Changing mx logs from tenths to hr+mn

[James331]

I'm thinking of switching my aircraft logs and time keeping for my plane from tenths of hours to hours plus minutes.

IE. 2.5 hrs vs 2+27

Figure I'm logging hours on my plane I shouldn't over the long run and between overhauls, based on rounding by logging by tenths.

Anyone do this, suggestions?

 

[jesse]

I'm confused. How are you planning on doing this? Do you have a tach that will track hours plus minutes?

Even if you did I'm confused as to how you'd be logging hours on the plane you shouldn't be with tach time. It's not like it resets for each flight. It's a running count...

I guess can you better explain how you think you're going to do this instead and how that is going to reduce the time on the airplane in the Engine/Airframe logbooks. I just can't make sense of what you're proposing and what it would fix. I'm slow.

 

[Seanaldinho]

Seems like a waste of time. A 10th is six minutes, I see no need to be more precise than that.

And as Jesse said, the tach keeps a rolling count. It doesn't go from .69 at engine shutdown to .60 the next time you start.

 

[frfly172]

If tenths bother you,round down instead of up. Your talking six minutes a tenth,in the overall picture no big deal.

 

[jesse]

If tenths bother you,round down instead of up. Your talking six minutes a tenth,in the overall picture no big deal.

Even so how the hell does that make a difference when it comes to aircraft total time or maintenance events? It's only a "one time" error at that point in time- not a cumulative error that carries forward and adds up.

 

[Greg Bockelman]

The only way it makes a difference is if the airplane has no hour recording device on it at all. No Hobbs, no recording tach, nothing.

 

[kgruber]

You will need an iWatch!

 

[RotorAndWing]

Better yet, hook an hour meter to a air switch.

My C310 had that set up, the switch engaged at about 30mph and disengaged at 30mph, so no aircraft time accumulated taxing.

Most helicopters use a collective switch or weight on skids switch.

 

[write-stuff]

10ths of hours will be a heck of a lot easier to total than a column of minutes.

 

[Seanaldinho]

Better yet, hook an hour meter to a air switch.

My C310 had that set up, the switch engaged at about 30mph and disengaged at 30mph, so no aircraft time accumulated taxing.

Most helicopters use a collective switch or weight on skids switch.

Thats how the maintenance meters work at UND. Usually see .2-.4 less on the MX time than on the hobbs.

 

[James331]

Thats how the maintenance meters work at UND. Usually see .2-.4 less on the MX time than on the hobbs.

Hobbs?

Most schools use tach.

I'll look for the tenths to minutes stats, company I work for has a rather large fleet and that's how they've been doing it, apparently it saves a noticeable amount of time.

So I take it no one times their mx HH:MM eh?

 

[Seanaldinho]

Hobbs?

Most schools use tach.

Students are charged off the Hobbs meter and maintenance is done off the MX meter which is as R&W described.

 

[jesse]

Hobbs?

Most schools use tach.

I'll look for the tenths to minutes stats, company I work for has a rather large fleet and that's how they've been doing it, apparently it saves a noticeable amount of time.

So I take it no one times their mx HH:MM eh?

How are you planning on timing it? With a watch?

Might have trouble selling if your logs aren't based on a recording instrument in the airplane.

 

[RotorAndWing]

Hobbs?

Most schools use tach.

I'll look for the tenths to minutes stats, company I work for has a rather large fleet and that's how they've been doing it, apparently it saves a noticeable amount of time.

So I take it no one times their mx HH:MM eh?

So where does the PC12 get it's information from? A squat switch or an air switch?

Airbus records it's on time based on TO roll to Landing roll, it does it in an hour and minute format.


Back in the 72' days we had nothing, so we logged aircraft time via the watch entered on the flight log, hours and minutes.

 

[Greg Bockelman]

So I take it no one times their mx HH:MM eh?

If you have a recording tach, there is no point.

 

[Greg Bockelman]

How are you planning on timing it? With a watch?

Might have trouble selling if your logs aren't based on a recording instrument in the airplane.

My Taylorcraft didn't have any time recording device installed whatsoever.

Come to think of it, neither did either of the Twin Otters I used to fly.

 

[TUPilot]

Better yet, hook an hour meter to a air switch.

My C310 had that set up, the switch engaged at about 30mph and disengaged at 30mph, so no aircraft time accumulated taxing.
.

I'd hate to have a long taxi on a windy day!

 

[Silvaire]

...apparently it saves a noticeable amount of time...

As Jesse pointed out a couple of times, the most it can possibly save over 100,000 hours of operation is six minutes

Unless you are considering the inevitable and cumulative math errors that would occur trying to tabulate a maintenance log in HH:MM but that could go either way.

 

[Henning]

You can if you want, but there is no significant advantage to be had. I'm not sure I would want to create that confusion in my log book being the only pilot on the planet to do it that way.

If you're looking to maximize TBO issues, Rotor and Wing had it with the air switch.

 

[bnt83]

Assume the hour meter in the tach is calibrated for 2450.

So the 10 minutes of ground ops on each flight the tach is going to record maybe 30% of it since RPM is very low during those periods.

 

[petrolero]

Hobbs?

Most schools use tach.

I'll look for the tenths to minutes stats, company I work for has a rather large fleet and that's how they've been doing it, apparently it saves a noticeable amount of time.

So I take it no one times their mx HH:MM eh?

I just don't understand that rationale for doing this. Maintenance usually goes off tach time and that is in tenths. Converting that to HH:MM wouldn't change anything mx-wise and you'd never be more than 6 minutes off of the actual time.



I agree with others that air switches and the like would make a difference because you're not counting low-power taxi time. But that is different than what you asked.

 

[James331]

Think I'll just switch to timing flights on airtime off my watch.

Thanks guys!

 

[Henning]

Out of curiosity, why do you want to keep a log book in hours and minutes?

 

[schmookeeg]

Think I'll just switch to timing flights on airtime off my watch.

Thanks guys!

Is your company tracking its maintenance scheduling based on your reported (and decimal-rounded) flight time? In that case, I'd think the company would need to adjust its policies, not its log entries. I've NEVER seen hh:mm logbooks, and I've read way too many of them. Hobbs meters are like $50 and do the counting for everyone without wasting the "change".

Absent procedural strangeness, I'd suggest that hh:mm math is WAY more complicated vs integer math. Plenty of mechanics can't even get whole-number math correct, much less hundredths, so hh:mm will melt a lot of minds and cause an outsized "alcohol" line item to appear in the parts section of every mx bill. It won't be for de-ice, but rather on-ice.

I also think it increases the chance of miscalculating a "time in service" interval, which may draw FAA ire, fines, or the worst thing possible (plaintiff's attorneys) in the event of an accident.

0:02.

- Mike

 

[weirdjim]

Seems to me another case of picking the flyspecks out of the pepper. Who cares? A couple of tenths/minutes more or less is insignificant when dealing with hundreds of hours.

Jim

 

[James331]

Is your company tracking its maintenance scheduling based on your reported (and decimal-rounded) flight time? In that case, I'd think the company would need to adjust its policies, not its log entries. I've NEVER seen hh:mm logbooks, and I've read way too many of them. Hobbs meters are like $50 and do the counting for everyone without wasting the "change".

Absent procedural strangeness, I'd suggest that hh:mm math is WAY more complicated vs integer math. Plenty of mechanics can't even get whole-number math correct, much less hundredths, so hh:mm will melt a lot of minds and cause an outsized "alcohol" line item to appear in the parts section of every mx bill. It won't be for de-ice, but rather on-ice.

I also think it increases the chance of miscalculating a "time in service" interval, which may draw FAA ire, fines, or the worst thing possible (plaintiff's attorneys) in the event of an accident.

0:02.

- Mike

The question was for my plane, not work stuff.

For work no matter how you track it, your maintace software is going to give you a count down to due items, just a matter of how its displayed.

 

[Henning]

The question was for my plane, not work stuff.

For work no matter how you track it, your maintace software is going to give you a count down to due items, just a matter of how its displayed.

I don't think you will see any significant gains. If doing math in hh.mm is simple for you, go for it, otherwise it seems far more of an error prone hassle than any value you gain.

 

[flyingron]

Maintenance time is based on the FAA definition of TIME IN SERVICE which for the entire aircraft is the the time it is off the ground. The FAA will accept just about any approximation of that (tach time, hobbs time connected to a variety of sensors), as long as you are consistent.

My plane has no recording tach. There's a hobbs on the gear which is about as close to the book definition as I can get.

 

[Henning]

I just don't understand the desire to account for it in HH.mm format. Put an air switch on the Hobbs and you probably get as good as you can unless you always run at the bottom of the green for RPM, then a recording tach is probably going to do better.

Is this because you're putting the plane on a 135 certificate?

 

[schmookeeg]

The question was for my plane, not work stuff.

For work no matter how you track it, your maintace software is going to give you a count down to due items, just a matter of how its displayed.

I'm having trouble figuring out how you are getting an accumulated rounding loss when you calculate TIS for the aircraft then. If there is no recording tach and no hobbs in the plane, then I see why you'd want hh:mm, as it's easier for you to log after a flight... but I think it will play hell in the logs still

In the above instance, I'd feel very comfortable using a 5-minute conversion to decimal fraction, and rounding DOWN. So every 5 minutes flight = 0.083 of an hour.

In the case of no tach or hobbs, I think adding either instrument will show less time ("more savings") over the above. I think the FAA-acceptable "savings" happen in this order:

Hobbs: Saves any fraction rounding from accumulating.

Hobbs with Oil Pressure switch: Only logs when the engine is running

Tach: only records when the engine is running AND only counts one hour as 2700 x 60 revolutions (or 2566 or 2400 or a few others), so taxi time counts proportionally "less" in the recording

Hobbs with Air switch: only logs when the plane exceeds 30kts.

Depending on how you fly, those last two may be very close to one another. I think the air switch favors rentals where they fly "full rental power" a lot, and the tach favors most owner-flown or training loads, where RPMs are likely to be more varied and seldom max RPM outside of a climb.

 

[jesse]

If he does have a recording device in the airplane, which he hasn't answered for some reason, and is ignoring it and logging airframe time using hours and minutes with his watch in an effort to protect his airframe value he's not thinking this through. If anything that will devalue the airframe when the buyer goes WTF trying to figure out what he was thinking and wondering how much time he was trying to hide.

 

[Henning]

If he does have a recording device in the airplane, which he hasn't answered for some reason, and is ignoring it and logging airframe time using hours and minutes with his watch in an effort to protect his airframe value he's not thinking this through. If anything that will devalue the airframe when the buyer goes WTF trying to figure out what he was thinking and wondering how much time he was trying to hide.

Yep, at the end of the day, any buyer or the FAA is going to look at the recording device, and if the logs aren't in synch, you have a situation.

 

[James331]

If he does have a recording device in the airplane, which he hasn't answered for some reason, and is ignoring it and logging airframe time using hours and minutes with his watch in an effort to protect his airframe value he's not thinking this through. If anything that will devalue the airframe when the buyer goes WTF trying to figure out what he was thinking and wondering how much time he was trying to hide.

Yeah I'm really secretive about my tach

It's a recording tach, just like every other cessna, no Hobbs.

Maybe I'll if I do the EI digital primary replacement, I might ask if there is a speed option for recording time.

How is recording time on my airframe IAW the FARs "trying to hide" anything?

 

[Henning]

Yeah I'm really secretive about my tach

It's a recording tach, just like every other cessna, no Hobbs.

Maybe I'll if I do the EI digital primary replacement, I might ask if there is a speed option for recording time.

How is recording time on my airframe IAW the FARs "trying to hide" anything?

If you run with the prop pulled back most of the time, I think the tach is going to get you better than your watch recording just air time unless your flights are mostly all short ones.

 

[Bonanza]

If you run with the prop pulled back most of the time, I think the tach is going to get you better than your watch recording just air time unless your flights are mostly all short ones.

I ran a check on my tach and it is accurate at about 2400 RPM. I usually fly at 2300 so with the low revs at taxi speeds I use the tach time and probably get a pretty accurate overall read of actual flight time for maintenance purposes.
However I am old enough with enough grey hair that I still keep my personal flying log in hours and minutes. I started off doing that to the exact minute and looking back in my log to my student days shows flights of 1hr 27mins etc. After a while I got lazy and went to the nearest 5 mins. These days I enter to the nearest 10 just because it is so much easier to add up when I get to the bottom of a page and I figure that no one really cares anyway..
Stephen.

 

[Henning]

I ran a check on my tach and it is accurate at about 2400 RPM. I usually fly at 2300 so with the low revs at taxi speeds I use the tach time and probably get a pretty accurate overall read of actual flight time for maintenance purposes.
However I am old enough with enough grey hair that I still keep my personal flying log in hours and minutes. I started off doing that to the exact minute and looking back in my log to my student days shows flights of 1hr 27mins etc. After a while I got lazy and went to the nearest 5 mins. These days I enter to the nearest 10 just because it is so much easier to add up when I get to the bottom of a page and I figure that no one really cares anyway..
Stephen.

Adding a column of 1/10s is way easier than adding a column of 1/60ths, at least for me. If your mind does it easily then you're certainly welcome to do it, adding up old time cards was always a PITA to me.

In the end you are correct, nobody gives a rat's ass about that level of accuracy. If you tell the insurance company you had 10 hrs in type, and down the line it turns up you had 9.9, no one will care.