Dogs..
That would be a good way to describe them
But heres the stuff i remember
Starter Gen, PTO seals leak regularly not uncommon to have to replace them every 100
Wiring is a major pain, 15 Alpha panel needs boost pump wires directed soldered to board, they burn out
Beep motor make sure it works and isnt siezed..happens
Seal up tunnel from engine bays, suck in oil leaks of which there are heaps and blows it into cooler fans
Skid springs check for flatness, like any AS350
Push on terminals come loose on engine transmitters and cause fluctuating instruments
Throttle gates, make sure the idle gate is positive or it pops back and takes the engine back to a pre-idle position that burns out turbine as re-light comes on without throttle closed.
Watch for clutch slippage, start one engine then wind it up to 80% then start other engine to idle and bring first one back, otherwise sudden engagement of second engine induces clutch slipping and torque spikes later
Good luck