Tachometer Hours

RyanB

RyanB

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Might be a dumb question, is the Tach reset when an overhauled engine is installed? If not what hours is the Tach showing? One tach shows about 7600 hours and has recently had an overhaul. So the time on the tach is not engine hours, what does it show?
 
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Ryanb said:
Might be a dumb question, is the Tach reset when an overhauled engine is installed? If not what hours is the Tach showing? One tach shows about 7600 hours and has recently had an overhaul, so how come the tach has not been reset?
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It's like the odometer on a car's speedometer. It doesn't get reset. You'd need to buy a new tach to get a zero reading. Look in the logs to see what the tach time was when the engine was installed.

Dan
 
Dan Thomas said:
It's like the odometer on a car's speedometer. It doesn't get reset. You'd need to buy a new tach to get a zero reading. Look in the logs to see what the tach time was when the engine was installed.

Dan
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This makes sense, and what I figured, thanks Dan!
 
My plane had a digital tach added at some point in the past. They programmed it to show aircraft total time, which I find is much more useful for finding various events in the planes logbook history. Not everything in the logs relates to engine time, but everything shows ACTT
 
Dan Thomas said:
It's like the odometer on a car's speedometer. It doesn't get reset. You'd need to buy a new tach to get a zero reading. Look in the logs to see what the tach time was when the engine was installed.

Dan
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They can be reset.
 
Greg Bockelman said:
They can be reset.
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That.

Also it's much more usefull for me for the tach to read TSMO then AC TT, this is how every plane I've flown that had a recording tach was configured too.
 
StinkBug said:
My plane had a digital tach added at some point in the past. They programmed it to show aircraft total time, which I find is much more useful for finding various events in the planes logbook history. Not everything in the logs relates to engine time, but everything shows ACTT
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Hmmmm... That sounds great.

Anyway, my plane has had a number of tach changes. They go bad, etc... As long as the logbooks are constructed properly, not much to worry about.
 
ahkahn said:
Hmmmm... That sounds great.

Anyway, my plane has had a number of tach changes. They go bad, etc... As long as the logbooks are constructed properly, not much to worry about.
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If I went to go fly a plane and the tach said 5,000 I think I would find another plane :lol:
 
It's a recording device that keeps track of hours of usage. The actual number doesn't have to equate to anything in particular since all times are derived from the current reading minus the recorded reading taken when any particular component was replaced or overhauled. If it is the original tach then the number will equate to TTAF, TTE and TTP unless a factory overhauled or new engine or new propeller had been installed at some time. Otherwise TSMOH will be derived from what the tach read when the overhauled engine was installed.

If the tach is replaced at some time then it is entered in the log and all of the total times are carried forward with zero time as the new base for deriving them. You can have a new tach installed or reset your existing tach at the time of overhaul if you wish but it is not necessary outside of your personal preference or desire. It doesn't change the actual totals.

With good record keeping you should be able to readily tell exactly how many hours are on every component such as magnetos, starter, alternator, vacuum pump, governor etc...
 
James331 said:
If I went to go fly a plane and the tach said 5,000 I think I would find another plane :lol:
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If I went to fly a 40 year old plane and the tach said only a few hundred hours I think I'd find another airplane. :rolleyes:
 
James331 said:
If I went to go fly a plane and the tach said 5,000 I think I would find another plane :lol:
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LDJones said:
If I went to fly a 40 year old plane and the tach said only a few hundred hours I think I'd find another airplane. :rolleyes:
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The first BE99 I flew had 32,000 hours on it. I flew B727-100's with over 100,000 hours.

It's a number. :dunno:
 
LDJones said:
If I went to fly a 40 year old plane and the tach said only a few hundred hours I think I'd find another airplane. :rolleyes:
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Huh?

Maybe it has a overhauled/new engine in it, not exactly uncommon at all :dunno:


RotorAndWing said:
The first BE99 I flew had 32,000 hours on it. I flew B727-100's with over 100,000 hours.

It's a number. :dunno:
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A 727 with 100k under pt 121 mx, vs a pt91 172 that appears to have 5000 TSMO, are two very diffrent animals, I think you know this.
 
My plane has original tech, they installed a separate hour meter when the engine was overhauled. I can view TTAF and hours on engine.

On another note the FBO I worked for had to add a separate hour meter because the Forest Service required actual flight time. We added a switch that activated the hour meter at 40mph. Forest service is big business in Alaska and the FBO wanted to keep them happy.
 
James331 said:
That.

Also it's much more usefull for me for the tach to read TSMO then AC TT, this is how every plane I've flown that had a recording tach was configured too.
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I disagree, but that's just personal opinion. To me it seems easier to subtract the TBO from the current total time for engine hours than it is to do a math problem to figure out hours on everything other than the engine, especially if it's a part that has been replaced before. That would require several addition subtraction steps that aren't needed if you just start with total time. Either way if the logs are well kept it's not a huge deal and not hard math, I just find it simpler to have everything on one timeline from day 1.
 
Agree. I don't think that knowing the exact number of hours and minutes your engine has on it since it was last overhauled is information that is of any particular use or importance during a flight. For maintenance purposes the time on any component of the aircraft is going to be it's total time at last log entry plus the difference between that entries tach time and the present tach time.
 
James331 said:
Huh?

Maybe it has a overhauled/new engine in it, not exactly uncommon at all :dunno:




A 727 with 100k under pt 121 mx, vs a pt91 172 that appears to have 5000 TSMO, are two very diffrent animals, I think you know this.
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If it's been recently overhauled by a known quantity ( verses a shade tree mechanic) the buyer should rejoice. Completely different from a heavy or commercial jet, etc. As stated, totally different. As I matured I gained valuable knowledge speaking with builders, good mechanics, etc. You learn a lot about logs, what to look for, etc. And by simply watching and speaking with the seller. Their house, car and hangar conditions will say plenty.
 
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James331 said:
A 727 with 100k under pt 121 mx, vs a pt91 172 that appears to have 5000 TSMO, are two very diffrent animals, I think you know this.
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How about a C-150 with 22,000 hours (pipeline patrol), or a Cessna 172 with 12,000 hours (busy flight school)?

It's all in the maintenance.
 
The tach is nice to have, but that's all
The logbook(s) is the final answer
Without the log(s) the tach tells you nothing other than recorded operating hours on the tach since the tach was manufactured
maybe in that plane
maybe not
 
I'm just used to seeing TSMO on the tach, nothing that can't be figured out, but yeah if I went up with a buddy and his tach said 5,000 I'd ask if what the TSMO was


RotorAndWing said:
How about a C-150 with 22,000 hours (pipeline patrol), or a Cessna 172 with 12,000 hours (busy flight school)?

It's all in the maintenance.
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What's your point, we were talking about TSMO not AC TT, and I highly doubt that 172/50 had over 10k TSMO right?
 
Simple math makes tach time and engine time very easy to reconcile. When I replaced my tach I had it set to match the time shown on the original.

I know a 185 that had 12,000 + hours that sold for well north of $100K. Beavers in the 20,000 hour range are common. Hours don't always indicate worn out.
 
Stewartb said:
Simple math makes tach time and engine time very easy to reconcile. When I replaced my tach I had it set to match the time shown on the original.

I know a 185 that had 12,000 + hours that sold for well north of $100K. Beavers in the 20,000 hour range are common. Hours don't always indicate worn out.
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Yeah, but high hours or damage history on a 185/DHC2/DHC3/etc is a little different from a 172, different missions and buyers.

Still, run out or near runout engine will effect the value with any demographic.

And for the OP, who's just looking for a 182, no need to even bother with runout or near runout engines, toss a rock at a airport chances are you'll hit a 182 :yes:
 
I fly a 65 year old plane and it doesn't even have a recording tach (anymore). Back when it did the tach digits was off the actual airframe time in service by around 1000 hours.
 
3103.7 Tach (from the plane)
6774.1 Hobbs (from the plane)
5905.5 Total time matched to 3103.7 Tach time in logs (from the airframe log)
4011.7 Engine overhauled and installed in my aircraft at aircraft total time (from the airframe log)
1893.8 SMOH (math)

Yes, resetting the tach would have made that easier, but it is traceable and clear.

Engine installed in July of 1997. So I am running on just under 1900 hours on an 18 year old rebuild. I so want to pull out this Lycoming O-320-D2A and put in an IO-390...
 
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Seems silly for how easy it is to zero things on after overhaul.

But yeah, whatever as long as you can decipher the important information.
 
Here's a bigger issue: TIME IN SERVICE does *NOT* reset to zero after an overhaul (even on the engine).
 
Only factory remanufactured engines get zero timed. TSMOH does not reset TTE. A factory reman engine has TSMOH of 0 or N/A.
 
Silvaire said:
Only factory remanufactured engines get zero timed. TSMOH does not reset TTE. A factory reman engine has TSMOH of 0 or N/A.
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Precisely. A factory rebuilt (to use Lycoming's term) engine is essentially a new part. Other than that a part accumulates time in service when ever it is flown no matter how many times it has been overhauled. You should NOT reset the TIS clock on overhaul. Some of the Macaulay propeller owners are learning this the hard way. There is now an TIS limit on these props and those who don't have a documented total TIS (not SMOH) are NOT AIRWORTHY.
 
Silvaire said:
Only factory remanufactured engines get zero timed. TSMOH does not reset TTE. A factory reman engine has TSMOH of 0 or N/A.
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I understand that, but Ron's post seemed to indicate it affecting the airframe time in some way also.
 
flyingron said:
You should NOT reset the TIS clock on overhaul.
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Why not? The logbook rules. The tach hour meter is just a number.

Some of the Macaulay propeller owners are learning this the hard way. There is now an TIS limit on these props and those who don't have a documented total TIS (not SMOH) are NOT AIRWORTHY.
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Well, that doesn't really have anything to do with whether the tach was reset or not. It is just a math exercise, just like it would be on the engine. Time in service just isn't that hard to figure out.

Unless, of course, when the tach was reset it wasn't properly documented in the logbook and the original number was lost to posterity.
 
Greg Bockelman said:
Why not? The logbook rules. The tach hour meter is just a number.
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I didn't say you couldn't reset the tach meter. I said you can not reset TIME IN SERVICE. TIME IN SERVICE continues to accrue until a new part is install.

Do you understand what I am saying. TIME IN SERVICE has SQUAT to do with your recording tach. It has to do with how much time your aircraft was in the air. The FAA will allow any reasonable and consistent approximation of the time (like a recording tach corrected to whatever zero meant on it). I have not had a recording tach for ten years. I have a hobbs that is connect to the gear switch. This plus nine hours is the time in service for my engine (factory new minus a few hours it was on a Bonanza before they went through the turbine conversion) and propeller but it's about 6000 hours more TIS on the rest of the airframe.
 
Greg Bockelman said:
Well, that doesn't really have anything to do with whether the tach was reset or not. It is just a math exercise, just like it would be on the engine. Time in service just isn't that hard to figure out.
.
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This is a specific problem on certain Macaulay props. There are people out there who do NOT know how much time they have on the prop. It generally happened like this. You bought a used Mac prop with a fresh overhaul (or you overhauled it yourself) and put it on your plane. Now you know how many hours you have since overhaul and how many hours it was on your plane, but you don't have the time in service. If you can't compute the time in service to the time the prop was manufactured, it's officially scrap metal.
 
flyingron said:
I didn't say you couldn't reset the tach meter. I said you can not reset TIME IN SERVICE. TIME IN SERVICE continues to accrue until a new part is install.

Do you understand what I am saying. TIME IN SERVICE has SQUAT to do with your recording tach. It has to do with how much time your aircraft was in the air. The FAA will allow any reasonable and consistent approximation of the time (like a recording tach corrected to whatever zero meant on it). I have not had a recording tach for ten years. I have a hobbs that is connect to the gear switch. This plus nine hours is the time in service for my engine (factory new minus a few hours it was on a Bonanza before they went through the turbine conversion) and propeller but it's about 6000 hours more TIS on the rest of the airframe.
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I think most folks are more concerned with time since overhaul...
 
James331 said:
If I went to go fly a plane and the tach said 5,000 I think I would find another plane :lol:
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I have worked on a lot of small airplanes in my time. I have seen 1500-hour airplanes that were essentially junk, and 12,000-hour airplanes that were nearly as good as new. It's all in the maintenance and the attitude of the owner. If you set a 5000-hour limit on anything you fly, you will find diminishing opportunities as the years go by. The fleet is aging badly.

And further, you might kill yourself in the rotten 2500-hour airplane when it quits or falls apart in the air, while the outfit across the field had well-maintained and trustworthy 10,000-hour airplanes for rent.

Dan
 
Like everyone has said, the logbook is what determines actual time in service for any component.

My point was simply that it's easier to do one math computation to figure out the time since overhaul of my engine, rather than having to do a math problem for every single other part of the plane. The math isn't difficult, but I find life is simpler when I have to do less of it. That's why I prefer the tach to simply show total time. It also makes for less digging through log books to figure out all the numbers that need to be used to find the time in service for a particular part.
 
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