Back to publication catalog

Published 2023-02-07 · Federal Register document 2023-02529

Airworthiness Directives; Airbus SAS Airplanes

Publication summary

The FAA is adopting a new airworthiness directive (AD) for all Airbus SAS Model A300 B2K-3C, B2-203, B4-2C, and B4-203 airplanes. This AD was prompted by a determination that internal system pollution can occur, most likely due to corroded unions in the pressurization lines, with an associated risk of contamination of the check valves. This AD requires repetitive inspections (functional checks) of the pressurization of the hydraulic system reservoirs, and corrective actions if necessary, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products.

Why this record is shown

Source: Federal Register annual FAA metadata. Acquired 2026-09-03T22:24:14.395624+00:00. The title, summary and date are source facts.

Source revision
federal_register_ad_metadata_2023-81e907e5105d0f2c
Source row
results[28]
Raw source SHA-256
81e907e5105d0f2c522e15b6fa8c7277117367b7f70b363862619549836b75e8

Final-rule publication

Recorded publication clauses

AD identifier printed in this edition
2023-02-07
Effective date printed in this edition
2023-03-14
Read 11 complete recorded clauses
Effective Date
(a) Effective Date

    This airworthiness directive (AD) is effective March 14, 2023.

Exact source excerpt. Text positions 10650–10738, end exclusive, in the original decoded publication. SHA-256: aa68f0db2216317e19b3e7b8e171e8e5ec6ee4d78414d22bfb3a1706c3a6475d

Affected ADs
(b) Affected ADs

    None.

Exact source excerpt. Text positions 10738–10767, end exclusive, in the original decoded publication. SHA-256: 871a4afc60ceeae06e8010585055188633d616078500c45937092bfe892239c0

Applicability wording · Applicability
(c) Applicability

    This AD applies to all Airbus SAS Model A300 B2K-3C, B2-203, B4-
2C, and B4-203 airplanes, certificated in any category.

Exact source excerpt. Text positions 10767–10912, end exclusive, in the original decoded publication. SHA-256: fd1d330e30b8b1514a085fba6ef4702f3d81dd36842717e661fd6615401da221

Subject
(d) Subject

    Air Transport Association (ATA) of America Code: 29, Hydraulic 
power.

Exact source excerpt. Text positions 10912–11001, end exclusive, in the original decoded publication. SHA-256: ba5981fd36e37c1f89383f583f3edd20506d0197dd55abc59cfd12f15412d46b

Unsafe Condition
(e) Unsafe Condition

    This AD was prompted by a determination that internal system 
pollution can occur, most likely due to corroded unions at 
pressurization lines level, with an associated risk of contamination 
of the check valves. The FAA is issuing this AD to address check 
valve contamination, which could lead to hydraulic reservoir 
pressurization issues and, if combined with an air pressurization 
line rupture, could lead to loss of hydraulic systems and possibly 
result in loss of control of the airplane.

Exact source excerpt. Text positions 11001–11526, end exclusive, in the original decoded publication. SHA-256: e18d2f7f48220a12a0ea7c4f0511fd73996160a81f987a50d3eff117a49519c3

Compliance
(f) Compliance

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

Exact source excerpt. Text positions 11526–11628, end exclusive, in the original decoded publication. SHA-256: 00fbfa31932483f627d0ce0a11cbd2e35e15d9231842b91ac85623ce533912d3

Requirements
(g) Requirements

    Except as specified in paragraph (h) of this AD: Comply with all 
required actions and compliance times specified in, and in 
accordance with, European Union Aviation Safety Agency (EASA) AD 
2022-0116, dated June 21, 2022 (EASA AD 2022-0116).

Exact source excerpt. Text positions 11628–11895, end exclusive, in the original decoded publication. SHA-256: 2ff9bdd59da0920f286edb92830c5e13913010cdf0e2acbf2c73b530d03238c2

Exceptions to EASA AD 2022-0116
(h) Exceptions to EASA AD 2022-0116

    (1) Where EASA AD 2022-0116 refers to its effective date, this 
AD requires using the effective date of this AD.
    (2) Paragraph (3) of EASA AD 2022-0116 specifies to report the 
first functional check (test) results to Airbus within a certain 
compliance time. For this AD, report the first functional check 
(test) results at the applicable time specified in paragraph 
(h)(2)(i) or (ii) of this AD.
    (i) If the inspection was done on or after the effective date of 
this AD: Submit the report within 30 days after the inspection.
    (ii) If the inspection was done before the effective date of 
this AD: Submit the report within 30 days after the effective date 
of this AD.
    (3) The ``Remarks'' section of EASA AD 2022-0116 does not apply 
to this AD.

Exact source excerpt. Text positions 11895–12702, end exclusive, in the original decoded publication. SHA-256: f3a56f5abb98067443cfdc4917108dbd7e05ef67b646afc740259b74e8b48814

Additional AD Provisions
(i) Additional AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, 
International Validation 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 responsible Flight Standards Office, as 
appropriate. If sending information directly to the International 
Validation Branch, send it to the attention of the person identified 
in paragraph (j) of this AD. Information may be emailed to: [email protected]. Before using any approved AMOC, notify your 
appropriate principal inspector, or lacking a principal inspector, 
the manager of the responsible Flight Standards Office.
    (2) Contacting the Manufacturer: For any requirement in this AD 
to obtain instructions from a manufacturer, the instructions must be 
accomplished using a method approved by the Manager, International 
Validation Branch, FAA; or EASA; or Airbus SAS's EASA Design 
Organization Approval (DOA). If approved by the DOA, the approval 
must include the DOA-authorized signature.
    (3) Required for Compliance (RC): Except as required by 
paragraph (i)(2) of this AD, if any service information contains 
procedures or tests that are identified as RC, those procedures and 
tests must be done to comply with this AD; any procedures or tests 
that are not identified as RC are recommended. Those procedures and 
tests that are not identified as RC may be deviated from using 
accepted methods in accordance with the operator's maintenance or 
inspection program without obtaining approval of an AMOC, provided 
the procedures and tests identified as RC can be done and the 
airplane can be put back in an airworthy condition. Any 
substitutions or changes to procedures or tests identified as RC 
require approval of an AMOC.

Exact source excerpt. Text positions 12702–14630, end exclusive, in the original decoded publication. SHA-256: dc3b4540cd6f96b3a81ee1334da9e511b60e8dda224ec39ea2b39bdb354948f9

Additional Information
(j) Additional Information

    For more information about this AD, contact Dan Rodina, 
Aerospace Engineer, Large Aircraft Section, FAA, International 
Validation Branch, 2200 South 216th St., Des Moines, WA 98198; 
telephone 206-231-3225; email [email protected].

Exact source excerpt. Text positions 14630–14897, end exclusive, in the original decoded publication. SHA-256: 40f3aef00116d6ddc9b2b137ea67e7d5c2129005b6cf800c372356dc3621b6fb

Material Incorporated by Reference
(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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 this AD specifies otherwise.
    (i) European Union Aviation Safety Agency (EASA) AD 2022-0116, 
dated June 21, 2022.
    (ii) [Reserved]
    (3) For EASA AD 2022-0116, contact EASA, Konrad-Adenauer-Ufer 3, 
50668 Cologne, Germany; telephone +49 221 8999 000; email 
[email protected]; website easa.europa.eu. You may find this EASA 
AD on the EASA website at ad.easa.europa.eu.
    (4) You may view this material 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.
    (5) You may view this material that is incorporated by reference 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at NARA, email 
[email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

Exact source excerpt. Text positions 14897–16122, end exclusive, in the original decoded publication. SHA-256: b79144d0a409682fd17d3a65e2857ac22603ad1e258b52091db84022fe327420

No replacement link has been established from this edition. The complete historical rule chain and current legal effect remain unknown.

Find all recorded historical references to AD 2023-02-07 · 0 printed reference observations in this pinned collection.

These are observations from one dated publication. Current legal status is unknown; aircraft applicability, installed configuration, compliance and burden require separate evidence. Missing or unparsed conditions remain unknown.

Why these observations are shown

They were extracted offline from the same immutable official HTML source as the complete recorded text. The dated source wording, original text coordinates and exact quote digests are retained. PDF/text agreement and current regulatory effect have not been qualified.

Observation revision: whole-ad-publication-clause-observations-1.0.1. Text SHA-256: 2d837931da6c273aa63a71a0c4b9dcedf2db4aba2b3b31a9d2303fb3cbcdbfdc. Source manifest: 2bcdbcc20be0069c620a1563fc9aacae57f93a357ef79a0b3961540275be3287.

Official source · 2023-02-07

Publication text

This is the complete recorded text of this dated publication.

Current legal effect is unknown. Aircraft applicability, installed configuration and compliance require separate evidence. PDF/text agreement has not been evaluated.

Read the complete official publication text
[Federal Register Volume 88, Number 25 (Tuesday, February 7, 2023)]
[Rules and Regulations]
[Pages 7864-7866]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-02529]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1412; Project Identifier MCAI-2022-00805-T; 
Amendment 39-22314; AD 2023-02-07]
RIN 2120-AA64


Airworthiness Directives; Airbus SAS Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Airbus SAS Model A300 B2K-3C, B2-203, B4-2C, and B4-203 airplanes. This 
AD was prompted by a determination that internal system pollution can 
occur, most likely due to corroded unions in the pressurization lines, 
with an associated risk of contamination of the check valves. This AD 
requires repetitive inspections (functional checks) of the 
pressurization of the hydraulic system reservoirs, and corrective 
actions if necessary, as specified in a European Union Aviation Safety 
Agency (EASA) AD, which is incorporated by reference. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective March 14, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of March 14, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2022-1412; 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, the mandatory continuing airworthiness 
information (MCAI), 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.
    Material Incorporated by Reference:
    <bullet> For material incorporated by reference in this AD, contact 
EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221 
8999 000; email [email protected]; website easa.europa.eu. You may 
find this material on the EASA website at ad.easa.europa.eu.
    <bullet> You may view this material at the FAA, Airworthiness 
Products Section,

[[Page 7865]]

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 in the AD docket at regulations.gov 
under Docket No. FAA-2022-1412.

FOR FURTHER INFORMATION CONTACT: Dan Rodina, Aerospace Engineer, Large 
Aircraft Section, FAA, International Validation Branch, 2200 South 
216th St., Des Moines, WA 98198; telephone 206-231-3225; email 
[email protected].

SUPPLEMENTARY INFORMATION: 

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all Airbus SAS Model 
A300 B2-203, A300 B2K-3C, A300 B4-203, and A300 B4-2C airplanes. The 
NPRM published in the Federal Register on November 18, 2022 (87 FR 
69222).
    The NPRM was prompted by AD 2022-0116, dated June 21, 2022, issued 
by EASA, which is the Technical Agent for the Member States of the 
European Union (EASA AD 2022-0116) (also referred to as the MCAI). The 
MCAI states that internal system pollution can occur, most likely due 
to corroded unions at the pressurization lines, with an associated risk 
of contamination of the check valves. The three hydraulic system 
reservoirs are pressurized by air coming from the engine or the 
auxiliary power unit bleed air duct or from the ground connection. Air 
tightness of the pressurization system of the reservoirs is achieved by 
check valves that are located on the respective pressurization lines 
and on top of each hydraulic reservoir.
    In the NPRM, the FAA proposed to require repetitive inspections 
(functional checks) of the pressurization of the hydraulic system 
reservoirs, and corrective actions if necessary, as specified in EASA 
AD 2022-0116. The FAA is issuing this AD to address check valve 
contamination, which could lead to hydraulic reservoir pressurization 
issues and, if combined with an air pressurization line rupture, could 
lead to loss of hydraulic systems and possibly result in loss of 
control of the airplane. See the MCAI for additional background 
information.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2022-1412.

Discussion of Final Airworthiness Directive

Comments

    The FAA received no comments on the NPRM or on the determination of 
the cost to the public.

Conclusion

    This product has been approved by the aviation authority of another 
country and is approved for operation in the United States. Pursuant to 
the FAA's bilateral agreement with this State of Design Authority, it 
has notified the FAA of the unsafe condition described in the MCAI 
referenced above. The FAA reviewed the relevant data and determined 
that air safety requires adopting this AD as proposed. Accordingly, the 
FAA is issuing this AD to address the unsafe condition on this product. 
Except for minor editorial changes, this AD is adopted as proposed in 
the NPRM. None of the changes will increase the economic burden on any 
operator.

Related Service Information Under 1 CFR Part 51

    EASA AD 2022-0116 specifies procedures for repetitive detailed 
inspections by performing functional checks for air leakage of the 
hydraulic system reservoirs and corrective actions. Corrective actions 
include a fault isolation to identify the source of depressurization 
and replacement of the check valves. EASA AD 2022-0116 also specifies 
procedures for reporting the inspection findings.
    This material 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.

Costs of Compliance

    The FAA estimates that this AD affects 2 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                           Labor cost                               Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
4 work-hours x $85 per hour = $340..............................              $0            $340            $680
1 work-hour x $85 per hour = $85 (reporting)....................               0              85             170
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data on which to base the cost 
estimates for the corrective actions specified in this AD.

Paperwork Reduction Act

    A federal agency may not conduct or sponsor, and a person is not 
required to respond to, nor shall a person be subject to a penalty for 
failure to comply with a collection of information subject to the 
requirements of the Paperwork Reduction Act unless that collection of 
information displays a currently valid OMB Control Number. The OMB 
Control Number for this information collection is 2120-0056. Public 
reporting for this collection of information is estimated to take 
approximately 1 hour per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information. All responses to this collection of 
information are mandatory. Send comments regarding this burden estimate 
or any other aspect of this collection of information, including 
suggestions for reducing this burden, to: Information Collection 
Clearance Officer, Federal Aviation Administration, 10101 Hillwood 
Parkway, Fort Worth, TX 76177-1524.

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 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.

[[Page 7866]]

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.

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:

2023-02-07 Airbus SAS: Amendment 39-22314; Docket No. FAA-2022-1412; 
Project Identifier MCAI-2022-00805-T.

(a) Effective Date

    This airworthiness directive (AD) is effective March 14, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Airbus SAS Model A300 B2K-3C, B2-203, B4-
2C, and B4-203 airplanes, certificated in any category.

(d) Subject

    Air Transport Association (ATA) of America Code: 29, Hydraulic 
power.

(e) Unsafe Condition

    This AD was prompted by a determination that internal system 
pollution can occur, most likely due to corroded unions at 
pressurization lines level, with an associated risk of contamination 
of the check valves. The FAA is issuing this AD to address check 
valve contamination, which could lead to hydraulic reservoir 
pressurization issues and, if combined with an air pressurization 
line rupture, could lead to loss of hydraulic systems and possibly 
result in loss of control of the airplane.

(f) Compliance

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

(g) Requirements

    Except as specified in paragraph (h) of this AD: Comply with all 
required actions and compliance times specified in, and in 
accordance with, European Union Aviation Safety Agency (EASA) AD 
2022-0116, dated June 21, 2022 (EASA AD 2022-0116).

(h) Exceptions to EASA AD 2022-0116

    (1) Where EASA AD 2022-0116 refers to its effective date, this 
AD requires using the effective date of this AD.
    (2) Paragraph (3) of EASA AD 2022-0116 specifies to report the 
first functional check (test) results to Airbus within a certain 
compliance time. For this AD, report the first functional check 
(test) results at the applicable time specified in paragraph 
(h)(2)(i) or (ii) of this AD.
    (i) If the inspection was done on or after the effective date of 
this AD: Submit the report within 30 days after the inspection.
    (ii) If the inspection was done before the effective date of 
this AD: Submit the report within 30 days after the effective date 
of this AD.
    (3) The ``Remarks'' section of EASA AD 2022-0116 does not apply 
to this AD.

(i) Additional AD Provisions

    The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, 
International Validation 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 responsible Flight Standards Office, as 
appropriate. If sending information directly to the International 
Validation Branch, send it to the attention of the person identified 
in paragraph (j) of this AD. Information may be emailed to: [email protected]. Before using any approved AMOC, notify your 
appropriate principal inspector, or lacking a principal inspector, 
the manager of the responsible Flight Standards Office.
    (2) Contacting the Manufacturer: For any requirement in this AD 
to obtain instructions from a manufacturer, the instructions must be 
accomplished using a method approved by the Manager, International 
Validation Branch, FAA; or EASA; or Airbus SAS's EASA Design 
Organization Approval (DOA). If approved by the DOA, the approval 
must include the DOA-authorized signature.
    (3) Required for Compliance (RC): Except as required by 
paragraph (i)(2) of this AD, if any service information contains 
procedures or tests that are identified as RC, those procedures and 
tests must be done to comply with this AD; any procedures or tests 
that are not identified as RC are recommended. Those procedures and 
tests that are not identified as RC may be deviated from using 
accepted methods in accordance with the operator's maintenance or 
inspection program without obtaining approval of an AMOC, provided 
the procedures and tests identified as RC can be done and the 
airplane can be put back in an airworthy condition. Any 
substitutions or changes to procedures or tests identified as RC 
require approval of an AMOC.

(j) Additional Information

    For more information about this AD, contact Dan Rodina, 
Aerospace Engineer, Large Aircraft Section, FAA, International 
Validation Branch, 2200 South 216th St., Des Moines, WA 98198; 
telephone 206-231-3225; email [email protected].

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference 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 this AD specifies otherwise.
    (i) European Union Aviation Safety Agency (EASA) AD 2022-0116, 
dated June 21, 2022.
    (ii) [Reserved]
    (3) For EASA AD 2022-0116, contact EASA, Konrad-Adenauer-Ufer 3, 
50668 Cologne, Germany; telephone +49 221 8999 000; email 
[email protected]; website easa.europa.eu. You may find this EASA 
AD on the EASA website at ad.easa.europa.eu.
    (4) You may view this material 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.
    (5) You may view this material that is incorporated by reference 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at NARA, email 
[email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on January 20, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-02529 Filed 2-6-23; 8:45 am]
BILLING CODE 4910-13-P


Why this text is shown

The complete text was extracted from the official GovInfo HTML edition for this publication. Acquired 2026-10-09T01:37:24.943177+00:00. Text extraction preserves the recorded source wording; it does not determine current requirements.

Open the captured official edition

Source SHA-256
766bc6ae7f0a8427fea03b1ab4c4d9253a4352ba1246b7645833c143e5fd19f5
Text SHA-256
2d837931da6c273aa63a71a0c4b9dcedf2db4aba2b3b31a9d2303fb3cbcdbfdc

Return to the full metadata catalog · Search complete publication text · Explore retained publication text and evidence

Coverage and limits

These are dated publication metadata, recorded clauses and literal source observations. Word, model-label, header and reference matches do not establish current legal effect, manufacturer/model identity, aircraft applicability, installed configuration or compliance.

The collection uses 33 explicit annual source snapshots. Source captures and operative-text qualifications have separate states. Missing information remains unknown.