GA engines On Condition
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the most economical time to overhaul the engine would be at the manufactures TBO (or a little over depending on the type of operation), the further you run the engine obviously there will be more wear on the various internal components.
If a crankshaft that would have been within limits at say 2000-2200 hrs needed to be replaced because you ran the engine to 2400-2500 Hrs then that 200hrs could have easily cost you an extra $10k
The other thing to think of is at overhaul parts are subject to all types of non destructive testing (magnaflux, fluro penetrant, ultrasonic) to check for defects, cracks etc. i seriously doubt that the manufacturers invented these checks just so that they could sell more parts
Whilst an engine might be running great at 2500Hrs might have good compression, oil pressure, develop power etc does your LAME have a crystal ball to look into that will tell him that the No. 3 Conecting rod bolt has a microscopic fatigue crack that is about to grow out of controll and spoil your day ?
If a crankshaft that would have been within limits at say 2000-2200 hrs needed to be replaced because you ran the engine to 2400-2500 Hrs then that 200hrs could have easily cost you an extra $10k
The other thing to think of is at overhaul parts are subject to all types of non destructive testing (magnaflux, fluro penetrant, ultrasonic) to check for defects, cracks etc. i seriously doubt that the manufacturers invented these checks just so that they could sell more parts
Whilst an engine might be running great at 2500Hrs might have good compression, oil pressure, develop power etc does your LAME have a crystal ball to look into that will tell him that the No. 3 Conecting rod bolt has a microscopic fatigue crack that is about to grow out of controll and spoil your day ?
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Syd Chrome makes an interesting point...
"They (prosecution) will not accept CASA ADs in court and will merely use the Lycoming or Continental Rec TBO as the limit for that engine..thats why a lot of LAMEs will not entertain the idea. LAMEs should be able to stand behind CASA ADs as being law and if that causes people to be injured then CASA should be held resposnible not the LAME.
SC'
There are plenty of engines in the US that are running well beyond TBO and calendar time. Some have never been touched since they were new in the 70's and 80's. They almost always have good compressions and low oil consumption and pose no real problems when they do eventually decide to overhaul them. No doubt that was the basis of the CASA condition report A/D. However, as to whether its legal. here ... well AWB 02-003 (June 06)seems to suggest that CASA are having two bob each way. They refer to CAR 42 which says something about the C of R holders responsibility to maintain the aircraft in an airworthy condition using a maintenance schedule. They go on to say that the best folks to decide on the maintenance schedule are the manufacturers and good old Sched 5, which has been used as the excuse for not working to the manufacturer's schedule for years, does not mean you don't have to do what the manufacturer recommends.
Here's one scenario I hope is totally wrong.... The problem now is if your donk or any other component is outside what the manufacturer recommends and you end up in court after a bingle caused by the failure of that component, trying to prove your aircaft has been maintained to a schedule that assures its airworthiness, in the light of that AWB and CAR 42, might be tricky even if you have complied with the CASA (all care but no responsibility) A/D's.
That AWB refers to test cases where components have not been changed in accordance with the manufacturer's recommendations and CoR holders and LAME's have been found liable. Funny thing is CASA don't seem to have publicised that AWB much, which does have major ramifications for all of the Sched 5 maintenance that is going on and has gone on for many years. - So maybe it is just a butt covering exercise that they can pull out of their back pocket when one of us poor buggers ends up in court having thought we were legal working to CASA A/D's that apparently allow on-condition maintenance and that we believed are the law???
Who'd be a LAME? (or a CoR holder for that matter!)
"They (prosecution) will not accept CASA ADs in court and will merely use the Lycoming or Continental Rec TBO as the limit for that engine..thats why a lot of LAMEs will not entertain the idea. LAMEs should be able to stand behind CASA ADs as being law and if that causes people to be injured then CASA should be held resposnible not the LAME.
SC'
There are plenty of engines in the US that are running well beyond TBO and calendar time. Some have never been touched since they were new in the 70's and 80's. They almost always have good compressions and low oil consumption and pose no real problems when they do eventually decide to overhaul them. No doubt that was the basis of the CASA condition report A/D. However, as to whether its legal. here ... well AWB 02-003 (June 06)seems to suggest that CASA are having two bob each way. They refer to CAR 42 which says something about the C of R holders responsibility to maintain the aircraft in an airworthy condition using a maintenance schedule. They go on to say that the best folks to decide on the maintenance schedule are the manufacturers and good old Sched 5, which has been used as the excuse for not working to the manufacturer's schedule for years, does not mean you don't have to do what the manufacturer recommends.
Here's one scenario I hope is totally wrong.... The problem now is if your donk or any other component is outside what the manufacturer recommends and you end up in court after a bingle caused by the failure of that component, trying to prove your aircaft has been maintained to a schedule that assures its airworthiness, in the light of that AWB and CAR 42, might be tricky even if you have complied with the CASA (all care but no responsibility) A/D's.
That AWB refers to test cases where components have not been changed in accordance with the manufacturer's recommendations and CoR holders and LAME's have been found liable. Funny thing is CASA don't seem to have publicised that AWB much, which does have major ramifications for all of the Sched 5 maintenance that is going on and has gone on for many years. - So maybe it is just a butt covering exercise that they can pull out of their back pocket when one of us poor buggers ends up in court having thought we were legal working to CASA A/D's that apparently allow on-condition maintenance and that we believed are the law???
Who'd be a LAME? (or a CoR holder for that matter!)
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From actual experience, an O320 in a C172P 3150hrs without any cylinder work during its life. Finally bit the bullet and sent it for overhaul/exchange when the dollar was good. Strip report concluded the engine was still sound but wear starting to appear on the camshaft. Hardly forestalling the inevitable in this case. This engine paid for itself one and a half times!
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CAR 41 States
Maintenance schedule and maintenance instructions
Maintenance schedule and maintenance instructions
(1) The holder of the certificate of registration for a class B aircraft must
ensure that all maintenance required to be carried out on the aircraft
(including any aircraft components from time to time included in or
fitted to the aircraft) by the aircraft’s maintenance schedule is carried
out when required by that schedule.
Penalty: 50 penalty units.
(2) A person must not use a class B aircraft in an operation if there is not a
maintenance schedule for the aircraft that includes provision for the
maintenance of all aircraft components from time to time included in,
or fitted to, the aircraft.
Penalty: 50 penalty units.
This is not a new rule, You have to comply with CAR 41 even if you are using Schedule 5 for the maintenance schedule, meaning in addition to schedule 5 you should be changing and maintaining items that the manufacturer lists in the aircraft maintenance schedule, if the manufacturer says a paticular item like a vacuum pump must be changed every 500Hrs you have to follow that. I does get confusing with an engine where the manufacturers (airframe) maintenance schedule will tell you to look at the engine manufacturers recomended TBO for the engine life limit, then you have AD/ENG/4 telling you otherwise, but the manufacturers life is RECOMENDED, once you go beyond that you are on your own so to say.
ensure that all maintenance required to be carried out on the aircraft
(including any aircraft components from time to time included in or
fitted to the aircraft) by the aircraft’s maintenance schedule is carried
out when required by that schedule.
Penalty: 50 penalty units.
(2) A person must not use a class B aircraft in an operation if there is not a
maintenance schedule for the aircraft that includes provision for the
maintenance of all aircraft components from time to time included in,
or fitted to, the aircraft.
Penalty: 50 penalty units.
This is not a new rule, You have to comply with CAR 41 even if you are using Schedule 5 for the maintenance schedule, meaning in addition to schedule 5 you should be changing and maintaining items that the manufacturer lists in the aircraft maintenance schedule, if the manufacturer says a paticular item like a vacuum pump must be changed every 500Hrs you have to follow that. I does get confusing with an engine where the manufacturers (airframe) maintenance schedule will tell you to look at the engine manufacturers recomended TBO for the engine life limit, then you have AD/ENG/4 telling you otherwise, but the manufacturers life is RECOMENDED, once you go beyond that you are on your own so to say.
Does anyone know about the effectiveness or otherwise of these electric pre-oiling pumps that are advertised. They are switched on and pressurised the oil lines before start so that you have oil pressure the second your engine starts rather than wait for it to build up after start.
They claim to reduce wear during start up where most of the engines wear occurs. But do they work as their makers claim.
They claim to reduce wear during start up where most of the engines wear occurs. But do they work as their makers claim.
Nomorecatering.
For aircraft not used regularly, (say once a week) they are a great idea, the reason is self-evident ---- starting dry --- how long does it take to get oil all around the engine, not just registering on the pressure gauges. Likewise I also use an oil heater, get it nice and warm before I use the pre-oiler. If you have a low usage engine, always us a multi-grade oil with corrosion inhibitor.
I have seen several "high-cam engine" cams recently, that has less than half the lift remaining, so worn they could not be re-profiled, had to be replaced. One was about 550 hours over about 12 years, with long periods of complete inactivity.
If an engine is going to be inactive (read the manufacturers instructions) use inhibiting oil and silica gel plugs. Unfortunately in my opinion, the "approved" aircraft oils are not nearly as good as some of the modern auto oils.
In some "warbirds" (Experimental) engines in US, auto multi-grades are being used with great success, reduced consumption, reduced "bits"(carbon) in the filters, and nil internal corrosion via the boreoscope.
Tootle pip!!
Tootle pip!!
For aircraft not used regularly, (say once a week) they are a great idea, the reason is self-evident ---- starting dry --- how long does it take to get oil all around the engine, not just registering on the pressure gauges. Likewise I also use an oil heater, get it nice and warm before I use the pre-oiler. If you have a low usage engine, always us a multi-grade oil with corrosion inhibitor.
I have seen several "high-cam engine" cams recently, that has less than half the lift remaining, so worn they could not be re-profiled, had to be replaced. One was about 550 hours over about 12 years, with long periods of complete inactivity.
If an engine is going to be inactive (read the manufacturers instructions) use inhibiting oil and silica gel plugs. Unfortunately in my opinion, the "approved" aircraft oils are not nearly as good as some of the modern auto oils.
In some "warbirds" (Experimental) engines in US, auto multi-grades are being used with great success, reduced consumption, reduced "bits"(carbon) in the filters, and nil internal corrosion via the boreoscope.
Tootle pip!!
Tootle pip!!
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Leaddie,
I also wonder about the issue of higher tech auto oils, and the products like aeroshell 15W-50 is a better option as you suggest.
The biggest problem with say Mobil 1 which is the leading synthetic auto oil is the use of AVGAS and the deposits in the oil. Hence the semi synthetic blends like the Aeroshell and others.
Heating and priming the system has to be worth it with infrequent use engines.
J
I also wonder about the issue of higher tech auto oils, and the products like aeroshell 15W-50 is a better option as you suggest.
The biggest problem with say Mobil 1 which is the leading synthetic auto oil is the use of AVGAS and the deposits in the oil. Hence the semi synthetic blends like the Aeroshell and others.
Heating and priming the system has to be worth it with infrequent use engines.
J
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higher tech auto oils, and the products like aeroshell 15W-50 is a better option
As you suggest aviation oils will no longer be formulated to deal with lead but also have other issues such as handling heat loads (air cooled engines typically run at nearly double the temp of an water cooled auto - which has viscosity implications also), auto engines run at low power whereas aviation spend their life at a constant high power (take off and cruise settings), auto oils also typically contain zinc and phosphorus. Ash deposits produced from these metal containing additives tend to form in the combustion chamber where they can cause pre-ignition. This in turn can lead to engine failure, hence aviation oils are formulated from metal free additives. Zinc will quickly destroy the master rod bearing of a radial for example and phosphorus is literally capable of dissolving your copper bearing material.
The reverse is also true in using aviation oil in automotive applications ie its not formulated to handle the requirements. Seems like oils aint oils as the ad used to say.
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Brian,.....Oils ain't Oils Sol!
The aeroshell 15W-50 is a semi Synthetic aviation oil with the Lycoming additives. I am sure some others have a similar product, however this is the one I use for the availability of it.
I do not use it in the car, mind you get this, 12 x 946ml bottles of the aeroshell I think cost me $99, and 1 x 5L of Mobil 1 is about $65-70 I think, so something in aviation is not so bag after all!
J
The aeroshell 15W-50 is a semi Synthetic aviation oil with the Lycoming additives. I am sure some others have a similar product, however this is the one I use for the availability of it.
I do not use it in the car, mind you get this, 12 x 946ml bottles of the aeroshell I think cost me $99, and 1 x 5L of Mobil 1 is about $65-70 I think, so something in aviation is not so bag after all!
J
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The problem with pre-oilers - as I see it - is that they still don't lube the areas of the engine that are "splash lubricated" prior to starting. So - yes they're good (and better than nothing) - but not the be all and end all.
Grandpa Aerotart
To those so enamoured with overhauling engines at TBO how do you reconcile the fact that most engine failures happen in the first 500hrs from new/overhauled and those that don't then show few problems all the way through to TBO+++...particularly if they are flown often, operated knowledgeably and maintained/monitored properly?
When I overhauled my first life IO550 5 years ago at TBO+10% it was running like a swiss watch...had I known then what I know now I would have simply just kept running it and monitored it via oil analisys, boroscope, compression testing etc...and it likely would still be running perfectly now as the previous owners had 'topped it' with all new cylinders about 500 hrs before I bought it. The only reason they needed to top it were all the compressions were low from the engine not being set up/operated properly...and quite possibly from **** OEM cylinders.
If it is running well next time it reaches TBO I won't be touching it.
When I overhauled my first life IO550 5 years ago at TBO+10% it was running like a swiss watch...had I known then what I know now I would have simply just kept running it and monitored it via oil analisys, boroscope, compression testing etc...and it likely would still be running perfectly now as the previous owners had 'topped it' with all new cylinders about 500 hrs before I bought it. The only reason they needed to top it were all the compressions were low from the engine not being set up/operated properly...and quite possibly from **** OEM cylinders.
If it is running well next time it reaches TBO I won't be touching it.
