Accelerometers do not affect (good or bad) drift in a hover.
Assuming the gyro is in a hover or simply sitting on the ground, the accelerometers let the gyro know where "down" is.
Assuming the gyro (heli) is "level", the X & Y accelerometers sense 0g and the Z accelerometer senses 1g (gravity).
If the heli is tilted on the ground (like a Goblin), the the X shows 0.02g, Y shows 0g and the Z shows 99.08g.
You may think that the drift is detected by the accelerometers.
But the drift is such a slow acceleration (or none), that the accelerometers are not sensitive enough to detect it or the designers cannot spare any CPU cycles to deal with it.
Gyros like the MSH brand (iKON and Brain) will use the accelerometers for "Rescue" or "Auto Level".
They will Rescue the heli to an upright position (because they help the gyro know where "down" is), but will not "Rescue" to a stable (stationary) hover.
In the MSH gyros, "Rescue" will flip the heli "upright" and apply a little positive collective. Then, after a set-time, it will release control back to the transmitter and act more like "Auto Level".
"Auto Level" will flip the heli upright and keep it within a 30-deg cyclic angle. You can drive the heli around in "Auto Level", but not in "Rescue".
The only way to "cancel" drift is GPS.
Normal stance of a perfectly balanced heli in a stable hover is slightly tilted on the Y axis but the rotor disk needs to be, more or less, "level". The "less" is when the rotor disk is slightly correcting for tail rotor anti-torque thrust.
By adjusting the swash links, you are basically canceling out the correction the gyro is applying based on what it is sensing due to the tilt.
This is more about the FBL gyro's gyros and not the accelerometers. A fybar is a gyro.
But, drift also occurs due to a tilt associated with a nose-heavy / tail-heavy heli. Or the nitro heli with a big pipe sticking out one side with no counter-balance on the other side (like the 2oz header tank).
The software developers for MSH recommend zeroing out the drift in a hover. And it is typically done by some of the most awesome 3D /smack heli pilots as a routine part of setting up the heli.
I know of at least 1 incredible 3D pilot that does not use a swash leveler or zip-tie at all. They eye-ball it, then adjust the links as necessary to cancel out the drift.
That's not me.
I use the swash leveler tool and then adjust linkages
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