i have opened a few t53s up and there is nothing to control n2 inside the engine the most basic way to describe a turbine gas producer is its a big blowtorch.....n1 and n2 control levers are strickly in the fuel control system? how does n2lever govern n2 speed? does it cut fuel or open bleed band? my brother is maintaince head at a power plant with 4 ge over 1 million hp gas turbines they are big and fasinating inside also helping a freind restore a few migs those engines are shakers you can grab the first row of blades and they are very loose and sound like wind chimes as it rotates at slow speed they lock in with centrifical force still does not seem right!
Its all controlled by fuel. If the Bleed ban opens to late the compressor
would force to much air into the combustor and a Stall will most likely
occur. This is when the in coming air actualy changes direction.
Comes right out the intake

I would love to get a tour of your brothers operation.
Come get me in one of those migs and the first round is on me.
What is amazing is the fuel control. It is a very complex unit.
You have to have some serious patience or alot of Corona to
take one of these apart. Even Arruda sends these out.
it has little fly weights that measure rpm of n1 n2 systems
Bellows that measure air density (altitude) It measures outside air temp.
incoming air pressure. It is all Mechanical.
It controls the air inlet vane guides, The bleed band, and of course
the fuel. It plots fuel schedules like takeoff, acceleration,deceleration
this is done with little internal cams and ramps.
You really have to give these guys credit it was late 1940s and 50,s
technology. In todays engines its all computer controlled.
Something else i find interesting is no one to my knowledge has replaced
this unit. with lets say a modified Motec. It has simple inputs and outputs.
and the Flow divider is really what controls the primary and secondary fuel nozzles.via incoming pressure. Perhaps it is what it is reliable.
Now I will Take my Freakin geek hat off now and go get some coffee.
Here is what the fuel control looks like.
Makes a holley Dominator look like a cereal box surprise.