Overheating with tape on radiator?

[tennesseect]

I had a little scare this week when I flew back to Nashville from Gulf Shores.  I put tape on my radiator a couple weeks ago - as I do every year when temps drop. All Dynon EMS readings were normal on the trip down. The outside temp at 6500 feet was in the upper 30's and low 40's. Climbing out on the return trip I started getting intermittent audible alarms and flashing red lghts, so I shallowed my climb and the alarms abated somewhat.  I considered turning back until I noticed that it was only the right CHT bouncing into the red arc.  I've had previous iissues with the Dynon as well as erroneous sensor readings caused by loose wire connectors, so I throttled back and made a VERY shallow climb to 5500 feet where the ouside temp was in the upper 40's. The engine continued to run fine despite the intermittent alarms.  The oil temp was normal. I pushed the 'silence' and 'ACK' buttons numerous times to reduce distractions while I troubleshot  I didn't call for flight following because the persistent, but intermittent alarms would've made communicating difficult.  Because only one of the CHT's was reading high and bouncing around and everything else appeared normal, I chose to continue the flight with lower rpm's - between 4800 and 5000.  Luckily I had a pretty good tailwind so my ground speed was 125-135 knots.  After a while I pulled and reset the EMS ckt breaker to see if that helped.  It didn't.  Right or wrong, I chose to push on toward home, hoping the temps would fall as I flew north. At some point, I pulled the EMS ckt breaker and flew without it except for turning it back on every 15 minutes or so to verify nothing had changed. About a hundred miles south of Nashville the outside temp fell back into the lower 40's. The EMS alarms disappeared and the right CHT stayed in the green arc but still bounced around.  I landed in Nashville without incident and immediately verified the oil and coolant levels were OK.  I guess I'll try removing a portion of the tape on the radiator and test fly.  Does anyone have other suggestions?

[GrassStripFlyBoy]

28 minutes ago, tennesseect said:

The outside temp at 6500 feet was in the upper 30's and low 40's.

Standard lapse rate being ~3.5 degrees F per 1k ft computes to ~ 60F on the ground?   That is at a point where little to no tape is required. 

In milder fall season I had a shorter segment placed on center, the oil cooler is not the full span of coolant radiator, so a smaller segment on center is sufficient in the cooler days, full strip when cold.  

You're on the right track, use less tape.  

 

[Ed Cesnalis]

I would expect the possibility of needing tape adjustments on any leg.  

In flight : propeller pitch adjustments; fuel mixture adjustments and cooling air-flow adjustments are all too complex for us with mere sport pilot privileges. Simplicity is the holy grail of light sport regulation. These are stupid rules. 

[Mike Koerner]

Ed,

The lack of fuel mixture adjustments and cooling air-flow adjustments are design choices made by Rotax and Flight Design - not really rules, per se.

Mike Koerner

[Ed Cesnalis]

Mike,

I'm to tired to re-read the rule now.  I agree there are such differences between SLSA and ELSA.  Only one of these groups seems constrained by in flight adjustable cooling, mixture where both groups are constrained by in flight adjustable prop.  

I think the prop is a rule/pilot issue and the mixture and cooling are rule/slsa issues. Don't ELSA and SLSA have different requirements for adherence to the consensus standard?  One  looks to the owner/builder and the other looks for a LOA.

What would FD say is I asked for a LOA for mixture control and louvers?

[Tom Baker]

Early on someone from Minnesota was making louvers, and I think they had Flight Design approval. They worked well in the cold conditions, but you did lose some summer cooling with them installed. I doubt you would get an approval for mixture from them, since they will defer to Rotax. Rotax will not approve it. I am pretty sure the Continental powered SLSA's have a mixture control. The prop is the only thing covered by regulation. I am not aware of any ASTM requirement that prevents installation of either. 

[Ed Cesnalis]

Thanks @Mike Koerner  and @Tom Baker

[Jim Meade]

My friend's ELSA Dynamic has separate air and oil radiator air ducts for his Rotax 912ULS.  The oil air duct has a controllable flap on it.  He never has oil temp issues because he can control the flap.  It is preposterous that Flight Design has grown men posting information on how much tape to place where in order to fly a sophisticated modern airplane, and then we be sure to carry extra and are prepared to land enroute in case we guessed wrong on where or how much tape.

[GlennM]

Why would only one CHT be affected and jump around if it were the radiator? TCs don't bounce. It is probably a connection problem. My CHTs "bounce" when I need to clean my grounds for the Dynon.