Greetings, 412 Drivers All,
Thank you muchly, Bomber, for pointing out that I WAS indeed (quite clearly) talking about the inherent dangers of
RUNNING LANDINGS in ATT Mode.
Hovering in ATT Mode is actually bloody daft if you are a Bell pilot. Precision maneuvering, winching by day, landings, take-offs, underslung and ops close to the ground are all recommended by Bell as being carried out in SAS MODE. Although
some pilots insist on using ATT all the time, you will end up with thumb-strain and will never be as smooth as the 'sloppy-stick' pilot using SAS. This is the way Bells were designed to be flown - 'free and easy'!
'Clunking' the 412 Force-Trim in and out in ATT Mode does not make for smooth or comfortable flight
and unnecessarily wears out the Trim Release Switch & your thumb! Must be a Sea King/MIL driver, perhaps? Do you like that huge lump of hard skin on your thumb?
Today's reading is from the first book of the Bell 412 RFM (Before Take-Off):
"AFCS - Select ATT or SAS mode as desired (ATT mode shall be used during IFR Flight; SAS mode recommended for ground operation, hover and take-off)."
If you MUST (dementedly) continue to fly in ATT Mode for landing, then I would recommend (as Bell themselves do) that you do NOT do OEI run-on landings in that mode or you will likely need:
a) New skid shoes/cross-tubes/aircraft/job &
b) new underwear.
In ATT Mode, if you do not keep the Stick Trim Released during the smoothest of greasy-ace landings, you WILL find the aircraft/AFCS inputting exactly equal and opposite roll/pitching movements to the normal 'wobbles, bumps and grinds' encountered during this landing procedure. It is quite easy to thereby enter Ground Resonance, or into a joint aircraft/Pilot Induced oscillation of the very worst sort. That's why Bell specifically warns in the Bell 412 RFM (Before Landing):
"RUN ON LANDINGS MAY RESULT IN ROLL OSCILLATIONS WHILE ON THE GROUND. IF THIS OCCURS, LOWERING COLLECTIVE FULL DOWN OR TURNING SCAS OFF WILL STOP THE OSCILLATIONS."
I rest my case and go back to playing with my sloppy stick..........
O