S-92 Underslung Load Q:

[albatross]

Originally Posted by nowherespecial

jmdsm,

IIRC, there are no component penalties below 4000lb on the S-92.

Between 4-8000lbs there are huge penalties on the gearbox and restrictions on time spent doing load cycles per hour, rendering the S-92 basically uneconomic to use in the repetitive heavy external load category. I'm sure this is to do with what has been previously discussed here, but also to do with the OEM not having any plan as to what the S-92 does next once it's done in it's offshore role.

A rough rule of thumb was around 90% reduction in component life on the dynamic parts even if the cycles with weight attached part was obeyed.

I was told that the reason you don’t see Pumas doing logging is that the cycle count for every pick is huge. Leading to numerous components cycling out very quickly and requiring $$$$++ overhauls. Basically Eurocopter did not want the aircraft doing such operations.

I lost a good friend in the early 80s when the BBQ plate on a Puma failed during logging operations. The transmission rotated ripping out one engine drive shaft which led to an overspeed on that engine and engine overspeed protection shut the engine down. ( overspeed protection on the second engine is disabled when this happens ). The transmission rotated back and tore out the other engine drive shaft which led to the a massive engine overspeed on the now unprotected engine and a engine explosion as the aircraft descended from the high hover. Both crew were killed in the crash and fire.

I well remember when the only cycles we counted were engine starts on all of our turbine helicopters. Nothing else was recorded.Then suddenly you had to record 0.25 of a cycle for each subsequent takeoff or sling load pickup. ( I may be wrong on that 0.25 number)
Then years later they came up with RINS which were, initially so confusing as to be useless unless you carried a secretary to record them. Merely adding power to climb above max continuous incurred a penalty.Lowering power for a descent then increasing power to land another “event” Torque, N1, T4 all were factors. Just how we were supposed to record all that crap and fly the aircraft was not explained. Nor was the requirement for all this explained on aircraft that had been reaching TBO with no problems for years.
Towing a survey bird up and down hilly terrain for 7-8 hours a day was a nightmare. Needless to say some gross estimates +- were made.