Standardization News

In the world of international aircraft regulation, the term “general aviation” includes aircraft with two to 19 seats and weighing less than 8600 kg (19,000 pounds). These vehicles serve a wide range of purposes, including recreational flying, business travel, medical transport, aerial mapping, and search and rescue. In rural and disaster-stricken areas they provide a lifeline of goods and services. In the United States alone, general aviation aircraft log almost 23 million hours annually and fly to over 5,000 public airports.

For the past four years, dozens of stakeholders in this broad field have been hard at work in ASTM International’s committee on general aviation aircraft (F44) — developing standards for design and construction, systems and performance, quality acceptance tests, and safety monitoring.

With 30 standards to its credit, Committee F44 has now published a specification (F3264) that serves as a sort of catalog of its work. F3264 is the specification for normal category aeroplanes certification. Users of
the new specification can easily find which F44 standards are relevant to myriad aspects of general aviation aircraft — from stall speed, controllability, and structural design loads to aeroelasticity, design and construction, powerplant installation, and lightning protection.

The Standards Developer of Choice

The F3264 specification is especially necessary since the promulgation of new regulations released by both the U.S. Federal Aviation Administration and the European Aviation Safety Agency, says Boyd Rodeman, propulsion regulatory compliance lead at Textron Aviation, Wichita, Kansas.

“The [agencies’] intent was to use a group of performance-based standards as a means of compliance to these new rules,” Rodeman says. “ASTM is the means in which those performance-based standards are being developed.”

That both the FAA and EASA would select ASTM International as the literal standards bearer on general aviation aircraft is noteworthy. Undoubtedly, the coming together of two major international agencies is an accomplishment in itself.

What makes the pairing exceptional, though, is each agency’s approach to standards. The FAA tends to follow private sector standards, such as those created by ASTM International, while EASA has historically adhered to government-developed ones. However, considering the solid track record of ASTM International’s reliable, industry-driven aviation standards, EASA’s willingness to accept them is not surprising.   

Benefits of F44 Standards

Committee F44’s work takes into account that not all general aviation aircraft are the same and that a one-size-fits-all approach to certification can be inefficient. The committee’s work helps streamline how
small aircraft are manufactured and certified, not only in the United States but around the globe.

According to Larry van Dyke, president of ICX Consulting LLC, validating airplanes manufactured in one country and sold in another has long been a costly, time-consuming task for applicants and local civil aviation authorities. Committee F44’s standards strive to alleviate these issues.

“Because the standards are international standards that include the requirements from all of the participating countries, an applicant can be confident that, when the airplane is approved in the originating country, it can be validated in one of the participating countries with little or no additional validation activity required,” van Dyke says.

Standards for General Aviation Aircraft Technology and Safety

The international standards developed by F44 address design, construction, systems and performance, quality acceptance tests, and safety monitoring. The standards allow manufacturers of general aviation craft to select the appropriate certification for their planes, sparing them from applying complex certification processes — which are intended for more complicated planes — to these relatively simpler vehicles. The standards streamline retrofits for currently operating, certified aircraft and keep down the costs of manufacturing and ownership. Furthermore, the standards help manufacturers stay on top of advances in technology and safety. 

A perfect example of this last feature is F44’s specification for icing protection (F3120), which focuses on systems designed to safeguard against in-flight icing and ensure safe operations. Not only airplane manufacturers but also producers of icing protection systems and retrofitters use it to confirm that their equipment meets certification criteria. The cataloging specification F3264 lists this standard under “Flight,” “Powerplant Installation Information,” and “Flight Crew Interface and Other Information,” making the lives of manufacturers a little easier as they navigate international standards and certification.

The specification for emergency conditions, occupant safety, and accommodations (F3083), details what equipment should be in place for emergency situations. Listed under “Structures” and “Design and Construction” in F3264, its requirements include everything from seat belts and passenger information signs to fire protection, emergency exits, and evacuation plans.

Although F44 has already created 30 standards in its short history, members of its subcommittees continue to develop more. This includes the subcommittee on performance and handling (F44.20).

“One issue of particular concern that F44.20 addresses is ‘low-speed handling characteristics,’” says Marten Bosman, of Advanced Aviation Safety Services in Le Born, France. “Both the FAA and EASA have expressed the objective that one of the major accident causes in general aviation, the so-called ‘stall-spin’ accidents, should be eradicated.”

To address this, the subcommittee developed a standard for low-speed handling characteristics (F3180). “Very limited experience and data existed,” Bosman says. “This made the development of the standard more an engineering exercise where individual experiences of test pilots and flight engineers were bundled to come to an engineering ‘best knowledge,’ upon which the new standard is based,” Bosman says.

“One of the most exciting endeavors we are currently working on is found in the working group … developing the standards to support the certification of electric and hybrid electric propulsion systems in Part 23 aircraft,” Rodeman says.

Committee Successes

Ask members of Committee F44 what the committee’s greatest accomplishment has been thus far and you’ll hear what many marvel at in the development of consensus standards — the ability of stakeholders from competing companies to come together for the sake of quality and safety.

“Another success, in my view, is that the aviation industry is very seriously taking up the responsibility they are given in this committee, mainly by appointing some of their most experienced and knowledgeable people to this process and the subcommittees,” Bosman says.

Van Dyke believes F44’s biggest success to date may be the harmonization of requirements between EASA and the U.S. FAA. “They aren’t perfectly harmonized yet, but this is an activity that I have personally been involved in for about 25 years, and I can’t compliment the FAA and EASA enough on their ability to get as far as they did on harmonization. Harmonization alone significantly reduces the effort required to write and implement the standards and makes the process of certification and validation much easier, faster, and less costly for all,” van Dyke says.

Responsibility, cooperation, and the publication of international consensus standards — Committee F44 may still be in its infancy, but it has truly taken off, for the good of the international aviation industry.

Sidebar

Keeping It Organized: A New Specification

To help users track down the general aviation standards they need in order to comply with international regulations, Committee F44 has published the specification for normal category aeroplanes certification (F3264). The specification lists the international industry standards demonstrating compliance to Level 1, 2, 3, and 4 Normal Category aircraft requirements.

“Without F3264, applicants and the CAAs [local civil aviation authorities] would each be required to create their own cross-reference index from the CAA requirements to the standards, or search through each of the individual standards for each project to find the standard they needed to use to satisfy a particular CAA requirement,” says Larry van Dyke, who has 45 years of aircraft certification experience with Cessna, Beechcraft, and Learjet. “Neither of these approaches is acceptable for either the CAAs or the applicants.

There would be a significant administrative expense for each CAA and each applicant to maintain their own cross-reference, and it would be difficult to ensure they were always up to date. This eliminates that administrative effort from the CAAs and the applicants.

Van Dyke notes that the committee anticipates updating F3264 at least once a year, depending on the rate of change to the included standards. “Having F3264 ensures that all of the CAAs and applicants have the same standards at the same revision level identified in a single place,” he says.