GA engines On Condition
GA engines On Condition
Was talking to a bloke last week who owns an Archer. He said his engine was just on the 2000 hrs recomended TBO time and was wondering if he should have it overhauled now or keep it running on condition. A few salient points>
It was a factory newie when it was installed by him, straight out of the box.
Its carefully flown for private use, mosty on 2 to 4 hr legs.
Aircrafts 100 hrlys are done at one of the better shops around. has an oil analysis done each time and no signs of metal in the oil so far.
He will get new cylinders when an overhaul is done, can anyone recomend superior, ECI or factory Lycomming.
Lastly, if the engine is running fine, how long could he go for before finally doing the overhaul. Has anyone had experiance with past TBO ops.
It was a factory newie when it was installed by him, straight out of the box.
Its carefully flown for private use, mosty on 2 to 4 hr legs.
Aircrafts 100 hrlys are done at one of the better shops around. has an oil analysis done each time and no signs of metal in the oil so far.
He will get new cylinders when an overhaul is done, can anyone recomend superior, ECI or factory Lycomming.
Lastly, if the engine is running fine, how long could he go for before finally doing the overhaul. Has anyone had experiance with past TBO ops.
Grandpa Aerotart
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Good old CAA in EnZed are in the process of banning 'on condition'. I have no idea why. I know of a few people whose engines are running out of calendar time who aren't too happy!
I wouldn't be surprised if the engine in the aforementioned Archer went to 3000hrs. I've seen plenty of lycoming 4 bangers exceed this total with no problems. Every hour you get past TBO is a bonus and almost like money in the bank! If it were my motor, I'd not hesitate to run it on condition as there is no evidence to suggest that doing so compromises safety. The Avweb article mentioned by CC is on the money!
I wouldn't be surprised if the engine in the aforementioned Archer went to 3000hrs. I've seen plenty of lycoming 4 bangers exceed this total with no problems. Every hour you get past TBO is a bonus and almost like money in the bank! If it were my motor, I'd not hesitate to run it on condition as there is no evidence to suggest that doing so compromises safety. The Avweb article mentioned by CC is on the money!
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Where I worked in NZ we routinely ran our engines "on-condition" in commercial ops. That approval gave us a 10% engine-life extension -extremely valuable at any time, but particularly so during the peak season. On one memorable occasion, one of my engines (an O-540) which had reached TBO+10%, came out of the airframe and was dispatched to the overhaul facility. A few days later the phone went, it being the engineer from the overhaul shop. He wanted to know "why was the engine in his workshop?" I asked him had he checked the engine logbook -he hadn't, so I told him he should, then ring me back. When he did ring back, his words were something like "there's nothing wrong with this engine, stick it back in the airframe and put another 2,200 hrs on it". So yeah I conditionally agree with what has been said so far, and the article linked...
I have also seen an identical engine "babied" by its operator fall over in just 1,200 hours. So my conditional endorsement is based on how the engine is treated throughout its life. However, if an engine gets to 2,000 hours (on-going, appropriate maintenance checks) without major issues, it should manage to go further without a problem!
There was an excellent thread here previously about big-bore mills that raised many interesting points -and exploded more than a few myths. Worth revisiting I reckon, well relevant to this discussion.
I have also seen an identical engine "babied" by its operator fall over in just 1,200 hours. So my conditional endorsement is based on how the engine is treated throughout its life. However, if an engine gets to 2,000 hours (on-going, appropriate maintenance checks) without major issues, it should manage to go further without a problem!
There was an excellent thread here previously about big-bore mills that raised many interesting points -and exploded more than a few myths. Worth revisiting I reckon, well relevant to this discussion.
Last edited by kiwiblue; 20th Aug 2007 at 01:04.
Bugsmasherdriverandjediknite
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I managed nearly 5K on a O320D2J in a mustering bus, with one top overhaul at about 2200 and another at 4000. when stripped at 4000, everything was miked and it was all still well within limits. then again, I have seen other engines that didn't make half of TBO before giving up.
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If the engine is deemed mechanically fine by a LAMEy, then there is no reason why you cannot safely run the engine on condition.
Don't have much experience with them, but did fly an aircraft that went for I think another 200 or so hours. Owners and operators must be pleased at the extra use/revenue and delayed overhaul cost...
Of course it depends on previous treatment, some engines dont last the TBO period, some last a little longer and some longer still.
Just when you run it on condition, every subsequent 100hrly could possibly be a bit more thorough.
If the said person has money to burn (we all must be able to in this game
) then he could spend now and do the overhaul. Its really up to them, but going back to the first sentence, if its checked fine by the appropriate person (be it before or after the TBO) then it should be right for the next 100hrs !
Don't have much experience with them, but did fly an aircraft that went for I think another 200 or so hours. Owners and operators must be pleased at the extra use/revenue and delayed overhaul cost...
Of course it depends on previous treatment, some engines dont last the TBO period, some last a little longer and some longer still.
Just when you run it on condition, every subsequent 100hrly could possibly be a bit more thorough.
If the said person has money to burn (we all must be able to in this game
) then he could spend now and do the overhaul. Its really up to them, but going back to the first sentence, if its checked fine by the appropriate person (be it before or after the TBO) then it should be right for the next 100hrs !
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If the engine is deemed mechanically fine by a LAMEy, then there is no reason why you cannot safely run the engine on condition.
SC
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I was a little surprised to hear recently that for $180 CASA will give an excemption for an engine to run 'on-condition' indefinitely whilst in the charter category. Good for those that didn't budget for their overhaul as the extra hours you get might cover an overhaul.
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I was a little surprised to hear recently that for $180 CASA will give an excemption for an engine to run 'on-condition' indefinitely whilst in the charter category
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one thing to i have found overhauling these engines is some of the private operators that are only doing two three hundred hours a year with a month or more of inactivity having the cam at the top the engine is the oil drains and leaves the camshaft dry and on overhaul I have seen a few camshafts
very badly worn
very badly worn
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I'd say run it out to 2200 hours if it is going well. Engines "on condition" require the lame to fill out an "Engine Condition report" at every periodic inspection. I'd definitely be getting 50 hrly oil & filter change with filter inspection.
And yes - leaving your engine sit for weeks on end without running will lead to an early o'haul from excessive wear, corrosion etc.
I'd like to hear some professional opinions on the liabillity side of things in a post (fatal) accident senario with an engine "on condition". Syd Chrome does raise some valid Q's.
In my experience - don't touch ECI cylinders. We've replaced about 7 ECIs on a 6 cylinder engine in a C414A we maintain. The cracks appear quite suddenly (ie within 55 hrs of flight time). Mind you it is a TSIO-520-NB which is working much harder than an O-360 (and yes I know the 520 is a TCM and the 360 being discussed is a Lyc). But it certainly has soured my opinion of ECIs (look up the AD's on the ECIs
).
And yes - leaving your engine sit for weeks on end without running will lead to an early o'haul from excessive wear, corrosion etc.
I'd like to hear some professional opinions on the liabillity side of things in a post (fatal) accident senario with an engine "on condition". Syd Chrome does raise some valid Q's.
In my experience - don't touch ECI cylinders. We've replaced about 7 ECIs on a 6 cylinder engine in a C414A we maintain. The cracks appear quite suddenly (ie within 55 hrs of flight time). Mind you it is a TSIO-520-NB which is working much harder than an O-360 (and yes I know the 520 is a TCM and the 360 being discussed is a Lyc). But it certainly has soured my opinion of ECIs (look up the AD's on the ECIs
).
My LAME refuses to have anything to do with "On condition".
He is firmly of the belief that the potential liability risk in the event of a failure leading to fatalities is simply NOT acceptable.
Dr
He is firmly of the belief that the potential liability risk in the event of a failure leading to fatalities is simply NOT acceptable.
Dr
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We run our Archer3 out to 2300 hours on its first life o 360,sent it in for a blue seal o/haul with eci cylinders.
Made black oil from day one, lost compression on 1 cyl. @ 300hrs.Turns out theres a random problem with the plasma coated rings in some installs in oz,hone and cast iron rings and alls good.Excellent service from the distributer/overhaul shop, all costs covered.
Bit of a shame, all the data reads good in theory just doesn't seem to be so in practice.Don't know what I'd use next time.
From our lame's point of view,it had been maintained by them from new and they were comfortable with signing it out.
Made black oil from day one, lost compression on 1 cyl. @ 300hrs.Turns out theres a random problem with the plasma coated rings in some installs in oz,hone and cast iron rings and alls good.Excellent service from the distributer/overhaul shop, all costs covered.
Bit of a shame, all the data reads good in theory just doesn't seem to be so in practice.Don't know what I'd use next time.
From our lame's point of view,it had been maintained by them from new and they were comfortable with signing it out.
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The biggest problems lie with the Insurance Companies. They will frown on anything over 200 TBO. Then the poor old LAME is going to cop it up the backside as soon as there is an accident due to engine failure as he signed it out last. So they will be reluctant to let it go too long.
FWIW If the engine has good compressions, oil consumption is good and the analysis is good, and everything is within parameters, well there is no mechanical reason why it should not be allowed to continue on condition. Of course the components will have to be overhauled as required.
FWIW If the engine has good compressions, oil consumption is good and the analysis is good, and everything is within parameters, well there is no mechanical reason why it should not be allowed to continue on condition. Of course the components will have to be overhauled as required.
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Insurance coverage is not a problem - nor is it the issue here. We have and I believe any MRO can get insurance to cover OC engines up to a limit of 20% over-run. The issue here is the plight of the LAME that signs it out. He is not covered at all in a court of law and certifies the engine at his own risk. What should happen, is that the LAME is able to stand behind the CASA AD (the last 'A' in CASA stands for Authority [LOL] ) and if its an AD , made by parliament via due process, then its law. Bullet-proof law. In court its not. Prosecution dismisses CASA as an 'authority' and will use the engine manufactuers rec TBO to base their claim. LAME should be protected by the fact that he is complying with law as derived by CASA but he is all alone. The only way to protect yourself as a LAME is IAW the engine manufacturers recommendations. Dont stand behind CASA - it will cost you dearly. Don't start me on CAR Sched 5. Have a nice day!!
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AD/ENG/4 Amdt 10 lays out the conditions that must be met to allow an engine to remain in service. The use of the term "on condition" is quite often used to describe an engine that is outside the manufactures recomended overhaul period (for exampole 2000 hr / 12 yr) when actually all engines are maintained "on condition" from the day they are installed.
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I'm curious about actual experience with engines that have gone as much as 50% beyond the recommended TBO.
When overhaul time actually arrives, does it come with greater expense?
Do major components that aren't normally replaced perhaps require it?
e.g. replacing a crankshaft instead of regrinding it.
Would like to know folks opinion on whether this is a genuine cost saving or simply forestalling the inevitable.
When overhaul time actually arrives, does it come with greater expense?
Do major components that aren't normally replaced perhaps require it?
e.g. replacing a crankshaft instead of regrinding it.
Would like to know folks opinion on whether this is a genuine cost saving or simply forestalling the inevitable.