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In 2021 the Federal Aviation Administration in collaboration with the National Research Council of Canada performed research on altitude ice crystal icing of aircraft engines using the modular compressor rig, ICE-MACR, in an altitude wind tunnel. The aim of the research campaign was to address research needs related to ice crystal icing of aircraft engines outlined in FAA publication Engine Ice Crystal Icing Technology Plan with Research Needs. This paper reports the findings on ice accretion from a configuration of ICE-MACR with two compression stages. Inherent in two-stage operation is not just additional fracturing and heating by the second stage but also higher axial velocity and potentially greater centrifuging of particles. These factors influence the accretion behavior in the test article compared to single stage accretion.

High Ice Water Content (HIWC) has been identified as a primary causal factor in numerous engine events over the past two decades. Previous attempts to develop a remote detection process utilizing modern commercial radars have failed to produce reliable results. This paper discusses the reasons for previous failures and describes a new technique that has shown very encouraging accuracy and range performance without the need for any modifications to industry’s current radar design(s). The performance of this new process was evaluated during the joint NASA/FAA HIWC RADAR II Flight Campaign in August of 2018. Results from that evaluation are discussed, along with the potential for commercial application, and development of minimum operational performance standards for future radar products.

NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.

Although Unmanned Aircraft Systems (UAS) have now for some time been used in segregated airspace where separation from other air traffic can be assured, potential users have interests to deploy UAS in non segregated airspace. Recent technological and operational improvements give reason to believe that UAS safety and performance capabilities are maturing. But the skies can only really open up to UAS when there is an agreed upon UAS safety policy with commonly accepted UAS Safety Risk Management (SRM) processes enabling to show that the risks related to UAS operations in all the different airspace classes can be adequately controlled. The overall objective is to develop a UAS SRM framework, supporting regulators and applicants through provision of detailed guidelines for each SRM step to be conducted, including 1) system description, 2) hazard identification, 3) risk analysis, 4) risk assessment, 5) risk treatment.

Unmanned Aircraft Systems (UAS) emerge as a viable, operational technology for potential civil and commercial applications in the National Airspace System (NAS). Although this new type of technology presents great potential, it also introduces a need for a thorough inquiry into its safety impact on the NAS. This study presents a systems-level approach to analyze the safety impact of introducing a new technology, such as UAS, into the NAS. Utilizing Safety Management Systems (SMS) principles and the existing regulatory structure, this paper outlines a methodology to determine a mandatory safety baseline for a specific area of interest regarding a new aviation technology, such as UAS Sense and Avoid. The proposed methodology is then employed to determine a baseline set of hazards and causal factors for the UAS Sense and Avoid problem domain and associated regulatory risk controls.

This paper compares the flammability of plastic automotive components to that of commodity, engineering, and specialty plastics as well as those used in commercial aircraft cabins with regard to performance in microscale combustion calorimetry tests. Not surprisingly, automotive components used in engine and passenger compartments are as flammable and ignitable as the commodity and engineering plastics of which they are made and much more flammable than those used in the interiors of aircraft.

Weather is a major cause of aircraft accidents and incidents and the single largest contributor to air traffic system delays. Through improvements in the knowledge of current weather conditions and reliable forecasts, the Federal Aviation Administration (FAA) can improve aviation safety, increase system capacity, and enhance flight planning and fuel efficiency. The FAA has established an Aviation Weather Research (AWR) program to address specific requirements for weather support to aviation by providing the capability to generate more accurate and accessible weather observations, warnings, and forecasts and also by increasing the scientific understanding of atmospheric processes that spawn aviation weather hazards. The goal of AWR is to provide meteorological research that leads to the satisfaction of specific aviation weather requirements.

“As we handle more operations and passengers in the air, we must make certain we have the capacity to handle increased traffic on the ground.” - Jane Garvey, FAA Administrator (4/20/98) The FAA Technical Center (Aviation System Analysis and Modeling Branch, ACT-520) has been responsive to the FAA Airport Capacity Program customers for the past 22 years, developing, testing, and applying airfield and airspace simulation models. More than 90 capacity studies have been completed with ACT-520 personnel contributing their technical expertise to the Airport Design Teams. The teams are comprised of FAA personnel, airport operators, air carriers, other airport users and aviation industry representatives at major airports throughout the US. Initial studies focused on modeling airport operations from final approach, taxi, gate operations and departure processing. Later in the program, local airspace studies were included in some airport study efforts.

Recent changes in DoD procurement directives have encouraged the purchase of civilian products for use in certain military applications. One such application is the upgrade of avionics suites with the Global Positioning System (GPS) in military air transport aircraft to meet joint civil-military operational requirements. This paper reviews the Commercial Off-the-Shelf (COTS) concept and the proper use of TSOs, ACs, and FARs in both the design and integration process.

Numerical simulations indicate that blast loading on aircraft structural joints can impart loading rates in excess of 10 Mlb/sec (ten million pounds per second, Reference 1). Experimental evidence, on the other hand, suggests that mechanical joint failure loads are highly loading rate dependent; for example, the failure load for a dynamically loaded tension joint can double from its static value. This paper discusses the progress and to-date findings of research on the assessment of strength failure of aircraft structural joints subjected to loading rates expected from an internal explosive detonation, and several associated experimental procedures to generate such dynamic loading. This work is conducted at MDC and at the University of Dayton Research Institute (UDRI) in support of the FAA Aircraft Hardening Program.

The crash impact characteristics of commuter category airplanes has recently been established using empirical procedures based on full scale aircraft impact test data for a range of aircraft sizes[1]. To compliment that empirical approach the Federal Aviation Administration (FAA) initiated a full scale commuter category airplane vertical impact test program. Those airplane vertical impact tests were structured to evaluate the airframe's capability to maintain its structural integrity and provide a protective shell for its occupants, to quantify the acceleration impact response characteristics of the airframe, and to evaluate the means necessary to provide occupant pelvic/lumbar column load injury protection up to the limits of survivable impact conditions.

As a part of its International Aging Aircraft Research Program, the Federal Aviation Administration is establishing a state-of-the-art Flight Loads Data Collection Program. Data collected in this program will provide the necessary mission profiles and load spectra information to characterize typical fleet service usage for the regional/commuter service life extension program. In addition, these data are applicable for both a safe life fatigue analysis and a damage tolerance fracture mechanics analysis. This paper describes the FAA approach and schedule for instrumenting fleet service aircraft, and the data reduction process.

Since the first airplane was certified in 1927, the standard configuration has been with the main lifting surface or surfaces forward of the stabilizing surface. Although some of the advantages of the canard configuration were recognized quite early - by the Wright Brothers, for example - canard surfaces have been used to date only as additional control surfaces on some military airplanes, and on some amateur built airplanes. As a result, the Airworthiness Regulations of Reference 1 address only tail aft configurations. When FAA was first approached regarding certification of a canard configured small airplane, an FAA/Industry Empennage Loads Working Group was formed to develop technical proposals for the necessary rule changes and policy. The concerns addressed by this working group are discussed in the following sections.

Microprocessor technology is allowing functions in aircraft to be implemented to a greater degree by digital process control than by conventional mechanical or electromechanical means. A review of this technology indicates a need for updated certification criteria. A high level of commitment to the technology such as fly-by-wire is completely beyond the scope of existing certification criteria. This paper emphasizes the areas of software validation levels, increased concern with basic power system qualification, and increased environmental concerns for electromagnetic interference and lightning.

One Engine Inoperative takeoff climb performance of the XV-15 tilt rotor aircraft was analytically determined from level flight data and compared to the proposed powered-lift aircraft criteria. The results of this analysis can be useful in establishing the takeoff profile and highlighting potential certification issues.

Powered-lift aircraft, such as the V-22 tilt-rotor, are likely to spin-off a civil version. The present FAA airworthiness certification standards are not considered to be adequate for these unique aircraft. The FAA has drafted certification criteria and held a public conference to review the draft and identify significant technical certification issues that require further effort to establish correct standards for powered-lift aircraft. Some of those issues are discussed.

The Federal Aviation Administration is charged with the promotion of aviation safety. It is made up of three levels of administration within which are the functional organizations that manage the FAA programs and services. The Flight Standards service, which develops and enforces all regulations affecting aircraft and airmen, is the functional organization directly responsible for promoting aviation safety. This paper describes the Flight Standards aviation safety program.

This paper will discuss some considerations regarding man-machine interface during helicopter instrument flight. Several misconceptions have existed regarding FAA helicopter IFR certification. In response to some concerns pertaining to “excessive workload considerations,” designers have responded with several configurations. Some of these configurations have highlighted the need to educate the designer and the pilot population that the pilot must have the option to “actively participate” in the flight activity during helicopter IFR operations. “Active participation” includes the option of flying the vehicle through the normal flight controls. In addition, there has been some confusion regarding the terms “stability augmentation systems” and “autopilot.” Some individuals use the terms interchangeably. This paper will discuss the various lessons learned during FAA certification of helicopters for IFR flight from a certification test pilot's viewpoint.

Average continuous flow rates for each type of aircraft exit were examined in 89 full-scale evacuation demonstrations. Passengers tend to form continuous lines at available exits when evacuating an airplane. The study concludes that, with rare exception, the passenger rates of egress from the same type exit on different make and model airplanes are not significantly different. Passenger cabin configuration, seat pitch, and aisle width have no significant bearing on the egress rates provided the aircraft certification requirements for minimum aisle width and exit accessibility are met. Injuries resulting from actual emergency evacuations and evacuation demonstrations are also examined.

The advent of digital electronics for use in civil aircraft, particularly the new technology represented by central processor and microprocessor controlled systems, represents a major challenge to the aviation industry. The Federal Aviation Administration (FAA) is charged with the responsibility of evaluating these systems to determine if they can be used safely. The complexity of these systems as compared to their analog counterparts in use today makes their evaluation difficult. This paper outlines the major concerns of the FAA with the use of software controlled digital systems for airborne applications. The methods which can be used by members of the aviation industry to obtain FAA certification of these systems are also discussed. The proposal of Special Committee SC-145 of the Radio Technical Commission for Aeronautics (RTCA) form the basis of the design methodology which is described for the successful development of the computer programs (software) to be used by these systems.