We on 78 qualified in the Summer when there were not enough Bernoullis at Saiq for fixed wing operations - but at (from memory) about 6500 ft amsl and +50 ish C it was off most performance graphs
It's a good job the Twin Pioneer had no graphs. Mental arithmetic and the back of a fag packet was all there was between getting the job done and disaster. ISTM 80 gallons (2 hours fuel) was the ballpark figure to carry 2000lbs up the mountain four times regardless of temperature. Turbulence, particularly on the 600 yard Rwy 30 approach after midday, was the biggest hazard. I still remember the heat while kneeling on top of the wing to refuel at Firq from 4 gallon cans through an old chamois leather filter.