UA.I.E.K17: Exposed rotating parts.

ACS Area I — Regulations Task E: Operations Over People References: 14 CFRCode of Federal RegulationsCloseThe federal rulebook where Part 107, Part 89, Part 48, and other aviation rules live. parts 89 and 107; ACAdvisory CircularCloseFAA guidance that explains acceptable ways to comply with rules or understand FAA procedures. 107-2; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-H-8083-25; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-G-8082-22

Key Concepts

Understanding the Category 1 “Exposed Rotating Parts” Rule

For Operations Over People (OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios.), Category 1 has two defining eligibility criteria: the small unmanned aircraft (sUA) must weigh 0.55 pounds (250 grams) or less at takeoff and throughout the operation, and it must not contain any exposed rotating parts that would lacerate human skin upon impact with a human being. If your aircraft’s propellers or other rotating components are exposed in a way that could cause a laceration, it is not eligible for Category 1 OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios., even if it meets the 0.55-pound weight limit. Category 2 and Category 3 do not use this “exposed rotating parts” test; instead, they rely on performance-based safety requirements that limit injury risk and severity. Category 4 relies on an airworthiness certificate under 14 CFRCode of Federal RegulationsCloseThe federal rulebook where Part 107, Part 89, Part 48, and other aviation rules live. part 21 with applicable operating limitations.^[3]

Practical takeaway: If your under-0.55-pound drone has unguarded propellers that present a laceration risk, you cannot conduct Category 1 OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios.. You would need a different OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios. category pathway (e.g., a compliant Category 2 or 3 aircraft) or avoid flight over people entirely.^[3]

Who Counts as “People,” and Where You May Fly Over Them

Section 107.39 prohibits flight over a person who is not under a safe cover (such as a protective structure or a stationary vehicle) unless the operation complies with one of the four OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios. categories in subpart D. Direct participants—remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation., persons manipulating the controls, visual observer, or other required crewmembers—may be flown over because they are part of the operation. Everyone else is “non-participant” unless properly protected.^[3]

Open-air assemblies carry additional limits. For Category 1 and Category 2, sustained flight over open-air assemblies is prohibited unless the operation meets § 89.110 or § 89.115(a); this prohibition is waivable. Category 3 eligible aircraft must not operate over open-air assemblies (§ 107.125(b)). Category 4 may conduct OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios. if not prohibited by operating limitations, but sustained flight over open-air assemblies is likewise prohibited unless § 89.110 or § 89.115(a) are met (also waivable).^[2]

Moving Vehicles and Closed/Restricted-Access Sites

Outside a closed- or restricted-access site, an sUA must not maintain sustained flight over any moving vehicle. In this context, Categories 1–3 are limited to “transit only, no sustained flight” over non-participants in moving vehicles. Category 4 may operate over moving vehicles if the FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-approved Flight Manual or Administrator’s limitations do not prohibit it. Within a closed- or restricted-access site, OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios. rules allow flight over moving vehicles under the conditions shown in the ACAdvisory CircularCloseFAA guidance that explains acceptable ways to comply with rules or understand FAA procedures.’s tables, with “on notice” requirements for non-participants in Categories 1–3, and Category 4 subject to its operating limitations.^[1]

Practical takeaway: If you are not within a closed/restricted site, plan your route so that any overflight of moving vehicles is momentary transit only—do not loiter or orbit over roadways. This constraint applies even if you satisfy Category 1’s “no exposed rotating parts” requirement.^[1]

Documentation, Configuration, and Preflight (Day or Night)

Before conducting OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios., the remote pilot is responsible for ensuring the aircraft is eligible for the intended category and verifying it is properly labeled and listed on an FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-accepted Declaration of Compliance (DOCDeclaration of ComplianceCloseManufacturer compliance document that matters for some Operations Over People categories.), as applicable. Perform all recommended preflight actions.^[6] Remote pilot operating instructions (RPOIResponsible Person of InterestCloseAn FAA contact or responsible-party role used in some operational and compliance contexts.) must clearly describe how to configure the aircraft to meet the chosen category; the remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation. is ultimately responsible for safe operational parameters. Follow any modification instructions provided for the eligible aircraft.^[4]

Configuration discipline matters. For Category 2/3 eligible aircraft, only use pre-approved payloads listed in the RPOIResponsible Person of InterestCloseAn FAA contact or responsible-party role used in some operational and compliance contexts., and ensure they are securely attached throughout Category 2/3 OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios.. Failure to comply (e.g., adding unlisted payloads) makes the aircraft ineligible for those categories. Some Category 3 configurations may include rotor blades and guards as required components—use the specified parts to preserve eligibility.^[8] Incorporate OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios.-specific preflight assessment items, such as the location of people and a review of RPOIResponsible Person of InterestCloseAn FAA contact or responsible-party role used in some operational and compliance contexts., into your checklist.^[5]

Night OOPOperations Over PeopleClosePart 107 rules for flying over people, open-air assemblies, and related scenarios. uses the same categories and restrictions as day operations. If operating at night, you must still comply with §§ 107.29 and 107.39. Manufacturers declaring Category 2 or 3 eligibility may need to account for the mass of an anti-collision light when showing compliance with §§ 107.120(a) or 107.130(a).^[6]

Bottom line for the exam: Category 1 requires ≤0.55 pounds (250 g) and no exposed rotating parts capable of laceration. If you can’t meet that, you need a different eligible category or avoid flight over people.^[3]