Conti engines on SR20 - why the corrosion?

Maybe it will be obvious when you look at who owned them.

The thing which I find useful is a google on the reg. It usually shows immediately where the plane has been, and if you don’t get any/many hits then it’s a fair bet that it has not flown much. Sometimes you get zero hits, which for a plane some years old is extremely suspicious. I get asked all the time to do an “informal prebuy” for someone. I am not a mechanic so I don’t do prebuys but it takes me only a minute to do a google and tell the guy what I think, and I offer to put them in touch with my mechanic. In most cases the person was probably hoping to get a free prebuy because I never hear from them again.

It’s obvious a lot of people don’t do a prebuy at all; they travel a long way to see the thing and don’t want to come back empty handed. They fall in love with it, and that’s it.

You did the right thing to walk away. Never regret walking away from a bunny boiler

useful is a google on the reg

Another tool is the use of Flightradar24 or similar, and look at the history.
Used on the latest pre-buy I did for a friend, the seller claiming regular flying which we verified and found all correct

There was an infamous case which caused a lot of damage to GA here, which involved an engine which had been mistreated like this.

A Piper Lance with a Lycoming O540 crashed after take off killing all on board. Prior take off, people present heard the engine misfire and bang. It obviously did not develop sufficient power. The aircraft lifted off after 800 m of ground roll but did not climb well, stalled and crashed.

It was found out that the engine was massively corroded and had not flown almost for a year before the flight, before that it only had 25 hours per year. All tappets were corroded and no cylinder fulfilled the necessary compression. the camshaft had up to 4mm reduced lobes on 2 cylinders.

A year before the accident, the aircraft was checked by a large maintenance organisation with the purpose of importing the airplane into Switzerland. They found no engine deficiencies then. But the airplane had been standing outside until the accident day, when it was flown empty to pick up two passengers at Saanen and fly them to Zurich. It crashed on the take off at Saanen.

That is a lycoming engine, which had been in the airplane for 33 years and never overhauled. It had 1200 hrs since new. Apparently, when the airplane was last checked, the engine still was within tolerance, even though I have my doubts regarding the cam lobes. But I readily believe that it is possible that the engine got corroded as it did when it was left outside for a year.

That accident prompted the Swiss TSB to recommend strict adherence to TBO calendar limits (and hour limits of course) on all engines, regardless of private or commercial operation. The consequence was actionism on behalf of the FOCA, who found themselves under pressure by the SUST, ordering inspections of all engines which were over a certain age by pulling jugs and boroscoping… it appears that one of the inspected engines failed catastrophically shortly after and killed it’s pilot, most probably because of inadequate re-assembly. Swiss GA was saved from the consequences of this accident (Strict calendar TBO adherance) by EASA, but the reprecussions of this accident are still felt.

So corroded cylinders very often are a sign for a less than often used airplane. If the cylinders are corroded, it is quite necessary to check the rest of the engine as well, particularly camshaft and camlobes.

I hope those 3 Cirri will be checked thoroughly by the new owners. But at least they have the CAPS if not.

Taking things apart and messing with them for no reason is usually not the best idea if you have other options. If you make a full power run up and check static RPM occasionally, it provides an easy way to check power output, with a built in dynamometer. There aren’t many vehicles that provide for that, but aircraft do. My plane is particularly suitable as the electric CS prop can be locked in fine pitch. You have to watch pretty carefully as power varies as cube of RPM, but you can see it. Fuel flow on the upwind is another way, if you monitor it, and obviously climb rate trends from home base.

I’m not a huge believer in compression tests as an indication of cylinder health, although as a ‘blunt instrument’ they will tell you if something is really screwed up.

My 51 year old, never overhauled O-320 continues to make good power, complete with some corrosion on the bottom of three cylinders. It also continues to burn a quart of oil every 12 hrs or so, deposit zero metal in the oil filter and generally run well. I’m not going to expend effort and $5K to swap or service the cylinders (or more) until I get an indication that it’s necessary.

Silvaire wrote:

My 51 year old, never overhauled O-320 continues to make good power, complete with some corrosion on the bottom of three cylinders. It also continues to burn a quart of oil every 12 hrs or so, deposit zero metal in the oil filter and generally run well

That’s a secret only a few people know! Shussshhh

Silvaire’s engine has probably spent its life in a dry climate and/or been operated regularly. That it has lasted for thousands of hours more than it “should have” is no surprise; crankshafts are known to make 5k-10k hours before they are trashed.

The GA scene in Europe is very different: a lot of the hardware is in an absolutely atrocious condition, and most people accept that as normal. Well, most have no option. And activity is mostly depressed relative to the US.

These three SR20s are likely to have something in common, however.

I might overhaul it just to take a look in another 5 years, when I’ll with a bit of luck be retired with time on my hands. 56 years to overhaul seems like a good number to me (the engine, not me)

@Peter the engine’s only got about 1150 hrs over 51 years, owned for three decades by a guy who was very busy with his job but who always lived on an airport with his planes etc. in New York, Michigan and Florida, before moving west in 2005.

Gals and guys, excuse the short thread drift, thanks.

Mooney_Driver wrote:

it appears that one of the inspected engines failed catastrophically shortly after and killed it’s pilot, most probably because of inadequate re-assembly.

Unless you know more of the accident and circumstances than the investigation board or myself, this is a just blind assumption, or worse utter BS.
The SUST final investigation report, available in Fr or Ge (German report) language states the following: Bei dieser Sonderkontrolle wurden die Zylinder Nr. 2 und Nr. 3 teilweise ausgebaut, um die geforderte boroskopische Untersuchung vorzunehmen. Die entsprechenden Kolben und Pleuel wurden nicht demontiert. Dadurch konnten die auf dem Pleuelfuss Nr. 3 festgestellten Mikrorisse nicht erkannt werden.
Also to be found later in the text: Der Bruch des Pleuels Nr. 3 ist auf Mikroermüdungsrisse zurückzuführen, welche Korrosion und Russablagerungen aufweisen.

In a nutshell for all non-German speaking members, this means that the con-rod failure on #3 cylinder of HB-YEA was due to micro fatigue cracks showing corrosion and soot deposits. Let’s call it fatigue… and the major reason I will now rather buy a new engine rather than whatever overhaul is on offer…
Having suffered almost the same failure on January 3rd of 2008 in my Falco, I know this can and does happen.

Now back to the original thread: Conti engines on SR20 – why the corrosion?

We’re the cylinders continental or superior?

The former don’t seem to have a good reputation theses days.