REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable

[Scott Derrick]

There are 3 issues here:

1st and most important is the aileron cables.  You do have fire sleeve 
on the portion of the cables that are in the engine compartment? This 
was a mandatory change/addition back in 2005 or there abouts. Its for 
engine fires but it also insulates the cable from engine heat somewhat.

2nd and 3rd are your oil and cht temps.

The first to address is the cht's because high cht's directly effect 
your oil temps.  You need to get those CHT's under control!  445 is 
right at the limit for Continentals. 450 is redline, any sustained temp 
above 400-410 is really too high. Large VG's 6 to 18 inches in front of 
your roof NACA's can help.  A really tight plenum is also needed. I 
ended up adding a cowl scoop to lower the lower cowl pressure, which 
reduced my climb cht's by 20 degrees. get the cht's under control and 
your oil temp problems may go away or at the least be much less in severity.

The oil temp is definitely to high.  Above 250F requires an oil change 
as you have cooked some of the ingredients in the oil above their 
rating.  I normally run with one one large oil cooler in the nose. I 
added an adjustable cowl flap to the exit duct that can be opened wider 
for summer departures. that helped a lot. I also have a secondary cooler 
under the rear seat with a couple bilge fans that can provide a small 
amount of additional oil cooling for hot departure climbs and long 
taxis.  I normally never turn it on, but short gas stops where I'm 
departing with a hot engine it helps a bit, maybe 5 degrees.

You definitely need to get your temps under control. Most important is 
the seized control cable, but your also significantly shortening the 
life of your engine.

Scott

-------- Original Message --------
Subject: REFLECTOR: XL FG Hi Temps/ Siezed Aileron Cable
From: Mark Magee <edjonesbrady at gmail.com>
To: reflector at tvbf.org <reflector at tvbf.org>
Date: 11/09/2011 09:28 AM

> 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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