REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable

Mark Magee edjonesbrady at gmail.com
Wed Nov 9 16:13:19 CST 2011


Ruben,
Thanks. Vernatherm will be hot water checked for a full close. 
Regards 

Mark B. Magee
Sent from IPhone 

On Nov 9, 2011, at 3:50 PM, "Ruben Creus" <ruben at vainneg.com> wrote:

> 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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