The realities of operating these (ex USSR) a:c in certain parts of Africa have little to do with published performance figures.. basically they're good workhorses when maintained to the basic standards but in the hands of impoverished companies who see them as a disposable asset good for making a few bucks they can be lethal... gross overloading is commonplace and one russian pilot (Ukrain to be precice) I talked to at Mbandaka was quite open about how they sold space (no seats on cargo a:c) to locals after the freight was loaded.. as it was well overweight before the pax climbed aboard the mind boggles at the performance expected once 10 to 20 people found seating space...a bit like the merchant marine in its early days... all of us familiar with flying in places such as DRC have become accustomed to old Russian stock taking to the air and relying on the curvature of the earth to gain altitude;; often stil at 2 to 3 hundred feet when disappearing over the rooftops 5 miles away... they don't need to lose an engine... any engine producing less than 100% is likely to result in a disaster..