Your AULA could get too fat

Recently, COPA has received some questions about empty weights for Advanced Ultralight Aeroplanes (AULAs) which shows that there is some confusion here.
Many AULA owners don’t realize that there is a limit to how much extra equipment you can add to your AULA before it ceases to become an AULA. It literally gets too fat to fly legally.
The rules on this one actually make sense – there is a requirement to make sure that your AULA has enough weight available to carry crew and fuel without going over the manufacturer’s imposed gross weight.
As some ultralighters have discovered flying over gross can lead to crashes.
The CAR’s definition of an AULA, the manufacturer’s Declaration of Compliance and the individual aircraft’s Statement of Conformity all state that an AULA must at all times conform to the Design Standards for Advanced Ultralight Aeroplanes.
One of the requirements of that standard is that the aircraft must adhere to a minimum useful load when initially registered and also throughout its life.
That minimum useful load is determined by the following simple formula:
For a single place aeroplane (Wu) = 175 + 0.5P, in pounds, where P is the rated engine power in Brake Horse Power.
For a two place aeroplane (Wu) = 350 + 0.5P, in pounds, where P is the rated engine power in Brake Horse Power
The idea is that the 175 pounds for single-place aircraft and 350 pounds two-place give enough weight for one or two standard-sized people.
The “0.5P” or half the horsepower is to allow fuel to be carried.
For instance, the minimum useful load for a Quad City Challenger II AULA two-seater with a 50 hp Rotax 503 would be 350 pounds + 25 pounds = 375 lbs.
With a maximum gross weight of 800 pounds, the empty weight cannot be more than 425 pounds.
It is worth noting that there is no extra allowance for floats or ballistic parachutes.
TC does not allow gross weights on AULAs to be raised without written approval of the manufacturer; so keeping the empty weight low is the only way to keep the aircraft legally flying.
Operating an AULA over the gross weight approved by the factory is not only foolish, it invalidates the registration of the aircraft.
If you add enough extra equipment to the aircraft to reduce the remaining useful load below the Design Standard requirements then the aircraft will no longer qualify as an AULA.
These are all good points to consider when adding equipment to your AULA – remember your minimum useful load!