SNS',
So if you're operating at ground idle in an AirTractor you're not complying with the procedures outlined in the Flight Manual. No biggie till you have to explain to the accident investigators why the condition lever was at ground idle.
What are the engineering reasons for avoiding beta or reverse?
Taxiing in Flight Idle and using Beta to control speed has less effect on ITT than taxiing in ground idle and using Alpha. It mightn't sound that great but I haven't had any engineers tell me its bad for the plane.
I happily use beta on late, late finals if I'm a little hot over the fence. It's an asset in the 802 because its such a heavy aircraft (more inertia) and you're better off having a little more rather than less speed on the approach.
My point here is that there is nothing in the Flight Manual to say 'Don't use Beta or Reverse' but it clearly states that Flight Idle should be selected prior to Take-off. So far I haven't heard a convincing argument for anything different.