Rotor clearance standards

Rick E

Feb 21, 2013
Sydney, Australia
Cavalon and an MTO Sport
Total Flight Time
In Australia we have recently amended one of our rotor clearance standards from " must remain clear" of prop to an actual given measurement of 2" or 50mm when the stick and rotor head is in the fully aft position with static blades.
I was wondering if the USA has a similar standard and if not is there any hard evidence supporting that such clearance is not necessary.
My understanding is that the Europeans have less than zero rotor to tail clearance and minimum rotor to prop clearance???


Gyroplane CFI
Oct 30, 2003
Givens Predator
Total Flight Time
2400+ in rotorcraft
I am not aware of any such standard in the USA for Experimental, Amateur built gyroplanes.

On all of the gyroplanes I have flown with the cyclic full back and the rotor stopped the rotor blade will hit the vertical stabilizer, the rudder or the propeller.

Most have a procedure to keep from having a mishap.

For instance; on The Predator I do not use full aft cyclic until I see 120 rotor rpm.

On the Cavalon I do not use full aft cyclic below 180 rotor rpm.

It does not seem to be an issue even with student pilots as long as they follow procedure.

To provide two inches of clearance to the rudder on The Predator the mast would need to be taller by a foot i would have less teeter movement or I would lose some back stick angle to provide that sort of clearance.

I would not care for any of or a combination of those options.

I prefer to be responsible for following procedure rather than give up any those features.


AR-1 gyro manufacturer
Oct 31, 2011
Tampa, FL
Total Flight Time
3600+ .. New to gyroplanes
Giving prescriptive solutions to imagined problems is sometimes done in aviation standards and every time I have seen this, I have also found in one way or another how stupid prescriptive solutions really are. DULV has the requirement for having a 2.5 degree pre-cone in the hub bar of the rotors I am told. Another dumb idea and number pulled from somewhere.
One of the good things about ASTM standards was to try and stay away from prescriptive solutions or at least provide an alternative path like "in absence of another rational analysis" you can do XYZ and so on.
ASTM standards tried to specify performance and descriptions of safety spec desired and left methods of achieving that to the designer and engineer. For instance, it would state something like: It should not be possible to hit the propeller blades and/or the tail while following normal operating procedure as described in the POH with full deflection of controls