Fueled by modernized Part 23 certification rules using consensus-based standards, a renaissance of the stagnant four-seat single-engine aircraft market could begin by 2016, spurring new competition among legacy airframers and bold new startups.

The FAA says it is committed to changing the outdated rules, but not yet. The agency is mulling over recommendations in a 350-page final report from a Part 23 reorganization aviation rulemaking committee (ARC) it launched in 2011. That group says the reform can halve certification costs while doubling safety in general aviation flying, the sector with the highest accident rate.

“Part 23 has not seen a review like this in 30 years,” says Greg Bowles, the reorganization ARC co-chair and director of engineering and manufacturing for the General Aviation Manufacturers Association (GAMA). In concept, the ARC's recommendations would remove most technical requirements from Part 23 regulations and place them into international consensus standards.

A Part 23 rewrite could parallel the revitalization seen in the two-seat aircraft market after the introduction of consensus-based light sport aircraft (LSA) manufacturing rules in 2004. For a factory-built LSA, a manufacturer states it built an aircraft to ASTM consensus standards and the FAA audits the documents, validates the standards used and issues an airworthiness certificate for each aircraft built.

The market has decided the concept works. According to Dan Johnson, president of the Light Aircraft Manufacturers Association, there are currently 132 models of LSA built by about 90 manufacturers worldwide, with only “five or six” manufacturers dropping out over the last nine years as more enter.

Several LSA companies are already planning to produce certified four-seat aircraft under the new Part 23 rules, including Flight Design for the C4, Tecnam for the P2010, Evektor for the Cobra and Pipistrel for the Panthera. They are banking on significantly lower costs than a traditional certification, which for a four-place Part 23-certified aircraft today can cost an estimated $50-$75 million. Depending on the size of the production run, the sales price of each aircraft may have to be increased hundreds of thousands of dollars to cover the certification costs.

Terrafugia, builder of a light sport Transition roadable aircraft, is confident the new rules will allow it to make a four-place flying car that “drivers” can learn to operate in 5 hr. Priced similar to a “very high-end” luxury car, the TF-X will automatically avoid other traffic, bad weather and restricted and tower-controlled airspace, the company says. Along with an airframe parachute, the hybrid-electric aircraft will operate in manual or automatic modes as selected, including an option to auto-land at the nearest airport if the operator becomes non-responsive.

Terrafugia chief executive Carl Dietrich, a member of the ARC, says the new certification rules will be much more agile when it comes to embracing advanced technologies, a requirement for the TF-X.

“By 2020, when all aircraft have [Automatic Dependent Surveillance-Broadcast] and the certification pathways are in place, it will become a question of what we can physically do,” says Dietrich. “The TF-X is entirely computer-controlled to provide flight-envelope protection and prevent loss of control or controlled flight into terrain, the two biggest causes of general aviation accidents. Fly-by-wire technology will also simplify pilot training.” He adds, “They will be able to update ASTM standards much more quickly than federal regulations. It is working very well with light sport aircraft.”

The final form of the revamped Part 23 rules—which include certification requirements for structure, design and construction, engine and avionics, and can cover propeller and jet aircraft in some cases weighing up to 19,000 lb.—are likely to be different from the LSA model in that the FAA will remain fully involved in the process. “We're not changing what the FAA does,” says Bowles. “We're changing what the applicant does to meet the threshold.”

A new bill moving through the U.S. Congress aims to force the FAA to implement the updated regulations before 2016. According to Congress, the average small aircraft is now 40 years old, and over the past decade the sector has lost about 10,000 active private pilots annually. Supporters of the bill say the decline can be mitigated or reversed by the new Part 23 rules.

While the FAA says the legacy rules have produced safe airplanes “for decades,” technological advances have changed the original assumptions of the Part 23 divisions, which were based on weight and engine type. “The new small-turbine engines, composite airframes and lightweight digital electronics offer Part 23 airplanes the operational capability and performance of traditionally larger Part 25 airplanes,” the FAA says in a 2009 study on Part 23 certification processes, work the Part 23 reorganization ARC used as its starting point. “Part 23 standards have evolved beyond their original intent to address the increasing performance and complexity,” the FAA says. “Unfortunately, the slow, simple Part 23 airplanes have suffered as the standards have shifted toward more complex airplanes.”

GAMA's Bowles says ARC's recommendations represent an evolution of the rules rather than a revolution. “The things you do to certify [an aircraft or component] will continue to evolve, but this change lets us do that much more quickly and flexibly,” he says. Under today's rules, for example, when “someone comes along with a really good idea,” he says, they have to work with the FAA for 2-3 years to develop special conditions to allow the technology to be used in a one-off application.

“For the new Part 23, someone would say, 'I have a new idea for a new way to deal with an issue,' and industry would sit down and develop a standard in 6-12 months,” says Bowles. The FAA would review and, ideally, accept the new standards, which would then be available for anyone in the U.S. to use, as well as regulators in countries with an aviation bilateral agreement with the FAA.

Bowles says “any of the standards bodies” could develop the consensus standards, including ASTM, SAE and RTCA, but that efforts will not be duplicated. ASTM has formed a new international committee, F44, to specifically target general aviation improvements.

A different ASTM group, F39, is finishing standards for angle-of-attack (AOA) indicators as part of an FAA and industry effort that is a prelude to the Part 23 rule change. An AOA indicator gives a pilot a direct measurement of an aircraft's margin with respect to a stall, rather than the indirect readings of airspeed and attitude generally used today.

“The FAA's general aviation joint safety implementation team identified that AOA can save lives,” says Bowles. “The ARC has been working to streamline efforts to get that into peoples' hands, and the FAA is working on a process to do that, including a policy paper.” Industry officials say an owner today can install an uncertified AOA detector in a home-built experimental aircraft for about $800—compared to $5,000 for the same unit installed in a certified aircraft—due to regulatory requirements.

Beyond the AOA, Bowles says the list of possible safety improvements coming through a consensus process could be “huge”—airbags, parachutes, traffic alert and collision avoidance systems, terrain awareness and warning systems and more. “The thought process and mentality is beneficial for everyone,” he says.

Once the new Part 39 rules are out, Bowles says the immediate safety benefit will be for retrofits and alterations to the existing fleet of approximately 150,000 piston-powered general aviation aircraft. “When people see the price difference between an uncertified Garmin unit for the experimental market and the same unit for a certified installation, the price threshold is crazy,” he says. “The price difference from an uncertified product to a certified product will be much more graduated in the future. It will be much more gray.”

Reducing the certification costs will be a more streamlined process on the FAA's side. While the agency will continue to perform independent testing and make site visits and issue type certificates, there will be less bureaucracy in the process, in part because issue papers and other project-specific documents will not be needed, says Bowles. “In the future, FAA will have standards that match the product to be certified much more closely,” he says.