Hobbs

That is interesting. Does the FAA specify tach vs. oil pressure Hobbs,
vs. electric Hobbs?

Think of how many pilot logbooks are based on electric Hobbs time.


Neither is correct to the letter of the regulation, both are acceptable
to the FAA.

Pilot time is the real time from the time that the aircraft first moves
under its own power for the purpose of flight until it comes to rest at
the destination. The oil pressure time is pretty darned close (I
assert the aircraft moves forward a tiny bit as soon as the engine
starts and isn't really at "rest" until it stops). Unless you leave
the master on for a long time in a prolonged preflight, the difference
is probably within the tenth of an our accuracy of the unit.

For maintenance, it's time in service. Frankly, even putting the hobbs
on a gear switch is acceptable to the FAA (saves you some time if you
operate out of places like Dulles where you can wait / taxi for a long
time before taking off).

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message
...
B A R R Y wrote:
Orval Fairbairn wrote:

Sometimes, unscrupulous owners will wire the Hobbs to the master
switch, so you get charges whenever the MS is ON.

My Hobbs is on the master, but the airplane has never been rented.

Which brings up a very interesting question. I'm building a plane that
will be licensed as an Experimental. Once inspected I'll have to test fly
for 40 hours for phase one. If I use a Hobbs as the official time and hook
it to the MS I would probably end up reducing the phase one time
considerably.


Maybe. At what RPM is your tach even with elapsed time?

All of the rentals and the only plane I have owned turn the tach faster than
elapsed time at higher RPM. (By the way, what do you call the counter thingy
in a tach?) My max RPM is 2650. I have to bring it back to around 2350 to be
even with elapsed time. That happens to be at the top of a restricted zone
so I would never be at an advantage using Hobbs to log flight time unless I
spent most of the flight idling around the airport.

I happened to do most of my renting from a club that charged by the tach
time. Everyone thought that was great - and maybe it was for students who do
less cruising - but the tach time was always more than elapsed for my
weekend trips.

Is there some specficiation or reg as to what RPM equals elapsed time? If
you're renting, fly slower. You'll log more hours cheaper. If your test
flying, fly faster. You'll chew up more tach time per elapsed hour.
-------------------------------
Travis
Lake N3094P
PWK

On Jul 2, 12:31 pm, Orval Fairbairn wrote:
In article ,
B A R R Y wrote:

Larry R wrote:
Ok, I am *almost* embarrased to ask this question, but here goes. Do
Hobbs meters ever "go bad"?

Sure, it's a mechanical device.

On two occasions over the last few years, my Hobbs has failed to move.

For this reason, I always note my tach time and time off. The extra
start numbers will help just in case I don't notice for a while that the
Hobbs isn't running, and I need to have a fuel consumption figure.

Sometimes, unscrupulous owners will wire the Hobbs to the master switch,
so you get charges whenever the MS is ON.

My hobbs is wired to the master. Am I unscrupulous somehow??? What
would be the reason for someone to sit so long with the master on and
the engine not running?

-Robert

Robert M. Gary wrote:

My hobbs is wired to the master. Am I unscrupulous somehow??? What
would be the reason for someone to sit so long with the master on and
the engine not running?

Apparently the minute and a half (or less) that it takes you (and I) to
do the "electric loop" during preflight is flogging logs. G

At least in my case, I flip the switch, check the fuel pressure and
guages, do the lights / strobes / pitot heat / stall horn walk-around
checks, and turn it back off. That's pretty much it without the engine
running.

On Jul 3, 11:26 am, B A R R Y wrote:
Robert M. Gary wrote:

My hobbs is wired to the master. Am I unscrupulous somehow??? What
would be the reason for someone to sit so long with the master on and
the engine not running?

Apparently the minute and a half (or less) that it takes you (and I) to
do the "electric loop" during preflight is flogging logs. G

At least in my case, I flip the switch, check the fuel pressure and
guages, do the lights / strobes / pitot heat / stall horn walk-around
checks, and turn it back off. That's pretty much it without the engine
running.

Yes. even when I'm flying the glass cockpit planes I don't think I
have the master on without the engine running for more than a couple
of minutes. I don't think it would be a good idea to sit there with
the master on for long periods. Seems like the smart FBO would wire
the hobbs to the master to prevent people from running the battery for
no reason.

On Tue, 03 Jul 2007 23:32:32 -0000, "Robert M. Gary"
wrote:
Seems like the smart FBO would wire
the hobbs to the master to prevent people from running the battery for
no reason.


Even though fuel is used, I actually feel it's beneficial to have the
engine running while I pick up clearances, program the GPS, set the
radios, etc...

On cold days, we get a bit of heat spread around the oil and engine
block before I go full throttle for takeoff. On hot days, the
spinning prop keeps the cockpit cooler. G I do lean the mixture
while ground idling and taxiing, to prevent fouling the plugs. Once
the engine is started, I'm rolling within a few minutes.

Robert

I've set in the parking area with the radio on waiting for an IFR
clearance,

Big John

************************************************** *****

On Tue, 03 Jul 2007 18:11:27 -0000, "Robert M. Gary"
wrote:

On Jul 2, 12:31 pm, Orval Fairbairn wrote:
In article ,
B A R R Y wrote:

Larry R wrote:
Ok, I am *almost* embarrased to ask this question, but here goes. Do
Hobbs meters ever "go bad"?

Sure, it's a mechanical device.

On two occasions over the last few years, my Hobbs has failed to move.

For this reason, I always note my tach time and time off. The extra
start numbers will help just in case I don't notice for a while that the
Hobbs isn't running, and I need to have a fuel consumption figure.

Sometimes, unscrupulous owners will wire the Hobbs to the master switch,
so you get charges whenever the MS is ON.

My hobbs is wired to the master. Am I unscrupulous somehow??? What
would be the reason for someone to sit so long with the master on and
the engine not running?

-Robert