CHT cooldown alarm
- Thread starter MD11AV8R
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SkyView does not. We had this in the Gen 1 products (D10 / D120 / D180) and it appeared to be rarely used.
Lots of people don't even believe shock cooling exists:
https://www.avweb.com/news/maint/182883-1.html
http://www.pprune.org/pacific-general-aviation-questions/493896-shock-cooling-myth-busted.html
https://www.reddit.com/r/flying/comments/431flj/is_shock_cooling_real/
Lots of people don't even believe shock cooling exists:
https://www.avweb.com/news/maint/182883-1.html
http://www.pprune.org/pacific-general-aviation-questions/493896-shock-cooling-myth-busted.html
https://www.reddit.com/r/flying/comments/431flj/is_shock_cooling_real/
Does that mean shock cooling alarms can be turned off in the D120 then? How?
Given how many glider tugs crack at the base flanges of their cylinders, and how few other aircraft do so, there might be something to shock cooling...
I knew someone who drove his overheating VW Golf (Rabbit) into a river ford and seized it solid, bending all the con-rods. I'd say shock cooling definitely exists! ;D
Given how many glider tugs crack at the base flanges of their cylinders, and how few other aircraft do so, there might be something to shock cooling...
I knew someone who drove his overheating VW Golf (Rabbit) into a river ford and seized it solid, bending all the con-rods. I'd say shock cooling definitely exists! ;D
- Joined
- Mar 23, 2005
- Messages
- 13,226
Page 5-12 of the D120 install guide covers configuring shock cooling as well as turning it on and off.
DBRV10
Active Member
Just for the historical record, Shock cooling DOES NOT EXIST.
Let me explain. The issues that cause cracking in in heads are built in from the start, and the thing that brings them about is pressure cycles (about 20 per second) and temperature of the head (less strength at high temp).
The greatest period for these factors to combine is at takeoff and during climb, which is why we (APS) teach the 400dF CHT limit and to keep under 380 in the cruise. TCM and Lycoming agree.
When you see the data from accelerometers in the head, you start to appreciate this.
Now running a cylinder up to the certification limit of 500dF and chopping the power and diving at the ground might be unkind on the heads, and doing it repeatedly might be considered abuse, but we do not know how anyone could fly like that, even in a glider tug or grass dart operation.
The rate of change in CHT is also faster in the takeoff and climb than it is on descent, so be careful of Shock heating ya hear!
Disable or make the alarm limit so wide it cannot bother you. My colleague John Deakin has written about this many years ago on AvWeb if you want an entertaining read.
Best Regards,
David Brown
Advanced Pilot Seminars
Let me explain. The issues that cause cracking in in heads are built in from the start, and the thing that brings them about is pressure cycles (about 20 per second) and temperature of the head (less strength at high temp).
The greatest period for these factors to combine is at takeoff and during climb, which is why we (APS) teach the 400dF CHT limit and to keep under 380 in the cruise. TCM and Lycoming agree.
When you see the data from accelerometers in the head, you start to appreciate this.
Now running a cylinder up to the certification limit of 500dF and chopping the power and diving at the ground might be unkind on the heads, and doing it repeatedly might be considered abuse, but we do not know how anyone could fly like that, even in a glider tug or grass dart operation.
The rate of change in CHT is also faster in the takeoff and climb than it is on descent, so be careful of Shock heating ya hear!
Disable or make the alarm limit so wide it cannot bother you. My colleague John Deakin has written about this many years ago on AvWeb if you want an entertaining read.
Best Regards,
David Brown
Advanced Pilot Seminars