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  #1  
Old 05-22-2018, 03:44 PM
gblwy's Avatar
gblwy gblwy is offline
 
Join Date: Jun 2007
Location: Perth, Scotland
Posts: 492
Default Original AV control module

Hi,

After 7 years of service the plane suffered a complete electrical failure after switching off the Master Switch, or possibly at the subsequent switch on. There was no sign of life whatsoever. The battery was fully charged.

After significant diagnosis the fault was isolated to the control module, with a suspicion that the master switch was the culprit. In fact the switch was OK but one of the PCB tracks in the vicinity of the switch was found to be bubbling, a sign of excessive heat. The cooling fans were working correctly.

A competent electronics friend spotted the problem, and repaired it by soldering a wire to bypass the bad area. This involved removing the back plate from the module, and temporarily removing the large capacitor to allow access to the affected area. His view was that the track size was marginal, having measured the current flow.

The plane is now up and running but it begs the question what happens if the module has to be repaired/replaced. Can a replacement be ordered, and at what potential cost bearing in mind that this unit is no longer supplied? Should this, unusual, problem be formally reported to Vans? Scott?

Incidentally, all of the switches are soldered to the PCB and are therefore not readily replaceable. And for the same reason the PCB is not readily accessible for inspection or repair.

Thanks...Keith Boardman
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  #2  
Old 05-22-2018, 06:06 PM
Piper J3's Avatar
Piper J3 Piper J3 is online now
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,153
Default

I had same thing happen last summer. In my case the master relay solenoid mounted to front of firewall failed and caused foil burn as you described. I called Van's and new replacement switch/circuit board was ~$700USD and is available. This is first generation switch panel. I have RV-12 SN 120058.

In my case I couldn't access the burned foil (much less see it) so I soldered hard wire from master switch terminal and ran wire directly to master relay solenoid on firewall. Worked a charm. Also, replaced master relay solenoid on firewall which was root cause of my problem.

I also did a "Macgyver" fix to the Stabilator electric trim control because I got fed up with the PWM on the circuit board. I am very pleased with this fix. See...http://www.vansairforce.com/communit...&postcount=299

Ingenuity is the Mother of Invention...
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #3  
Old 05-23-2018, 10:18 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,873
Default

Quote:
Originally Posted by gblwy View Post
Hi,

After 7 years of service the plane suffered a complete electrical failure after switching off the Master Switch, or possibly at the subsequent switch on. There was no sign of life whatsoever. The battery was fully charged.

After significant diagnosis the fault was isolated to the control module, with a suspicion that the master switch was the culprit. In fact the switch was OK but one of the PCB tracks in the vicinity of the switch was found to be bubbling, a sign of excessive heat. The cooling fans were working correctly.

A competent electronics friend spotted the problem, and repaired it by soldering a wire to bypass the bad area. This involved removing the back plate from the module, and temporarily removing the large capacitor to allow access to the affected area. His view was that the track size was marginal, having measured the current flow.

The plane is now up and running but it begs the question what happens if the module has to be repaired/replaced. Can a replacement be ordered, and at what potential cost bearing in mind that this unit is no longer supplied? Should this, unusual, problem be formally reported to Vans? Scott?

Incidentally, all of the switches are soldered to the PCB and are therefore not readily replaceable. And for the same reason the PCB is not readily accessible for inspection or repair.

Thanks...Keith Boardman
When production ended on the D-180 avionics kit, a bunch of spares were built an put into inventory so they are available.
I am only aware of one spare being purchased since production ended.
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Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #4  
Old 05-23-2018, 10:32 AM
Piper J3's Avatar
Piper J3 Piper J3 is online now
 
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Location: Hinckley, Ohio
Posts: 1,153
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There should be some available in the used market as some aircraft have been updated to 10" Skyview systems...
__________________
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #5  
Old 05-23-2018, 01:21 PM
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gblwy gblwy is offline
 
Join Date: Jun 2007
Location: Perth, Scotland
Posts: 492
Default Thanks

Thanks, Scott. Thanks, Jim.
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  #6  
Old 05-23-2018, 03:22 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 244
Default Meantimes between system failures analysis....

Quote:
Originally Posted by rvbuilder2002 View Post
When production ended on the D-180 avionics kit, a bunch of spares were built an put into inventory so they are available.
I am only aware of one spare being purchased since production ended.
Is it a matter of when, not if, the master relay will cause this to happen to all RV-12's, as they age? Any trend analysis except to say this happened to two aircraft in recent years??
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  #7  
Old 05-23-2018, 03:45 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,873
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Quote:
Originally Posted by AirHound View Post
Is it a matter of when, not if, the master relay will cause this to happen to all RV-12's, as they age? Any trend analysis except to say this happened to two aircraft in recent years??
I guess it depends on how you define "trend".

These two failures mentioned are the only ones I am aware of (now, because of them being mentioned here in the forum). Besides knowing they happened, there is has been no other info provided (total time in service, etc.)

By regulation, any failure in an S-LSA RV-12 is required to be reported using the form or on-line process detailed in the Maint Manual. For E-LSA, it is desired (and in the best interest of the RV-12 community as a whole) but there is nothing regulator to require an owner to do so.
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Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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