LML Gang,
Today I was happily flying my 320 from Colorado to the
Lancair factory fly-in when I entered actual IMC. I encountered a few
light snow showers in the clouds when the P-static started in. The usual
cracking and buzzing in the headsets, hair standing on end, etc. The
encounters lasted only 30 seconds or so. On the first encounter my TruTrak
DigiFlight II autopilot disengaged. When I looked at it the display was
blank and the circuit breaker had not blown. I cycled power to the
autopilot and only the LCD backlight would come on. At this time I
discovered that the VM1000 engine instrumentation system had frozen. The
display was showing all the parameters as they had been but nothing would move
or react to changes. Cycled power to this and it worked again.
A couple minutes later another P-static encounter.
This time the VM1000 started displaying garbage and then blank. Power
cycle to the VM1000 did nothing – it was dead. The Jim Frantz AOA
also started going nuts and then just quit. I also discovered that the
Ray Allen pitch trim indicator (LED type) quit, although the trim servo still
worked.
All though this the UPS Apollo transponder, GPS/COM and
NAV/COM kept working flawlessly. I quickly contacted center for a 180 out
of the ICM and amended flight plan to get me back in the clear and on the
ground. A few minutes after back in the clear and the AOA began working
again.
So, now I have a couple problems. 1) get the broken
equipment fixed; and 2) figure out how to prevent this from happening again.
I talked with Jim Younkin at TruTrak today and he has a good
idea of what the problem is with the autopilot. It’s already on its
way to Jim. The folks at VisionMicro don’t work on Fridays, so I
have no answer there yet.
What concerns me the most is the prevention part of this.
Because my plane is made of e-glass, static wicks are not an option. Can
any of you give me pointers on what I might do to protect the sensitive
electronic gear in the future, besides avoid flying through snow? BTW, I’ll
do my best to avoid that again!
It is interesting to me that some of the equipment worked
like a charm through this all. The avionics stack and LCD clock/OAT/volts.
Am I missing something in my grounding system? Is there some static
protection built into some of the avionics but not others?
I am also very interested in the experience others have had
in IMC. I have only had my 320 in IMC twice. Once in warm, wet
clouds and rain. Today in cold, snowy clouds. Unless I can put my
finger on something that can protect the gear, I will have almost no confidence
to take it in any IMC – warm or cold.
I look forward to your replies.
Best Regards,
Dan
P.S. Have fun in Redmond for me!