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Tack vs Hobbs

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BobbyPaulk(at)comcast.net
Guest

Posted: Mon Mar 13, 2017 7:42 am Post subject: Tack vs Hobbs

Getting back to the Tach vs  Hobbs



My Pitts had a Tach calibrated for 2450 RPM to equal an hour. 



Flight time was only accurate if you kept that RPM. Most times I was throttled back to 1900 and 2000 rpm to fly cross country with slower planes. When I accumulated 500 hrs plus on the Tach the actual flight time was over 700 hours. If you want accurate flight time for logging, oil changes, and maintenance you should definitely use Hobbs time. 



Bobby

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Mar 13, 2017 8:30 am Post subject: Tack vs Hobbs

That just brings up the debate...should your maintenance be based on 

clock time, or accumulated rpms? If you are at low power, low rpms, you 

probably prefer the latter.



On 3/13/2017 8:38 AM, BobbyPaulk(at)comcast.net wrote:

 	  Quote: 	
		  

 Getting back to the Tach vs  Hobbs

 My Pitts had a Tach calibrated for 2450 RPM to equal an hour.

 Flight time was only accurate if you kept that RPM. Most times I was

 throttled back to 1900 and 2000 rpm to fly cross country with slower

 planes. When I accumulated 500 hrs plus on the Tach the actual flight

 time was over 700 hours. If you want accurate flight time for logging,

 oil changes, and maintenance you should definitely use Hobbs time.



 Bobby

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

alec(at)alecmyers.com
Guest

Posted: Mon Mar 13, 2017 8:36 am Post subject: Tack vs Hobbs

In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require?

 	  Quote: 	
		   On Mar 13, 2017, at 12:28 PM, Kelly McMullen <kellym(at)aviating.com> wrote:

 That just brings up the debate...should your maintenance be based on clock time, or accumulated rpms? If you are at low power, low rpms, you probably prefer the latter.

> On 3/13/2017 8:38 AM, BobbyPaulk(at)comcast.net wrote:

> 

> Getting back to the Tach vs  Hobbs

> My Pitts had a Tach calibrated for 2450 RPM to equal an hour.

> Flight time was only accurate if you kept that RPM. Most times I was

> throttled back to 1900 and 2000 rpm to fly cross country with slower

> planes. When I accumulated 500 hrs plus on the Tach the actual flight

> time was over 700 hours. If you want accurate flight time for logging,

> oil changes, and maintenance you should definitely use Hobbs time.

> 

> Bobby

tshankland(at)sbcglobal.n
Guest

Posted: Mon Mar 13, 2017 9:24 am Post subject: Tack vs Hobbs

I'm flying a Zenith Zodiac 610HD with a Status Subaru engine. During the 

build I decided I didn't want two sensors for oil pressure attached to the 

engine. The idea of a T fitting with two sensors vibrating gave me thoughts 

cracked fittings. My solution was to use the existing oil pressure gage. The 

gage is electric and it is not difficult to determine the voltage present at 

the gage input that indicates that the engine is running. I built a small 

circuit that monitors that voltage turns the Hobbs meter on when a 

sufficient pressure is present. This way the Hobbs only runs when the engine 

is running and not just when the master switch is on.



Tim Shankland



--

yellowduckduo(at)gmail.co
Guest

Posted: Mon Mar 13, 2017 11:17 am Post subject: Tack vs Hobbs

One can always fit a squat switch on the landing gear.  I set my EIS 

tach threshold  so it does not accumulate time below a specific rpm such 

that it ignores warm up and ground maneuvering. With my geared engine, 

it also ignores flight time when I do power off landings though.

My most successful option by far though was to marry a former tower 

controller who just can't break the habit of recording off and on 

times...  

Ken



On 13/03/2017 12:33 PM, Alec Myers wrote:

 	  Quote: 	
		   



 In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require?



> On Mar 13, 2017, at 12:28 PM, Kelly McMullen <kellym(at)aviating.com> wrote:

>

> 

>

> That just brings up the debate...should your maintenance be based on clock time, or accumulated rpms? If you are at low power, low rpms, you probably prefer the latter.

>

>> On 3/13/2017 8:38 AM, BobbyPaulk(at)comcast.net wrote:

>>

>> Getting back to the Tach vs  Hobbs

>> My Pitts had a Tach calibrated for 2450 RPM to equal an hour.

>> Flight time was only accurate if you kept that RPM. Most times I was

>> throttled back to 1900 and 2000 rpm to fly cross country with slower

>> planes. When I accumulated 500 hrs plus on the Tach the actual flight

>> time was over 700 hours. If you want accurate flight time for logging,

>> oil changes, and maintenance you should definitely use Hobbs time.

>>

>> Bobby

cluros(at)gmail.com
Guest

Posted: Mon Mar 13, 2017 12:21 pm Post subject: Tack vs Hobbs

 	  Quote: 	
		   	  Quote: 	
		  In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require? 	
	




For private aircraft in Canada (excepting 604) I can't think of a single maintenance item that is required to be done on a time basis. Yes you have to total the air time in the Journey Log (which any most handheld GPSs will keep track of for you), but since all required maintenance is based on calendar times, you can use whatever hourly time measure you want to when deciding what maintenance to do. 



Sebastien



On Mar 13, 2017, at 12:14, C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>



One can always fit a squat switch on the landing gear.  I set my EIS tach threshold  so it does not accumulate time below a specific rpm such that it ignores warm up and ground maneuvering. With my geared engine, it also ignores flight time when I do power off landings though.

My most successful option by far though was to marry a former tower controller who just can't break the habit of recording off and on times...  

Ken



On 13/03/2017 12:33 PM, Alec Myers wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)>



In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require?



 	  Quote: 	
		  On Mar 13, 2017, at 12:28 PM, Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)> wrote:

	
 	  Quote: 	
		  

	
 	  Quote: 	
		  --> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com (kellym(at)aviating.com)>

	
 	  Quote: 	
		  

	
 	  Quote: 	
		  That just brings up the debate...should your maintenance be based on clock time, or accumulated rpms? If you are at low power, low rpms, you probably prefer the latter.

	
 	  Quote: 	
		  

	
 	  Quote: 	
		   	  Quote: 	
		  On 3/13/2017 8:38 AM, BobbyPaulk(at)comcast.net (BobbyPaulk(at)comcast.net) wrote:

	
	
 	  Quote: 	
		   	  Quote: 	
		  

	
	
 	  Quote: 	
		   	  Quote: 	
		  Getting back to the Tach vs  Hobbs

	
	
 	  Quote: 	
		   	  Quote: 	
		  My Pitts had a Tach calibrated for 2450 RPM to equal an hour.

	
	
 	  Quote: 	
		   	  Quote: 	
		  Flight time was only accurate if you kept that RPM. Most times I was

	
	
 	  Quote: 	
		   	  Quote: 	
		  throttled back to 1900 and 2000 rpm to fly cross country with slower

	
	
 	  Quote: 	
		   	  Quote: 	
		  planes. When I accumulated 500 hrs plus on the Tach the actual flight

	
	
 	  Quote: 	
		   	  Quote: 	
		  time was over 700 hours. If you want accurate flight time for logging,

	
	
 	  Quote: 	
		   	  Quote: 	
		  oil changes, and maintenance you should definitely use Hobbs time.

	
	
 	  Quote: 	
		   	  Quote: 	
		  

	
	
 	  Quote: 	
		   	  Quote: 	
		  Bobby

	
	
 	  Quote: 	
		  

	
 	  Quote: 	
		  

	






	
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alec(at)alecmyers.com
Guest

Posted: Mon Mar 13, 2017 12:34 pm Post subject: Tack vs Hobbs

I wasn't suggesting that Canadian aircraft are subject to any particular maintenance or inspection requirements. Rather, that when they are, the relevant "run time" that has to be accounted for is wheels-up to wheels-down. 

Let me as the question again: when the FAA mandates usage-based inspection or maintenance (for instance, mandatory 100 hour inspections for aircraft used for instruction) - what is the time that is counted towards those 100 hours? Is it engine run time, or air time, or tach time, or some other measure?

On 13Mar2017, at 4:17 PM, Sebastien <cluros(at)gmail.com> wrote:

 	  Quote: 	
		  > In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require?

For private aircraft in Canada (excepting 604) I can't think of a single maintenance item that is required to be done on a time basis. Yes you have to total the air time in the Journey Log (which any most handheld GPSs will keep track of for you), but since all required maintenance is based on calendar times, you can use whatever hourly time measure you want to when deciding what maintenance to do. 

Sebastien

On Mar 13, 2017, at 12:14, C&K <yellowduckduo(at)gmail.com> wrote:

 	  Quote: 	

 One can always fit a squat switch on the landing gear.  I set my EIS tach threshold  so it does not accumulate time below a specific rpm such that it ignores warm up and ground maneuvering. With my geared engine, it also ignores flight time when I do power off landings though.

 My most successful option by far though was to marry a former tower controller who just can't break the habit of recording off and on times...  

 Ken

 On 13/03/2017 12:33 PM, Alec Myers wrote:

> 

> 

> In Canada maintenance time is based on aggregate flight time, strictly wheels-up to wheels-down, so you have to use a clock or wristwatch even if you have a Hobbs meter. What does the FAA require?

> 

>> On Mar 13, 2017, at 12:28 PM, Kelly McMullen <kellym(at)aviating.com> wrote:

>> 

>> 

>> 

>> That just brings up the debate...should your maintenance be based on clock time, or accumulated rpms? If you are at low power, low rpms, you probably prefer the latter.

>> 

>>> On 3/13/2017 8:38 AM, BobbyPaulk(at)comcast.net wrote:

>>> 

>>> Getting back to the Tach vs  Hobbs

>>> My Pitts had a Tach calibrated for 2450 RPM to equal an hour.

>>> Flight time was only accurate if you kept that RPM. Most times I was

>>> throttled back to 1900 and 2000 rpm to fly cross country with slower

>>> planes. When I accumulated 500 hrs plus on the Tach the actual flight

>>> time was over 700 hours. If you want accurate flight time for logging,

>>> oil changes, and maintenance you should definitely use Hobbs time.

>>> 

>>> Bobby

>> 

>> 

> 

> 

> 

> 

> 

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donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Tue Mar 14, 2017 3:48 am Post subject: Re: Tack vs Hobbs

 	  alec(at)alecmyers.com wrote: 	
		  Let me as the question again: when the FAA mandates usage-based inspection or maintenance (for instance, mandatory 100 hour inspections for aircraft used for instruction) - what is the time that is counted towards those 100 hours? Is it engine run time, or air time, or tach time, or some other measure? 	




When I had a TC aircraft, every shop used tach time. Not a single maintenance facility ever looked at the hobbs meter unless they needed the total airframe hours. 



I can't say if there's a FAR enforcing that though and if there is, which one.

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Mar 14, 2017 11:25 am Post subject: Tack vs Hobbs

At 03:32 PM 3/13/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Alec Myers <alec(at)alecmyers.com>



 I wasn't suggesting that Canadian aircraft are subject to any particular maintenance or inspection requirements. Rather, that when they are, the relevant "run time" that has to be accounted for is wheels-up to wheels-down. 



 Let me as the question again: when the FAA mandates usage-based inspection or maintenance (for instance, mandatory 100 hour inspections for aircraft used for instruction) - what is the time that is counted towards those 100 hours? Is it engine run time, or air time, or tach time, or some other measure? 	


   Don't know what the suggestion is today but when

   we owned 1K1, only our revenue generating aircraft

   were subject to 100 hour inspections . . . by what

   ever means was fitted to the panel.



   The J-3, with no electrical system and rudimentary

   tach was serviced based on rental time. An old

   Mooney was golden using tach time. The reset of

   the TC fleet had hobbs meters . . . some

   in addition to tach time but in our neck of the

   world, the Hobbs was preferred both for maintenance

   and billing practices.



   It was explained to me that there was nothing magic

   about inspecting every 100.00 plus or minus 0.01

   hours. It was only necessary that the inspections

   be done regularly in that general time frame.



   Of course, tach hours are really engine revolution

   counters. Hour recording tachs were spin-offs from

   automobile speedometers where revolutions were directly

   related to miles traveled.



 

 

   Bob . . .

alec(at)alecmyers.com
Guest

Posted: Tue Mar 14, 2017 11:32 am Post subject: Tack vs Hobbs

Good to know. 



Someone else was kind enough to point me towards 14 CFR 1.1:



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





On 14Mar2017, at 3:20 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:



At 03:32 PM 3/13/2017, you wrote:

 	  Quote: 	
		   

 

 I wasn't suggesting that Canadian aircraft are subject to any particular maintenance or inspection requirements. Rather, that when they are, the relevant "run time" that has to be accounted for is wheels-up to wheels-down. 

 

 Let me as the question again: when the FAA mandates usage-based inspection or maintenance (for instance, mandatory 100 hour inspections for aircraft used for instruction) - what is the time that is counted towards those 100 hours? Is it engine run time, or air time, or tach time, or some other measure?


	


  Don't know what the suggestion is today but when

  we owned 1K1, only our revenue generating aircraft

  were subject to 100 hour inspections . . . by what

  ever means was fitted to the panel.



  The J-3, with no electrical system and rudimentary

  tach was serviced based on rental time. An old

  Mooney was golden using tach time. The reset of

  the TC fleet had hobbs meters . . . some

  in addition to tach time but in our neck of the

  world, the Hobbs was preferred both for maintenance

  and billing practices.



  It was explained to me that there was nothing magic

  about inspecting every 100.00 plus or minus 0.01

  hours. It was only necessary that the inspections

  be done regularly in that general time frame.



  Of course, tach hours are really engine revolution

  counters. Hour recording tachs were spin-offs from

  automobile speedometers where revolutions were directly

  related to miles traveled.

  Bob . . .

kjashton(at)vnet.net
Guest

Posted: Tue Mar 14, 2017 12:43 pm Post subject: Tack vs Hobbs

You are correct, Sir.  One of the rites of passage to being a pilot is to learn the difference between “flight time” and “time in service”.  



 	  Quote: 	
		   Flight time means: 

 

 (1) Pilot time that commences when an  aircraft moves under its own power for the purpose of flight and ends when the  aircraft comes to rest after landing; or

https://www.law.cornell.edu/cfr/text/14/1.1
	




 	  Quote: 	
		   On Mar 14, 2017, at 3:29 PM, Alec Myers <alec(at)alecmyers.com> wrote:

 

 

 

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

bobsv35b(at)aol.com
Guest

Posted: Tue Mar 14, 2017 4:48 pm Post subject: Tack vs Hobbs

The FAA only requires that time for maintenance purposes be listed from actual lift off to actual touchdown. The engine recording tachometer has been accepted as a legal substitute for actual lift off to touch down figure. It all depends on what you think is most convenient for you.  Many helicopters use a switch on the collective. Others use tach time. Either could probably be supprted at a hearing.   

 

  Almost all airlines use lift off to touch down times. 

 

  Happy Skies,

  

 

  Old Bob

 

  --

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