Originally Posted by
SASless
Moving the triple Tach had more to do with the Bristow Mod designed in their mind to prevent Loss of RPM actions.....part of which was disabling the Torque Limiting system...which also removed the Torque Damping which made Torque Control really dodgy...and led to lots of overtorques and a mod to the mod for a system to record overtorques.....and ultimately the whole mess was **** canned and the aircraft returned to Factory Spec.....as I recall it.
The moving of the control panel was done by other operators as well....not just Bristow.
I do not know of another Operator who used any such Mod as the Bristow Torque thing.
I'm sure other operators will have moved the panel - it certainly made no sense ergonomically and the mistake described is very expensive!
The Bristow Tq modification was a direct result of a fatal accident in the North Sea, which MAY have been averted if the factory standard system had not been designed to limit Tq to 104% - saving the MGB vs the airframe is maybe not the best design compromise. The UK AAIB recommended that it be investigated whether the Tq limiting be increased, and a recording device installed to record any overtorques. The limiting was not removed, but "wound up". Governor instability was a natural result and a recognised issue. Later in service they installed the 'Hi Power mod' (TB-138/145) with an increased TO Tq limit, and a trim actuator for No 2 Nf, using a beep switch on the collective to help match Tqs as they became unstable.
AAIB report here:
https://assets.publishing.service.go...982_G-BIJF.pdf