The rewrite of the EASA’s CS-23 and the FAA’ s Part 23 rules (known as the “CS/Part 23 Reorganization” initiative) is taking shape, and at a workshop last month in Brussels European authorities expressed unconditional support for the effort. Manufacturers of light aircraft (up to 12,500 pounds) are propelling this effort to establish more practical rules.

The current rules encompass single-engine aircraft as light as a single-seat piston model and as heavy as the PC-12 NG turboprop, the King Air 250 twin turboprop or the Phenom 100 twinjet. Mtow can go as high as 19,000 pounds for twin-turboprop commuters with up to 19 seats. In fact, within these limits, weight is no longer a criterion.

The authorities and industry are devising instead “airworthiness levels” based on the number of passengers, divided into four levels, from zero to 19 passengers. The idea is that the level of acceptable risk should decrease as the number of passengers grows. However, discussions in Brussels revealed some confusion between “passengers” and “seats,” and the limits between some levels appeared unclear.

These levels “will be one of the factors [in addition to performance and complexity factors such as VFR/IFR] that will determine what is necessary for compliance,” Gregory Bowles, GAMA’s director for European regulatory affairs and engineering, told AIN.

Setting Airworthiness Design Standards

The reorganization of CS/Part 23 hinges on the breakdown between actual rules and airworthiness design standards. The EASA and the FAA are rewriting and further harmonizing the rules to reflect safety objectives. “They should not be design-specific,” said Boudewijn Deuss, an EASA rulemaking officer. Global standards body ASTM International leads the consensus-based development of airworthiness design standards.

Bowles urged the ASTM group to be concise and clear in establishing the safety objectives to avoid unintentionally setting a requirement that strays from that broader goal. “Thinking about one narrow circumstance while broadly categorizing it as encompassing many others can unintentionally set a rule interpretation that prevents expansion in the future,” he told AIN. Using exclusive language, such as “except for,” is not preferred, he emphasized.

A revised CS/Part 23 rule would list the means of compliance–the accepted airworthiness design standards. “The list will be the link between the safety objectives and the standards,” Deuss explained, and assembling the list will remain the prerogative of the authorities.

Rulemaking will therefore take place primarily within the ASTM framework, meaning manufacturers will participate. A manufacturer may introduce a technology that redefines the standard, and all stakeholders agree the new regulatory mechanisms will accelerate rulemaking, improve safety and foster innovation. Certification costs are expected to be cut thanks to rules that are better aligned with the role of the aircraft. “We are now in the driver’s seat, and we won’t be allowed to complain [about stifling regulations in the future],” noted Oliver Reinhardt, technical director of light piston aircraft manufacturer Flight Design.

According to the time line Deuss presented, the EASA is scheduled to issue a notice of proposed amendment in next year’s fourth quarter and the FAA is expected to issue a notice of proposed rulemaking simultaneously. An initial rule review took place last summer and a second one is scheduled for February. The ASTM expects to publish “Standards v1.0” in June next year.

EASA officials declined to comment about whether the Part 23 rewrite process in the U.S. has been dragging, but one panel expert emphasized the importance of maintaining the effort’s momentum. Reinhardt made it clear his boss will not allow him to attend ASTM meetings if CS/Part 23 Reorganization drags on for too long.

Two high-level European institution executives who attended the workshop expressed strong support. “The European Commission supports the range of initiatives identified by EASA and the GA sector to modernize the regulation,” said Filip Cornelis, head of aviation safety at the Commission’s mobility and transport directorate. He referred to “well intentioned and very safe but overly burdensome regulation in some areas.” General aviation regulation should no longer be based on slightly altered commercial aviation rules, he added, endorsing the notion of eliminating weight as a measure of performance and complexity.

Yves Morier, newly appointed head of general aviation at the EASA, said Europe needs a vibrant general aviation sector not only for aviation but also to fulfill a societal need, as general aviation can bring “good discipline” to the young. “We need to think out of the box,” he said, noting that the EASA is ready to accept various levels of certification in tune with aircraft complexity.

More than 90 representatives from industry and aviation authorities from around the world–including the CAAC–attended the session.