Peter wrote:
It is in IMC. Probably takes quite some time to happen; took some tens of mins on the TB20.
Then it’s possible if you don’t open alt air – which is mandatory in such conditions.
Does one have to be in visible moisture to open alternate air (or put pitot tube ON)?
Don’t recall there is any noticeable loss of performance in DA40 & DA42
I know some gets pedantic on “only in clouds” but I usually do both pitot ON & alt OPEN anytime it’s cold & clean air in cruise while before getting into clouds
I left PT heat OFF by mistake once in the Archer, aircraft looked bit sluggish after 20min of flying but it gained 25kts few seconds after I put it ON, I am sure leaving it PT ON & Alt OPEN all the time when IMC is suspected is a healthy thing: they make the aircraft will go faster 
Peter wrote:
How is that possible? No externally accessible items which could cause a conrod breakage.
I don’t know how it is possible but it happened. I found some information on a Swedish forum. The pilot got an oil pressure warning and shortly after the engine stopped. The picture shows what the engine looked like after landing. I do know that this was caused by a mistake during “regular” maintenance as the shop involved (which was not an engine shop) belonged to the same company as our CAMO and they were quite upset about the whole thing.
Ibra wrote:
Don’t recall there is any noticeable loss of performance in DA40 & DA42
There is some performance loss higher than FL140 at DA42 (a bit more on right engine due to different airflow). BTW I turn pitot heat always when temperature is below 5C (which is almost always on my flights) because pitot freeze will happen in seconds after hitting moist but opening alt air really isn’t needed in clear air.
Airborne_Again wrote:
I don’t know how it is possible but it happened.
Ok, now I know. A valve cover wasn’t properly fastened, leading to oil leakage and the eventual destruction of the engine.
That’s one way to lose oil; sure. But that’s fairly basic; also one doesn’t undo those covers except during the Annual. And I accept one could screw the filter on badly and lose oil that way.
However this does also indicate a total lack of preflight inspection. Oil would be absolutely everywhere.
Emir wrote:
There is some performance loss higher than FL140 at DA42 (a bit more on right engine due to different airflow)
Aha, I did not fly that high to notice that bit
Airborne_Again wrote:
The picture shows what the engine looked like after landing.
That conrod seems in t he abosolute wrongplace indeed: it seems to have gotten around the wrong shaft ;) (camshaft vs crankshaft)
Airborne_Again wrote:
A valve cover wasn’t properly fastened, leading to oil leakage and the eventual destruction of the engine.
Peter wrote:
That’s one way to lose oil; sure
Not so sure. Lycos and Contis have multiple screws. If ONE of them comes loose you could get a minor oil leak but you would notice before it become catastrophic: oil pressure in this area is the same as crankcase pressure, which is very low, compared with regular oil system pressure: you would need a big gap (ie multiple screws) for a leak to be that large.
It is quite normal for these screws to be overtorqued leading to leaks. A lot of us use silicone gaskets vs cork since they are less torque sensitive. One should always use lockwashers on these crews.
So, altogether multiple layers of protection against this problem:
-Low oil pressure in the area
-Multiple screws
-Lockwashers
-Preflight inspection detecting leaks.
Of course if your engine is always leaking, the minor head cover leak could go disguised=unnoticed for multiple flights…a good reason to keep your engine clean.
So I would not say “that is one way to lose oil” since it is not very frequent (to this non-native English speaker frequency seems implied) . Damage after cylinder replacement, for example, is way more prevalent in the accident stats.
edited for typo “one” vs “once”
Peter wrote:
That’s one way to lose oil; sure. But that’s fairly basic; also one doesn’t undo those covers except during the Annual. And I accept one could screw the filter on badly and lose oil that way.
Unless it’s a O-235 with screw adjusted valve clearance one doesn’t remove the valve covers very often, if at all. Also, it’s hard for me to imagine a leaky valve cover gasket moving quickly from the ‘making a big mess’ stage to the ‘losing all the engine oil in one flight’ stage. As noted, a little oil goes a long, long way in making a noticeable dripping mess even if the cowling design prevents a good preflight inspection of the cylinders.
Spin-on oil fillers do come loose occasionally in unusual circumstances, if they aren’t safety wired as per normal aircraft practice. Safety wiring on an oil filter is never very tight and the installation angle isn’t optimum but it prevents leaks because you need to spin the filter a long way before the gasket relaxes. A belt and braces approach that works in some installations is to install a large hose clamp around the filter too, with the screw clamp rotated to a position where it prevents filter rotation.
Silvaire wrote:
Also, it’s hard for me to imagine a leaky valve cover gasket moving quickly from the ‘making a big mess’ stage to the ‘losing all the engine oil in one flight’ stage. As noted, a little oil goes a long, long way in making a noticeable dripping mess even if the cowling design prevents a good preflight inspection of the cylinders.
If it were the first flight after the valve cover were replaced and the screws weren’t done up (perhaps just started and then never turned more than a thread or two), you could have a fairly serious leak that didn’t begin until after the pre-flight inspection was concluded and the engine started?
