Bit,
Most helicopters have marginal or negative LSS in corners of their envelope, the traits are virtually meaningless to pilots, and not detectable unless careful cookbook maneuvers are flown.
The speed stability and trim characteristics of helicopters are created by the rotor, which has excellent speed/stick stability, but can be disturbed by the fuselage and horizontal tail, which react to climbs and descents more than they do to small speed and angle changes. What the regs try to do is measure the cues a pilot gets which tell him that speed has changed. The stick is the last place he looks, especially if the aircraft has "normal" dynamic stability (where the pilot is constantly moving the stick to keep the greasy side down). The most important speed cue is the nose attitude gradient, where the nose goes progressively further down as speed increases. (remember the "60 knot attitude" that the instructor told you about?) With a good attitude/speed gradient, speed is easy to hold, because the pilot just flies back to the right attitude and all is OK. With LSS, the supposition is that the stick position tells the pilot that speed has changed, and that is just not true.
The funny thing is that FAR/JAR dictates LSS based on speed and stick, but never mentions attitude gradient at all. That is because the fixed wing folks who wrote the first CAM 6 and 7 regs were translating requirements from the airplane world, and airplanes have no attitude gradient, just stick gradients.
I could go on here, and you can't nudge me and tell me to stop, so I will just stop.
