Hi everyone,
interesting thread!
I only have about 750 hrs in the EC120B but NEVER even got close to a hot start!
Here it goes:
# NEVER even try to start below 17 V!b If you do, you risk a comlete electrical blackout with nothing to shut the throttle - here is one more: Watch these SAFT batteries!! There excellent until they get around 3 years - they show full charge but is just on the screen! With the aux-pump on and starting suddenly everything goes to below 15V in a hurrry!! We exchanged with a kit that uses a new maintenance free Concord....
# Don't worry about the 30 sec of the aux-fuel pump. It only puts pressure into the system until the engine-driven fuel pump takes over. Switch it on, at about 15 sec you crank the temp down, when Ng goes low, go ahead with the start! What if your fuel pressure goes low? The manual says to switch the aux-pump on! Again, no worry about the 30 sec or 60 sec or 300 sec!!
# Now the following WAS in the manual at some time, but I still use it as it works just perfect:
If you have some higher rest T4 showing, start in the shutoff position until Ng has 10%, then roll it into ground idle. You never will overtemp it. (This cools about as good as cranking to Ng10%, but the rest T4 doesn't start to climb again!)
I actually did various hot starts with a rest T4 of around 315°C, NO cooldown cranking, but starting at shutoff until 12% Ng. Sure, you want to watch T4 closely and modulate it accordingly, but I never even got to redline.
Now of course this was trying things out, so normally I crank it down to 230-200°C (but never more than Ng 10% on the cranking...), all while the aux-pump is on. The hotter rest T4 is, the higher you want Ng before rolling to ground idle, BUT never go beyond 14% ( personally I keep the limit at 12%) or you might risk to not light off.
Also on a regular start, be patient until you see the T4 rising a little faster after it passes 300°C. From there on you can push it a little towards the upper limit which will help to accelerate the engine faster ( remember: the hotter you can start the turbine the better - without exceeding limits!!!), and you get off the starter sooner.
On a regular cold start, if you leave the turbine to itself (with the throttle at ground idle) it will take forever to get to Ng 50%.
After T4 starts to go up faster passing 300°C, it will slow down and stop at around 650°C if you don't help it. So as soon as you see T4 rise slowing, start to roll on the throttle slowly. Actually if you are too slow you will reach Ng 50% before T4 ever sees 750°C.
Remember they couldn't make the 120 too good or they put these Squirrels out of business! LOL!!
3top
