Airworthiness Assurance and Component Tracking of Small Unmanned Aerial Systems

With the rising prominence of small Unmanned Aerial Systems (sUAS), there is an increasing need to maintain safety. Current Federal Aviation Administration (FAA) regulations require that each sUAS undergo a simple visual and operational preflight check. There is no detailed airworthiness assurance or tracking requirement as required for certificated aircraft. However, as the number of commercial sUAS increases, this requirement for detailed airworthiness assurance and component tracking may change. In order to familiarize students in an Unmanned Aerial Systems major with this possible change, a junior level course was structured around tracking sUAS in a way which mirrored certified aircraft. The course focused on integration on an off the shelf autopilot into a four pound 3d printed quadcopter. Student in groups of two were required to fly ten missions in outdoor, real world conditions. At the start of class, students within the class, created a course specific preflight checklist. Before each flight, there students were required to follow this checklist. Also, each component on the quadcopter had its own individual serial number recorded in a logbook. In the event of a hard landing or flight anomaly that required the replacement of a component, the student group has to file several pieces of paperwork which were recorded in the quadcopter's specific logbook. First, a flight incident report with weather conditions, operators, and description of the event was included. Then an FAA form 337 was filled out. Finally, the serial number of the components removed and the serial number of the new components were recorded. With this focus on airworthiness assurance and part tracking, students within the course are better prepared for future changes in sUAS regulations. Introduction Small unmanned aerial systems (sUAS) are currently the fastest growing aspect of aviation and current Federal Aviation Administration (FAA) regulations are slow to adapt this change. One of the biggest challenges in UAS is airworthiness assurance. Currently, under 14 CFR Part 107, a commercial operator needs to inspect the vehicle for airworthiness before flight. However, airworthiness is not currently defined within UAS. This is a challenge of unmanned aircraft systems (UAS) because there is no human on board the vehicle, and many of these practices are ignored. Current airworthiness certification practices for civilian aircraft are defined in 14 CFR Part 21. These practices are defined for manned aircraft, and are mainly concerned with the safety of the aircraft occupants with the safety of those on the ground secondary [1]. These practices have evolved over the life of aviation, and the adherence to these practices has increased the safety of aviation for those inside and outside of the aircraft. US military handbook, MIL-HDBK-516C, defines the airworthiness certification criteria for military aircraft. This handbook specifically states that the contents apply to both manned and unmanned aircraft. This safety equivocation is a good start to widespread standardization of UAS airworthiness certification standards. Airworthiness Assurance in Manned Aircraft Initial airworthiness certification standards are accompanied with standards to assure continued airworthiness throughout an aircraft’s life. One way this is achieved is through periodic maintenance and inspection procedures [1]. Proper maintenance of aircraft includes more than just using the right tool or the right replacement parts, it also includes the proper documentation. Proper documentation allows operators to track repairs, alterations and calibrations. This in depth understanding of an aircraft’s history is instrumental in/for/during maintenance activities. The FAA describes required maintenance and maintenance documentation in Advisory Circular 14 CFR Part 43. Maintenance is the “inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance” [2]. Preventive maintenance is “simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations” [2]. Preventative maintenance or maintenance activities accomplished during the 100-hour, annual, progressive, and other required or approved inspections require additional information to be maintained. Documentation for maintenance performed on aircraft, engine, propeller, appliance, or component must include, at a minimum, a description of the work performed, the date of the completion of the work, name of the person who performed the work, and assuming satisfactory work, the signature, certificate number, and certificate type of the person approving the work [3]. The information required is listed below [4]: ● Records that must include ○ A description (or reference to data acceptable to the Administrator) of the work performed; and ○ The date of completion of the work performed; and ○ The signature, and certificate number of the person approving the aircraft for return to service. ● Records containing the following information: ○ The total time in service of the airframe, each engine, each propeller, and each rotor. ○ The current status of life-limited parts of each airframe, engine, propeller, rotor, and appliance. ○ The time since last overhaul of all items installed on the aircraft which are required to be overhauled on a specified time basis. ○ The current inspection status of the aircraft, including the time since the last inspection required by the inspection program under which the aircraft and its appliances are maintained. ○ The current status of applicable airworthiness directives (AD) and safety directives including, for each, the method of compliance, the AD or safety directive number and revision date. If the AD or safety directive involves recurring action, the time and date when the next action is required. ○ Copies of the forms prescribed by §43.9(d) of this chapter for each major alteration to the airframe and currently installed engines, rotors, propellers, and appliances. Records are defined by the FAA as: “any writing, drawing, map, recording, tape, film, photograph or other documentary material by which information is preserved or conveyed in any format, including, but not limited to, paper, microfilm, identification plates, stamped marks, bar codes or electronic format, and can either be separate from, attached to or inscribed on any product, part, appliance or material” [5]. In addition to creating them, the records must also be maintained for the life of the aircraft and transferred with any sale of the aircraft [4], because any time, the FAA may request access to the records for inspection. Airworthiness is defined as “aircraft conforms to its type design and is in a condition for safe operation” [5]. These records allow operators to easily understand the current configuration of the aircraft and the maintenance history of the aircraft, and are part of what makes the aircraft airworthy. Parts and components used on aircraft are certified by the FAA to be considered airworthy through the use of Title 14 CFR part 21 of the United States federal regulations which gives approval for parts manufacturing. Title 14 CFR 21 provides users with a detailed description of materials, manufacturing location and, at times, the individual who manufactured the part. An example of this is an aircraft part that was constructed of Aluminum 2024-T4 from a known company that has been certified while in contrast, many sUAS parts have limited markings and can lack part and serial numbers. This lack of traceable part information can severely hamper the capability of operators to ensure that replacement parts are of the same quality as the initial parts. Electronic speed controllers (ESCs), the components responsible for translating controlling the power output of the motors, provide a good example of this problem. Two different ESC brands may be rated the same, but could vary widely in their in-flight performance. This discrepancy between parts can impact the performance of the aircraft but, under current regulations, does not affect the airworthiness of the aircraft. Adapting current Title 14 CFR part 21 regulations to the sUAS would require a test flight of the aircraft when a component has been replaced that could affect flight characteristics. Applying these regulations to unmanned aircraft is meant to simulate the current regulatory environment of manned commercial aviation, and foster a culture of safety and professionalism [6]. By requiring students to fill out additional forms regarding sUAS incidents it is giving them an advantage of being better prepared if additional legislation regarding sUAS is published. By using the checklists that the students create it can help mitigate part failure. Through the initial creation of the checklists students will begin to generate a general understanding of how the vehicle in theory is supposed to operate. The checklist will show the students what the vehicle is supposed to do and is expected to do. Running through the checklist will help students that have had limited experiences with them such as the non-pilot major students gain more familiarity with how checklists should be designed and run through [7] Incident reports in manned aviation in the United States are filled when there has been loss of life of someone other than the pilot or damage exceeding a value of 25,000 USD [8]. Current sUAS regulations require “damage of over 500 USD to property other than the drone itself or if injury or death has occurred due to a collision with a person or causing injury” during commercial operations to be reported [8]. The reporting for this class goes more in-depth than what the current FAA requires by using the current weather information for the flight, who was operating at the time of the incident, and a description of the event. When reporting the accident in the class the students are re