets of the 
TR due to airflow through structural gapping that could occur at the 
interface between the leading edge of the IFS and the engine 
splitter structure during flight. Failure of the IFS forward upper 
fire seal could cause the loss of seal pressurization and degrade 
the ability to detect and extinguish an engine fire, resulting in an 
uncontrolled fire. Damage to the TR insulation blanket could result 
in thermal damage to the TR inner wall, the subsequent release of 
engine exhaust components, and consequent damage to critical areas 
of the airplane. Furthermore, damage to the TR inner wall and IFS 
forward upper fire seal could compromise the integrity of the 
firewall and its ability to contain an engine fire, resulting in an 
uncontrolled fire.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Except as specified by paragraph (h) of this AD: At the 
applicable times specified in the ``Compliance'' paragraph of Boeing 
Alert Requirements Bulletin B787-81205-SB780041-00 RB, Issue 001, 
dated March 31, 2020, do all applicable actions identified in, and 
in accordance with, the Accomplishment Instructions of Boeing Alert 
Requirements Bulletin B787-81205-SB780041-00 RB, Issue 001, dated 
March 31, 2020.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
B787-81205-SB780041-00, Issue 001, dated March 31, 2020, which is 
referred to in Boeing Alert Requirements Bulletin B787-81205-
SB780041-00 RB, Issue 001, dated March 31, 2020.

(h) Exceptions to Service Information Specifications

    Where Boeing Alert Requirements Bulletin B787-81205-SB780041-00 
RB, Issue 001, dated March 31, 2020, uses the phrase ``the Issue 001 
date of Requirements Bulletin B787-81205-SB780041-00 RB,'' this AD 
requires using ``the effective date of this AD.''

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (j)(1) of this AD. Information may be 
emailed to: <a href="/cdn-cgi/l/email-protection#281105696665057b4d495c5c444d05696b67056965676b057a4d595d4d5b5c5b684e4949064f475e"><span class="__cf_email__" data-cfemail="90a9bdd1deddbdc3f5f1e4e4fcf5bdd1d3dfbdd1dddfd3bdc2f5e1e5f5e3e4e3d0f6f1f1bef7ffe6">[email&#160;protected]</span></a>.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by The Boeing Company Organization Designation 
Authorization (ODA) that has been authorized by the Manager, Seattle 
ACO Branch, FAA, to make those findings. To be approved, the repair 
method, modification deviation, or alteration deviation must meet 
the certification basis of the airplane, and the approval must 
specifically refer to this AD.

(j) Related Information

    (1) For more information about this AD, contact Tak Kobayashi, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA; phone: 206-231-3553; email: 
<a href="/cdn-cgi/l/email-protection#d480b5bfb5bcbda7b5fa9fbbb6b5adb5a7bcbd94b2b5b5fab3bba2"><span class="__cf_email__" data-cfemail="e1b5808a8089889280cfaa8e83809880928988a1878080cf868e97">[email&#160;protected]</span></a>.
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (k)(3) and (4) of this AD.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Alert Requirements Bulletin B787-81205-SB780041-00 
RB, Issue 001, dated March 31, 2020.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-
5600; telephone 562-797-1717; internet <a href="https://www.myboeingfleet.com">https://www.myboeingfleet.com</a>. You may view this referenced service 
information at the FAA, Airworthiness Products Section, Operational 
Safety Branch, 2200 South 216th St., Des Moines, WA. For information 
on the availability of this material at the FAA, call 206-231-3195.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability 
of this material at the FAA, call 206-231-3195.

[[Page 83759]]

    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email <a href="/cdn-cgi/l/email-protection#cdaba8a9bfa8aae3a1a8aaaca18da3acbface3aaa2bb"><span class="__cf_email__" data-cfemail="1f797a7b6d7a7831737a787e735f717e6d7e31787069">[email&#160;protected]</span></a>, or go to: <a href="https://www.archives.gov/federal-register/cfr/ibr-locations.html">https://www.archives.gov/federal-register/cfr/ibr-locations.html</a>.

    Issued on December 9, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-28268 Filed 12-22-20; 8:45 am]
BILLING CODE 4910-13-P