Tachometers and Flight Logging

[q400link]

Hey Guys,

So I've been hiring out a few lighties which are charged on tacho time, and I'm told i should be logging tacho time as well. Can someone help explain the benefit of tacho time?, what actually makes it go up compared to a VDO? Some ppl have told me i should be logging chock to chock

TIA

[43Inches]

Hey Guys,

So I've been hiring out a few lighties which are charged on tacho time, and I'm told i should be logging tacho time as well. Can someone help explain the benefit of tacho time?, what actually makes it go up compared to a VDO? Some ppl have told me i should be logging chock to chock

TIA

It's very straight forward, flight time is considered from when the craft moves under its own power for the intention of flight to when it comes to a stop at the destination after completion, chock to chock. Tacho is for engine maintenance, the timer will vary according to engine load or RPM, Flight switch is for airframe maintenance and VDO is engine running time, usually a very close approximation, unless you spend 20 minutes warming up that is.

[Checkboard]

As long as you're not adding swathes of time to your actual flights, nor making up flights you didn't do - no one cares. It's your logbook, and what you log is up to your honesty.

[India Four Two]

43Inches is correct but in practice, a lot of people, including me, use tach time. It’s much simpler and easier. Just look at the tach hours after shutdown and subtract the previous value in the logbook.

Yes, I know the argument that I am wasting TBO hours, but it’s minuscule in the grand scheme of things.

[Lead Balloon]

Errrm, how does logging tach time mean you’re “wasting TBO hours”?

I’m having trouble in even understanding what “log” or “logs” this thread is referring to. Old timer’s disease I suppose….

[megan]

In all the types I've flown tacho time has always been less than the actual elapsed time, depends on the rpm at which you run the engine and time spent on the ground.If you use the tach time for your pilot logbooks entries, you could be shorting yourself on your flight hours because tach time can be as much as 20 percent lower than the Hobbs time.

https://doublemaviation.com/hobbs-time-vs-tach-time/

[43Inches]

In theory if you used Tacho time for flight and duty compliance you would be exceeding your actual flight time limits if you were calculating to the maximum without an adjustment. Hence why there is a strict method for calculating flight time. Tacho 'time' is misleading as it does not measure hours and minutes, its a counter that measures engine usage. It does relate about 80% to real time, depending on things like length of flight and taxi, but obviously the lower the average RPM used for a particular flight the slower the counter will tick over. VDO/HOBBS would be the closest approximation to the legal requirement. For private operations, who cares, if you are building hours for your commercial or experience in general you will shaft yourself out of approximately 20% flight time.

[Lead Balloon]

With respect, 43, you’ve got it the wrong way around, for the reason stated by megan.

Of course, so much depends on what kind of tacho we’re talking about. In the case of a ‘standard GA’ steam driven tacho, one hour only equals one hour at one specific RPM (usually around 2.350 as I recall, but someone will correct me if I’m wrong). A steam driven GA tacho is actually the same as a steam driven car speedo/odometer.

So, one hour taxiing around at 1,200 RPM results in less than an hour clocking over on the tacho. One hour cruising at 2,450 RPM results in more than an hour clocking over on the tacho.

And I’m still not sure if we’re talking about pilot logged time or aircraft logged time in service or whatever, none of which has any necessary relationship to how an aircraft owner chooses to charge for the use of the aircraft.

[43Inches]

The OP is hiring an aircraft and paying via the Tacho counter. He is asking if they should be logging the flight time (personal log) via the Tacho or chock to chock. I explained clearly that Tacho is a maintenance counter which generally under-reads block time. Chock to Chock is most accurately represented by VDO, if you don't actually record it via watch times, which is perfectly acceptable, we do that in airline operations. The other option to Tacho counter for maintenance is Air switch with a factor for engine time. As for airframe maintenance airborne time (airswitch) is all that matters in most cases. In airline ops you just manually enter watch time off and on block for personal logbook, and the airborne and landing times for maintenance. Then the smart guys in tech do fancy calculations based on how it flew as to what cycles and hours remain.

[Lead Balloon]

I think we’re in heated agreement about the technicalities of what various things measure and those measurements’ correspondence or otherwise with various times recorded for regulatory purposes.

Not sure what flight and duty times have to do with a privately hired GA aircraft. But I take your point in the case of pilots logging flight time on the basis of a steam driven GA tacho that is, on ‘average’, run below the RPM at which 1 tacho hour equals 1 real hour, the logged flight time will usually be less than actual flight time. However, I reiterate that - as always - so much depends on what specific kind of tacho is fitted to the aircraft. Digital tachos don’t work the same as steam driven ones. And a steam driven tacho (and most ‘Hobbs’ meters) will record time spent warming up then taxiing to the fuel bowser to fill up before a flight, none of which time counts as flight time for the pilot nor time in service for the aircraft.

(And I still have no idea how logging tacho time as pilot flight time results in “wasting TBO hours” as suggested by India Four Two.)

[43Inches]

However if you were ever questioned about logging your flight time and responded I just logged the VDO time, CASA would not give a damn. However in a commercial operation if you used Tacho you could find yourself having exceeded flight time limitations, I'm only stateing where the logging of flight time becomes a strict process that CASA will care about. As I stated earlier for private ops, who cares. The only issue being if you are logging it for experience purposes you will shaft yourself out of hours needlessly. Standard factors we'd apply in the old days is .2-.3 for tachos and .3-.4 for airswitch for say a session of circuits, reduced number for say navex. that's if you couldn't be arsed looking at your watch at blocks on/off. CASA seemed happy with that. Engineers had factors for converting Tacho use for airframe calcs and for reverse flight switch back to engine time with no tacho. The reason I went further to explain commercial reasoning is that inevitably someone will ask that question if you just focus on private ops. In any case the same rule applies for both as to how flight time is calculated, just one is more critical legally.

(And I still have no idea how logging tacho time as pilot flight time results in “wasting TBO hours” as suggested by India Four Two.)

Yeah that one I have no idea, in a private operation anyway, it would only waste TBO if you owned the aircraft and wanted to minimise cost per logged hour for experience, maybe that's the angle. For a hired aircraft you would just waste unnecessary hire time if you logged 20% less each flight for experience gaining.

[Lead Balloon]

And what of digital tachos that measure real time at anything over e.g. 1,000RPM?

[43Inches]

And what of digital tachos that measure real time at anything over e.g. 1,000RPM?

No idea, out of my league, all this fancy modern stuff. I mean its pretty easy to just use your own watch. The only question I have there is you are probably getting ripped off for maintenance if its recording higher numbers than the conventional tacho, unless there's some calculation for that as well.

[Squawk7700]

To make it complex, ~90% of RAAus aircraft have just a gauge on the VDO / Rotax branded hour meter that ticks over as soon as the engine starts. Add to that, some of them have a flight/air-switch that starts ticking over when the aircraft exceeds a specific speed. Some maintenance organisations use that figure for engine maintenance.

Some manufacturers such as Jabiru, specifically state that the engine maintenance must be based on the VDO time, which is engine runtime hour-for-hour. Otherwise, if the aircraft is a circuit queen in a training environment, it could hit the 1,000 TBO and have actually had the engine running for 1,400 hours.

[Office Update]

.
The tacho clock is just a convenient method of recording time; what ever time you want it to be. It is an American invention for convenience.

Before American aircraft/helicopters became the the majority; most British or European aircraft had no time recording clock fitted !

Aircraft maintenance and pilot logged flight time is based upon honesty.

For maintenance: Engine and airframe time is based upon wheels' off' to wheels 'on'; simple as that. (for simplicity - operators may fit an air switch to start recording at a pre determined airspeed - for helicopters that may be a torque setting or similar)

Pilot log book time: Based upon Start taxi to finish taxi at conclusion of each sector or flight. In commercial Operations where flight and duty time may be an issue over a 30/90/365 day period, CASA may accept via the approved Ops Manual; wheels on to wheels off + 5 minutes or 0.1 if logging digital time.

That's it ....

If you see aircraft sitting idling whilst conducting maintenance runs; waiting for take-off etc, none of that time is recorded for maintenance.

Flight schools need to make a dollar to cover overheads, power, light, air-con, admin staff, rent etc so they may well fit a VDO or Hobbs meter which would be oil pressure operated at engine start. They would bill the student or client by this method as they require money to make the business work.

If you check out the big name flight schools; you will find two Hobbs meters; one is for engine running time (billing hours) and the other is for airframe/engine maintenance. It is quite possible to have a C172 in a flight school with say 2000 hrs total time for engine/airframe maintenance; but showing 3000+ hours for billed out engine running time to the student or private hire. In this example the 3000+ hours has nothing to do with eng/airframe maintenance.

If you are a responsible owner/operator you do not require ANY time clocks in your flying machine. IF you carry out commercial operations the contract client may require a time clock to verify billed time is indeed maintenance time, otherwise you would have operators idling for 20 or 30 minutes to pad the billing time.

If in doubt refer to the CASA regs..

[megan]

Don't know how digital tachs handle the recording of time in operation, the old mechanical tachs are set to a particular RPM for the recording of one hour, manual I have has tachs ranging from 1,800 to 3,000 RPM for that one hour setting, typical Cessna is set at 2,566.

[tossbag]

Look at your watch the moment the engine kicks over, write the time down. As soon as you pull the mixture to shut the engine down, again look at your watch, note the the time. Secure the aircraft, while you're sitting down with your brew of choice calculate the time you will then enter your logbook.

[Standby Scum]

I don't recall the name of the flying club at Biggin Hill (Sportair?) who operated Fournier RF 3s in the 70s. The hire cost was the engine by tachometer and the chock to chock airframe time by the hour. On one occasion someone hired one of these and learnt soaring very quickly and stayed aloft for over 6 hours having used the engine for less than half an hour. He was able to log 6+ hours P1 powered flight and was very unpopular with the club and the 5 people who never got to fly the aircraft that day. I forget the aftermath but I think the CAA put a stop to this practice. Bitches. On a different matter, I think there were a few English Electric Lightning pilots who were able to get automatic multi engines stamped on their UK civil PPL licence until some spoil-sport advised the CAA that the Lightning engines were one above the other and not side by side. Bitches.

[deja vu]

When hiring an aircraft, log what you are asked to pay for, otherwise chock to chock.

[Lead Balloon]

The obligation to log flight time, as defined, in the regulations is unaffected by how an aircraft hirer chooses to charge for the use of the aircraft.

[deja vu]

The obligation to log flight time, as defined, in the regulations is unaffected by how an aircraft hirer chooses to charge for the use of the aircraft.
I don't have a copy of the regulations in front of me so please elaborate the definition of flight time for us.

[Lead Balloon]

Just go to the new, ever-so-simple Part 61. Here are the highlights from the TOC:Division 61.A.2—Flight time and other aeronautical experience 87

61.070................... Flight to which Division 61.A.2 applies........................... 87

61.075................... Definition of aeronautical experience for Part 61............. 87

61.080................... Definition of flight time as pilot for Part 61...................... 87

61.085................... Definition of flight time as co‑pilot for Part 61................. 87

61.090................... Definition of flight time as pilot in command for Part 61.. 88

61.095................... Definition of flight time as pilot in command under supervision for Part 61 88

61.100................... Definition of flight time as flight engineer for Part 61....... 88

61.105................... Definition of instrument flight time for Part 61................. 89

61.110................... Definition of instrument ground time for Part 61............. 89Then you go to the definition of 'flight' in the Act.

[Ascend Charlie]

If you were in a helicopter, as soon as the rotor starts to turn, the aircraft is moving - rattling side to side, up and down - for the purpose of flight. And it is capable of flight - doesn't need to taxy to a runway and then gain airspeed for it to get off the ground. A careless movement with the left hand, or sometimes left leg, and the machine leaves the ground, though only for a very short time.

So, chopper drivers usually log start to stop time in their books, but maintenance is skids off to skids on. Robinson may nominate something else.

[Lead Balloon]

I’ve an idea: Howz about we enter “flight time” as defined in the regs as “flight time” in our pilot logbooks kept in accordance with the regs? Crazy, I know, but I’m getting a bit flaky in my old age.

So flaky that I’ll go so far as to suggest that we should enter “time in service” as defined in the regs as “time in service” on maintenance documentation for the aircraft we fly.

And guess what? Neither of those definitions has squat to do with what a tacho says.

The fact that these issues are debated in the 21st century in Australia is a testament to the great success of the regulatory ‘reform’ program and the performance of CASA’s education function.

The fact that there are so many and varied practices is a testament to how unimportant the exact numbers are to real-world pilot competence and aircraft continuing airworthiness. But that won’t stop CASA, when CASA decides precision is important. So be careful.

[43Inches]

I really don't understand how hard it must be to look at your watch at taxi start and taxi completion and log that time (provided you intended to get airborne). As I said earlier VDO/HOBBES is the closest approximation to it however it will be erroneous if the recording starts with battery power or extended engine operation prior to taxi.

Maintenance will run off whatever the approved maintenance system specifies, whether it uses tacho, airswitch, cycles, dates, that's all specified in the maintenance manual, not pilot related stuff. Those meters may or may not be reliably recording flight time as per the regulations, most likely they will under-read the required flight time definition for pilots log books. A flying club/org could charge by any switch, dry or wet, day rates, weekend rates, air services in or out, bulk hour rates, or no charge at all, that's up to them. What a pilot logs for legal purposes has been covered, chock to chock for the intention of flight. If the craft taxis by itself, or becomes airborne in a gust of wind, extreme vibrations, earthquakes or floats down the river in a once in a 100 year flood (that's happening every 5 years) etc etc, that is not moving with intention of flight. I once jumped in a self taxiing twin whilst it was moseying along by itself in a strong wind. I did not log the time from when I hopped in and brought it to a stop, as I was not sure that the aircraft had the intention of becoming airborne.

Logging of flight times for pilots has a legal definition, so follow that as per above posts containing the references, especially if you intend to use the hours for qualifications or duty limitations. I've seen passengers keep logs of flight time, there is no legality that says you can't you can log anything you want as long as you don't use it for something you are not legally entitled to.

[Lead Balloon]

43B Time‑in‑service to be recorded on maintenance release

(1) On the completion of flying operations on each day that an aircraft is flown, the owner, operator or pilot in command must record on the maintenance release the total time‑in‑service of the aircraft on the day.

Penalty: 25 penalty units.

(2) An offence against subregulation (1) is an offence of strict liability.

Note: For strict liability, see section 6.1 of the Criminal Code.Time in service has a definition. Doesn't matter squat what the approved maintenance system says.

[43Inches]

That's a general rule, the time in service must be recorded for overall airframe life, however various parts have maintenance requirements based on whatever the maintenance manual says for that part. Landing gear, pressurisation systems, certain engine parts are on cyclical limits on most types, usually based on landings, pressure cycles or starter cycles. The engine life can be run off tacho for instance, or VDO as one poster said above for Rotax installations. If you were to set up your own schedule of maintenance for your type you could set the limits as per your own limitations to whatever counter should you have the data to back it up.

[Lead Balloon]

Be that as it may, it has nothing to do with the OP’s question.

[Lead Balloon]

“Compelling evidence” of what? It’s only compelling evidence that the flight time logged in a pilot’s log book matches the hirer’s charging methodology. I think you’ll find CASA’s more worried about whether the logged flight time equals the pilot’s actual flight time. (Crazy as it may seem.)

“Many practices are generally considered acceptable” by whom? I don’t doubt that there are many and varied practices out there. As I said, it just goes to show how unimportant the exact numbers are to pilot competence and airworthiness in the real world.

I remain in awe at our apparently endless ability to complicate simple concepts.

[megan]

Originally Posted by Lead Balloon View Post (https://www.pprune.org/pacific-general-aviation-questions/645407-tachometers-flight-logging.html#post11191932)
The obligation to log flight time, as defined, in the regulations is unaffected by how an aircraft hirer chooses to charge for the use of the aircraftSometimes there can be quite a disparity between what is logged in the maintenance release and what the customer is invoiced. Some helo tasks require considerable ground running, one operator at least, charged the customer for the total running time while the maintenance release had the correctly defined flight time recorded.

[Lead Balloon]

Exactly.

I can hire my aircraft to pilots at $3,300 per day if I want, irrespective of how many hours it is or is not flown each day, because that’s the opportunity cost to me of not having the aircraft available for my use each day. Doesn’t make a schmick of difference to what the regulations require the pilots to enter in their logbooks and in the aircraft’s MR at the end of each day’s flying (if the aircraft is flown).

[megan]

I should add, that as a pilot I used to log the total running time, not flight time I know, but still in control of a running aircraft, CASA would not be amused if you hopped out and went walk about while leaving it running.

[Ascend Charlie]

Megan, more than one pilot has stood outside his helicopter, d1ck in hand, splashing his boots, and watched as the machine vibrated itself off the rock / cliff on which he stopped for a wee.

Like you, I logged engine start to engine stop, and the customer paid for that time as well. Maintenance time was as per the regs.

[tossbag]

more than one pilot has stood outside his helicopter, d1ck in hand, splashing his boots, and watched as the machine vibrated itself off the rock / cliff on which he stopped for a wee.

Surely if you got the wind right you could swing your legs out, cyclic friction on, holding the collective down, dick in one hand, probably splash the boots a bit more but be in a position to save it if it vibrated too much?

[Training Risky]

I should add, that as a pilot I used to log the total running time, not flight time I know, but still in control of a running aircraft, CASA would not be amused if you hopped out and went walk about while leaving it running.
I'm sure you did....:zzz:

More tall tales from the Walt of Walts!

[First_Principal]

Surely if you got the wind right you could swing your legs out, cyclic friction on, holding the collective down, dick in one hand, probably splash the boots a bit more but be in a position to save it if it vibrated too much?

Should this be a manoeuvre examined in the flight test? Seems to me it could be, er, discriminatory against some pilots who might not be able to complete all facets of the exercise :}

Otherwise not saying anything much new here but I've always logged engine on to engine off (except for engine failure!), given that's when one is - hopefully - in control of the craft, however some aircraft operators I've known have charged based on hobbs meter with a switch on the handbrake. Quite decent of them I thought; if you were sitting somewhere on the ground waiting for departure clearance and you had the brake on that's not being charged, however once the brakes off and you're rolling the clock was ticking. I'm fairly sure there was an airspeed switch involved as well, although I never tried it I should think they had ways of preventing unscrupulous types flying along with the handbrake on...

FP.

[43Inches]

Hand brake mechanism sounds like a good idea, however, in my experience there are lots of hirers that will work that to set the brake to a position it won't tick over. The oil pressure switch is pretty fool proof for charging as it is difficult to tamper with or circumvent. Old fashioned tacho or flight switch even better as you promote proper warm up and taxi technique to reduce wear and tear on the aircraft. Although I have seen airswitch tampered with to slow metering. VDO/HOBBS inevitably pushes users to 'rush' into the air and possible increase wear on things. I was always in favor of Airswitch usage for charging and a flat taxi fee for consumables on the ground. Operators don't like this though as they get an extra .2-.3 on the ground where the maintenance is technically not ticking over when using VDO/HOBBS and therefore it covers misuse theoretically.

I've also seen a few Ag ops refueling/refilling with engine running while the pilot takes a break, more than a few times.

[megan]

unscrupulous types flying along with the handbrake onSome of us used to have to do that, brakes on after take off at home base, make up to a dozen landings or so, brakes off prior to landing at home base. ;)

[Ascend Charlie]

There was an operator, still in business, which, in the early 90s, had a B206 on cross-hire from its private owner. The owner looked forward to a monthly cheque to offset his costs, but the amount kept getting less and less.
He contacted the owner of the school and asked what was happening. "Oh, not much demand for a B206 at the moment."

One Sunday, he was passing the airport and saw his machine fly overhead. "Great, some money this month!"
But no cheque. He asked again, "No, it hasn't flown."
Owner checks the maintenance release, no entries.
He says to himself, "Self, something isn't right here."

He gets his maintenance company (different from the school) to fit a hidden Hobbs meter in the broom closet.

Next month, again "no flight", so he looks at the secret Hobbs which shows that it has been flown. The school had been pulling the circuit breaker for the Hobbs and flying unrecorded time - the maintenance had to be way overdue. He blew the whistle to CASA, and the Chief Pilot went for the high jump - a shame, because he was a nice guy and it was the hungry Owner of the school who got away with it and kept on going. Without the private B206.

The school was known as The Breaker Brothers since then.

[43Inches]

Just more proof that all the over regulating of GA ever did was hamstring honest operators. And those that bend the rules to make cash survive as long as they are smart enough to do it carefully to not attract attention. The frustration I had in GA when competing with unscrupulous operators that undercut legit operators and did quasi illegal things that were hard to prove, let alone get CASAs interest. One of the main issues that should be addressed is that the owner/manager needs to bear the brunt of legal consequences, not the staff. Start sending the shonky bosses to jail for accidents and rule breeches, things clean up very fast. In any case I feel that was by far one of the biggest issue for GA for the last 50 years.

Start putting the owner on trial for why a plane busted a minima, why a pilot busted flight and duty limits, why an aircraft went past maintenance. The owner will hire and pay staff that wont put him in jail and the industry cleans up. At present the PIC and CP wear the consequences of actions that can really be grouped into commercial pressure, which is directed down the chain by company culture. You want the culture to change, start at the top.

[Clinton McKenzie]

Start putting the owner on trial for why a plane busted a minima, why a pilot busted flight and duty limits, why an aircraft went past maintenance. The owner will hire and pay staff that wont put him in jail and the industry cleans up.There was a whole lot of fanfare when this section was added to the Civil Aviation Act:28BE Duty to exercise care and diligence

(1) The holder of an AOC must at all times take all reasonable steps to ensure that every activity covered by the AOC, and everything done in connection with such an activity, is done with a reasonable degree of care and diligence.

(2) If the holder is a body having legal personality, each of its directors must also take the steps specified in subsection (1).

(3) It is evidence of a failure by a body and its directors to comply with this section if an act covered by this section is done without a reasonable degree of care and diligence mainly because of:

(a) inadequate corporate management, control or supervision of the conduct of any of the body’s directors, employees or agents; or

(b) failure to provide adequate systems for communicating relevant information to relevant people in the body.But.... read on:

(4) No action lies, for damages or compensation, in respect of a contravention of this section. And .... despite the thousands of strict liability and other offences in the aviation law, it is not an offence to breach s 28BE(1).

The law with most 'teeth' in this regard would be WHS law. Look what happened in the Outback Ballooning case.

[43Inches]

The first wording of that ACT allows them to get away with it. The court has to first prove without doubt that the company failed to take reasonable steps. Simple things like saying the Ops manual said don't do that, when behind the scenes it was clear to employees that breaching the Ops manual was expected of them, one is hard proof, the other is speculative. If the Directors/owners were on trial first that they are responsible for their employees no matter what, like the OHS situation, then we would see much greater push from them to do the right thing. 3 Pilots are caught busting duty limits, there is no doubt there was a lack of oversight and therefore management is responsible and must suffer the most penalty. An aircraft is flown well beyond maintenance limits as above for pure greed, no doubt the ownership was involved and must wear the highest of the penalties.

That last option (4) basically says that if you fail to prove they took reasonable steps in criminal court you can't then take them to civil court for recompense, which is ridiculous.

If the CFI/CP keep wearing the blame because of the position, the owners keep employing less than capable puppet CFI/CPs that do what the owner wants without involvement. If the Owner ends up facing the courts every time the employees stuff up, they will either pack up or employ people of the correct morality for the job so they don't.

The same is starting to happen in other businesses, where the 'accredited' person is not the owner, so they are positioned to take the fall when things go wrong. We are seeing a number of transport industries where accidents are increasing because of this.

[172510]

we should enter “time in service” as defined in the regs as “time in service” on maintenance documentation for the aircraft we fly.

I agree with you. Yet after having been through the Cessna 172 Maintenance Manual I couldn't find a definition of "time in service".

[Lead Balloon]

That’s because the Cessna 172 Maintenance Manual is not the regulations. Regulations are legislation made by legislators. The Cessna Maintenance Manual is a manual published by Cessna.