The resurrected Boeing thread prompted me to ask a buddy just back from G-V recurrent about stab trim ops and training. He mentioned that he doesn’t know/remember … not part of re-current and does not recall it being part of G-V initial.

His answer became; stab trim runaway on the G-V is impossible, but could not begin to explain how/why.

Anyone able to enlighten me?

Up through at least the GV/550 (G1 - G550) Stab trim just compensates for flap position. There is a mechanical connection between the flaps and the stab trim.

Actual pitch trim is done with trim tabs on the elevator.

So you could get elevator trim runaway, but not stab trim

Which will never fail or be improperly assembled or maintained?

I'm skeptical of that claim.

Mike C.

Technically, it would be a runaway pitch trim, not stab trim runaway, and that is very possible to occur in the G-V and family of aircraft. The checklist that covers this situation is "Runaway Pitch Trim"

Which will never fail or be improperly assembled or maintained?

I'm skeptical of that claim.

Mike C.

Which will never fail or be improperly assembled or maintained?

I'm skeptical of that claim.

Mike C.

That's not what I would call a "mechanical connection".

Software is involved.

Clearly, stab trim runaway is possible.

Mike C.

When the flaps are repositioned, a signal is sent to a MCU to drive the stab actuator. The command comes from the flap position based on an RVDT, or there's a backup system where the pilot or co-pilot trim switch on the yoke can move the stabilizer as well.

Which claim? My description of the stab trim or something else?