Disconnecting Hobbs Meter

[Learsforsale]

That was a great idea - they said they'd fax me over a few wiring diagrams.


Yup :beer: I just hope they get the right diagrams. They should be able to since i filled out the request form with the serial number and tail number.

Would you mind sending me a copy of those diagrams when you get them. I am interested in having a closer look at the C172's electrical system. TIA

 

[GravityHater]

We shall live with the mystery of 'for reason this was being done'.
Those of us who believe the posted 'outcome'.
(my guess is there aint a fsdo out there that has any such wiring diagrams, let alone would provide such assistance)

 

[erj-145mech]

You're right, it would be the first time in recorded history that an FAA office would do something like that. Plus the fact that they don't have technical information or drawings there. Too much liability for keeping it current and up to date. One inspector from the HOU office contacted me for some data for a field approval for another mech one time.

 

[spirit05]

While I don't agree with "rigging" a hobbs meter, I don't see where one is required for part 91 ops. My 150 has an engine tach. We use it for all inspections, oil changes, etc. The hobbs has no use. The plane is not used for any flight school training and I quit logging flight time years ago. I had an IA take it out and put a carb heat guage in its place.

 

[minitour]

While I don't agree with "rigging" a hobbs meter, I don't see where one is required for part 91 ops. My 150 has an engine tach. We use it for all inspections, oil changes, etc. The hobbs has no use. The plane is not used for any flight school training and I quit logging flight time years ago. I had an IA take it out and put a carb heat guage in its place.

Agreed...but maybe we're not thinking outside the box enough.

Maybe this isn't to "fool" someone as the Tach would never allow that.

SMOH, 100 HR, ADs all based on Tach.

Perhaps he's wanting a switch that he can figure out how many hours he has his lights on? Or maybe how many hours his carb heat is on? Or maybe he wants to log how many hours he flies on even numbered days after 2pm in London but Tuesdays don't count and neither do Sundays except between 3am and 1pm PST??? If you had a switch to turn it on/off at will, you could keep track of anything you wanted.

...and who said you have to log flight time by Hobbs time? A plane at the old FBO I worked at had no hobbs time, we always used Tach...

I don't see the big deal.

-mini

 

[PreRVSM]

I wonder what the inline fuse next to the battery marked CLOCK is for? Does it power the hobbs?

 

[CLR2LAN]

Agreed...but maybe we're not thinking outside the box enough.

Maybe this isn't to "fool" someone as the Tach would never allow that.

SMOH, 100 HR, ADs all based on Tach.

Perhaps he's wanting a switch that he can figure out how many hours he has his lights on? Or maybe how many hours his carb heat is on? Or maybe he wants to log how many hours he flies on even numbered days after 2pm in London but Tuesdays don't count and neither do Sundays except between 3am and 1pm PST??? If you had a switch to turn it on/off at will, you could keep track of anything you wanted.

...and who said you have to log flight time by Hobbs time? A plane at the old FBO I worked at had no hobbs time, we always used Tach...

I don't see the big deal.

-mini

Its good to see theres a few thinkers out there.

Basically theres only a certain number of time i need to track to bill to a client, otherwise keeping track of a hole flights time is useless. It would be easier to turn the hobbs on/off then trying to figure out what time to bill to who and when......Tach can keep running as per inspection intrevals.

 

[GravityHater]

Basically theres only a certain number of time i need to track to bill to a client, otherwise keeping track of a hole flights time is useless.

If thats the case I guarantee you are going to find it a whole lot easier to buy a WestBend digital kitchen timer for 18$, stick it on the yoke with 1$ of velcro and use the start/stop feature of the timer to keep track of the billable hours than trying to get the hobbs switched as you described. Good luck.

here is one.

http://www.pilotstore.com/store/item.asp?ITEM_ID=1889

 

[avbug]

Still not a legitimate task. Trying to bamboozle the "client" by using a reading off a hobbs meter, rather than using a watch? Thinking outside the box--garbage. You can't do the work yourself, or you wouldn't have asked such a stupid question. You aren't legitimate, else you would have answered the questions posed to you. You continue to hide the reason for the switch; you have no good or legitimate reason for doing what you do.

You're not qualified to do the work. Likely if you ask any legitimate mechanic to do the work, he or she will properly refuse (you can always find someone as beneath board and deceitful as yourself to do the work, however). As has been heretofore pointed out, do the work yourself, and you invalidate the airworthiness of your aircraft.

You lied about the FSDO; clearly flame bait, outright lie, or just an idiot.

If you're renting this aircraft and playing with the hobbs, chances are that whatever you're up to isn't above board, and that applies regardless of weather you're the person renting it to someone else, or weather you're the one receiving it.

Hobbs meters work based on a number of types of switches, ranging from oil pressure to aerodynamic pressure to weight on wheels, gear position, etc. You cannot alter or add to the electrical system without appropriate authority, and executing the appropriate approval documentation...and you don't know what that is or what must be done...you're nosing around trying to get information from folks who do, and refusing to state your purpose or show that you're anything more than either a criminal or an idiot.

So far, you appear to be both.

 

[a&p cfiguy]

This is very simple. It's a certificated aircraft, not experimental. That means you can't just change the design of the aircraft as you please. If you add any additional items, you need a 337 for a major repair or ALTERATION. To sign off on this ALTERATION, you either need an STC or field approval. You may or may not be able to get this field approval, depends on what kind of mood the inspector is in that day, but I'm guessing that as long as you have some other way of tracking time in service (like a tach), I wouldn't see a problem with it. However, seems like an aweful lot of trouble to go through, when you can just get a stopwatch!

So to answer your question, if I was doing an annual on this airplane and I saw this extra switch, I'd question where's the 337 form for this alteration. If it's in the books and signed with a field approval or STC, I'm okay with it. If not, I'm gonna rewire it per the original factory wiring diagram. Chances are if you hide the switch behind the panel somewhere, I'm might not notice it, but now you are being deceiving and here's where you'll run into trouble.