A series of tests by a customer air force on Islanders in the 1970s concluded that when operated in high-ish ambient temperatures the "aircraft should be regarded as a single-engine aircraft and landed immediately following an engine failure". They bought it for its other qualities, but operated it in accordance with that report.
The reason was that they found that regardless of the weight of the aircraft, the remaining engine, at any setting that maintained level flight, overheated within a few minutes.
Strangely, the civilian authorities never picked up on that.
And a Trislander, when called upon to do what the book said after losing power on one engine (centre? wing? not sure) on take-off to the West from Jersey in the 1990s was landed pronto on the beach between the airport and the sea; that was the only viable option available to the pilot. Maintaining height, letting alone climbing, was evidently impossible, according to the reports I read; someone may know of another reason.