REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable

[Ruben Creus]

Mark,

In fact, the Vernathem normal position is open, allowing the oil to bypass
the cooler. With temperature, it extends and closes the bypass cavity,
making all the oil go to the cooler. 

The tip of the Vernatherm is a cone shape and it should have a bit of play.
That way with the expansion of the valve the cone seats properly in the
bypass, so the play allows to find it own way to make a the perfect seals
and fully closing the bypass. 

In my case the original valve had no play, so it extended fine, but it could
not fully close the bypass, allowing half the oil to by pass the cooler and
return to the engine with no cooling at all. I could see the marks of the
bypass on the tip of cone, and the marks were off centered  So even it was
extending completely is was not perfectly landing on the bypass. 

The new valve has a bit of play on the cone. My oil temperature is now
around 185 cruising and 210 climbing at full throttle and full weight,
climbing around 500ft/m with no issues.
 
Not sure if you would have this same issue, but in my case this was it. 

Ruben


-----Original Message-----
From: Mark Magee [mailto:edjonesbrady at gmail.com] 
Sent: Wednesday, November 09, 2011 2:31 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable

Ruben,
I did verify that both of my oil coolers started heating up at the
prescribed temp (190f?). I did not pull the vernatherm and confirm it was
opening fully. After mods all temps were good in hot weather flying SOLO and
small fuel load. It was just this latest takeoff near gross weight  (and
relatively warm temps aloft) that I got hot again. I will pull the
vernatherm and confirm it's opening the whole way. My A&P friend said he
couldn't recall one failing. However it may not be opening all the way
possibly?

I'll have a look at it.

Mark B. Magee
Sent from IPhone 

On Nov 9, 2011, at 12:32 PM, "Ruben Creus" <ruben at vainneg.com> wrote:

> Mark,
> 
> Do you have a vernatherm on your engine?
> 
> I had a similar problem, and after checking everything again and again, I
> found out that he Vernatherm valve was not fully closing the bypass. So,
> some oil was going to the radiator making it feel hot, and making me
believe
> that worked, but the fact is that not enough oil was circulating and most
> was returning into the engine through the bypass.   
> 
> The effect was all my temps went to the roof at climb, as effectively my
> only cooling system was air pushed into the engine. Went flying level all
> temps looked good as more air was cooling down the engine. So, technically
> was like flying with no radiator. 
> 
> After replacing the Vernatherm valve, the change was drastically
different.
> Oil temp went down around 25F, CHT went down also, and now I can climb
full
> throttle all the way to any altitude with no problem at all and not
> suffering about temps any more! All stay cool and nice.
> 
> Ruben
> 
> -----Original Message-----
> From: Mark Magee [mailto:edjonesbrady at gmail.com] 
> Sent: Wednesday, November 09, 2011 11:29 AM
> To: reflector at tvbf.org
> Subject: REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable
> 
> All,
> N34XL has some overtemp issues I have been addressing for about 9 months.
> With previous mods I had been running acceptable Oil Temps and CHT's, when
> flying SOLO/Lower fuel loads. Before the overtemp probs were solved the
> summer of 2010 after landing from flying the bird from Livermore CA to
> central Texas the ailerons were frozen after shutdown. After diagnosing,
the
> RH side aileron cable was determined to have siezed, in some way from
heat.
> I pulled and replaced with a new cable last summer. Scary but looked at as
> an anomaly. After a trip this weekend to Wichita Falls TX (166NM trip) the
> ailerons are again seized after shutdown after getting home (Thank You
> Lord!). On the trip home Oil temps peaked at 257F and CHT's peakedat 445F.
> At level off at 12,500 MSL all temps fell back to very normal ranges. I
> climbed out at 120KTS getting 500ft/min up at that speed. After calling
the
> factory John told me to look at vortex generators on the top of the
fuselage
> for the NACA's for the engine and to climb at 130KTS and 300 ft/min which
he
> theorized would actually turn into 500 ft/min. I forgot to mention on the
> way back from Wichital Falls I was right at max gross weight and we had a
> 76F ambient temp on the runway at takeoff. Temp at 12,500FT was 53F. After
> landing and debarking wife and kids, hangaring the bird and unloading I
> tried the stick and have siezed ailerons again. Initial troubleshooting
> points to RH Aileron cable again. As well I lost my vacuum pump (in the
CLAG
> of course). After discussing with my A&P IA hangar mate, he felt that that
> the overtemp must be related to the stuck aileron cable and failed vacuum
> pump: basically all heat related.
> Anyone sized aileron cables on an Xl, or any Velocity. I have now seized
> TWO! Fortunately it appears that it is the heat soak after taxi in &
> shutdown that does the melting that complete's the seizing of the cable.
> Any help appreciated.
> 
> Thanks
> Mark Magee
> Brady TX
> N34LX FG 300 HP 75 HRS
> 
> Mark B. Magee
> Sent from IPhone 
> 
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