a few points.
First off, on many larger aircraft the propeller is driven towards coarse as well as fine pitch by hydraulic oil, while counterweights will push the propellet towards typically 50 degrees of pitch if it is left without oil pressure. A reservoir of oil that can only be used by the feathering pump (which is generally electrically driven) is kept to make sure that you'll always be able to feather the propeller even if the oil system develops a leak somewhere.
Turboprops can go far below -7 degrees in reverse mode. The aircraft I work with go to -16 (typically only using -15.5 since it is in constants speed mode in the reverse region) and -16.5 degrees.
In beta, you most certainly don't have flat pitch. The beta range typically goes from the zero-thrust pitch setting up to 14 degrees or so. In this region, the control lever setting controls the propeller pitch directly rather than controlling engine power and leaving pitch to the pitch control unit. This is described in more detail below along with the reason to have a beta range in the first place.
Free turbine engines are just that, free turbine engines. They don't care much about the pitch setting during startup. With turboprops which aren't free turbine and recips it is a good idea to have the propeller in flat pitch for the reasons you mentioned. Perhaps you got them mixed up?
As for how anything of what you'd wrote would make a P&W engine superior in any way... well, clearly you know something the rest of the world doesn't and I'll leave it at that.
Below is an excerpt from a supplement to my thesis, explaining the very basics of engine management in the SAAB 340.
You have two levers for each engine, Power Lever (PL) and Condition Lever (CL). The range of the CL is divided into
- Fuel off where the engine goes to feather (83.5 degrees pitch) and the fuel is cut off
- Start, where you are supplying fuel to the engine but the prop is still feathered
- UNF, UNFeathered, where the prop is out of feathered and basically in constant speed mode trying to maintain 1180 RPM but without the bottoming governor (more on that later)
- Min to max constant speed (CS) range where the prop RPM is controlled to be within 1180 RPM (min) and 1384 RPM (max).
- T/M (torque motor) lockout, which will lockout, the engine control unit (ECU, or digital ECU, DECU, in B model a/c) if it malfunctions. Once T/M lockout is activated, you have to shut down the engine (put the CL in fuel off) to reactivate it.
The power lever range goes from full reverse through ground idle (GI) to flight idle (FI) and then on up to full power. Below FI you are operating in the beta range where the PL position (unless the CL is in feather or you feather manually) directly controls the prop pitch from -16.5 to +10 degrees. Above FI there is a minimum pitch stop ranging from +10 (FI) to +25 (full power) degrees pitch. As you go from PL full aft to PL full forward, more and more fuel is added to the engine (naturally) through signals to the Hydro-Mechanical Unit (HMU). At low power settings (below approx 30%), this amount of fuel is not enough to spin the propeller up to the commanded 1180 RPM at the pitch setting commanded by PL in beta range or at the minimum pitch stop.
Why do we have a beta range? Due to the slow response to throttle setting changes in turbo engines it is very impractical to use the throttle to control movement on the ground. You would have to wait for the gas generator to spin up (Ng increase), providing more torque through the power turbine (PT) increasing the prop RPM (Np). The prop CS governor would then tell the pitch control unit (PCU) to increase the prop pitch and then you would get additional power. In beta mode, you change the pitch first instead using the inertia in the propeller system to provide thrust, letting the Ng accelerate or decelerate in response to Np to keep Np constant.
If the amount of fuel burned below 30% won’t keep the prop spinning at 1180 RPM, what keeps it at constant speed in the beta range? This is where the previously mentioned bottoming governor (BG) comes into play. The BG is active when the CL is above UNF and will send a signal to the HMU to add fuel above what the PL setting is dictating to keep the Ng up. The normal reference Np for the BG is 1040 RPM but to give more power in full reverse the BG reference will change to 1200 RPM Np when the pitch goes below –10 degrees (<-10 on both engines on older versions).
Early on it was discovered that the torque set in the beginning of the take-off roll would increase as the ram air effect increased with airspeed. To avoid having to stare at the torque (Nq) reading during the entire takeoff roll, decreasing the PL setting to keep it at 100% and not above a CTOT (Constant Torque on Take-OFF) system was added. When active, this system will signal to the HMU through the ECU to add fuel until the preset Nq is reached as soon as you set the PL above a certain position.
If an engine dies there’s an autocoarsen (AC) system, which will detect this. It then proceeds to feather the dead engine automatically. There’s an inbuilt safety making it impossible to feather both engines in flight should this system fail. The AC system continues to monitor a failed engine and will bring it out of AC mode should the engine parameters used to detect a flameout increase above the threshold values again.
340B a/c has something called automatic power reserve (APR) which when one engine goes into AC during CTOT operation automatically adds 7 percent units of torque to the other engine to compensate for the loss of thrust.
I thought I was doing good trying to avoid those airport hotels... and look at me now.