On condition engines
On condition engines
Are people still being able to get engines flown beyond the manufacturers tbo for pvt and aerial work ?
Some say yes, some no. What is the truth ?
Some say yes, some no. What is the truth ?
Yes.
LAMES approve them according to quite valid engineering guidelines.
But ask your insurer if they will continue cover for the level of flying you intend.
The answer might be interesting.
happy days
LAMES approve them according to quite valid engineering guidelines.
But ask your insurer if they will continue cover for the level of flying you intend.
The answer might be interesting.
happy days
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"On condition"
Yes it does happen quite a lot, however, the number of maintenance shops signing them out is decreasing at a rapid rate. It depends on what relationship you have with the shop.
Good point Poteroo. I must check with my insurers as I have a few that are "on condition".
Good point Poteroo. I must check with my insurers as I have a few that are "on condition".
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Has anyone ever made a study of the number of failures in the first 100 hours after rebuild compared to the first 100 after TBO on condition?
And to make the comparison even more one sided sompare those past TBO's for say 200 or more hours.
I have a feeling a good engine at TBO statistically is more reliable. But would love to see if that is true.
And to make the comparison even more one sided sompare those past TBO's for say 200 or more hours.
I have a feeling a good engine at TBO statistically is more reliable. But would love to see if that is true.
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My 172 engine has just gone OC, with only 450hrs TSN, the LAME has ok'ed it for the next 100 hourly but as I understand it's na for Charter but ok for private hire & I'll also check with the insurer on status, .... not like the buggers haven't haven't made enough out of it over the past 45 years though ... 
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Good answer Jaba. I certify engines on-condition and it is really the accessories that need the careful inspection and consideration.
I am a firm believer of 'On-Condition' engines.. at least you know what you have got.
I have seen figures like you spoke of, from memory it was something like 6 times more likely to fail in the first 50 hours after overhaul compared to keeping it in service.
You can play with the figures any which way of course... I will post a few links here to some of the American views on it.
The Savvy Aviator #4: Debunking TBO
The Savvy Aviator #45: How Risky Is Going Past TBO?
The Savvy Aviator #48: Reliability-Centered Maintenance (Part 2)
The carb and mags really need to be in good condition, - no engine will be reliable if you have adverse wear in these components. Given that the components are serviceable then the engine should be able to continue in service subject to satisfactory completion of the On-condition check list.
I am a firm believer of 'On-Condition' engines.. at least you know what you have got.
I have seen figures like you spoke of, from memory it was something like 6 times more likely to fail in the first 50 hours after overhaul compared to keeping it in service.
You can play with the figures any which way of course... I will post a few links here to some of the American views on it.
The Savvy Aviator #4: Debunking TBO
The Savvy Aviator #45: How Risky Is Going Past TBO?
The Savvy Aviator #48: Reliability-Centered Maintenance (Part 2)
The carb and mags really need to be in good condition, - no engine will be reliable if you have adverse wear in these components. Given that the components are serviceable then the engine should be able to continue in service subject to satisfactory completion of the On-condition check list.
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Beeza 
Just what I suspected.
While not a LAME, as an engineer the articles you linked line up with what I expected.
With 500hrs in just over 2 years I will be expecting to hit TBO in 2018 and hopefully a new engine in 2020.
Just what I suspected.While not a LAME, as an engineer the articles you linked line up with what I expected.
With 500hrs in just over 2 years I will be expecting to hit TBO in 2018 and hopefully a new engine in 2020.
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I should have added that TBO is just based on hours. Not all that relevant compared to the environment, utilisation, type of operation and type of maintenance, - oils used etc..
There is now a calendar catch on TBO also but that really just tries to address the low utilisation aspect of some engines.
Modern oils such as Philips XC20/50 and Philips anti-rust oil are just so much better in my opinion. I have heard so many good news stories and it makes it difficult to compare hours to hours, apples to oranges etc..
The NZ leaflet on running engines On-Condition stresses the need for the engines to run hot also. I have seen many engines in this country that had previously been running far too cold. I could not believe my eyes when I saw the ball in the OPRV of one engine red rusty and pitted. What chance did that poor engine have ?
There is now a calendar catch on TBO also but that really just tries to address the low utilisation aspect of some engines.
Modern oils such as Philips XC20/50 and Philips anti-rust oil are just so much better in my opinion. I have heard so many good news stories and it makes it difficult to compare hours to hours, apples to oranges etc..
The NZ leaflet on running engines On-Condition stresses the need for the engines to run hot also. I have seen many engines in this country that had previously been running far too cold. I could not believe my eyes when I saw the ball in the OPRV of one engine red rusty and pitted. What chance did that poor engine have ?
Last edited by baron_beeza; 19th Sep 2011 at 00:28.
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Yeah BB... those "on condition" engines just never seem to quit. Remember Fat Fingers and the PA28-235 of his? As I recall that engine ran "on condition" for bloody years!!!
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Lets face it,
your whole airframe passes every 100 hourly/annual 'on condition' anyway. The sum of the parts is only as good as the attention to detail.
I've seen 'owners' approach on condition in a couple of different ways recently, and the results have been surprising. Being able to fly both aircraft, and note the differences in performance/oil burn etc has been quite interesting. The performance drop off on the 172 in q has been amazing to see, as its oil burn levels.
Some say running them on condition will cost you in the long run, some say it won't if you handle it with a management plan, (which in my opinion should have been implemented at hour zero). The well managed ones I have flown, you wouldn't know.
No different to anything mechanical really.
your whole airframe passes every 100 hourly/annual 'on condition' anyway. The sum of the parts is only as good as the attention to detail.
I've seen 'owners' approach on condition in a couple of different ways recently, and the results have been surprising. Being able to fly both aircraft, and note the differences in performance/oil burn etc has been quite interesting. The performance drop off on the 172 in q has been amazing to see, as its oil burn levels.
Some say running them on condition will cost you in the long run, some say it won't if you handle it with a management plan, (which in my opinion should have been implemented at hour zero). The well managed ones I have flown, you wouldn't know.
No different to anything mechanical really.
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I once owned a 2200 hour O360 Lycoming - ran like clockwork, super smooth, never missed a beat and over 10 hours per litre of oil. Would probably still be running fine now if it had been allowed. I guess we cannot blame LAME's for being reluctant to sign them out though... I wouldn't if it was my livelyhood at stake, even if risk is minimal.
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AS long as the engine stays within the parameters of leakdown, oil consumption, oil analysis, filter cut etc.. I had a twin of which the engines were factory new in 1975 had 1400 hrs on them in 2005 and didn't use a drop of oil and had absolutely no leaks. Compressions all 70's/80. Its the components that you must look at especially the mags and FCU's, lines, hoses etc. Personally i don't go much on the chronological age of the engines but the condition and maintenance is very important. I often liken aircraft engines to taxis....some can be only twelve months old but have done a million k's. Don't agree with the 12 yr life for chtr also.
Folks,
Be very clear, the manufacturers only publish a RECOMMENDED TBO, there is nothing sacrosanct about the number.
For years before the "on condition" CAAP was published, most of the big commercial operators of PA31 etc had engine life extension programs, a typical extension for a Chieftain or similar was 2600 hours, and long term statistics showed NO ADVERSE reliability trend.
The enemy for seldom used engines is rust!!
Tootle pip!!
PS: The yanks have almost 100 years of experience, with 100s of 1000s of engines running on condition, including thousands of big radial in the days of piston engine RPT (likewise Australia), what more proof do you need.
Insurance company restrictions --- because they can, no competition in Australia, and they have been lobbied very heavily by those who overhaul engines in AU --- surprise, surprise. Believe me, LAMEs (with honourable exceptions) are not necessarily the experts on engine life.
Be very clear, the manufacturers only publish a RECOMMENDED TBO, there is nothing sacrosanct about the number.
For years before the "on condition" CAAP was published, most of the big commercial operators of PA31 etc had engine life extension programs, a typical extension for a Chieftain or similar was 2600 hours, and long term statistics showed NO ADVERSE reliability trend.
The enemy for seldom used engines is rust!!
Tootle pip!!
PS: The yanks have almost 100 years of experience, with 100s of 1000s of engines running on condition, including thousands of big radial in the days of piston engine RPT (likewise Australia), what more proof do you need.
Insurance company restrictions --- because they can, no competition in Australia, and they have been lobbied very heavily by those who overhaul engines in AU --- surprise, surprise. Believe me, LAMEs (with honourable exceptions) are not necessarily the experts on engine life.
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Leadie,
Aint that the truth!
And a few other things about engines I have found.
Believe me, LAMEs (with honourable exceptions) are not necessarily the experts on engine life.
And a few other things about engines I have found.
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LAME's might not be the experts on engine life, however, they sign the MR and may end up in the big house if they don't follow the recommendations.
The best thing you can do is build a strong relationship with your facility and get their opinion on "on condition" engines (early in the engines life, not 20 hours TBO). If you don't like their opinion, feel free to get another opinion. Once you have built a good relationship, stick with the one shop if you can help it.
I've seen O-320's that have done WELL over 4000hrs, I'm under no illusions that they can go the distance, and based on that, I would have no qualms signing out an "on condition" engine if I:
- knew the history of the engine
- knew the operator
- knew that the operator understood what liability I was undertaking while trying to save him some money.
At the end of the day, I believe that getting an engine "on condition" is a privilege, not a right.
The best thing you can do is build a strong relationship with your facility and get their opinion on "on condition" engines (early in the engines life, not 20 hours TBO). If you don't like their opinion, feel free to get another opinion. Once you have built a good relationship, stick with the one shop if you can help it.
I've seen O-320's that have done WELL over 4000hrs, I'm under no illusions that they can go the distance, and based on that, I would have no qualms signing out an "on condition" engine if I:
- knew the history of the engine
- knew the operator
- knew that the operator understood what liability I was undertaking while trying to save him some money.
At the end of the day, I believe that getting an engine "on condition" is a privilege, not a right.
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WWWW
That is a pragmatic approach
As for a privilege not a right. I do not think so. It is not a privilege, nor a right, it is an analysis of facts, many of which are covered in your comments above.
I've seen O-320's that have done WELL over 4000hrs, I'm under no illusions that they can go the distance, and based on that, I would have no qualms signing out an "on condition" engine if I:
- knew the history of the engine
- knew the operator
- knew that the operator understood what liability I was undertaking while trying to save him some money.
- knew the history of the engine
- knew the operator
- knew that the operator understood what liability I was undertaking while trying to save him some money.
As for a privilege not a right. I do not think so. It is not a privilege, nor a right, it is an analysis of facts, many of which are covered in your comments above.
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I agree with most of the last few posts, - basically that is how it is.
Certainly the operator has to be factored in, - some are just too pushy or dare I say, even devious. Any suspicion of doctored oil consumption figures, secret filter changes, or otherwise 'economical with the truth' then it all stops.
It happens.
Some pilots are just hopeless also... the operators can be difficult customers.
What do you think the chances are of this character getting beyond TBO on his engine ?
Certainly the operator has to be factored in, - some are just too pushy or dare I say, even devious. Any suspicion of doctored oil consumption figures, secret filter changes, or otherwise 'economical with the truth' then it all stops.
It happens.
Some pilots are just hopeless also... the operators can be difficult customers.
What do you think the chances are of this character getting beyond TBO on his engine ?