Just got an eMail from Avionik Straubing. L3 wants $ 3869 to repair my Skywatch 497 unit. Plus freight, plus installation, of course. It only says “processor has to be changed”.
Anybody have a Skywatch in the basement they don’t need? ;-) …
(Maybe I should cancel that € 130 room for Aero :-))
I’ve had endless problems with Skywatch and have had two new processors, both supplied by L3 under warranty, neither of which fixed the problem. (Yes, my avionics shop did download the failure codes and sent them to L3).
There is a great deal of information about Skywatch troubleshooting on COPA. The bottom line is that the problems seem mostly to be related to the antenna wiring. I would recommend a search on there assuming you are a member. If not, please let me know and I’ll have a look for you.
FWIW, in my case, I recently upgraded my GNS 430s to GTN 750/650 and since then have never had a failure.
yes, I know the thread on COPA … it was initiated by me :-)
Avionik Straubinghave checked my unit and it seems to be bad, that’s why we sent it in. The loaner unit works perfectly in my plane, and Avionik Strauning was sure it’s not the antenna grounding.
It’s in the member section, that’s why. Opens ok for me …
Come on chaps, I don’t want to look like a dictator but posting internal links into a pay-to-view forum is really bad form and useless to approx 99% of EuroGA readers. Next time I will delete them.
By all means discuss the topic here. That’s unless the said forum prohibits reposting content – as one UK one does – in which case you cannot copy/paste, and you probably should not post material which would be embarrassing to the poster (I say “probably” because anybody who posts something anywhere on the internet with an expectation of confidentiality is obviously a fool).
I posted a link to a topic on COPA that I thought would be helpful to a fellow Cirrus pilot who asked about a problem that I know to be common to a number of Cirrus pilots. If you think that is inappropriate then I won’t do so again but have to say I really don’t see what harm it does.
Take it easy, Peter. Jonzarno wanted to point me to an interesting link in COPA, probably not even beeing aware you cannot open it.
These were the main postings on COPA about the issue:
Be aware that if the antenna connection is poor, then the skywatch transmitter can over heat and destroy itself. A flat rate repair (in the USA) is $3100 (last I heard). So it might be worth checking it. It is easy to hook up a serial cable and a laptop to monitor the error messages (if any). If you do anything at all (re-seat connectors, etc), the skywatch should be re-calibrated. I think this poor antenna connection is the main reason people have so much trouble with the skywatch – targets jumping around, disappearing. And they believe that is how the skywatch is supposed act….. They have never had an experience with a good skywatch.
When you get a failure of 20 times in one flight your processor is pretty much toast. The poor antenna grounding caused the processor to overheat. On one of the overheats the processor got damaged and the only fix at that point is R & R (remove and replace).
It will always be the transmitter that fails. But what caused it to fail? Most likely it was a bad ground connection on the antenna. See this post. The antenna ground connection must be 20 MILIOHMS or less! This is direct information from L3 (the manufacturer of the skywatch). Does your avionics shop have a miliohm meter? When there is a poor ground, the transmitter will be mismatched to the antenna. So it will cause the transmitter to heat up, That is why the skywatch shutdown – it overheated internally. When you reset the breaker, it would start the cycle all over again. Sooner later, the transmitting transistors will fail from overheat. So you can put in a new skywatch with the same poor antenna ground – and it will work perfectly for a while. The antenna connection can be good one day and marginal the next (it might vary with the temperature, plane vibration). The fact that your skywatch worked while flying to the avionics shop makes it likely that it is an intermittent antenna connection.
So I had my plane in the avionics shop today to work on the XM radio, and having seen this post, asked them to pull down the headliner to see what the condition of my sky watch antenna was. The same shop had already spotted an external antenna in need of some caulking as a preventative measure, which they fixed right away. The only thing different about the sky watch antenna is that you can’t see through the headliner, you have to remove it, which as easy as it is (as Roger said) they naturally had not planned to do. I mentioned it, they said sure they’d look, and in five minutes came to me to say two bolts were loose, which they tightened and then checked resistance with a micro ohm meter. My sky watch transistors were spared.
Pull the weather strip back. Check each bolt to make sure it’s snug against the foil groundplane. If not, have your A&P remove the the nut and add the appropriate washers. Chances are the bolt thread length is too short to tighten the nut fully hence the addition of a washer or two. Reseal the screw heads with the appropriate sealer. Checking this takes 5 minutes and could potentially save you 3 grand.