Light Sport Aircraft

General

With an installed weight anticipated to be less than 120lbs (54kgs), the TA120TP has a distinct weight advantage over the Rotax 912 engine which is the predominant choice of engine for LSAs.  With a TA120TP installed in a LSA instead of a Rotax 912, this weight advantage would correspond to a 30-40lbs increase in payload capability for the aircraft.  For many LSAs, this would make the difference between being able to carry full fuel and two regular guys, versus full fuel and two lightweights or alternatively two regular guys and reduced fuel.

At Oskosh 2016, the TA120TP engine was introduced to many LSA manufacturers.  One manufacturer referred to it as the "ultimate" powerplant for LSAs, given its light weight, small size and useful power rating.

The current regulatory framework precludes the use of turbine engines in LSAs. However, Turbine Aeronautics intends to petition the FAA for regulatory change/exemption and develop an applicable ASTM standard for turboprop engines.  Once these initiatives are completed, it is the intention of Turbine Aeronautics to undertake ASTM approval for its engines, thereby making them eligible for use in LSAs.

Regulatory Framework

At present, the LSA regulatory framework precludes the use of turbine engines and in-flight-adjustable/constant speed propellors in LSAs.  This is due to the definition of a LSA which stipulates that a LSA is an aircraft which is fitted with a single reciprocating engine and must not be fitted with an in-flight-adjustable propellor.

Having spoken with a member of the committee that drafted the original set of regulations for LSAs, Turbine Aeronautics has been advised that the reason for turbines being precluded was quite simply that there were no commercial turbine engines available in the marketplace at the time the regulations were drafted, nor were there any turbine engines knowingly under development at that time.  Consequently, turbines were simply not included in the definition of a LSA because it was not anticipated that turbines would ever be used in a LSA.

There is also some conjecture that the FAA considered turbines to be "complicated" and that the intent of LSAs was for simple aircraft that were simple to design, build, operate and maintain.  Consequently had turbines been proposed for use in LSAs, there could have been some apprehension on the part of the FAA to approve such a proposal.

In reference to the concerns that turbines are complicated, in reality this is not correct.  The TA120TP will be simpler in design than the piston engine offerings, with a significantly lower parts count.  It is also anticipated that the TA120TP will have fewer failure modes, better reliability and a longer TBO than the piston engines currently used.  With the TA120TP offering "single lever control", which means that the throttle will control engine speed/power and also the in-flight adjustable propellor, operation of the TA120TP could not be any simpler.  In actual fact, the TA120TP is likely to be simpler in design, operation and maintainability than equivalent reciprocating engines.  This simplicity, in turn, will enhance safety.

Turbine Aeronautics, hopefully with the support and assistance of the Light Aircraft Manufacturers Association (LAMA) and the Experimental Aircraft Association (EAA) will commence the petitioning process to the FAA for regulatory reform in order to permit the use of turbine engines and IFA/CS propellors in LSAs.  With evidence to support that the TA120TP is "simpler" than equivalent reciprocating engines, combined with the enhanced safety benefits of the TA120TP, we feel that there is a strong chance of success in gaining the necessary amendments/exemptions to the regulatory framework to permit the use of turbine engines coupled to an IFA/CS propellor in LSAs.

ASTM Certification

If approval is given to use turbine engines in LSAs, a relevant ASTM standard will need to be drafted and once approved, will need to be complied with.

Turbine Aeronautics has approached ASTM to discuss this issue, along with some industry participants.  It is envisaged that Turbine Aeronautics would drive the relevant ASTM Committee to draft and gain approval of an ASTM standard for the design and construction of a turboprop engine for Light Sport Aircraft.