Getting the hydraulics going (Right or Wrong)

[ghancock]

So we had to completely flush the skydrol from my system and replace all the o-rings throughout. Now it's time to replace the skydrol and flush all the air from the system.  My question is:  The mechanics are turning the engines (without plugs) over with the starters in order to work the air out and the skydrol in.  I've always been told doing something like this was extremely bad on the starters and just wondering if it's a good way to deal with this or should I respectfully request they use another method?

Thanks,

Glenn

[Willis]

Starters (and starter generators, that I know of) have a duty cycle.

The Usual duty cycle is 30 seconds on, 10-20 seconds off, repeat once, then one minute off.  Repeat once, then wait at least 1/2 hour.  Turboprops have more rugged systems and even then its 1 min on, 1 min off, then wait up to 30 minutes.  (which is why 121 ops like start carts.)

the only way to confirm if there is a seriously weak Duty cycle to be conformed to is to find out how much heat is being generated by the starter.

Cycle the starter for 10, 20, 30 seconds and feel the cables, starter body and terminals and any solenoids (bendix).  Also check the starter relays and cables/terminals for heat.

A normal duty cycle will result in any one of the components to "Just Too Hot to Touch".  Thats the way we measured it in the test cells and I always passed this intel along to the design engineers.


Since, its very likely your POH is a POS and wont address this, consult the Maintenance manual.  (Im buying one on-line for the 500 series).

Ill know more about this in about 2 weeks. hopefully by then the MM will have arrived.

[ghancock]

thanks,  The only question here is the fact that all plugs are removed from cylinders so only pressure on the starter is from the mechanical turning of the engine components and no compression.  So the question is:  If I run the started for an hour and it never gets very hot is that ok? 

Thanks,

Glenn

[Willis]

Heat is the only enemy I can think of.  If its stays cool, then fine.  Thats a really robust system.

remember AMPS x Volts = Power (watts).

So if you're not pulling much power, the amps should stay low enough.

At least that what they taught me in kindergarten. 


Some time, you may want to try and see what happens with a failed start.  IIRC the system is not complex but BIG.  Batteries in the back, cable runs to each engine.  Relays.  Lots of places for voltage drops.

[ghancock]

Thanks for the help.

Glenn