ASTM F3338-20

Standard Specification for Design of Electric Propulsion Units for General Aviation Aircraft

SCOPE
1.1 This specification covers minimum requirements for the design of Electric Propulsion Units (EPU).  
1.2 Distributed propulsion is not excluded; however, additional requirements will be needed to address the additional issues that distributed propulsion can create. Some of those issues may include: use of a common motor controller/inverter, segregated electric harnesses, cooling systems, electric power supplies, and others.  
1.3 This specification does not address all of the requirements that may be necessary for possible hybrid configurations where an EPU and a combustion engine drive a common thruster. This specification may be used for the EPU aspects with supplemental requirements for the thruster and the combustion engine.  
1.4 Although this specification does not include specific requirements for EPUs that include gearboxes, thrusters, or any energy storage systems, it also does not preclude such capabilities. This specification may be used for the base EPU aspects of the design, with supplemental requirements for any additional features prepared by the manufacturer and submitted to the Civil Airworthiness Authority for acceptance. This version of this ASTM specification also does not address all of the requirements necessary for configurations of motor driven ducted-fans. It is anticipated that the fan would be subject to parts of 14 CFR 33 or CS-E and/or 14 CFR 35 or CS-P, or equivalent, in particular blade-off and bird strike. These would be conducted on the fan as a unit (including motor) rather than on motor or fan alone.  
1.5 The applicant for a design approval should seek the individual guidance of their respective civil aviation authority (CAA) body concerning the use of this specification as part of a certification plan. For information on which CAA regulatory bodies have accepted this specification (in whole or in part) as a means of compliance to their general aviation aircraft airworthiness regulations (hereinafter referred to as “the Rules”), refer to ASTM Committee F39 webpage (www.ASTM.org/COMITTEE/F39.htm), which includes CAA website links.  
1.6 When applicable, this specification may be used for EPUs with a fixed-pitch propeller or fan. These configurations may be type-certificated as an EPU including a thruster. There may be additional requirements not currently included in this specification for this type configuration. In addition, 5.25 is included as a test requirement for the EPU. That section recognizes that when the EPU does not have an integral thruster it will need to be tested with a representative load on the drive shaft to assure EPU ability to operate properly with static and dynamic loads.  
1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 31-Aug-2020
• ICS: 49.050 - Aerospace engines and propulsion systems
• Technical Committee: F39 - Aircraft Systems
• Drafting Committee: F39.05 - Design, Alteration, and Certification of Electric Propulsion Systems

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F3338 −20
Standard Specification for
Design of Electric Propulsion Units for General Aviation
1
Aircraft
This standard is issued under the fixed designation F3338; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope a means of compliance to their general aviation aircraft
airworthiness regulations (hereinafter referred to as “the
1.1 This specification covers minimum requirements for the
Rules”), refer to ASTM Committee F39 webpage
design of Electric Propulsion Units (EPU).
(www.ASTM.org/COMITTEE/F39.htm), which includes CAA
1.2 Distributed propulsion is not excluded; however, addi-
website links.
tional requirements will be needed to address the additional
1.6 When applicable, this specification may be used for
issues that distributed propulsion can create. Some of those
EPUs with a fixed-pitch propeller or fan. These configurations
issuesmayinclude:useofacommonmotorcontroller/inverter,
may be type-certificated as an EPU including a thruster. There
segregated electric harnesses, cooling systems, electric power
may be additional requirements not currently included in this
supplies, and others.
specification for this type configuration. In addition, 5.25 is
1.3 This specification does not address all of the require-
included as a test requirement for the EPU. That section
ments that may be necessary for possible hybrid configurations
recognizes that when the EPU does not have an integral
where an EPU and a combustion engine drive a common
thruster it will need to be tested with a representative load on
thruster. This specification may be used for the EPU aspects
the drive shaft to assure EPU ability to operate properly with
with supplemental requirements for the thruster and the com-
static and dynamic loads.
bustion engine.
1.7 The values stated in inch-pound units are to be regarded
1.4 Although this specification does not include specific
as standard. The values given in parentheses are mathematical
requirementsforEPUsthatincludegearboxes,thrusters,orany
conversions to SI units that are provided for information only
energy storage systems, it also does not preclude such capa-
and are not considered standard.
bilities. This specification may be used for the base EPU
1.8 This standard does not purport to address all of the
aspects of the design, with supplemental requirements for any
safety concerns, if any, associated with its use. It is the
additionalfeaturespreparedbythemanufacturerandsubmitted
responsibility of the user of this standard to establish appro-
to the Civil Airworthiness Authority for acceptance. This
priate safety, health, and environmental practices and deter-
version of thisASTM specification also does not address all of
mine the applicability of regulatory limitations prior to use.
the requirements necessary for configurations of motor driven
1.9 This international standard was developed in accor-
ducted-fans. It is anticipated that the fan would be subject to
dance with internationally recognized principles on standard-
parts of 14 CFR 33 or CS-E and/or 14 CFR 35 or CS-P, or
ization established in the Decision on Principles for the
equivalent, in particular blade-off and bird strike. These would
Development of International Standards, Guides and Recom-
be conducted on the fan as a unit (including motor) rather than
mendations issued by the World Trade Organization Technical
on motor or fan alone.
Barriers to Trade (TBT) Committee.
1.5 The applicant for a design approval should seek the
individual guidance of their respective civil aviation authority
2. Referenced Documents
(CAA) body concerning the use of this specification as part of
2.1 ASTM Standard:
a certification plan. For information on which CAAregulatory
F3060 Terminology for Aircraft
bodies have accepted this specification (in whole or in part) as
2
2.2 Code of Federal Regulations:
14 CFR 33 Airworthiness Standards: Aircraft Engines
14 CFR 35 Airworthiness Standards: Propellers
1
ThisspecificationisunderthejurisdictionofASTMCommitteeF39onAircraft
Systems and is the direct responsibility of Subcommittee F39.05 on Design,
Alteration, and Certification of Electric Propulsion Systems.
Current edition approved Sept. 1, 2020. Published October 2020. Originally
2
approved in 2018. Last previous edition approved in 2018 as F3338–18. DOI: Available from U.S. Government Publishing Office (GPO), 732 N. Capitol St.,
10.1520/F3338-20. NW, Washington, DC 20401, http://www.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 -----
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F3338 − 18 F3338 − 20
Standard Specification for
Design of Electric Propulsion Units for General Aviation
1
Aircraft
This standard is issued under the fixed designation F3338; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers minimum requirements for the design of Electric Propulsion Units (EPU).
1.2 Distributed propulsion is not excluded; however, additional requirements will be needed to address the additional issues that
distributed propulsion can create. Some of those issues may include: use of a common motor controller/inverter, segregated electric
harnesses, cooling systems, electric power supplies, and others.
1.3 This specification does not address all of the requirements that may be necessary for possible hybrid configurations where an
EPU and a combustion engine drive a common thruster. This specification may be used for the EPU aspects with supplemental
requirements for the thruster and the combustion engine.
1.4 This Although this specification does not include thespecific requirements for EPUs that include gearboxes, thrusters, liquid
cooling/lubrication, or any energy storage systems. systems, it also does not preclude such capabilities. This specification may be
used for the base EPU base aspects aspects of the design, with supplemental requirements for these additional features. any
additional features prepared by the manufacturer and submitted to the Civil Airworthiness Authority for acceptance. This version
of this ASTM specification also does not address all of the requirements necessary for configurations of motor driven ducted-fans.
It is anticipated that the fan would be subject to parts of 14 CFR 33 or CS-E and/or 14 CFR 35 or CS-P, or equivalent, in particular
blade-off and bird strike. These would be conducted on the fan as a unit (including motor) rather than on motor or fan alone.
1.5 The applicant for a design approval shallshould seek the individual guidance of their respective civil aviation authority (CAA)
body concerning the use of this specification as part of a certification plan. For information on which CAA regulatory bodies have
accepted this specification (in whole or in part) as a means of compliance to their general aviation aircraft airworthiness regulations
(hereinafter referred to as “the Rules”), refer to ASTM Committee F39 webpage (www.ASTM.org/COMITTEE/F39.htm), which
includes CAA website links.
1.6 When applicable, this specification may be used for EPUs with a fixed-pitch propeller or fan. These configurations may be
type-certificated as an EPU including a thruster. There may be additional requirements not currently included in this specification
for this type configuration. In addition, 5.245.25 is included as a test requirement for the EPU. That section recognizes that when
the EPU maydoes not have an integral thruster but it must it will need to be tested with a representative load on the drive shaft
to assure EPU ability to operate properly with static and dynamic loads.
1
This specification is under the jurisdiction of ASTM Committee F39 on Aircraft Systems and is the direct responsibility of Subcommittee F39.05 on Design, Alteration,
and Certification of Electric Propulsion Systems.
Current edition approved Dec. 1, 2018Sept. 1, 2020. Published December 2018October 2020. Originally approved in 2018. Last previous edition approved in 2018 as
F3338–18. DOI: 10.1520/F3338–18.10.1520/F3338-20.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F3338 − 20
1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles
...