• A Brumby 760 prototype fitted with a Rotax 915 iS 141-hp engine. (Brumby Aircraft)
    A Brumby 760 prototype fitted with a Rotax 915 iS 141-hp engine. (Brumby Aircraft)

In a move that looks sure to shake up the aircraft manufacturing industry, the US Federal Aviation Administration (FAA) this week released a pre-publication version of a Notice of Proposed Rulemaking (NPRM) that will re-define light sport aircraft.

Known as the Modernisation of Special Airworthiness Certification (MOSAIC), the NPRM is intended to permit manufacturers to take advantage of new technology and safety features without the constraints of the current LSA definition and the costs of full certification to FAR Part 23.

The NPRM proposes to remove the maximum take-off weight limitations from the category and instead define LSA using other parameters.

LSA rules, which the FAA implemented in 2004, contained many restrictions including an MTOW limit of 600 kg for landplanes and, in the USA, a top speed of 120 KCAS. 

"The proposed amendments would enable enhancements in safety and performance and would increase privileges under a number of sport pilot and light-sport aircraft rules," the FAA states in the NPRM.

"These enhancements include increasing suitability for flight training, limited aerial work, and personal travel. This proposed rule would expand what aircraft sport pilots may operate."

The rules placed LSA on a safety spectrum between type-certified aircraft and amateur-built experimental aircraft, and the FAA believes the safety record over the past 20 years has proven the integrity of the category.

"Since the 2004 rule, light-sport category aircraft have shown a lower accident rate than experimental amateur-built airplanes.

"The FAA considers that the successful safety record of light-sport category aircraft validates certification requirements established in the 2004 final rule and provides support for expanding the scope of certification for light sport category aircraft and operations."

Some of the proposed amendments to the LSA definition include:

  • including rotorcraft
  • removing the arbitrary MTOW limit
  • setting a upper stall speed limit of 54 KCAS for aeroplanes
  • setting a maximum speed of 250 KCAS
  • permit four-seat aircraft to be registered as LSA
  • remove the reciprocating engine restrictions to allow any engine type
  • include aircraft with retractable landing gear

Although this proposal removes the specific weight limits for lightsport category aircraft, the proposed rule would indirectly limit aircraft weight via the new stall speed limitations. The FAA believes the stall speed would result in LSA MTOWs of no more than 1360 kg.

Although an LSA would be allowed to have four seats, pilots in the USA flying on sport pilot licences would still be restricted to carrying one passenger only.

In Australia, LSAs can be placed on the VH register via CASA, or registered with Recreational Aviation Australia (RAAus). CASA is expected to adopt the new LSA rules, which will provide a standard for new factory-built aircraft to fit into the new 760-kg MTOW Group G soon to be introduced by RAAus.

"Recreational Aviation Australia welcomes the pre-release NPRM for the MOSAIC program, and we look forward to more news to come out of Oshkosh next week," said RAAus CEO Matt Bouttell.

"The NPRM shows how far the Light Sport aircraft industry has come and this is the greatest reform in these standards since they were introduced. 

"This will be one of the most significant developments in recreational aviation ever. 

"RAAus is Australia's representative on the ASTM F37 steering committee, enabling us to influence these new consensus standards with the aim to adopt these in Australia. 

"RAAus has regularly engaged with CASA to minimise any delay in Australia's adoption of the FAA rules, and we are very confident that current administration within CASA remains supportive. 

"This is great news for Australia's aviation industry and RAAus looks forward to the benefits it will bring our members."

If the new rules are adopted in Australia, it will provide a standard for Australia's aircraft manufacturers to build larger, more capable aircraft without having to go through full FAR 23 type certification.

Aircraft currently offered only as kits in the Experimental category, such as the Rotax 915-powered Brumby 760, could now be offered as factory-built LSAs.

The FAA is due to publish the 318-page NPRM on Monday 24 July.

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