Standard Active Last Updated: Nov 18, 2021
ASTM F3389/F3389M-21

Standard Test Method for Assessing the Safety of Small Unmanned Aircraft Impacts

Significance and Use

5.1 The test method is intended to be used by sUAS manufacturers, sUAS operators, and CAAs to assess the safety of sUA impacts to people on the ground during operations involving flight over people.

5.2 The test method provides a framework for creating new designs and evaluating existing designs to determine the sUA’s blunt force trauma injury potential to the head or neck, or both, during a collision with a person on the ground.

5.3 Applicants can determine whether to use Methods A, B, C, or D based upon their specific sUA characteristics, flight operations, and CAA requirements. In some cases, sUA with low impact KE below 54 ft-lbf [73 J] may not require rigorous testing to ensure safety to the nonparticipating public and can use Method A. Vehicles with higher impact KEs should conduct impact testing using Method B, Method C, or Method D. Method B is simpler than Method C and, therefore, less costly for the applicant. Method B results may be more conservative since the test setup is more rigid and can result in an increase in the amount of energy transferred during the impact than the injury metrics established using a full ATD. Method C testing is costlier and schedule-intensive, but provides a higher level of certainty of the injury potential of the sUA and is more directly comparable to established automotive injury metrics and injury metrics derived from ATD testing and used by the governing CAA. Method D allows for the direct comparison to energy-based requirement of some CAAs.

5.4 The output of Method A is a verification that the sUA or sUA with mitigation does not exceed the 54 ft-lbf impact KE throughout its flight envelope based upon flight test data as means of obtaining approval for flight over people for Category 2 or 3 operations for the FAA. Other governing CAAs may only require a weight metric or other impact energy metric in lieu of the 54 ft-lbf impact KE.

5.5 The output from Methods B and C is a characterization of the forces (measured in acceleration of the head form or ATD) expected during an MPWC head impact as a function of sUA KE. For Method B, this result is compared to the minimum impact energy resulting in a skull fracture based solely upon peak acceleration to determine the impact KE associated with this injury based upon energy transfer. Method C testing is more rigorous and may be correlated to other standards for both head and neck injury (such as the FMVSS 208 or other automotive standards) to determine whether the sUA is sufficiently safe to operate in Category 2 and 3 Operations.8 By evaluating sUA KE in the MPWC orientation and a variety of ATD impacts, the applicant should assess the sUA for injury potential using the governing CAA injury thresholds. The limiting impact KE may establish the operational limits that correspond to that specific value. This test method proposes the use of the standards called out in the ASSURE impact tests conducted as part of Task A14.9

5.6 The output from Method D is a verification that the sUA does not exceed the comparison metrics associated with the transfer of energy resulting from the impact of a rigid object at a specified impact KE for the rigid impactor. The impact KE of the rigid impactor is determined by the CAA for different categories of operations over people. For example, an sUA meets this standard if its impact test results are lower than the rigid object test results.

5.7 Outputs from Methods A, B, C, and D may be used in conjunction with governing CAA’s metrics for certifying the sUA for flight over people.

Scope

1.1 This test method is applicable to small unmanned aircraft (sUA) that are limited in the United States in accordance with 14 CFR § 107.3 to be less than 55 lbf. The test method provides a standardized method for assessing the safety of sUA impacts with a person on the ground. Results from testing using Methods A, B, C, or D are intended to be used to support an applicant in obtaining permission from the governing Civil Aviation Authority (CAA) for flight over people. Approval of reports for the conduct of tests and the decision to grant permission rests with the governing CAA based upon adherence to the methodologies outlined in this test method.

1.2 This test method is based on methods researched by the FAA Center of Excellence for Unmanned Aircraft Systems (UAS) supported by the Alliance for System Safety of UAS through Research Excellence (ASSURE). These methods expand on extensive research and testing conducted by the automotive industry to support quantitative automotive passenger safety standards and testing and test data on sUA collected by ASSURE.

1.3 The purpose of this test method is to define a method to establish confidence in the overall injury potential of a particular sUA configuration under probable failure conditions. This testing is not meant to simulate the worst possible impact for the most conservative set of the population. It is expected that CAAs should determine what injury thresholds are acceptable under their public policy and determine operational limitations for various operations by using the data from this testing in conjunction with the specific concept of operations proposed by the applicant.

1.4 The test method provides four methods for evaluating the potential for impact injury: a simple analytical method, a simplified test, a more rigorous test, and a test method normed to approximate energy transfer values with appropriate safety margins applied to each approach to address uncertainty in each of the approaches.

1.5 The applicant should understand the actual operating characteristics of their sUA before starting the process outlined in this test method. It is assumed that the applicant is able to substantiate the most probable, worst-case (MPWC) impact orientation of the sUA; typical and maximum operating heights and speeds; and terminal velocity of their sUA as a function of altitude to compare the results of the impact analysis with the proposed operation for the sUA. This test method is intended to supplement the verification requirements of Specification F3298 and Specification F3322, as well as a supplement to Specification F2910. This test method should not be used as a stand-alone document without consideration of other ASTM UAS standards.

1.6 These methods assume that a blunt force head impact is the most likely injury mechanism leading to serious injury or fatalities. The level of blunt force injury to the head may be adjusted for various applications (such as sUA operations around first responders with helmets) and compared with the amount of force or load factor that the sUA transfers during a collision.

1.7 Method B is not appropriate for foam-built fixed-wing sUA due to the stiffness of the FAA Hybrid III ATD Head and Neck. Until a different impactor can be developed for Method B, these sUA should use Method C or D for evaluation.

1.8 Units—The values stated in either International System (SI) units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.9 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.

1.10 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.

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Details
Book of Standards Volume: 15.09
Developed by Subcommittee: F38.01
Pages: 13
DOI: 10.1520/F3389_F3389M-21
ICS Code: 49.020