Piper seminole Hobbs meter?

av8or91

av8or91

Well-Known Member
When does the hobbs start counting time in the Seminole. I know its obviously when the engines are running but does it start when one engine is running?
 
Most hobbs meters start when you flip the battery switch. All they do is count when electricity is flowing.
 
The 2000 model of the Seminole had a hobbs that was linked to the battery master. The 1979 model didn't work that way.
 
will_fly_for_bandwith said:
I thought that oil pressure started them..

Renters can fly around with the master switch off and not get billed !!!
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Oil presusre is typical for singles. Since a lot of the time spent in twins training inludes shutting down an engine, you either need the hobbs to be connected to the oil pressure sensor on both engines (extra complexity), or it will stop counting when one of them is shut down. That's easily resolved by connecting it to the master. And yes, if you had the master off in flight, it would not tick but you'd have to explain why you're get more time on the tachs than the hobbs.
 
Depends on the plane. I've been in Seminoles where it runs off the right engine oil pressure and where it runs off electrical current (e.g. Battery/Master ON). I believe the other posters are correct in that the newer Seminoles' Hobbs all run off the electric system.

But if you're unsure and you really want to save on Hobbs time, you're going to have to feather and secure the right engine and turn-off the electric system. Also, I'm not flying with you... :rolleyes:
 
ILS37R said:
But if you're unsure and you really want to save on Hobbs time, you're going to have to feather and secure the right engine and turn-off the electric system. Also, I'm not flying with you... :rolleyes:
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That's funny ILS...I'll just sit and watch from the FBO, too. In conclusion, you can see both types of systems in planes you rent. It's not completely unheard of for owners in singles to hook up to the master so you can be charged before the motor starts turnin'....
 
ILS37R said:
Depends on the plane. I've been in Seminoles where it runs off the right engine oil pressure
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Correcto, the last one I flew it was off the right engine. You better believe I was hoping to shut that one down during lessons. ;)
 
In the seminole I flew (1989), it was off the oil pressure. I believe it was the right system. On the other hand, the Aztec I'm flying starts the hobbs when the gear doors close.
 
intern_mike said:
MASTER switch ON = Hobbs running.
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Not sure about the Seminole but our Duchess billing hobbs is oil pressure activated, as is every other airplane we have, the other hobbs in the duchess is for "tach" time and is air activated by a little vane under the belly.

Any correctly installed Hobbs should run even with the master switch off.
 
I found out today in class that in fact does run off of the the right engine oil pressure for the 1999 and up piper seminoles
 
at ATP the 2000 models were activated by the master. Once I was landing finishing up my last hour for my CFI training and ATC gave us a go-around, my CFI shut off one side of the master during the whole pattern, when I went to put the landing gear down, everything went dead, had to reboot everything. Saved him 30 bucks though. (ATP would charge the instructors 30 bucks for every .1 they went over on the hobbs with their students, Or so I was told)
 
Fly_Unity said:
at ATP the 2000 models were activated by the master. Once I was landing finishing up my last hour for my CFI training and ATC gave us a go-around, my CFI shut off one side of the master during the whole pattern, when I went to put the landing gear down, everything went dead, had to reboot everything. Saved him 30 bucks though. (ATP would charge the instructors 30 bucks for every .1 they went over on the hobbs with their students, Or so I was told)
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I talked to one of the mechanics at the airport and he said it goes off the right engine oil pressure. Must be different for each plane.
 
Ok, figure for any airplane you can fly, there are a few different types of hobbs meters that can be installed.

You can install off of a little hole in the wing. It starts to click away when you reach 60kts or what ever its calibrated at. This is good for maintenance because it essentially cuts .1 - .2 off of every flight if you're at a big airport.

Second you could have a hobbs that was run off of engine oil pressure. This is what most flight schools do for billing time. (That way you can't turn the bat master off and fly around for free and they get you for the taxi time)\

Third and finally you could have it hooked up to the bat master, though I don't really know why you'd want to. Which would mean that as long as the battery tie (or what ever) is connected the hobbs is turning. Great for charging people because you may get a little extra each time, but horrible for maintenance.

In commercial charter ops, I've heard of more than a few companies running an air hobbs for maintenance and a pressure hobbs for billing. Or as the previous post might have indicated, it might be a battery hobbs for billing and a pressure hobbs for maintenance. That seems like a bad idea for a school that's running a lot of students on a lot of cross countries, seems like a great way to get your ass handed to you by clever students.
 
Ive heard but am not sure but I believe the maintenance hobbs goes off the squat switch for the seminoles.
 
Different airplanes and different companys have different systems. It isn't a factory installed standard.
 
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