On routes like SMF/SFO or SRS/SFO (which are short hops of 60 to 75 miles), it seems like we never reach cruising altitude. There's barely enough time for beverage service.

My question is this: do such flights count as a compression/decompression cycle? It seems like you could save the operator some cycles and space out B checks, C checks, overhauls, etc.

It feels like these aircraft reach 18,000 feet at most? The plane only needs to pump in a small amout of air to keep pressures breathable.

Do regulations require logging these as cycles?

Yes they are frame and engine cycles.

During training when the aircraft is conducting circuits with touch and go landings, each touchdown is recorded as a cycle for the records.

I recall Qantas not using full power for reverse thrusters to reduce engine cycles until one of their 747 went off the runway in wet conditions in Bangkok. I think CASA fined them as a result and now they comply.

This thread belongs in tech ops, I suppose.
But anyway, yes, it's still cycles. Because "CYCLES" isn't merely measuring airframe pressurization.
Several components are tracked by cycles, including landing gear on some types (though other types just give you a flat 10 year landing gear TBO).
And it would because a monumental headache- with tons of room for human and computer/data entry error- to start tracking each individual component to a different number of cycles.

ABpositive wrote:

I recall Qantas not using full power for reverse thrusters to reduce engine cycles until one of their 747 went off the runway in wet conditions in Bangkok. I think CASA fined them as a result and now they comply.

An engine cycle is a start, run for however long and stop so the example you provide
is an incorrect description


The reason Qantas was using idle reverse
that day and the reason most operators
have adopted that practice since the advent of carbon brakes is the fuel savings
and quieter operation (conditions allowing)

ABpositive wrote:

I recall Qantas not using full power for reverse thrusters to reduce engine cycles until one of their 747 went off the runway in wet conditions in Bangkok. I think CASA fined them as a result and now they comply.

An engine cycle is a start, run for however long and stop so the example you provide
is an incorrect description


The reason Qantas was using idle reverse
that day and the reason most operators
have adopted that practice since the advent of carbon brakes is the fuel savings
and quieter operation (conditions allowing)

Max Q wrote:

ABpositive wrote:

I recall Qantas not using full power for reverse thrusters to reduce engine cycles until one of their 747 went off the runway in wet conditions in Bangkok. I think CASA fined them as a result and now they comply.

An engine cycle is a start, run for however long and stop so the example you provide
is an incorrect description


The reason Qantas was using idle reverse
that day and the reason most operators
have adopted that practice since the advent of carbon brakes is the fuel savings
and quieter operation (conditions allowing)

The practice is used also to reduce wear across the life of the engine. Eliminating the reverse cycle (or only using idle reverse) eliminates wear and tear on engines by cutting back a procedure that puts strain on engine components.

Cycles are used regardless of the time spent, because each 'flexing' of the pressure structure induces fatigue, no matter how long or short it was.

Think of a piece of wire that you are repeatedly bending: It can only take so many bends before it snaps.
Since the properties of the aircraft's construction materials are well known, they can put a certain number of 'bends' to it before it will fail.

As far as aircraft maintenance goes usually only three numbers are tracked.

- Calendar days: Exactly as the name suggests. Calendar due dates are common for corrosion checks and that sort of thing. An example might be a scheduled task to check underneath the galleys and lavatories for corrosion every six months, regardless of whether the aircraft flew once or if it flew a thousand times during those six months. Many components and inspections will also have a calendar due date in addition to an hour or cycle limit, for example an engine might say "overhaul at 6600 hours or ten years, whichever occurs first" or something like that. Paperwork items such as registrations, insurance, etc. are also usually calendar items.

- Flight time (hours): Flight time is the time the airplane took off till the time the aircraft landed, usually tracked in hours. Things like engine maintenance, filter replacements, and those sorts of things are usually due every x number of hours.

- Cycles: A cycle is one takeoff and landing. Usually things like landing gear and structural inspections will be tracked by cycles.

As far as engines and such go, anywhere I've seen they are just tracked using the hours and cycles of the aircraft they're attached to. If we install an engine today, and then the aircraft flies ten times, and then we take the engine off, the technical records office will call that ten cycles on that engine. Using different operating techniques (such as only idle reverse and such) will not change the hours/cycles/calendar time on that engine, but it will help it last longer and save money. For an example if the manufacturer says the engine is due for overhaul every 2000 hours, but you're pilots consistently run it hard, there's a good chance it will start developing issues and need to be removed and sent to the engine shop for some expensive repairs before you get your 2000 hours out of it, where as if you were to take good care of it then that same engine will probably be happy to give you the full 2000 hours of service without any major repair bills.

ABpositive wrote:

I recall Qantas not using full power for reverse thrusters to reduce engine cycles until one of their 747 went off the runway in wet conditions in Bangkok. I think CASA fined them as a result and now they comply.

They're thrust reversers. Once I start conning the Enterprise, I'll have access to reverse thrusters.

Short answer, yes, one cycle. Just as HA island hopping is one cycle. Some aircraft had issues if altitude wasn't reached as they needed to dry out parts. For example, island hopping A320s had more corrosion on certain parts. I use the past tense as Airbus did a coatings change that solved the issue. IIRC Air New Zealand found the issue. It is why all heavy maintenance is done at one third the life; issues are found with everything.

CanadianNorth wrote:

As far as aircraft maintenance goes usually only three numbers are tracked.

- Calendar days: Exactly as the name suggests. Calendar due dates are common for corrosion checks and that sort of thing. An example might be a scheduled task to check underneath the galleys and lavatories for corrosion every six months, regardless of whether the aircraft flew once or if it flew a thousand times during those six months. Many components and inspections will also have a calendar due date in addition to an hour or cycle limit, for example an engine might say "overhaul at 6600 hours or ten years, whichever occurs first" or something like that. Paperwork items such as registrations, insurance, etc. are also usually calendar items.

- Flight time (hours): Flight time is the time the airplane took off till the time the aircraft landed, usually tracked in hours. Things like engine maintenance, filter replacements, and those sorts of things are usually due every x number of hours.

- Cycles: A cycle is one takeoff and landing. Usually things like landing gear and structural inspections will be tracked by cycles.

As far as engines and such go, anywhere I've seen they are just tracked using the hours and cycles of the aircraft they're attached to. If we install an engine today, and then the aircraft flies ten times, and then we take the engine off, the technical records office will call that ten cycles on that engine. Using different operating techniques (such as only idle reverse and such) will not change the hours/cycles/calendar time on that engine, but it will help it last longer and save money. For an example if the manufacturer says the engine is due for overhaul every 2000 hours, but you're pilots consistently run it hard, there's a good chance it will start developing issues and need to be removed and sent to the engine shop for some expensive repairs before you get your 2000 hours out of it, where as if you were to take good care of it then that same engine will probably be happy to give you the full 2000 hours of service without any major repair bills.

Much of that is automated now. Later A320CEOs, NEO and in particular the 787. The first two years of the 787 components were screaming for attention and it was a headache. Now it is a major maintenance cost savings.

The nice thing about software, once debugged,you just reuse.

This also isn't old school. Early jets had no life! 737-100 34k cycles or 34k hours. Early 727, 50k cycle or same 50k for hours.
http://www.boeing.com/commercial/aeroma ... 2012_q4/2/

Note:. The 737 requires a very expensive inspection at 85,000 cycles. To my knowledge zero 737s have gone past that. If there are exceptions, please let me know.

Airlines care about maintenance bills, so there is a push to cut costs per calendar, cycle, and hours.

Calendar used to be on a 6 to 7 year corrosion (based off 18 to 21 year certification). Now everything seems to be 36 year certified, so calendar plays a reduced role.

To others:
Cycles and hours have grown. For example the A320 was serviced on 48k cycle/60k hour certification or a heavy maintenance cycle every 16k cycles, 20k hours,or almost 7 years.

Now with 60k cycle, 120k hours and a longer calendar (is it 36 years or less?) certification, Shop visits are fewer.

Due to added sensors, they are cheaper too. For example, JetBlue flies about 2500 cycles and under 4000 hours per year. So on cycles, a heavy maintenance every 8 years. On hours, about every 10. So they went from hour based maintenance to cycles as before they would hit the lower limit after 5 years.


HA is the other extreme, the fly just under 5k cycles per year, so all maintenance is cycle based.

A bit of expansion:
Maintenance by the calendar is to prevent corrosion.
Maintenance by the flight hour is for stuff that wears by the hour. Besides the filters you noted, for example engine oil.
Cycles is the structural you noted, but also thermal cycled. Some metals wear with hot (ground or take off) and cold (cruise).

For example,for some stuff the hot/cold wears, not the forces. Many seals are cycle limited for this reason while other seals are pressure cycle limited.

Note:. Maintenance intervals are not the same cycle/hour life as the LOV limit. For example, the 717 is maintained on it's certified 60k/60k or a heavy maintenance interval every 20k cycles or hours. Not the 110k it is really good for. It cost Airbus a lot of money to certify for 60k/120k. Money worth spending on thousands of paying support contracts, not worth it for small sales volumes.

Note: many business jets are on old-school programs and I've seen low limits on cycles and hours. But only major business jet companies even get 400+ cycles a year; they sell before enough life is used to impact the buyer's decision. Usually before an engine overhaul. From what I can tell, most business jets fly less in 40 years than a commercial jet in 2.

Lightsaber

Late edit: G650 is certified for 17k cycles and 40k hours. That is very high durability for a business jet:
https://www.google.com/url?sa=t&source= ... Bx5C2yxtbg

CanadianNorth wrote:

As far as aircraft maintenance goes usually only three numbers are tracked.

- Calendar days: Exactly as the name suggests. Calendar due dates are common for corrosion checks and that sort of thing. An example might be a scheduled task to check underneath the galleys and lavatories for corrosion every six months, regardless of whether the aircraft flew once or if it flew a thousand times during those six months. Many components and inspections will also have a calendar due date in addition to an hour or cycle limit, for example an engine might say "overhaul at 6600 hours or ten years, whichever occurs first" or something like that. Paperwork items such as registrations, insurance, etc. are also usually calendar items.

- Flight time (hours): Flight time is the time the airplane took off till the time the aircraft landed, usually tracked in hours. Things like engine maintenance, filter replacements, and those sorts of things are usually due every x number of hours.

- Cycles: A cycle is one takeoff and landing. Usually things like landing gear and structural inspections will be tracked by cycles.

As far as engines and such go, anywhere I've seen they are just tracked using the hours and cycles of the aircraft they're attached to. If we install an engine today, and then the aircraft flies ten times, and then we take the engine off, the technical records office will call that ten cycles on that engine. Using different operating techniques (such as only idle reverse and such) will not change the hours/cycles/calendar time on that engine, but it will help it last longer and save money. For an example if the manufacturer says the engine is due for overhaul every 2000 hours, but you're pilots consistently run it hard, there's a good chance it will start developing issues and need to be removed and sent to the engine shop for some expensive repairs before you get your 2000 hours out of it, where as if you were to take good care of it then that same engine will probably be happy to give you the full 2000 hours of service without any major repair bills.

Out of curiosity, how are flight time and cycles tracked? Is there something like an odometer in the flight deck that displays that info, or does the airline have to manually maintain records?

STLflyer wrote:

CanadianNorth wrote:

As far as aircraft maintenance goes usually only three numbers are tracked.

- Calendar days: Exactly as the name suggests. Calendar due dates are common for corrosion checks and that sort of thing. An example might be a scheduled task to check underneath the galleys and lavatories for corrosion every six months, regardless of whether the aircraft flew once or if it flew a thousand times during those six months. Many components and inspections will also have a calendar due date in addition to an hour or cycle limit, for example an engine might say "overhaul at 6600 hours or ten years, whichever occurs first" or something like that. Paperwork items such as registrations, insurance, etc. are also usually calendar items.

- Flight time (hours): Flight time is the time the airplane took off till the time the aircraft landed, usually tracked in hours. Things like engine maintenance, filter replacements, and those sorts of things are usually due every x number of hours.

- Cycles: A cycle is one takeoff and landing. Usually things like landing gear and structural inspections will be tracked by cycles.

As far as engines and such go, anywhere I've seen they are just tracked using the hours and cycles of the aircraft they're attached to. If we install an engine today, and then the aircraft flies ten times, and then we take the engine off, the technical records office will call that ten cycles on that engine. Using different operating techniques (such as only idle reverse and such) will not change the hours/cycles/calendar time on that engine, but it will help it last longer and save money. For an example if the manufacturer says the engine is due for overhaul every 2000 hours, but you're pilots consistently run it hard, there's a good chance it will start developing issues and need to be removed and sent to the engine shop for some expensive repairs before you get your 2000 hours out of it, where as if you were to take good care of it then that same engine will probably be happy to give you the full 2000 hours of service without any major repair bills.

Out of curiosity, how are flight time and cycles tracked? Is there something like an odometer in the flight deck that displays that info, or does the airline have to manually maintain records?

Every flight is recorded in the maintenance log, paper or electronic. Apart from pressurisation and OOOI times, another important item is gear cycles.

I'd wager a modern aircraft also records data automatically in the maintenance system.

Small aircraft do have odomoters of sorts. The "Hobbs meter" (which may or may not be made by Hobbs) runs as long as the electrics are powered, or by some other metric like airspeed. The tach runs while the engine is running.

STLflyer wrote:

Out of curiosity, how are flight time and cycles tracked? Is there something like an odometer in the flight deck that displays that info, or does the airline have to manually maintain records?

Where I work and at the flying club we just use the journey log book as the main source. As per Transport Canada a journey log book for an airplane must be on board for each flight. The pages are set up with designated spots for all the required information, and the pilot just goes to the next available line or page and fills in the blanks.

The layout of the book depends on the operator, there is a standard book you can buy and use, https://www.aircraftspruce.ca/pages/ps/logbooks_canada/atpjourneylog.php is an example. Most of the private operators, flying clubs, etc. I know use that one or one very similar to it. You can also develop your own custom log books as long as it contains all of the required information (usually a custom layout to include more information that the operator finds relevant to their operation), which is what most airlines do.

Basically each flight gets an entry in the book. Usually each entry line or page (depends on the layout) has a spot for the date, crew, takeoff airport, landing airport, times out/up/down/in, air time, flight time, total air time since new, total cycles since new, then some notes (every operator has their own ideas on what to put there which is fine, usually it's things operations or accounting or other such departments might care about more so than pilots or mechanics), and a space to write down any defects with the airplane and corresponding corrective action and maintenance release. For multiple takeoff and landings on one flight some operators log each leg individually and just count each line as a cycle, and others put it as one entry but list the number of landings for that flight. Either way works fine as long as it's clear and obvious how many takeoff/landing cycles were flown.

STLflyer wrote:

CanadianNorth wrote:

As far as aircraft maintenance goes usually only three numbers are tracked.

- Calendar days: Exactly as the name suggests. Calendar due dates are common for corrosion checks and that sort of thing. An example might be a scheduled task to check underneath the galleys and lavatories for corrosion every six months, regardless of whether the aircraft flew once or if it flew a thousand times during those six months. Many components and inspections will also have a calendar due date in addition to an hour or cycle limit, for example an engine might say "overhaul at 6600 hours or ten years, whichever occurs first" or something like that. Paperwork items such as registrations, insurance, etc. are also usually calendar items.

- Flight time (hours): Flight time is the time the airplane took off till the time the aircraft landed, usually tracked in hours. Things like engine maintenance, filter replacements, and those sorts of things are usually due every x number of hours.

- Cycles: A cycle is one takeoff and landing. Usually things like landing gear and structural inspections will be tracked by cycles.

As far as engines and such go, anywhere I've seen they are just tracked using the hours and cycles of the aircraft they're attached to. If we install an engine today, and then the aircraft flies ten times, and then we take the engine off, the technical records office will call that ten cycles on that engine. Using different operating techniques (such as only idle reverse and such) will not change the hours/cycles/calendar time on that engine, but it will help it last longer and save money. For an example if the manufacturer says the engine is due for overhaul every 2000 hours, but you're pilots consistently run it hard, there's a good chance it will start developing issues and need to be removed and sent to the engine shop for some expensive repairs before you get your 2000 hours out of it, where as if you were to take good care of it then that same engine will probably be happy to give you the full 2000 hours of service without any major repair bills.

Out of curiosity, how are flight time and cycles tracked? Is there something like an odometer in the flight deck that displays that info, or does the airline have to manually maintain records?

Smaller GA airplanes will use either a Tach meter to track engine run time (ran off of engine rotation), or Hobbs Meter to track actual flight time (most a powered and ran by different sources. Depends on airplane). Airliners will have ACARS track the times along with the FDR.

bigb wrote:

Smaller GA airplanes will use either a Tach meter to track engine run time (ran off of engine rotation), or Hobbs Meter to track actual flight time (most a powered and ran by different sources. Depends on airplane). Airliners will have ACARS track the times along with the FDR.

Depends on the aircraft and operator. Many do exactly that but many also use the paper log books. Both the 172 I fly and the airline I work for the log book is used as the main source.