Hobbs

"Dave S" wrote in message
nk.net...
B A R R Y wrote:
Gig 601XL Builder wrote:


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.


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.


If I understand, the stipulated value is "flight time". Not ground time.
Not hobbs time, not engine time.. nor master switch time.

But the feds are also taking it on the honor system that you will not tie
it down and let it run up 40 (or 25) hours on the ground, then sign off
phase 1.

My particular install has an engine monitor that records hobbs time, when
the engine is operating, and flight time, when the ASI is above 30 mph.

Dave

There's flight time and then there's PIC time. I log PIC time from engine
start to engine shutdown. I know some that log PIC time only when they're
moving. I know a guy who logs PIC time from ropes off to ropes on.

I log flight time from wheels off to wheels on (or the amphib equivilant).
None of that is based on tach time. I have no use for Hobbs time.

My personal checklist has Tach at S/U, Start time, T/O time, T/D time,
Shutdown time, Tach at S/D.

--
-------------------------------
Travis
Lake N3094P
PWK

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.

Travis Marlatte wrote:

There's flight time and then there's PIC time.

My answer is regarding a very specific question. The question pertains
to experimental aicraft undergoing phase 1 flight test. The FAA dictates
a minimum of 40 hours flight time prior to removal of phase 1
limitations, or in the case of an engine/prop combination that is
already certified for use in a "certified"/non experimental aircraft, 25
hours.

The airplane is not capable of logging PIC time. The pilot may be. But
I've yet to see a plane log it.

Running the engine on the ground for 40 hours may give you 40 hrs hobbs
time but 0 hours flight time. Having the hobbs wired to the master could
also pad the time significantly, without the engine even running.

Someone could sign off the books and nobody would be the wiser.. but
you'd only be cheating yourself, if you took your family/friends up in a
plane that wasn't shaken down properly.

"Dave S" wrote

Running the engine on the ground for 40 hours may give you 40 hrs hobbs
time but 0 hours flight time. Having the hobbs wired to the master could
also pad the time significantly, without the engine even running.

Someone could sign off the books and nobody would be the wiser.. but you'd
only be cheating yourself, if you took your family/friends up in a plane
that wasn't shaken down properly.

Also add that in those 40 hours all systems are to be checked in all
possible circumstances and all different parts of the flight envelope. The
plane is supposed to be evaluated to see what the limits of the flight
envelope are, and an operation manual written, with all of the applicable V
speeds logged in said manual, and emergency procedures written.

For planes like the RV that have thousands of copies flying, that might not
be too hard to do, but for a plane that is a one-off, or only has a few
copies flying, and likely with different engine and prop combinations, and
with who knows how many slight variations, I would think nailing down one of
these rare airplanes would need all of the 40 hours, to do the job well.
--
Jim in NC

Peter R. wrote:
On 7/3/2007 6:50:49 AM, Ron Natalie wrote:

Bonanza's don't even have recording tachs anymore. All they have is the
hobbs. My plane is similar, but it's on the gear so I don't pay for taxi.

Interesting. So Hobbs time is what gets logged in the aircraft/engine
logbooks?

Exactly. Time in service.

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).

"Ron Natalie" wrote in message
m...
Peter R. wrote:
On 7/3/2007 6:50:49 AM, Ron Natalie wrote:
Bonanza's don't even have recording tachs anymore. All they have is the
hobbs. My plane is similar, but it's on the gear so I don't pay for
taxi.

Interesting. So Hobbs time is what gets logged in the aircraft/engine
logbooks?

Exactly. Time in service.

Context please? Every engine/airframe log book I've ever seen (small, single
engine) is based on tach time.

--
-------------------------------
Travis
Lake N3094P
PWK

Morgans wrote:
I would think nailing down one of
these rare airplanes would need all of the 40 hours, to do the job well.

Maybe even longer.

One of the first turbo rotary powered cozy's was in phase 1 for well
over a year with teething problems. Primarily related to problems from
attempting to use stock turbo's and clipped versions of the stock turbos.

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

Travis Marlatte wrote:

Interesting. So Hobbs time is what gets logged in the aircraft/engine
logbooks?

Exactly. Time in service.

Context please? Every engine/airframe log book I've ever seen (small, single
engine) is based on tach time.

You won't find the words "Tach Time" anywhere in the regs.
The rules say "time in service." Actually most maintenance
entries don't require the time to be recorded at all, just
the date.

The definition of time in service from Part 1:

Time in service, with respect to maintenance time records, means the
time from the moment an aircraft leaves the surface of the earth until
it touches it at the next point of landing.

A squat switch / hobbs is a better indication. However, recording
tachs are cheaper and more common and the FAA has always allowed them.