LeSving wrote:
Not necessarily if running a high compression 360 on UL91/96 at WOT at low RPM, IMO.
You have a point, but then other 172R operators should have the same problem.
I don’t know if the engine is a “high compression 360”. It has the same compression as almost all other variants of Lycomings (I)O-360 series. Also, the performance diagrams in Lycoming’s engine handbook goes down to 1600 rpm at WOT and sea level. And actually Lycoming gives 160 hp @ 2400 rpm as the basic rating and 180 hp @ 2700 rpm as “alternate rating”.
If the fuel is the problem then the cylinders should be damaged by detonation, right?
Airborne_Again wrote:
So what’s likely to have happened? Did we get a set of bad cylinders in 2015 or is there some problem with the engine installation?
From Lyco point of view, 3 out of 4 cylinders made it well beyond TBO. So the only thing you need to ask is what made the first cylinder not make it to TBO. Could be everything from an individual quality issue to jut bad luck.
Malibuflyer wrote:
From Lyco point of view, 3 out of 4 cylinders made it well beyond TBO.
Sure, but we all know about the Lyco point of view.
pmh wrote:
What about this?
https://www.euroga.org/forums/maintenance-avionics/9980-lycoming-sb-on-retirement-of-cylinders-heads-from-2013-2015
Might well be. Actually, I’d hope that’s the reason because then the problem will be solved after overhaul.
Airborne_Again wrote:
This is a 180 hp engine which is derated to 160 hp on the 172R by limiting rpm to 2400
Fixed or variable-pitch prop?
Is there an actual RPM limiter, or just a redline? Any logical explanation for why it shouldn’t redline at a similar point to other IO-360s?
Graham wrote:
Fixed or variable-pitch prop?
Fixed.
Is there an actual RPM limiter, or just a redline?
Just a redline.
Any logical explanation for why it shouldn’t redline at a similar point to other IO-360s?
Because it is derated. Don’t ask me why.
At 1500 hours after overhaul, cylinder #4 had to be replaced.
At 2245 hours after overhaul, cylinder #3 had to be replaced.
At 2575 hours after overhaul, cylinder #2 had to be replaced.
At 2650 hours after overhaul, cylinder #1 had to be replaced.
A bad engine shop worked on it, or a particular person is mismanaging it. However, you don’t state what was actually wrong with them.
Peter wrote:
However, you don’t state what was actually wrong with them.
That’s because I don’t know offhand. I’m trying to find out.
Are you considering that all 4 cylinders demonstrated a weakness/fault or just cylinders #3 and possibly #4? Both of which might suffer most from cooling airflow.
I ask the question because in reading previous posts you seem to do really well with gettlng more than many would reasonably expect from their engines. I think many schools are happy to get more than 2400hrs before changing a cylinder.
