Hobbs

[Larry R[_2_]]

Ok, I am *almost* embarrased to ask this question, but here goes. Do
Hobbs meters ever "go bad"? No, this isn't a joke!

I recently took a flight from KLOU-KWWD-KLOU. It was IFR and I wrote
down my off and land times, which coorespond with the FlightTracking
times within a couple of minutes.

The hobbs time was 10.7. The flight time was 9.6. Not whining here,
but it was a little hard to believe that I had over an hour of taxi/
start time on this!

Just wondering..

--Man would that be some kind of AD-- LOL!

[B A R R Y[_2_]]

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.

[Orval Fairbairn]

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.

I have hated Hobbs ever since I discovered them 40+ years ago, since you
pay full rate for taxi and hold times.

An air switch is available, but hardly anybody uses them.

[john smith[_2_]]

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

> B A R R Y > wrote:
> 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.


I am a renter, so I have made a 5x8 index card to record the following
for each flight:
Date
Aircraft N-number
Departure Airport
Destination Airport
Left Main Fuel Tank Start/Stop
Right Main Fuel Tank Start/Stop
Left Tip Fuel Tank Start/Stop
Right Tip Fuel Tank Start/Stop
Hobbs Start/Stop
Tach Start/Stop
Clock Start/Stop
Clock Wheels Off/Wheels On

[[email protected]]

Larry R > wrote:
> Ok, I am *almost* embarrased to ask this question, but here goes. Do
> Hobbs meters ever "go bad"? No, this isn't a joke!

Everything eventually "goes bad", just some things sooner than others.

A Hobbs meter is a mechanical counter with gears, bearings, a motor,
etc. so yeah, it can go bad.

--
Jim Pennino

Remove .spam.sux to reply.

[Peter R.]

On 7/2/2007 3:31:14 PM, Orval Fairbairn wrote:

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

Isn't that true for the Hobbs installed by the aircraft manufacturer in newer
aircraft? I was taught that all the newer model C172s' Hobbs are wired to the
master, which results in about a 20% greater difference between their
readings and the tach.

--
Peter

[Peter Clark]

On Mon, 02 Jul 2007 18:53:49 -0000, Larry R >
wrote:

>Ok, I am *almost* embarrased to ask this question, but here goes. Do
>Hobbs meters ever "go bad"? No, this isn't a joke!
>
>I recently took a flight from KLOU-KWWD-KLOU. It was IFR and I wrote
>down my off and land times, which coorespond with the FlightTracking
>times within a couple of minutes.
>
>The hobbs time was 10.7. The flight time was 9.6. Not whining here,
>but it was a little hard to believe that I had over an hour of taxi/
>start time on this!

In my experience, usually they just stop. What kind of aircraft is
this?

[Peter Clark]

On Mon, 2 Jul 2007 16:35:20 -0400, "Peter R." >
wrote:

>On 7/2/2007 3:31:14 PM, Orval Fairbairn wrote:
>
>> Sometimes, unscrupulous owners will wire the Hobbs to the master switch,
>> so you get charges whenever the MS is ON.
>>
>
>Isn't that true for the Hobbs installed by the aircraft manufacturer in newer
>aircraft? I was taught that all the newer model C172s' Hobbs are wired to the
>master, which results in about a 20% greater difference between their
>readings and the tach.

The new 172,182,206 are all activated by oil pressure not the master
switch.

[Peter R.]

On 7/2/2007 4:42:14 PM, Peter Clark wrote:

> The new 172,182,206 are all activated by oil pressure not the master
> switch.

Ah, OK, then I was taught incorrectly. But then again, it has been at least
five years since I actually cared about a Hobbs meter. :)

--
Peter

[Peter Clark]

On Mon, 2 Jul 2007 17:06:55 -0400, "Peter R." >
wrote:

>On 7/2/2007 4:42:14 PM, Peter Clark wrote:
>
>> The new 172,182,206 are all activated by oil pressure not the master
>> switch.
>
>Ah, OK, then I was taught incorrectly. But then again, it has been at least
>five years since I actually cared about a Hobbs meter. :)

No problem. It is rather hard to keep track of all the different
hobbs hookups.....

[Larry Dighera]

On Mon, 2 Jul 2007 16:35:20 -0400, "Peter R." >
wrote in >:

>I was taught that all the newer model C172s' Hobbs are wired to the
>master,

Usually there's an oil pressure switch in series with the Hobbs meter,
so that it is only energized when the engine is running. I have no
idea if that is true of the newer aircraft, but it should be.

[El Maximo]

"Orval Fairbairn" > wrote in message
...

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

It's not unscrupulous if you know about it up front.

Unscrupulous is when you go to rent a U-haul truck for $19.99 a day, but
they consider a day to be the calender day(s) you use it. Pick it up at 8:30
Friday night, drop it off at 8:00 Saturday night, and that's 2 days. The
best one was when they said the would charge me a $50 cancellation fee. I
drove down, picked up the keys, and returned the truck thirty seconds later.
cost me $19.99 for the 'day'.

[Larry R[_2_]]

On Jul 3, 2:53 am, Airbus > wrote:
> I have seen dozens of Hobbs meters fail (they are used on plently of
> devices, other than airplanes) but never in they way you suggest.

This was on an Arrow, and that is what I thought as to how it would
fail.. Interesting about being wired to the master...
I just recently started renting this Arrow, so I'll keep a closer
watch on the Hobbs and tach now.

I suppose that we can all dream for a slower hobbs :)

[Steve Clayworth]

A couple of months ago, the C172N I was renting had a Hobbs that was still
running even after the master was *off*. I joked with the FBO owner that
they were figuring out a new scheme to make money with the planes stuck on
the ramp.




"Larry R" > wrote in message
ps.com...
> Ok, I am *almost* embarrased to ask this question, but here goes. Do
> Hobbs meters ever "go bad"? No, this isn't a joke!
>
> I recently took a flight from KLOU-KWWD-KLOU. It was IFR and I wrote
> down my off and land times, which coorespond with the FlightTracking
> times within a couple of minutes.
>
> The hobbs time was 10.7. The flight time was 9.6. Not whining here,
> but it was a little hard to believe that I had over an hour of taxi/
> start time on this!
>
> Just wondering..
>
> --Man would that be some kind of AD-- LOL!
>

[Airbus]

I have seen dozens of Hobbs meters fail (they are used on plently of
devices, other than airplanes) but never in they way you suggest. As
others here have mentioned, their failure mode is that they just stop.
Frequently it's a mechanical (gear-drive) failure, and you can see the
meter "trying" to advance, but it doesn't. These are
escapement-controlled devices (like mechanical watches) so a considerable
speed error would be unexpected. They are esay to misread though (grin).



In article m>,
says...
>
>
>Ok, I am *almost* embarrased to ask this question, but here goes. Do
>Hobbs meters ever "go bad"? No, this isn't a joke!
>
>I recently took a flight from KLOU-KWWD-KLOU. It was IFR and I wrote
>down my off and land times, which coorespond with the FlightTracking
>times within a couple of minutes.
>
>The hobbs time was 10.7. The flight time was 9.6. Not whining here,
>but it was a little hard to believe that I had over an hour of taxi/
>start time on this!
>
>Just wondering..
>
>--Man would that be some kind of AD-- LOL!
>

[Ron Natalie]

Peter R. wrote:
> On 7/2/2007 3:31:14 PM, Orval Fairbairn wrote:
>
>> Sometimes, unscrupulous owners will wire the Hobbs to the master switch,
>> so you get charges whenever the MS is ON.
>>
>
> Isn't that true for the Hobbs installed by the aircraft manufacturer in newer
> aircraft? I was taught that all the newer model C172s' Hobbs are wired to the
> master, which results in about a 20% greater difference between their
> readings and the tach.
>
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.

[Ron Natalie]

wrote:
> Larry R > wrote:
>> Ok, I am *almost* embarrased to ask this question, but here goes. Do
>> Hobbs meters ever "go bad"? No, this isn't a joke!
>
> Everything eventually "goes bad", just some things sooner than others.
>
> A Hobbs meter is a mechanical counter with gears, bearings, a motor,
> etc. so yeah, it can go bad.
>
I've seen more tach's fail than hobbs. A hobbs is much simpler.

[Ron Natalie]

Peter Clark wrote:
> On Mon, 02 Jul 2007 18:53:49 -0000, Larry R >
>> The hobbs time was 10.7. The flight time was 9.6. Not whining here,
>> but it was a little hard to believe that I had over an hour of taxi/
>> start time on this!
>
> In my experience, usually they just stop. What kind of aircraft is
> this?

The student's greatest fear: a runaway hobbs!
When given a choice which instrument to smash in an emergency, most
students choose the hobbs meter.

-Rod Machado

[B A R R Y[_2_]]

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.

[Peter R.]

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?

--
Peter

[Gig 601XL Builder]

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.

[B A R R Y[_2_]]

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.

[[email protected]]

Ron Natalie > wrote:
> wrote:
> > Larry R > wrote:
> >> Ok, I am *almost* embarrased to ask this question, but here goes. Do
> >> Hobbs meters ever "go bad"? No, this isn't a joke!
> >
> > Everything eventually "goes bad", just some things sooner than others.
> >
> > A Hobbs meter is a mechanical counter with gears, bearings, a motor,
> > etc. so yeah, it can go bad.
> >
> I've seen more tach's fail than hobbs. A hobbs is much simpler.

As I said, some things sooner than others.

--
Jim Pennino

Remove .spam.sux to reply.

[Gig 601XL Builder]

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.

I can't think of a single second in my log book that isn't based on Hobbs
time. Some were oil pressure activated but the vast majority were MS
activated.

[B A R R Y[_2_]]

Gig 601XL Builder wrote:
>
> I can't think of a single second in my log book that isn't based on Hobbs
> time. Some were oil pressure activated but the vast majority were MS
> activated.

Me too.

[Robert M. Gary]

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

[B A R R Y[_2_]]

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.

[Dave S]

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

[Robert M. Gary]

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.

[Travis Marlatte]

"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

[Travis Marlatte]

"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

[B A R R Y]

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.

[Dave S]

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.

[Morgans[_2_]]

"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

[Ron Natalie]

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.

[Ron Natalie]

>
> 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).

[Travis Marlatte]

"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

[Dave S]

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.

[Big John]

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

[Ron Natalie]

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.

[Gig 601XL Builder]

Morgans wrote:
> "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.

The FAA has a really good guide for phase one testing. But, so many of the
systems to be checked when following that guide don't exsist on the plane
I'm building that I will be flying a bunch hours inside that 25nm circle
after everything has been tested. Not that I have a problem with that but my
particular 25 nm circle is a little boring. I really kind of wish there was
a 3 phase program. Phase 1 as is, Phase 2 larger or unlimited area without
passengers, and then Phase 3 which would be like the current Phase 2.