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budyerly@msn.com
Joined: 05 Oct 2019
Posts: 290
Location: Florida USA
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 Posted: Thu Jan 16, 2025 7:37 am Post subject: What did you do with your Europa this week 10/01/25 |
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I have been looking at this thread and finally I see folks seeing what really needs to be done on annual and on an IRAN (Inspect and Repair As Necessary) on an airplane.
A borescope is a wonderful tool (properly sized and of descent quality). But it does not replace direct visual inspection, measurement and analysis.
The Rotax 912/912S and 914 are wonderfully simple engines and easily understood, but the maintenance, feeding and upkeep are often ignored.
I do not care what type of fuel one is using, deposits in combustion are a fact of life. I have been using 100LL with TCP lead scavenging for nearly 500 hours and at 500 hours I had Lockwood redo my gearbox, pull the heads and inspect for damage from an overspeed. Next to my engine was a 914 that ran purely unleaded fuel and frankly my engine was slightly cleaner. But both engines clearly had valve debris built up, and there was some crud on the pistons tops that wire brushed off, and after a valve lapping and piston head cleanup all was measured and found within service limits. After reassembly and some reassembly errors, the compressions were back up to roughly 79/80 on a differential compression tester.
The cost was $3500 ish and a week at Lockwood for my overspeed mistake. It was well worth it now that burping is quick and easy. Nominally for an aircraft engine, the cost per hour for maintenance of just the engine is about $10-$20 per flight hour which includes only oil changes and servicing to include repairs and inspection. Mine runs about $10 RETAIL COST per hour over the last 500 hours. Considering we run these engines hard (75% power 80% of the time, 95-100% power 10% of the time, and low power about 10% of the time) this is amazing. No stock car engine could hold up to these cost per hour numbers (as it would be considered a racing engine). I change oil every 25 hours and do a 25-hour inspection and an IRAN every 5 years. Hence, the engine and plane run very well. (I'd like to say all my experimental "upgrades" on the airframe did as well but alas.... not all ideas work out quickly and easily which is cost and downtime.) I change the plugs annually as the NGK types are cheap when I consider the time it takes to properly clean the plugs vs replacement and change the filter at 25 hours to inspect for metal and carbon as it is a turbo engine carbon can flake off into the oil. Carbs, I rebuild about every 200 hours or couple years because I can in about 2 hours during an annual so performance is assured. I tune by ear and only check the balance by manometers to assure balance from idle to full power.
As pilots most of us were taught to baby our engines to save the life of the engine. I push my engine to full power on takeoff, climb at recommended power, and cruise no less than 75% power. I am considered hard on the engine doing stalls, air-work, and occasional limit testing of the airframe and myself. The Rotax 914 and its electronics have held up extremely well to what many would call "rough service". I am confident that a simple top overhaul and inspection about every 500 hours in my case, is reasonable assurance that I can get 1500 hours of safe and reliable operations out of my Rotax before I need a no kidding overhaul or replacement.
Fly the engine often, and pay attention to any tell tale leaks, runs, drips or errors, service IAW the Rotax maintenance manual and these little stock Rotax engines are amazing.
Anyway, that is my opinion.
Best Regards,
Bud Yerly
From: owner-europa-list-server(at)matronics.com <owner-europa-list-server(at)matronics.com> on behalf of Area-51 <goldsteinindustrial(at)gmail.com>
Sent: Thursday, January 16, 2025 8:06 AM
To: europa-list(at)matronics.com <europa-list(at)matronics.com>
Subject: Re: What did you do with your Europa this week 10/01/25
--> Europa-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>
| Steven Dumesny wrote: | Totally agree with Erich what a great clean up job.
Also I don't ever recall seeing such pitting on an exhaust valve seat in any application, it looks like a chemical reaction?
After reading Mike Busch on engines, I plan to use a bore scope every 100 hours, it should pick up these signs earlier, and I can review images against previous services.
Steve |
[/quote]
Found bore scope to be totally useless; except for normal looking crowns and honing marks couldn't see s;&(at)... hence listen to my better judgement telling me to pull the heads off and scrutinise things properly on an unfamiliar unit.
Lifting the barrels also allows inspection with mirror beneath the piston crowns to confirm any excessive long term running temperature issues. Also allows visual of the camshaft condition.
Read this topic online here:
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 224
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| Posted: Thu Jan 16, 2025 1:49 pm Post subject: What did you do with your Europa this week 10/01/25 |
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<<.....All four exhaust valves exhibited pitted seats (same as recent 914 job) indicating either hot lean mixtures or acid chemical erosion....>>
'Acid chemical' erosion when stored/hangared/not used with exhaust pipes left unplugged? What was the storage environment like during its lifetime?
Duncan McF.
| Quote: | On 16/01/2025 10:40 GMT Area-51 <goldsteinindustrial(at)gmail.com> wrote:
Job done; my fingers are sore again... ready to box up swap out the 80hp.
This unit scrubbed up great in the end; as good as new, with 700hrs and 4years TBO remaining. Now just have to replace the few throttle arms and spark plug caps I raided off a while back for the 80hp in 181.
What was learnt through this process:
The rotax 912ULS-S2 will benefit greatly with a cylinder head service at 1000hrs. Which will prevent the exhaust valves having to be binned at 2000hrs TBO, and return the unit to full compression.
Inlet valve stem seals provide inadequate sealing of oil ingress into the inlet port at 1300hrs, causing carbon build up upon the inlet valve and combustion chamber. The symptom of this is seen via low compression on one cylinder during burping as loose bits get trapped under the valve seat. It blows out upon startup but is indicative inlet valve stem seals are failing.
Rear two cylinders of the 912 ULS-S2 run hotter than the front two cylinders. This shows up as minor evidence of detonation erosion on the piston crown and combustion chamber.
For reasons unknown #4 cylinder has had a Sodium "Inlet" Valve fitted.
All four exhaust valves exhibited pitted seats (same as recent 914 job) indicating either hot lean mixtures or acid chemical erosion. The valves are softer than the seats.
The pistons crowns in the 912 are very soft material. A head nut dropped from the barrel stud and fell onto the crown leaving a small indentation; very soft material.
Now that You have read all that nominal stuff I can discuss cleaning methods...
Firstly you will need "high end laboratory tools" like in the attached pictures. Secondly, expect to end the task with really sore fingers by the end from using some of the high end laboratory equipment. The secret to achieving the look achieved is knowing what materials to use; I will go on...
Ultrasonic cleaning bin; I have 5L and 25L units... This is great, but not that great for alloy motor bits; darkens the metal. I need to try sewing machine oil or sulphuric acid and see what the results are. So caustic alkaline fluids are no good for zinc, or zinc alloys.
Scotch pad; industrial grade "grey"; available in a roll at your local paint panel trade supplier... I use this with diluted sugar soap to "finish" clean everything before spray and wipe off with Wurth Rostoff. You will have tired and sore fingers afterwards if you scrub an entire engine.
Brass brush... used to descale corrosion off the engine exterior.
Tooth brush... used to scrub exterior of engine
Stainless brush... used to scrub bits i should be using the brass brush for.
215 or 225 Aluminium sheet. I use this to create some of the high end laboratory equipment. It is used to scrape off the piston crown, head ports, combustion chambers and cylinder wall, and is softer than the piston crown. The edges need to be kept dressed as you work scraping off the crap. You will have sore fingers by the end from scraping... Any piece of metal softer than the piston crown will do the job but you will struggle with lead; mercury would be totally useless though...
Threaded brass pipe. I use this on the exhaust valve stem as a rasp to get the tough shit off quickly.
A piece of flat 0.125" 2030 carbon steel. I use this on the exhaust valve to scrape off the really tough shit.
An oyster shucker. I use this to get the "nothing else will budge it" stuff out of the exhaust port. Its a delicate light handed job because the oyster shucker is hardened steel and will ruin a valve seat and slice through a finger instantly without taking any prisoners.
A piece of TIG welding rod, hammered flat and bent 90deg at one end. This is one of my favourite tools and is used to extract hydraulic lifters to check their face condition.
(When lifting the cylinder barrels you may notice three numbers felt tipped onto the barrel; record these numbers. They are your bore dimensions taken at the factory during engine assembly)
3D printer. Used to print the valve spring compressor.
A vacuum cleaner with a high end laboratory attachment such as repurposed piece of washing machine drainage pipe. Used to extract all the crap from the cylinder and ring lands, and valve ports as you go and keeps the work area clean. Wife will scream and be unhappy for a while, but its only momentary...
Air compressor. To blow out any thread bores before bolting up.
(x4) 2" sections of 3/8 fuel hose.. I use this to seal off the cylinder studs and hold the barrels in place as I work. Screw down two head nuts and you can roll the motor over while head is off. They can be fun to remove afterwards; i use pointed pliers to lift them up and off.
Wurth Rostoff... I use this to wash off the scotch brite residue when cleaning completed. I also skirt a bit into the valve port together with some oil when lapping in the valves. I use a cordless drill on the top of valve stem; much quicker than old timer method.
Each head takes about four hours to process. You will have sore fingers by about midway through the second cylinder onwards.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=515226#515226
Attachments:
http://forums.matronics.com//files/82f80629_5d6f_431a_988f_def7d1b1ab94_176.jpeg
http://forums.matronics.com//files/b54fcbdc_c2cd_4fa8_9cf4_b803bfa19f65_611.jpeg
http://forums.matronics.com//files/6720f7f1_9578_4957_bc82_79013a0eef39_210.jpeg
http://forums.matronics.com//files/d87e9a48_4dd6_4055_8dac_defd7d3cb284_202.jpeg
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http://forums.matronics.com//files/12edb5a5_29c3_4410_874b_da8ffb3deac6_191.jpeg
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Area-51
Joined: 03 May 2021
Posts: 414
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| Posted: Thu Jan 16, 2025 11:58 pm Post subject: Re: What did you do with your Europa this week 10/01/25 |
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Thanks Bud, that pretty much sums aviation up in a nutshell. In a previous life I once asked an old guy "which motorbike brand is the most reliable one", his response was gold, "they are all only as reliable as the person working on them"... A few days ago I was reading a question posted on a rotax forum, "who has any experience with a rotax engine failure during flight"; I was shocked and dismayed by the multitude of responses. But the plentiful failure situations is not what shocked me. What shocked me was these story tellers admitting that the engine failures were all direct a result of their own failure to maintain the engine or land the aircraft when they "heard something weird going on"... Bore scopes work great, on this occasion the bore scope was not leaving me convinced with enough information...
Duncan's question... the 914 was a complete engine situation stored on a shelf for 20years. The pitting on the exhaust valves was not a result of atmospheric exposure and inconsistent with the rest of the unit's condition.. The 912ULS had been removed from a very well maintained and cared for Tecnam, wrapped in plastic and stored correctly in the factory crate with factory sealing plugs. The wetness of oil residue within the combustion chambers was not a conducive environment for rust to form and cause the degree of pitting found in the time provided. To be honest I am not going to try and work out the why or how. I will simply be removing heads at 1000hrs for vapour blasting and servicing as part of my Line Maintenance schedule.
It's important to keep in mind these rotax units are designed to reach their TBO at 80% power all the way while following the provided factory Line Maintenance schedule. There is no shortcomings in the factory's strategy. The engine will reach its TBO, its job is complete as advertised and the unit is then required to be either "retired", or, "returned to an authorised rotax service center for overhaul". Running the engine further "on condition" has nothing to do with the factory and is all now upon the owner operator. Zero timing a TBO'd unit requires replacement of the crankshaft assembly, along with everything else the service centre is required to do...
Federal Mogal Valve Information Failure Mode Assessment pdf attached. An old one but a good one... first came across it some three decades ago..
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 224
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| Posted: Fri Jan 17, 2025 3:07 am Post subject: What did you do with your Europa this week 10/01/25 |
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By comparison, the exhaust valve head seats of my 700hr 20year old ULS look like they were cut yesterday. It's had an easy life (generally run at 50% or less) but not hangared in ideally dry conditions.
Duncan McF
| Quote: | On 17/01/2025 07:58 GMT Area-51 <goldsteinindustrial(at)gmail.com> wrote:
Thanks Bud, that pretty much sums aviation up in a nutshell. In a previous life I once asked an old guy "which motorbike brand is the most reliable one", his response was gold, "they are all only as reliable as the person working on them"... A few days ago I was reading a question posted on a rotax forum, "who has any experience with a rotax engine failure during flight"; I was shocked and dismayed by the multitude of responses. But the plentiful failure situations is not what shocked me. What shocked me was these story tellers admitting that the engine failures were all direct a result of their own failure to maintain the engine or land the aircraft when they "heard something weird going on"... Bore scopes work great, on this occasion the bore scope was not leaving me convinced with enough information...
Duncan's question... the 914 was a complete engine situation stored on a shelf for 20years. The pitting on the exhaust valves was not a result of atmospheric exposure and inconsistent with the rest of the unit's condition.. The 912ULS had been removed from a very well maintained and cared for Tecnam, wrapped in plastic and stored correctly in the factory crate with factory sealing plugs. The wetness of oil residue within the combustion chambers was not a conducive environment for rust to form and cause the degree of pitting found in the time provided. To be honest I am not going to try and work out the why or how. I will simply be removing heads at 1000hrs for vapour blasting and servicing as part of my Line Maintenance schedule.
It's important to keep in mind these rotax units are designed to reach their TBO at 80% power all the way while following the provided factory Line Maintenance schedule. There is no shortcomings in the factory's strategy. The engine will reach its TBO, its job is complete as advertised and the unit is then required to be either "retired", or, "returned to an authorised rotax service center for overhaul". Running the engine further "on condition" has nothing to do with the factory and is all now upon the owner operator. Zero timing a TBO'd unit requires replacement of the crankshaft assembly, along with everything else the service centre is required to do...
Federal Mogal Valve Assessment pdf attached. An old one but a good one...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=515230#515230
Attachments:
http://forums.matronics.com//files/federal_mogul_valve_information_card_111.pdf
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Area-51
Joined: 03 May 2021
Posts: 414
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| Posted: Fri Jan 17, 2025 2:18 pm Post subject: Re: What did you do with your Europa this week 10/01/25 |
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Duncan its important to consider the exhaust valve heads are made of inconel and they could probably be left on a seaside boatshed bench for 20 years and still look brand new after wiping off the dust.
Any pitting on the valve head itself will not be from normal atmospheric exposure. So deterioration of the inconel will be due to the introduction of some other heat/chemical/electrical/plasma induced corrosive element.
The 914 was being used in a humid coastal environment; the ULS a rural outback dry environment.
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