Temperature Alarm

[iaw4]

 

It's 100 degrees Fahrenheit here.  This means that within abut 5 minutes, the CTSW cylinder head temperature triggers the warning alarm in my Dynon (which I think occurs at 250 degrees).  I can silence or acknowledge it, but within 5 seconds, it goes off again.  Either:

(a) the rotax engine and airflow design of the ctsw is not suitable to pattern flying in hot weather.

(b) there must be a way to silence the alarm or increase the trigger threshold.  an airplane that requires hitting a button every 5 seconds is not flyable IMHO.

I know Roger and others are in Tucson, so it must be even worse there.  what do you guys do?

regards,

/iaw

 

[FlyingMonkey]

I get oil temps up around 245F climbing in hot weather, but never CHT anywhere near 250F.  And certainly just just flying the pattern.

Something sounds amiss.

[iaw4]

 

One of my cylinders is 10 degrees warmer than the other.  255F.  This triggers the alarm.  Roger says such a 10F difference is not that unusual.  I can get to 255F just idling at 1750rpm for 5 minutes in 105 degree weather.  (In 70 degree weather, I never get the alarm.)

any idea what might be amiss here?  I have good coolant and oil levels...

 

[Tom Baker]

The first thing I would do is try cleaning the radiator externally.

[okent]

Do you just blow that out with air or water?

[Warmi]

My CHTs pretty much always differ by about 8-10 degrees when they are their hottest and proportionally less when cooler and I rarely see them in the yellow- I was told a difference like that is normal.

[Anticept]

One CHT is in the front, and is exposed to a little bit cooler air.

[iaw4]

 

Roger L suggested that heat alarms on the ground in high-heat conditions (we hit 120F a few days ago in the valley, where the plane is parked) are not unusual.  the way to clear them is to climb shallow with 5300 rpm.  I am having a call in to dynon to see if I can extend the audible silencing interval from 3-5 seconds to something more useful.

 

[iaw4]

 

and Roger also explained the real cause of my problem: the sensors were flapping around.  the cure was "take a pair of pliers and squeeze the three spade connectors so they are snug and not lose. There is a CHT on the bottom front corner of #2 cyl. and on the bottom of the right side #3 cyl. The oil pressure sensor is the only wire on the front lower part of the engine by the oil filter."  I now get reliable CHT readings, with temperatures barely exceeding 200F.

the problem onset was not sudden, suggesting that it had been building up slowly and causing seemingly higher temps over time.  anyone who thinks they have high CHT issues should probably do this first.

roger is a ctsw saint in my book...

[okent]

Any way to post a pic?

 

Thanks

[iaw4]

 

you mean "post a pic of how to do this"?  sorry, no.  I had my shop do this.

[okent]

No problem.