Originally Posted by
gulliBell
Your point is escaping me a little bit there. Twin engine 5 minute takeoff limit is so you don't rip the guts out of the helicopter MGB/TGB/IGB and driveshafts. The OEI limits are so you don't rip the guts out of the engine.
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gulli:
We're drifting off topic, but the point was only to the time frame of the limit (2.5min) not the reasons behind it. This is one of those questions I would ask product support people to keep them on their toes. Nothing more. But I never really did get a good answer.
Why is a twin OEI limited of 2.5 mins exactly half the aircraft 5 min limit? Why not 3 mins or 1.5 mins?
If a twin OEI limit is higher, why not apply the same limit to the same core engine installed in a single engine aircraft?
And... if the aircraft had 3 engines would the OEI limit equal the aircraft limit divided by 3? Or 1.66 mins?