This is a good one, although it's fixed wing - details may be wrong, but some of the PNG long-timers may be able to confirm or deny.
A Nomad (twin fixed wing) was taking off out of Madang (I think) with a load of coconuts poorly secured. Accelerates down the runway, rotates, coconuts all roll down the back and throw the CG way behind where it should be, machine stalls and crashes.