ASTM F2840-14(2023)

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.
Designation: F2840 − 14 (Reapproved 2023)
Standard Practice for
Design and Manufacture of Electric Propulsion Units for
Light Sport Aircraft
This standard is issued under the fixed designation F2840; 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 3. Significance and Use
1.1 This practice covers minimum requirements for the
3.1 This specification provides designers and manufacturers
design and manufacture of Electric Propulsion Units (EPU) for
of electric propulsion for light sport aircraft design references
light sport aircraft, VFR use. The EPU shall as a minimum
and criteria to use in designing and manufacturing EPUs.
consist of the electric motor, associated controllers, discon-
3.2 Declaration of compliance is based on testing and
nects and wiring, an Energy Storage Device (ESD) such as a
documentation during the design, ground testing and flight
battery or capacitor, or both, and EPU monitoring gauges and
testing of the EPU by the manufacturer or under the manufac-
meters. Optional onboard charging devices, in-flight charging
turers’ guidance.
devices or other technology may be included.
3.3 Manufacturers of the EPUs are encouraged to review
1.2 This standard does not purport to address all of the
andincorporateappropriatestandardsandlessonslearnedfrom
safety concerns, if any, associated with its use. It is the
groundbasedsystemsasdocumentedinSAEJ2344andEASA
responsibility of the user of this standard to establish appro-
CRI F-58 (see Appendix X2).
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.4 Electric aircraft may contain potentially hazardous level
1.3 This international standard was developed in accor-
of electrical voltage or current. It is important to protect
dance with internationally recognized principles on standard-
persons from exposure to this hazard. Under normal operating
ization established in the Decision on Principles for the
conditions, adequate electrical isolation is achieved through
Development of International Standards, Guides and Recom-
physical separation means such as the use of insulated wire,
mendations issued by the World Trade Organization Technical
enclosures, or other barriers to direct contact. There are
Barriers to Trade (TBT) Committee.
conditions or events that can occur outside normal operation
that can cause this protection to be degraded. Some means
2. Referenced Documents
shouldbeprovidedtodetectdegradedisolationorgroundfault.
2.1 ASTM Standards:
Inaddition,processesorhardware,orboth,shouldbeprovided
F2245 Specification for Design and Performance of a Light
to allow for controlled access to the high voltage system for
Sport Airplane
maintenance or repair. A number of alternative means may be
F2972 Specification for Light SportAircraft Manufacturer’s
used to achieve these electrical safety goals including auto-
Quality Assurance System
matic hazardous voltage disconnects, manual disconnects,
interlocksystems,specialtoolsandgrounding.Theintentionof
2.2 Other Standards:
EASA CRI F-58 Lithium Battery Installations all these means is either to prevent inadvertent contact with
hazardous voltages or to prevent damage or injury from the
SAE J2344 Guidelines for Electric Vehicle Safety
uncontrolled release of electric energy. Lightning strikes are
not addressed in this Standard Practice because LSA aircraft
This practice is under the jurisdiction ofASTM Committee F37 on Light Sport
are limited to VMC flight only.
Aircraft and is the direct responsibility of Subcommittee F37.20 on Airplane.
Current edition approved Jan. 1, 2023. Published January 2023. Originally
approved in 2011. Last previous edition approved in 2014 as F2840 – 14. DOI: 4. Electric Propulsion Unit (EPU) Model Designation
10.1520/F2840-14R23.
4.1 Electric Propulsion Parts List—A detailed parts list is
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
required for each electric propulsion unit qualified in accor-
Standards volume information, refer to the standard’s Document Summary page on
dance with this specification.
the ASTM website.
Available from European Union Aviation Safety Agency (EASA), Konrad-
4.2 New Electric Propulsion Unit Model Designations:
Adenauer-Ufer 3, D-50668 Cologne, Germany, https://www.easa.europa.eu.
4.2.1 Each new EPU must be qualified in accordance with
Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
PA 15096, http://www.sae.org. this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2840 − 14 (2023)
4.2.2 Design or configuration changes that impact the in- shall incorporate electrical isolation-insulation materials ca-
stallation interface, performance, or operability of the EPU pable of shielding the occupants and ground personnel from
require a new EPU model designation. electrical shock in the event of an in flight or ground based
emergency. Wire insulation subject to arc tracking, such as
4.3 Design Changes of Parts—Each design change of a part
TM
Kapton , shall not be used. Isolation means the electrical
or component of an EPU model qualified to this specification
resistance between the battery high voltage system and any
shall be evaluated to the requirements of this specification.
airframe conductive structure.Avalue greater than or equal to
5. Data Requirements
500 ohms/volt at the maximum working voltage is defined as
isolated. As a minimum, the system shall:
5.1 Retained Data—The following data and information
6.2.1 Incorporate a non-resettable fuse as part of the energy
shall be retained on file at the manufacturer’s facility or
storage device which protects the main power lead wires from
alternative business entity for a minimum of 18 years after
an over-temperature or over-current condition. A warning or
production is discontinued.
indication device to alert the pilot shall be incorporated.
5.1.1 Drawings, reference specifications and other technical
6.2.2 Incorporate a pilot/mechanic operated main shutoff of
data that define the EPU configuration.
the energy storage device from the remainder of the EPU
5.1.2 Primary material and process (M&P) specifications in
system.Thisshutoffshallnotrelyonanyprocessororsoftware
effect at the time of Declaration of Compliance and referenced
actions to provide electrical isolation of the energy storage
in the parts drawings. Second tier, flow down M&Pdocuments
device.
are not required to be retained.
6.2.3 Incorporate an ESD which is electrically isolated from
5.1.3 Engineering analyses and test data prepared for quali-
the airframe.
fication with this specification.
6.2.4 Consider incorporation of a ground fault detection
5.2 Delivered Data—The following data shall be delivered
system that provides the pilot or ground personnel a warning if
to the airplane manufacturer to support design and operation of
the airframe is no longer fully electrically isolated from the
the applicable airplane.
energy storage device.
5.2.1 An EPU performance specification that defines the
6.2.5 Be designed for flight in (or flight subsequent to
system performance under all anticipated operating environ-
exposure to) heavy rain without risk to occupants or ground
ments.
personnel.
5.2.2 An installation manual that defines all functional and
6.2.6 Incorporate warnings, cautions or placards on compo-
physical interface requirements of the EPU. This should
nents and on the airframe exterior conveying the potential high
include an EPU installation drawing.
voltage hazards.
5.2.3 Detailed specifications for any caution or warnings
6.2.7 Develop maintenance procedures enabling continuous
that must be placed on the aircraft. The warnings shall ensure
airworthiness with minimal risk to mechanics or ground
that operators, maintenance crews, and emergency crews
personnel.
understand potential hazards with the electric propulsion sys-
tem.
6.3 Electrical Arcing—The EPU shall be designed to elimi-
5.2.4 An operating manual that defines normal and abnor-
nate the possibility of high voltage electrical arcing (or corona
mal operating procedures and any applicable operating
effect) at altitudes up to those specified as the maximum in the
limitations, including EPU and any aircraft limitations.
operating manual (see 5.2.4).
5.2.5 A maintenance manual that defines periodic installed
6.4 Cooling—The EPU must include provisions for cooling
maintenance, major inspections, replacement or overhaul
components as required for safe operation when operated
intervals, and any other maintenance limitations including
within the operational limitations (see 5.2.4). Provisions must
limited life components requiring replacement between over-
consider cooling requirements for all phases of flight (as a
haul intervals. Maintenance requirements for the continued
minimum take-off, climb, cruise, descent, and ground taxiing)
airworthiness of the EPU shall be specified. This manual shall
at all power settings, and also ground operations at all power
identify any special equipment or testing required to ensure the
settings.As a minimum, the operating manual required in 5.2.4
electric propulsion system is safe for continued operation.
must specify motor and energy storage device temperature
5.2.6 An overhaul manual that provides instructions for
limits. Cooling provisions for the energy storage device during
disassembling, replacing or overhauling components identified
charging must also be considered.
in the manual for such, in order to return the EPU to airworthy
6.5 Motor Mounting—The motor and motor attach load
condition that is safe for operation until the next major
factorrequirementsshallcomplywiththeflightandemergency
overhaul.
landing load factors of the applicable airframe specification,
6. Design Criteria
that is, Specification F2245, et al. Attach points on the motor
must have data for the correct design of mounting structures to
6.1 Materials—The materials and components used in the
EPUmustbeadequatefortheintendeddesignconditionsofthe the airframe. The maximum allowable limit and ultimate loads
for the motor mounting attachments and related structure must
system.
be specified.
6.2 Fire and Electric Shock Prevention—The design and
construction of the EPU shall minimize the probability of the 6.6 Energy Storage Device (ESD) Mounting—The ESD-
occurrence and spread of fire and electric shock. The design EPU manufacturer shall provide to the airframe manufacturer
F2840 − 14 (2023)
anticipated flight and emergency landing loads to be trans- 6.13.2 Considerincorporationofa“recommended”warning
ferredtotheairframe.AttachpointsontheESDmusthavedata lighttoinformthepilotthatthereisminimumenergyleftinthe
for the correct design of mounting structures to the airframe. system.
The maximum allowable limit and ultimate loads for the ESD 6.13.3 Incorporate tachometer informing the pilot of the
mounting attachments and related structure must be specified. motor RPM and the maximum allowable motor RPM.
6.13.4 Incorporate temperature gauge for the motor inform-
6.7 Processor Controlled Functions—The EPU shall be
ing the pilot of the motor temperature status and the maximum
designed such that it is tolerant of loss of non-essential
allowable temperature.
functions without loss of power to the propeller. Electrical
6.13.5 Incorporate a method to inform the pilot that the
system components having the potential for instantaneous
electric propulsion unit is in “run” mode.
failure versus wear out mode shall be identified. A safety
6.13.6 Incorporate instrument warning lights to inform the
analysis of instantaneous failure modes on critical components
pilot of any degraded performance modes or other safety
shall be identified by a safety analysis and consideration be
issues.
given for redundancy. Design consideration of EMI,
environmental, HIRF, and software influences on the perfor-
7. Qualification Tests
mance of digital and microprocessor controlled devices, shall
7.1 Calibration Test—Each EPU design shall be tested and
be made.
the characteristics of the system rated shaft power, speeds,
6.8 Pilot Controls—The EPU shall have a throttle and other
electricpowerconsumptionandenergystoragedevicecapacity
controls that are simple, non-confusing and intuitive.
shall be determined.
6.9 Low State of Charge Performance—Any significant
7.2 Energy Storage Device Charging Test—Each EPU shall
reductions in power with a “near empty” energy storage device
be tested to confirm that the (ESD) can be fully charged
or with an emergency “limp home” mode are acceptable
without incurring damage or degradation when charged by any
provided they are documented in the operating manual (see
source which the designer/manufacturer has specified for the
5.2.4)andthepilotisclearlyinformedofthelimitationthrough
system.Duringthespecifiedtesting,theelectricalcurrentatthe
the EPU instrumentation.
sourcemustbeconsideredtobeunlimitedandthevoltagetobe
the full range defined for the source. Additionally, the ESD
6.10 Reliability—Shall conform to the test described in 7.5.
shall be tested to determine the number of life cycles for which
6.11 Vibration—The EPU shall be designed and constructed
it is certified.The established cycle life shall be documented in
so that it will operate throughout its normal operating range of
the operating, maintenance, and overhaul manuals (see 5.2.2,
propeller speeds and power without inducing excessive vibra-
5.2.4 and 5.2.6).
tions or stress in any of the EPU or airframe parts. EPU design
7.3 Durability Test—Each EPU shall be subjected to a
considerationshallbegivenregardingvibrations-loadsinduced
system test that will verify durability by one of the following
from ground operations, that is, rough field operations etc.
methods:
6.12 Charger—The EPU charging system shall be designed
7.3.1 Accelerated Overhaul Test—This test simulates an
to safely enable ground personnel to recharge the energy
EPU overhaul interval. A protocol for this test shall
storage device. As a minimum the system shall:
incorporate, as a minimum, the following elements:
6.12.1 Be designed to prevent improper (reverse polarity)
7.3.1.1 At least 100 % of the time at maximum power that
connections. Incorporate fea
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