Most general aviation pilots today have no access to a readily available technology that can prevent loss-of-control accidents, the single-largest cause of small aircraft crashes.
The technology is called stability protection, offered as a sort of passive autopilot available in most Garmin flightdeck-equipped business jets introduced after 2010. It works not unlike the envelope protections found in more sophisticated, fly-by-wire-enabled jets. If the air data systems detect the pilot is banking too steeply, Garmin’s electronic stability and protection system “nudges” the stick back to wings level. If an inattentive pilot flies too slowly on approach, the stick gently lowers the nose to pick up speed and avoid a stall.
“I think the silver bullet [for preventing loss of control] is envelope protection,” says Greg Bowles, director of engineering and manufacturing at the General Aviation Manufacturers Association (GAMA).
But the technology remains too expensive for the general aviation market. When Garmin released a version of Electronic Stability Protection (ESP) for the Beechcraft King Air, the optional installation cost nearly $18,000. That’s a reasonable investment for a $7.5 million aircraft, but well over the budget of most general aviation pilots flying decades-old, four-seat aircraft with piston engines.
It doesn’t have to be this way. When an aviation rulemaking committee established by the US Federal Aviation Administration investigated a similar, safety-enhancing device called an angle of attack (AoA) indicator, the cost of components was only $500-$600, but the cost of installation was at least an order of magnitude more expensive. Most of that additional cost was to satisfy airworthiness and production regulations created by the FAA. The agency later accepted an industry-adopted standard for the design and production of a low-cost AoA, and the cost of installation has since dropped to as low as $1,000.
Today, a Cessna Skylane must meet the same design regulations as a Citation Latitude
Textron Aviation
But that standards-based approach was hard to fit under existing Part 23 regulations for general and business aviation. The FAA normally uses standards to approve non-critical hardware, such as screws and bolts. Applying the same approach to an advanced flight control system, such as stability protection technology, is not a possibility.
The low-cost AoA marked “the first time we’d seen a standard created for something that was a detailed part that was a little more complex”, Bowles says.
But stability protection “is an example of something we cannot fit under today’s regulations and that’s why the Part 23 rewrite is so important. The failure modes are more critical”, Bowles says.
At the Experimental Aircraft Association’s annual fly-in in Oshkosh, Wisconsin, starting on 24 July, the rewrite of Part 23 regulations is a highly charged topic. The FAA began the regulatory review process nine years ago. The ARC chaired by Bowles submitted its report three years ago. In March, the FAA released for public comment a notice of proposed rulemaking to make sweeping reforms of Part 23. The comment period closed in mid-May with about 70 submissions, so the agency should be able to propose a final rule to the Department of Transportation and the Office of Management and Budget in the White House as early as the end of the summer.
Most of the attention on the Part 23 rewrite has focused on the top-level reforms. The FAA is proposing to drop most “prescriptive” and weight-based regulations for the category of aircraft below 8,618kg (19,000lb) with fewer than 19 passengers. In its place, the new regulations would create consensus-based standards for the design of aircraft in four categories. Under Part 23 today, a two-seat piston aircraft and a 19-seat business jet must comply with the same design regulations. The rewrite breaks Part 23 into four classes divided by performance and complexity rather than seat-count and weight.
By overhauling the regulations, the goal is to stimulate the launch of safety-enhancing technologies and customer-pleasing innovations in a general aviation market that has been in long-term decline. In the USA, the average age of private pilots is over 60 and their numbers are at 50-year lows. As the supply of customers contracts, the cost of new aircraft continues to soar, with the list price of a four-seat Cessna 182 now above $850,000.
The exhibit areas at the EAA fly-in, however, will reveal a different vision of the industry. The exhibitors will offer a showcase of technologies not currently eligible for certification under Part 23, including electric-powered aircraft and new avionics with “flight-directing” features, which replace manual control inputs with digitised commands from take-off to landing.
As part of the rewrite, the industry and regulators teamed up to draft rules in a way that can accommodate new ideas, including technologies that have not yet been conceived. Bowles recalled the first meeting when the rewrite committee attempted to conceptualise how aircraft technology could change over the next 20 years.
“Within the first half hour we realised that was an un-doable task. So the path we chose to go down was writing rules in a way that was timeless,” Bowles says.
One example is a Part 23 rule that specifies how much energy a pilot seat must absorb during a crash. Such a specification assumes that aircraft designed in 2036 will have a pilot on board, Bowles says.
“So instead of that, that rule says the aircraft needs to protect the occupant at a certain amount of crash energy,” he adds.
Regulators took the same approach to redrafting the rules for aircraft engines. The current rules assume engines must have fuel lines, which are not always relevant with electric-powered motors.
“The new rule is about ‘energy transmission lines’. It’s not about a particular technology,” Bowles says.
As the FAA and industry strive to make aviation rules less prescriptive, the National Transportation Safety Board (NTSB) urges caution. The FAA modelled the Part 23 rewrite on the consensus-based standards adopted for the light sport aircraft category. Those new rules allowed dozens of new aircraft types to enter the market, including the Zenair CH-601XL. The NTSB investigated a series of in-flight break-ups of the CH-601XL caused by aerodynamic flutter. The consensus-based standards in the light sport aircraft category allowed the FAA to certificate the aircraft, but the NTSB concluded the CH-601XL would not have been passed the prescriptive rules in Part 23.
“Although the consensus standards process provides a collaborative framework for standards development, we are concerned that design standards important for safety considerations may be overlooked”, the NTSB wrote in comments submitted on 12 May for the Part 23 rewrite.
But the FAA and the Obama administration are under heavy pressure to approve the new rules for general aviation by the end of the year. With a new US president taking office in January, any delay to the rulemaking beyond 2016 could put the process on hold for several months as the new administration gets settled and develops priorities. In the meantime, the EU is likely to approve a similar rewrite to its general aviation design rulebook by the end of the year, so any delay to US approval means American manufacturers will be at a disadvantage to European competitors for several months or even longer.
“That kind of delay would be very problematic,” Bowles says.
Despite the NTSB’s concerns, there is broad support for the overall rulemaking package. But the Part 23 rewrite is just one of dozens of similar rulemakings queued for approval by the White House in the last months of the Obama administration.
Source: FlightGlobal.com
