Posted: Wed Sep 07, 2005 1:59 am Post subject: Power check while flying before going into a confined area.
Can someone explain to me how to do a power check, before attempting to go into a confined area. I was shown this once, and it didn't stick in the brain, but there was a lot going on at the time. Is it R22/R44 specific, or is the mechanism the same for all types?
Joined: Aug 23, 2005 Posts: 266 Location: On a course.... golf course
Posted: Wed Sep 07, 2005 10:08 am Post subject:
Fly past the CA at minimum power speed, straight and level, and see what your power is. Then check the placard for the alt/temp and see what your max allowable power is. Then pull that power to confirm you can get it. If the margin is 6" MAP, you can hover OGE. 5" is an easy IGE hover, 4" is getting iffy. If 3" or less, forget it.
These numbers only work for a piston engine - turbines have further factors with N1, torque and TOT limits, so rules of thumb don't really apply.
It's the difference between the bottom of the power curve (X knots) and the max power available. Slow down to the speed for the bottom of the curve and note power in use (manifold pressure). Now in the CBi you pull the collective to see what power the engine can produce (whilst pointing the nose down to keep level) and note that. So it takes 20" to fly at X knots and you can actually produce 27" of manifold pressure before you over-pitch, so you have 7" of power available - enough for any landing you like. However on a hot, high day you might only have, say, 4" in hand which means you will have to do a zero speed landing...
7" = OGE hover
6" = normal IGE approach
5" = low hover
4" = zero speed
less than that = run on landing
Thanks for the replies. I'm in Kazakhstan for the next three weeks so I don't exactly have an instructor to ask. I thought I'd use the power of the interweb to get the answer to something that's been bugging me. I wanted to have it clear in my head before I did it next, which will be with an instructor.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum