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Ringing the bell

I instruct in the TH-57 - very similar to the "news helicopters" of the 80s and 90s.  Carries 5 people, two blades, skids to land on.  We use it because it's cheap, reliable, easy to fix, has readily available parts, etc. etc.  Considering all we put the birds through, it's a beast.  For example, on any given day a bird may have its engine cut to idle in flight, float to the ground, and then run the engine back up to full speed, for anywhere between five to ten or more times.  Point being, we run the birds into the ground, but they're designed for it, so they perform admirably.

Overtorques are a very notable exception.  You see, we have a very capable engine that gives us about 420 shaft horsepower, but a transmission that is only rated to 317 shaft horsepower.

What a TH-57 may look like.

We also have a "droop compensation system" that responds at a rate commensurate with the rate at which you move the collective.  (The collective controls the pitch on the blades - more pitch = more thrust = needs more engine power.)  All of these things along with student jitters combine to create the overtorque.  We're normally allowed to go to 100% torque, with a 10-second allowance up to 110%.  Above that, you have to land the aircraft to get trucked back due to the fact that you may have damaged the drive train - and the aircraft doesn't fly for very long when disconnected from the engine.

Overtorques happen for many reasons - an improper pedal turn, bringing the engine online from idle while still applying pitch to the rotors, or, in my case the other day, a very quick increase in collective.  Instructors are given guidance to defensively posture themselves to avoid overtorques, to include advising you to place your hand over the collective to limit its travel when you think the student is about to increase it for whatever reason.  In my case, my student looked to end an approach early due to being in a bad place to make a safe landing.   He began to increase collective quickly and I wasn't in a good position to stop its travel and DING!  We hit 118%.  My first overtorque.

(for those wondering what "ringing the bell" is, it refers to the quickness with which the torquemeter's needle moves - and when it gets to 110% or more, the digital display flashes at you.  DING DING DING DING DING)

Today’s flight

Weather was skosh while driving in, but we briefed anyway in anticipation of the clouds lifting later in the afternoon.  After briefing I saw a lot of red CNX WX up on the ops board and my studs were giving me a bit of pressure to cancel.  I had a feeling that we just needed to give the weather a bit more time, so I said we'd sit for a while and see how the cloud decks turned out.  Sure enough, in an hour and a half we had enough sky to go flying for a couple of BI flights.

I was a bit nervous, as this was my first flight with students and I was the first guy from my squadron to launch and go fly BIs, which have a different set of weather requirements than all our other flights.  After going through checklists that seemed to take twice as long as usual we got out to the working area - weather was juuuuust good enough to complete all our maneuvers.  Not bad for a first flight. To top it off, the lineman gave us a ride back to the hangar!