ASTM F3389/F3389M-21

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: F3389/F3389M − 21
Standard Test Method for
Assessing the Safety of Small Unmanned Aircraft Impacts
ThisstandardisissuedunderthefixeddesignationF3389/F3389M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 The applicant should understand the actual operating
characteristicsoftheirsUAbeforestartingtheprocessoutlined
1.1 This test method is applicable to small unmanned
in this test method. It is assumed that the applicant is able to
aircraft (sUA) that are limited in the United States in accor-
substantiate the most probable, worst-case (MPWC) impact
dance with 14 CFR § 107.3 to be less than 55 lbf. The test
orientationofthesUA;typicalandmaximumoperatingheights
methodprovidesastandardizedmethodforassessingthesafety
and speeds; and terminal velocity of their sUAas a function of
of sUA impacts with a person on the ground. Results from
altitude to compare the results of the impact analysis with the
testing using MethodsA, B, C, or D are intended to be used to
proposedoperationforthesUA.Thistestmethodisintendedto
support an applicant in obtaining permission from the govern-
supplement the verification requirements of Specification
ing Civil Aviation Authority (CAA) for flight over people.
Approval of reports for the conduct of tests and the decision to F3298 and Specification F3322, as well as a supplement to
grant permission rests with the governing CAA based upon Specification F2910. This test method should not be used as a
adherence to the methodologies outlined in this test method.
stand-alone document without consideration of other ASTM
UAS standards.
1.2 This test method is based on methods researched by the
FAA Center of Excellence for Unmanned Aircraft Systems
1.6 These methods assume that a blunt force head impact is
(UAS) supported by the Alliance for System Safety of UAS
the most likely injury mechanism leading to serious injury or
through Research Excellence (ASSURE). These methods ex-
fatalities. The level of blunt force injury to the head may be
pand on extensive research and testing conducted by the
adjusted for various applications (such as sUA operations
automotiveindustrytosupportquantitativeautomotivepassen-
around first responders with helmets) and compared with the
ger safety standards and testing and test data on sUAcollected
amount of force or load factor that the sUAtransfers during a
by ASSURE.
collision.
1.3 The purpose of this test method is to define a method to
1.7 Method B is not appropriate for foam-built fixed-wing
establish confidence in the overall injury potential of a particu-
sUAdue to the stiffness of the FAAHybrid IIIATD Head and
lar sUA configuration under probable failure conditions. This
Neck. Until a different impactor can be developed for Method
testing is not meant to simulate the worst possible impact for
B, these sUA should use Method C or D for evaluation.
the most conservative set of the population. It is expected that
CAAs should determine what injury thresholds are acceptable
1.8 Units—The values stated in either International System
under their public policy and determine operational limitations
(SI) units or inch-pound units are to be regarded separately as
for various operations by using the data from this testing in
standard. The values stated in each system are not necessarily
conjunction with the specific concept of operations proposed
exact equivalents; therefore, to ensure conformance with the
by the applicant.
standard,eachsystemshallbeusedindependentlyoftheother,
1.4 The test method provides four methods for evaluating
and values from the two systems shall not be combined.
the potential for impact injury: a simple analytical method, a
1.9 This standard does not purport to address all of the
simplified test, a more rigorous test, and a test method normed
safety concerns, if any, associated with its use. It is the
to approximate energy transfer values with appropriate safety
responsibility of the user of this standard to establish appro-
margins applied to each approach to address uncertainty in
priate safety, health, and environmental practices and deter-
each of the approaches.
mine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accor-
1 dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee F38 on
UnmannedAircraftSystemsandisthedirectresponsibilityofSubcommitteeF38.01
ization established in the Decision on Principles for the
on Airworthiness.
Development of International Standards, Guides and Recom-
Current edition approved Sept. 1, 2021. Published November 2021. Originally
mendations issued by the World Trade Organization Technical
approved in 2020. Last previous edition approved in 2020 as F3389/F3389M–20.
DOI: 10.1520/F3389_F3389M-21. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3389/F3389M − 21
2. Referenced Documents Terminology Standard, and F3060,AircraftTerminology Stan-
2 dard. Terminology that is unique to this test method is defined
2.1 ASTM Standards:
in this section.
F2910Specification for Design and Construction of a Small
Unmanned Aircraft System (sUAS) 3.2 This test method uses terminology contained in Speci-
F3060Terminology for Aircraft
fication F3298 and Specification F3322. These terms are not
F3298Specification for Design, Construction, and Verifica- duplicated in this test method.
tion of Lightweight Unmanned Aircraft Systems (UAS)
3.3 Definitions of Terms Specific to This Standard:
F3322Specification for Small Unmanned Aircraft System
3.3.1 critical speed for Method D—the critical speed for
(sUAS) Parachutes
Method D testing varies from the definition in Terminology
F3341/F3341MTerminology for Unmanned Aircraft Sys-
F3341/F3341M. The critical speed for Method D testing is
tems
either the highest ground speed achievable in powered flight,
2.2 Code of Federal Regulations:
including the proposed environmental conditions (that is,
14 CFR § 107.3Definitions
wind),orthemaximumresultantspeedbasedonanunpowered
49 CFR Section 571.208Occupant crash protection
free-fall from the maximum attainable altitude, whichever is
49 CFR Part 572 Subpart EAnthropomorphic Test Devices
higher.Ifparachutesareusedasamitigation,thecriticalspeed
Subpart E - Hybrid III Test Dummy (§§ 572.30 - 572.36)
is defined in Annex A1.
2.3 FAA Documents:
3.4 Acronyms and Abbreviations:
DOT/FAA/AR-09/41Neck Injury Criteria for Side-Facing
3.4.1 AIS—abbreviated injury scale
Aircraft Seats
FAA AC 25.562-1 Rev BDynamic Evaluation of Seat
3.4.2 ARC—advisory rulemaking committee
Restraint Systems and Occupant Protection on Transport
3.4.3 ASSURE—Alliance for System Safety of UAS
Airplanes
through Research Excellence
FAA Docket Number FAA-2018-1087Operation of Small
3.4.4 ATD—anthropomorphic test device; a crash test
Unmanned Aircraft Systems Over People
dummy
2.4 NHTSA Standards:
FMVSS 208Federal Motor Vehicle Safety Standard 208 - 3.4.5 CAA—civil aviation authority
Defined in 49 CFR Part 571.208
3.4.6 CFC—channel frequency class
th
TP-208-14 Appendix A Part 572E (50 Male)Dummy
3.4.7 CONOPS—concept of operations
Performance Calibration Test Procedure
3.4.8 DAQ—data acquisition
2.5 SAE Standards:
SAE J211/1Instrumentation for Impact Test—Part 1: Elec-
3.4.9 IARV—injury assessment reference values
tronic Instrumentation
3.4.10 KE—kinetic energy
SAE J211/2Instrumentation for Impact Test—Part 2: Pho-
3.4.11 MPWC—most probable, worst case
tographic Instrumentation
SAE J1727Calculation Guidelines for Impact Testing
3.4.12 NHTSA—National Highway Traffic Safety Adminis-
SAE J1733Sign Convention for Vehicle Crash Testing
tration
2.6 UN Regulation:
3.4.13 NIAR—National Institute for Aviation Research at
UN Regulation No. 94Occupant Protection in Frontal Col-
Wichita State University
lisions: Uniform Provisions Concerning the Approval of
3.4.14 N —neck injury criteria
Vehicles with regard to the Protection of the Occupants in ij
the Event of a Frontal Collision
3.4.15 NPRM—notice of proposed rulemaking
3.4.16 OEM—original equipment manufacturer
3. Terminology
3.4.17 PMHS—post mortem human surrogate
3.1 Unique and Common Terminology—Terminology used
in multiple standards is defined in F3341/F3341M, UAS 3.4.18 PPE—personal protective equipment
3.4.19 sUA—small unmanned aircraft; the flying aircraft
only
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
3.4.20 sUAS—small unmanned aircraft system; an sUAand
Standards volume information, refer to the standard’s Document Summary page on
itsassociatedelements(includingcommunicationlinksandthe
the ASTM website.
Available from U.S. Government Publishing Office (GPO), 732 N. Capitol St.,
components that control the sUA) that are required for the safe
NW, Washington, DC 20401, http://www.gpo.gov.
and efficient operation of the sUA in a national airspace
Available from Federal Aviation Administration (FAA), 800 Independence
system.
Ave., SW, Washington, DC 20591, http://www.faa.gov.
Available from National Highway Traffic Safety Administration (NHTSA),
3.4.21 UAH—The University of Alabama in Huntsville
1200 New Jersey Ave., SE, Washington, DC 20590; described in http://
www.nhtsa.gov/cars/rules/import/FMVSS/#SN208.
AvailablefromSAEInternational(SAE),400CommonwealthDr.,Warrendale, 4. Summary of Test Method
PA 15096, http://www.sae.org.
4.1 This test method describes four methods for assessment
Available from GlobalAutoRegs, https://globalautoregs.com/rules/105-
occupant-protection-in-frontal-collisions. of the safety of an sUA to assess injury potential associated
F3389/F3389M − 21
with an impact. The applicant can choose the method that is low impact KE below 54 ft-lbf [73J] may not require rigorous
appropriatefortheirsUAbasedonmassandspeed,orbasedon testing to ensure safety to the nonparticipating public and can
the rigor required. use Method A. Vehicles with higher impact KEs should
conduct impact testing using Method B, Method C, or Method
4.2 Method A requires the applicant to use the sUA mass
D. Method B is simpler than Method C and, therefore, less
and operating characteristics to define an operating envelope
costly for the applicant. Method B results may be more
that shall keep the sUA below a safe KE threshold. This is
conservative since the test setup is more rigid and can result in
intended for lightweight or slow falling sUAthat present little
an increase in the amount of energy transferred during the
or no risk to the public.
impact than the injury metrics established using a full ATD.
4.3 Method B uses an instrumented ATD head form and
Method C testing is costlier and schedule-intensive, but pro-
requires the applicant to conduct a series of impact tests using
vides a higher level of certainty of the injury potential of the
the sUA. Impacts are conducted at the MPWC impact
sUAandismoredirectlycomparabletoestablishedautomotive
orientation, which is determined through a combination of
injurymetricsandinjurymetricsderivedfromATDtestingand
engineering judgment and experiments. The test allows a
used by the governing CAA. Method D allows for the direct
characterizationoftheaccelerationsthatmaybeexperiencedat
comparison to energy-based requirement of some CAAs.
impact as a function of sUAKE.Asafe threshold value of KE
5.4 The output of MethodAis a verification that the sUAor
is identified using a level of acceleration that corresponds to a
sUA with mitigation does not exceed the 54 ft-lbf impact KE
low risk of an AIS3 skull fracture. The weight limit for this
throughout its flight envelope based upon flight test data as
method is 8 lbf for sUA and larger sUA up to 55 lbf being
meansofobtainingapprovalforflightoverpeopleforCategory
tested at parachute speeds. Method B is not appropriate for the
2 or 3 operations for the FAA. Other governing CAAs may
testingoffoamfixed-wingsUAduetotheincreasedrigidityof
only require a weight metric or other impact energy metric in
the test setup.
lieu of the 54 ft-lbf impact KE.
4.4 Method C uses an instrumented ATD and requires
5.5 The output from Methods B and C is a characterization
impacts at multiple energies and three different impact angles.
of the forces (measured in acceleration of the head form or
Data is collected that give insight to possible head and neck
ATD) expected during an MPWC head impact as a function of
injuries based on FMVSS 208. These test results can be
sUA KE. For Method B, this result is compared to the
compared to automotive injury risk metrics associated with
minimum impact energy resulting in a skull fracture based
30% probability of an AIS 3 or greater injury or against
solely upon peak acceleration to determine the impact KE
defined injury metrics developed and used by the governing
associated with this injury based upon energy transfer. Method
CAA. The weight limit for this method is 8 lbf for sUA and
C testing is more rigorous and may be correlated to other
larger sUA up to 55 lbf being tested at parachute speeds.
standards for both head and neck injury (such as the FMVSS
4.5 Method D uses an instrumented ATD head form and
208 or other automotive standards) to determine whether the
neck and requires the applicant to conduct a series of impact
sUA is sufficiently safe to operate in Category 2 and 3
tests using the sUA and a rigid object. Impacts are conducted
Operations. By evaluating sUAKE in the MPWC orientation
in three different trajectories with respect to the ATD head
and a variety of ATD impacts, the applicant should assess the
usingtheMPWCorientation.MPWCorientationisdetermined
sUA for injury potential using the governing CAA injury
based on analysis of the CONOPS and potential failure modes
thresholds. The limiting impact KE may establish the opera-
of the aircraft. If parachutes are used as a mitigation, the
tional limits that correspond to that specific value. This test
MPWC should be determined with the mitigation applied.The
method proposes the use of the standards called out in the
test results of the sUA are compared with the head injury
ASSURE impact tests conducted as part of Task A14.
criteria (HIC ), peak acceleration, the N neck injury criteria,
15 ij
5.6 TheoutputfromMethodDisaverificationthatthesUA
and neck compression results for rigid object impacts at each
does not exceed the comparison metrics associated with the
orientation. This method allows the tailoring to an energy
transfer of energy resulting from the impact of a rigid object at
transfer requirement, which may be requested by some CAAs.
aspecifiedimpactKEfortherigidimpactor.TheimpactKEof
the rigid impactor is determined by the CAA for different
5. Significance and Use
categories of operations over people. For example, an sUA
5.1 The test method is intended to be used by sUAS meets this standard if its impact test results are lower than the
manufacturers, sUAS operators, and CAAs to assess the safety rigid object test results.
of sUA impacts to people on the ground during operations
5.7 Outputs from Methods A, B, C, and D may be used in
involving flight over people.
conjunction with governing CAA’s metrics for certifying the
sUA for flight over people.
5.2 The test method provides a framework for creating new
designsandevaluatingexistingdesignstodeterminethesUA’s
bluntforcetraumainjurypotentialtotheheadorneck,orboth,
Mertz, H. J., “Biofidelity of the Hybrid III Head,” SAE Technical Paper
during a collision with a person on the ground.
851245, 1985.
Arterburn,D.,Olivares,G.,Bolte,J.,Prabhu,R.,Duma,S.,FinalReportforthe
5.3 Applicants can determine whether to use MethodsA, B,
FAA UAS Center of Excellence Task A14: UAS Ground Collision Severity
C, or D based upon their specific sUA characteristics, flight
Evaluation 2017-2019, prepared for the FAA under Grant # 15-C-UAS-UAH-07,
operations, and CAA requirements. In some cases, sUA with September 2017.
F3389/F3389M − 21
6. Apparatus 7. Hazards
7.1 This test method involves impacts with significant KE.
6.1 Method A does not require any specific apparatus.
The test apparatus should be set up to control the sUAimpact
6.2 MethodBrequirestheuseofaninstrumentedheadform
to stay within the test apparatus throughout the impact.
with three accelerometers (one in each orthogonal axis).
th 7.2 The impacts may break the sUA. The test apparatus
Testing shall be conducted with an FAA Hybrid III 50
should be designed to prevent flying debris from becoming a
PercentileMaleheadandneckorotherheadformapprovedfor
hazard. Participants must use appropriate PPE or remain
use by the governing CAA for vertical impact tests.
protected during the test.
6.3 MethodCrequirestheuseofaninstrumentedATDwith
7.3 When testing an sUAwith fuel power plants or lithium
three accelerometers and three angular rate sensors in the head
batteries, or both, an appropriate fire extinguisher for each
form, and neck load cells capable of recording data in
application should be within reach. Participants should be
accordance with the FMVSS 208 standard to determine peak
made aware of the hazards of lithium batteries, and which fire
acceleration, HIC , for assessing head injuries, as well as N
15 ij
extinguishers are appropriate for lithium-based fires. Batteries
and neck compression values for assessing neck injuries.
should be tested when they are at their minimum level of
th
Testing may be conducted with an FAA Hybrid III 50
charge. Consideration should be made for the amount of fuel
Percentile Male ATD or other ATD approved for use by the
contained in the vehicle during the impact to minimize the risk
CAA for vertical and lateral head impact tests.
of fire.
6.4 MethodDshalluseanAnthropomorphicTestingDevice
th
8. Test Articles
50 Percentile Male FAA Hybrid III ATD head and neck
instrumentedATD with three accelerometers and three angular
8.1 sUA used in this test shall be mechanically and struc-
rate sensors in the head form, and neck load cells capable of turally equivalent to the actual flying configuration. The sUA
recording data in accordance with 49 CFR Section 571.208 to does not need to be operational or powered, but it shall be the
determine N and neck injury values. The use of a full FAA same mass, internal configuration of equipment, the same
ij
th
Hybrid III 50 Percentile Male ATD, or other ATD approved structuralelements,andwiththesamepowerplantastheflying
configuration. The test article must be representative of the
for use by the CAA is acceptable. The selected impactor used
final production article, and test article is selected in order to
should weigh between 1 and 5lb with an approximate frontal
create the critical case condition for the parameters being
area of 6 to 12 in. .
measured. It is important that the test is conducted with the
6.5 The instrumentation, collection of data, and filtering of
approved payload as defined by the manufacturer. If items of
that data in these tests should meet the requirements of SAE
any significant mass can become separated during flight, then
J211/1.
these payloads, batteries, etc. should be tested separately to
assess their injury potential.
6.6 The speed of the sUArelative to the stationary impactor
8.1.1 Batteriesthatpresentapotentialforfireduringimpact
justpriortothetimeofimpactshouldbemeasuredforeachtest
should be discharged as much as possible to minimize the risk
point. This test method does not require a specific method.
of a fire.Applicants may consider removing strap-on batteries
Possiblemethodsincludehigh-speedvideooftheimpactmade
and use a weight representative mass of similar size and
perpendicular to the fall, with a way of measuring the distance
stiffness to mitigate this hazard.
travelled between frames—radar, ultrasonic distance
measurements, or other sensors. Applicants may use SAE 8.2 Test articles may be used for more than one test if they
J211/2, which describes the test and analysis methods for are inspected between tests and found to be mechanically and
determiningvelocityfromvideodata.Instrumentationmethods structurally equivalent to the original configuration. Internal
must be documented in the test plan and included in the test parts must be mounted to the sUAif mounting locations exist,
and all mounted components must be present since these
description/procedure provided with the test report to the
governing CAA. The uncertainty of the measurement should structures can change the stiffness of the sUAduring collision.
Parts that are broken or cracked must be replaced to bring the
be documented.
test sUA into mechanical and structural equivalency with the
6.7 If an FAA Hybrid III Head and Neck is used for the
original configuration. Structurally equivalent and confor-
conduct of the Method D test, then consideration should be
mance means all load paths remain in place and all masses are
given to installing gas-damped accelerometers in the head of
located in their respective positions. Visual inspections are
the ATD. Gas-damped accelerometers are highly desirable for
sufficient. Repairs/changes to the sUA between tests from the
rigid body impacts since the head and neck configuration can
nominal configuration should be documented in the final
be substantially stiffer than a full FAA Hybrid III ATD. Data
report.
acquisition devices should use sampling rates of at least
8.3 The configuration of each sUAused in each impact test
250kHzwhentestingwithhead-andneck-onlyATDstoavoid
should be documented in the test plan and test report.
signalaliasing.Applicantsareencouragedtoconductsampling
studies as part of their means of compliance when using a 8.4 For Method D, the selection of the comparative impac-
head- and neck-only target to validate that their data is not
tor should be chosen to approximate the contact area and
being adversely affected prior to the start of testing. weight of the sUAunder consideration. The selected impactor
F3389/F3389M − 21
used should weigh between 1 and 5lb with an approximate KE threshold. If the sUAspeeds at impact are greater than
max
frontal area of 6 to 12 in. in a symmetrical fashion. resultant v , then the applicant should limit the operating
max
envelopetov .IfthesUAspeedsarelessthanv ,thenthe
max max
9. Preparation of Apparatus
applicant should declare the sUA speeds as the operating
envelope. Applicants should include environmental variables
9.1 Method B shall use a head form with a minimum of
such as sUA modes, failure conditions, wind, etc. when
three accelerometers (one in each orthogonal axis).Ahead and
th
substantiating the v under the provisions of Method A.
max
neck from a 50 Percentile Male FAAHybrid IIIATD may be
11.1.3 The applicant must also consider the case that the
used for this test. Alternate head forms may be used if
sUAfalls from altitude. The applicant should measure a curve
approved for use by the governing CAA.
of falling velocity versus height and use this to construct a
9.2 Method C shall use an instrumented ATD with three
curveoffallingKEversusheight.IfthesUAKEisevergreater
accelerometersandthreeangularratesensorsintheheadform,
than KE , then the applicant should limit the maximum
max
and neck load cells capable of recording data in accordance
operating altitude such that the KE at impact shall be equal to
with the FMVSS 208 standard to determine neck compression
or less than KE .
max
and N values associated neck injury. An Anthropomorphic
ij
11.1.3.1 If the applicant does not have a curve of falling
th
Testing Device 50 Percentile Male FAAHybrid IIIATD may
velocity versus height, then the applicant may define the
be used for Method C. The ATD shall be instrumented with
maximum operating altitude, alt , associated with 54 ft-lbf
max
accelerometers measuring around three orthogonal axes or a
[73J]usingpotentialenergyasafunctionofheight.Thistends
nine-accelerometer array that shall collect linear acceleration
to be very conservative, as this does not consider drag during
about the center of gravity of the head. The upper neck of the
falling.
ATD shall be instrumented with a six-axis load cell to measure
11.2 Method A Calculation and Interpretation of Results:
forces and moments about the x, y and z-axes.AlternateATDs
thatprovideequivalentdatamaybeusedifapprovedforuseby
11.2.1 Kinetic energy is calculated as: KE5 m3v .
the CAA.
11.2.2 The maximum safe resultant speed (v ), combined
max
9.3 MethodDshalluseanAnthropomorphicTestingDevice
horizontal and vertical speed, is calculated as v
max
th
50 Percentile Male FAA Hybrid III ATD head and neck
=
5 @~2 3 KE !⁄m#, where KE is the threshold shown in
max max
instrumented with three accelerometers in the head form, and
11.1.1 and m is the mass of sUA as it would be flown. Care
neckloadcellscapableofrecordingdatainaccordancewith49
mustbetakentoensurethecalculationisdonewiththecorrect
CFR Section 571.208 to determine N and neck injury values.
ij
units. While v is calculated from KE ,v is the
max max max
Alternate ATDs that provide equivalent data may be used if
2 2 2
resultant speed, v 5=~v 1 v 1 v ! and should be consid-
max x y z
approved for use by the CAA.
eredwhenapplyingthisvaluetotheassessmentsofoperational
speeds associated with any given operation and associated
10. Calibration and Standardization
failure modes.
10.1 ATD load cells shall be calibrated on an “as needed”
11.2.3 Maximum altitude (alt ) is calculated as either:
max
basis and a minimum of once every 12 months.ATD and head
11.2.3.1 The falling distance at which the KE of the sUAat
formaccelerometersshallbecalibratedonan“asneeded”basis
the ground equals KE . If the KE of the falling sUA is
max
and a minimum of once every six months. Need is determined
alwaysbelowKE (v max max
by a pre- and post-test shunt calibration. If bridge balance
limitation to the operating envelope.
remains unchanged and if full-scale shunt calibration results in
11.2.3.2 If the applicant does not know falling KE versus
the same factor, then the transducer characteristics are within
height, calculate alt 5@KE ⁄ ~m 3 g!#.
max max
calibration. If loads become suspect, linearity of the load cell
11.3 Method A Report:
shall be checked with a universal compression testing machine
11.3.1 A Method A report shall include at a minimum the
or other calibration device to determine serviceability. Exact
following information:
calibration procedure to be found in TP-208-14 Appendix A
th
11.3.1.1 Results of flight tests showing most probable fail-
Part 572E (50 Male) Dummy Performance Calibration Test
ure modes and associated descent rates though a minimum of
Procedure.
200 ft above ground level (AGL) following failures.
10.2 All ATDs and associated instrumentation should meet
11.3.1.2 A statement that states that this analysis was
the standards outlined in SAE J211/1 dated 2014-03-31 and
conducted in accordance with Method A of this test method.
SAE J211/2 dated 2008-11-18.
11.3.1.3 The sUA model considered, with any relevant
information about version or configuration.
11. Method A
11.3.1.4 ThesUAoperationalenvelopethatkeepstheKEof
11.1 Method A Procedure:
sUA impacts below 54 ft-lbf [73J]. This should include
11.1.1 Method A allows the applicant to define an opera-
maximum speeds or maximum altitude, or both.
tional envelope that shall keep the KE of the sUA below the
11.3.1.5 The maximum environmental conditions used in
threshold (KE ) of 54 ft-lbf [73J] at impact.
max the calculation of v .
max
11.1.2 Defining the operating envelope means the applicant
12. Method B
should compare the maximum sUAlateral and vertical impact
speeds to a resultant v defined by the sUA mass and the 12.1 Method B Procedure:
max
F3389/F3389M − 21
12.1.1 MethodBisconductedusingaheadformcontaining (5)Batteries that present a potential for fire during impact
a three-axis accelerometer. should be discharged as much as possible to minimize the fire
risk. The batteries should be tested separately to demonstrate
12.1.2 Applicants should develop a test plan/procedure that
that there is no risk of fire at impact (many battery manufac-
describes, at a minimum, the following:
turersperformsuchtestsaspartoftheirdevelopmentprocess).
12.1.2.1 The name and address of the test facility perform-
The manufacturer should maintain a report of the battery
ing the tests.
impact test, with photographic or video evidence, to demon-
12.1.2.2 The name and telephone number of the individual
strate the battery does not ignite at impact.
at the test facility responsible for conducting the tests.
(6)Test articles should not be used for more than one test.
12.1.2.3 Abrief description or photograph, or both, of each
For example, visual inspection of composite material may be
testfixture.Astatementconfirmingthatallinstrumentationand
found to be mechanically equivalent to the original
data collection equipment used in the test meet the facility’s
configuration, but they are not. Test articles should only be
internalcalibrationrequirements,thatthesecalibrationrequire-
reused if they are found to be mechanically and structurally
ments are documented and available for inspection upon
equivalent to the original configuration. Use of inspections to
request,thatallcalibrationsaretraceabletoanationalstandard,
determine mechanical and structural equivalency shall be
and that the records of current calibration of all instruments
included in the test report to the governing CAA for concur-
used in the test are maintained at the facility.
rence on the reuse of test articles.
12.1.2.4 Astatementconfirmingthatthedatacollectionwas
12.1.2.6 A description of the photographic instrumentation
done in accordance with the detailed description of the actual
system used in the tests.
procedure used and technical analysis showing equivalence to
12.1.2.7 Test Description—The description of the test
the recommendations of this test method.
should be documented in sufficient detail, so that the tests
12.1.2.5 Test Articles:
couldbereproducedsimplybyfollowingtheguidancegivenin
(1)In all cases, the test article (that is, sUA) should be
the report. The procedures outlined in the test plan can be
representativeofthefinalproductionarticleandshouldinclude
referenced in the report but should be supplemented by such
a structural frame, motors, propellers, electronics, batteries,
detailsasarenecessarytodescribetheuniqueconditionsofthe
and payload. The sUA does not necessarily need to be
tests. For example, pertinent dimensions and other details of
powered.ThesUAneednothavefullyfunctionalelectronicsif
the installation that are not included in the drawings of the test
theydonotcontributetothestructuralintegrityoftheplatform.
itemsshouldbeprovided.Theplacementandcharacteristicsof
All electronics should have a mass representative of the
electronicandphotographicinstrumentationchosenforthetest
production configuration and have the same stiffness and
beyond that information provided by the facility should be
shape. The configuration of each sUAused in each impact test
documented.Thiscanincludespecialtargets,grids,ormarking
should be documented, and this configuration should conform
used for interpretation of photo documentation, transducers,
to the production specification of the sUA for which the
etc.
applicant is submitting to the governing CAA. Specific modi-
12.1.2.8 Pass Fail criteria used for the tests.
fications to the sUA that are made to support or conduct the
12.1.3 Determine the MPWC impact orientation.
tests should be clearly documented, along with their potential
12.1.3.1 The MPWC impact orientation shall be specified
impacts on the results of the tests.
by the manufacturer (the sUA manufacturer or the OEM of a
(2)The payload may be replaced by a representative load
payload that shall be carried by a particular sUA). The
made of representative shape, stiffness, and mass. Fuel may be
manufacturer-providedMPWCimpactorientationisonlyvalid
replacedwithwaterorothernonflammableliquidofequivalent
for the specific sUA configuration tested by the manufacturer.
mass.
12.1.3.2 IncaseswheretheMPWCimpactorientationisnot
(3) Items of Mass—DefinedasanypartofthesUAthatcan
specified by the manufacturer or for an sUAconfiguration not
detach during impact (for example, removable cameras, bat-
tested by the manufacturer, the applicant may determine the
teries) and may become a projectile with enough energy to
mostprobableimpactorientationsforthesUAtohitaperson’s
cause a serious injury (see 6.5) to a person. Detachment of
head based on engineering judgment, flight test, any parachute
theseitemsmaybegroundsforretestandthemeansofrestraint
or recovery systems installed, and understanding the operating
for these items may need to be improved by changes to design
characteristics of the sUA.
or implementation. Detachment of an item of mass should not
leaveanysharporinjuriousedges.Onceretentionofanitemof 12.1.3.3 Failure flight-testing is essential for evaluating an
mass has been demonstrated using the standard configuration, sUA’s post-failure dynamic behavior. Many sUA tumble or
subsequent tests may be conducted with the item secured by stabilize in a predictable orientation while falling. Knowledge
means other than those in the standard operational configura- offailuredynamicsisessentialindeterminingprobableimpact
tion for the purposes of the test (if required by the governing orientations. The post-failure dynamics can affect the terminal
CAA). velocityofthesUAand,assuch,itsimpactKE.Longerperiods
(4) The manufacturer, governing specification, serial ofdataloggingimprovethefidelityofaerodynamicanalysis.It
number, and test weight of the ATDs used in the tests, and a is recommended that flight tests be initiated at 800 ft AGL to
description of any modifications or repairs performed on the allow a full 400 ft of fall before initiating recovery via
ATDs that could cause them to deviate from the governing parachute or other decelerative device. Flight tests should
specification. allowforaminimumof200ftoffallbeforeinitiatingrecovery
F3389/F3389M − 21
via parachute or other decelerative device. Flight-testing
as: KE5 m3v .
should be conducted under winds less than 5 kts in order to
provide data for aerodynamic analysis. Winds and gusty
12.2.2 Each impact shall have a 3-axis acceleration time-
conditions during flight test can lead to inaccurate estimates of series measurement of the peak acceleration on each axis.
sUAaerodynamic properties. See considerations for parachute
Calculate the resultant acceleration magnitude as: a
2 2 2
recovery systems in Annex A1.
5=~a 1 a 1 a ! for each point in the time series. Record
x y z
12.1.3.4 For each probable impact orientation, the applicant
the greatest value as the resulting a for the impact.
mag
shall perform a series of drop tests to determine the worst case
12.2.3 Make a linear fit to the data (KE, a ) using the
mag
of these probable orientations. These drop tests should consist
function a KE 5S3KE. S is the energy transfer slope and shall
~ !
of at least three drops in each orientation with a drop height as
have the units g/ft-lbf or g/J. The linear fit of the data should
specified below:
use the maximum points for each test condition. The linear fit
(1)For sUA with a mass less than 2.2 lbf [1 kg], the drop
should be forced to a zero intercept, that is, the resulting
height should be at least 10 ft [3 m].
acceleration from a zero KE impact is zero.
(2)For sUA with a mass greater than 2.2 lbf [1 kg], the
12.2.4 For Method B, calculate the maximum safe impact
dropheightshouldbechosensuchthattheimpactKEisatleast
energy by KE 5G⁄ S , where G is a threshold value of gs
~ !
20 ft-lbf [27 J]. safe
experienced by the head form, and report this value in ft-lbf or
(3)For sUA that employ parachute mitigations for uncon-
J. In the absence of a specific application threshold, the value
trolled flight, the drop height should be chosen such that the
G for skull fracture shall be the peak resultant head accelera-
impact speed is at least 8 fps [2.5 m/s].
tion metrics shown in Chapter 5 of Report for the FAA UAS
12.1.3.5 For each impact, the applicant should record the
Center of Excellence TaskA14: UAS Ground Collision Sever-
sUA details, sUA impact orientation, speed at impact, the
ity Evaluation 2017-2019, or the peak resultant head accel-
maximummagnitudeofmaximumresultantacceleration(a )
mag
eration metrics specified by the governing CAA. For example,
measured by the alternate head form, and any relevant notes
operations over people wearing PPE may utilize a different
about the impact. Any damage to the sUA shall be noted.
peak resultant head acceleration threshold to account for the
12.1.3.6 Average the measured maximum accelerations for
extra protective gear.
each impact orientation.
12.1.3.7 The MPWC impact orientation is the orientation
12.3 Method B Report:
that resulted in the greatest average measured maximum
12.3.1 AMethod B report shall include, as a minimum, the
acceleration over the three drops.
following information:
12.1.4 All further impact tests shall be conducted using the
12.3.2 A statement that states that this analysis was con-
MPWC impact orientation. The applicant should conduct a
ducted in accordance with Method B of this test method.
minimum of five (5) impacts each at two (2) drop test heights,
12.3.3 The sUAS model considered, with any relevant
for a total of at least ten (10) drop tests. The drop heights
information about version or configuration.
should be specified as below:
12.3.4 Information on the test target, including type of
12.1.4.1 For sUA with a mass less than 2.2 lbf [1 kg], the
target, configuration, serial number (if applicable), accelerom-
drop heights should be 10 ft [3 m] and 20 ft [6 m].
eter serial number(s), and calibration information.
12.1.4.2 ForsUAwithamassgreaterthan2.2lbf[1kg],the 12.3.5 Description of the test location, date performed, and
drop heights should be chosen such that the impact KE is 20
test setup and test procedure including description of test
ft-lbf [27 J] and 40 ft-lbf [54 J]. instrumentation.
12.1.4.3 For sUA that employ parachute mitigations for 12.3.6 Results and measurements for each test impact
uncontrolled flight, the drop height should be chosen such that performed, with notes as appropriate.
theimpactspeedis8fps[2.5m/s]and16fps[5m/s].Themass
12.3.7 Results describing how the worst-case orientations
ofthesUAwiththeassociatedparachuteequipmentattachedto that were considered and the data used to substantiate the
the sUA should be included in the tests. This test does not
MPWC; should include flight test results that were used to
define a specific weight since the descent speed and impact determine the terminal velocity and MPWC.
energy is depending on the parachute speed and sUA weight.
12.3.8 Data and calculations resulting in the determination
12.1.5 Foreachimpact,theapplicantshouldrecordthesUA
of the slope S in g/ft-lbf or g/J as well as the calculation of
details, impact orientation, speed at impact, the maximum KE and the threshold value G used in this calculation.
safe
magnitude of the resultant acceleration (a ) measured by the
12.3.9 An assessment of the safe operational envelope
mag
alternate head form, and any notes relevant to the impact.Any proposed including environmental conditions based upon the
damage to the sUA should be noted.
determination of KE .
safe
12.1.6 sUAcanbereusedintestingiftheyareinspectedand
found to have no mechanical damage after the impact. Dam- 13. Method C
agedsUAcomponentscanberepairedorreplacedasneededto
13.1 Method C Procedure:
bring the test article sUA back to the original mechanical and
13.1.1 Applicants should develop a test plan/procedure that
structural configuration.
describes, at a minimum, the following:
12.2 Method B Calculation and Interpretation of Results:
13.1.1.1 The name and address of the test facility perform-
12.2.1 For each impact, calculate the impact kinetic energy ing the tests.
F3389/F3389M − 21
13.1.1.2 The name and telephone number of the individual (6)Test articles should not be used for more than one test.
at the test facility responsible for conducting the tests. For example, visual inspection of composite material may be
found to be mechanically equivalent to the original
13.1.1.3 Abrief description or photograph, or both, of each
configuration, but they are not. Test articles should only be
testfixture.Astatementconfirmingthatallinstrumentationand
reused if they are found to be mechanically and structurally
data collection equipment used in the test meet the facility’s
equivalent to the original configuration. Use of inspections to
internalcalibrationrequirements,thatthesecalibrationrequire-
determine mechanical and structural equivalency shall be
ments are documented and available for inspection upon
included in the test report to the governing CAA for concur-
request,thatallcalibrationsaretraceabletoanationalstandard,
rence on the reuse of test articles.
and that the records of current calibration of all instruments
13.1.1.6 A description of the photographic instrumentation
used in the test are maintained at the facility.
system used in the tests.
13.1.1.4 Astatementconfirmingthatthedatacollectionwas
13.1.1.7 Test Description—The description of the test
done in accordance with the detailed description of the actual
should be documented in sufficient detail, so that the tests
procedure used and technical analysis showing equivalence to
couldbereproducedsimplybyfollowingtheguidancegivenin
the recommendations of this test method.
the report. The procedures outlined in the test plan can be
13.1.1.5 Test Articles:
referenced in the report but should be supplemented by such
(1)In all cases, the test article (that is, sUA) should be
detailsasarenecessarytodescribetheuniqueconditionsofthe
representativeofthefinalproductionarticleandshouldinclude
tests. For example, pertinent dimensions and other details of
a structural frame, motors, propellers, electronics, batteries,
the installation that are not included in the drawings of the test
and payload. The sUA does not necessarily need to be
itemsshouldbeprovided.Theplacementandcharacteristicsof
powered.ThesUAneednothavefullyfunctionalelectronicsif
electronicandphotographicinstrumentationchosenforthetest
theydonotcontributetothestructuralintegrityoftheplatform.
beyond that information provided by the facility should be
Allelectronicsshouldbemassrepresentativeoftheproduction
documented.Thiscanincludespecialtargets,grids,ormarking
configuration and have the same stiffness and shape. The
used for interpretation of photo documentation, transducers,
configuration of each sUA used in each impact test should be
etc.
documented, and this configuration should conform to the
13.1.1.8 Pass Fail criteria used for the tests.
production specification of the sUA for which the applicant is
th
13.1.2 Method C shall be conducted using a 50 Percentile
submittingtothegoverningCAA.Specificmodificationstothe
FAA Hybrid III ATD, capable of measuring acceleration and
sUA that are made to support or conduct the tests should be
rotation of the head, and bending forces and moments of the
clearly documented along with their potential impacts on the
upper neck.
results of the tests.
13.1.3 Tests should be conducted at three impact directions:
(2)The payload may be replaced by a representative load
a vertical drop, a horizontal impact onto the front of the head,
made of representative shape, stiffness, and mass.
and an angled impact onto the front of the head. Only the
(3)ItemsofMass—DefinedasanypartofthesUAthatcan
vertical test is a drop test. The horizontal and angled impacts
detach during impact (that is, removable cameras, batteries)
shall be conducted using a sled or some other method of
and may become a projectile with enough energy to cause a
creating a repeatable impact.
serious injury (see 6.5) to a person. Detachment of these items
13.1.4 For each test impact direction, the applicant shall
may be grounds for retest and the means of restraint for these
determine the most probab
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