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  #1  
Old 08-04-2008, 10:10 AM
Scott Will's Avatar
Scott Will Scott Will is offline
 
Join Date: Jan 2005
Location: ATL
Posts: 734
Default Lightspeed failure

Couldn't have made OSH anyway,,,

The last week I've experienced failure of my Lightspeed Plamsa III on my RV-7A IO-360. After taxi out and runup, the Lightspeed would completely fail when running just on it during the runup check. Completely obvious and not isolated to a single cylinder (all EGTs rose) and RPM dropped significantly...but I always switched back to bothe before it quit.

Taxi back and run-up in front of hangar... no problems! Like it was brand new. Pulled the cowl and inspected everything... all looked good. Put new plugs in and tried again. Similar results.

Well we finally pull the box and find a BNC connector with lots of charring and even some of the metal worn away. The male part of the connector was even worn with black on it. Almost looks like it was arcing. Kinda explains the intermittent results I was getting...taxiing probably knocked the connector in/out of position. Sending the box back to Klaus today.

Yeah, the box is mounted on the firewall but I did so only after hearing successful reports from others who've done the same. I think next time I need to put heatshrink or a protector for the connector on it.

Anyway, check the pics...

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  #2  
Old 08-04-2008, 12:49 PM
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Capflyer Capflyer is offline
 
Join Date: Feb 2005
Posts: 1,082
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Had the power supply in one of my two LSII+ boxes go out on me a few weeks ago. Klaus had me send both boxes back. Fixed the one and upgraded both with what appears to be new resistors.

Saw a Glasair II at Oshkosh where the builder had both his boxes on the engine side of the firewall and had hoses to vent cooler air into the open holes in the box ends visible in your pictures. Looked like a thoughtful idea to help with the heat build up although I did not see another hole to let the cool air out.
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  #3  
Old 08-04-2008, 06:03 PM
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Kahuna Kahuna is offline
 
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Location: Gold Hill, NC25
Posts: 2,400
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Since the install guide clearly states "The PLASMA CDI module should be mounted in a clean and dry place on the cold side of the firewall." you might consider changing the thread title. Finding a couple of folks like me that got away with not following the directions only means we got lucky. Klaus has been doing this a long long time. No doubt he has good reasons for wanting it cool and dry on the cold side of the firewall. I got away with it for a long time in my 6, looks like your an example of why its there.
best,
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  #4  
Old 08-04-2008, 06:10 PM
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kevinh kevinh is offline
 
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Location: San Mateo, CA
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Quote:
Originally Posted by Scott Will View Post
Well we finally pull the box and find a BNC connector with lots of charring and even some of the metal worn away. The male part of the connector was even worn with black on it. Almost looks like it was arcing. Kinda explains the intermittent results I was getting...taxiing probably knocked the connector in/out of position. Sending the box back to Klaus today.
If you are going to leave it on the hot side of the firewall, you might want to check for strain relief for that cable. Possibly the vibration of the engine caused the connector to jiggle...
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  #5  
Old 08-04-2008, 09:25 PM
elippse elippse is offline
 
Join Date: Dec 2006
Location: Arroyo Grande, CA
Posts: 938
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You'll notice that the connector shells are insulated from the chassis. That is because the cable shield carries a high current, low voltage signal which is used in the spark generation. That is why the cable shield should NEVER be grounded anywhere! I have my two units mounted to the upper-left (pilot side) of the firewall, but that is because ALL of the cooling air from the cylinders and oil cooler are ducted out so that there is no hot air impinging on the firewall. Even so, I have a very small inlet on the cowling which provides cooling air ducted to the four coils, the two ignition units, the oil separator, the fuel pump, and the gascolator. You who have your oil-cooler mounted on the rear baffling with no outlet duct are dumping a LOT of hot air onto the firewall! In my friend's Lancair with a typical baffle set-up I experienced vapor-lock several times on hot airports, but never once with my system. Keep your electronics cool to extend their life!
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  #6  
Old 08-08-2008, 06:54 PM
danbenua danbenua is offline
 
Join Date: Oct 2007
Location: Hillsboro, OR
Posts: 83
Default Another LSE failure mode...

I have another recent LSE failure story. The single LSE Plasma-III
box on my IO-540 (RV-10) failed in flight twice in hot weather last
month. After landing and cooling, the box would operate normally.

Sent it back to Klaus who reported that my box contained over-temp
sensors that could cause shut-down. Klaus admitted that he has
stopped using those sensors because of repeated problems,
and removed them from my box. The problem seems especially
acute on 6-cylinder Plasma-III boxes. If you have one these
units you might want to contact him to determine if your box
has these sensors!

Klaus also now recommends cooling air flow fthrough a 3/8" port
on the side of the box. My box had the port, but the older
installation instructions I received with it did not mention
any requirement for cooling air. I have it now!
(The latest instructions on the LSE web site do discuss
cooling air requirements.)

A further protection is to add short stand-off bushings
to separate the LSE base plate from the stainless firewall.
Pressing them together in close contact facilitates effective
conduction of heat from the hot forward side to the LSE
base plate; and you don't want that.

After these mods we flew from the west coast to OSH and
back through some very hot conditions with no issues.

- Dan Benua
RV-10 N755SB
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  #7  
Old 08-31-2008, 05:18 PM
longez360 longez360 is offline
 
Join Date: Sep 2007
Location: Australia
Posts: 23
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I had dual lightspeed ignition on my Long EZ and had 3 catastrophic failures in the first 10 hrs of operation of my aircraft. I had one Plasma I and one Plasma III. Failure mode was mechanical due to vibration. No other electronic component, mounted on the same node (both cert box and a engine monitor signal interface box) have failed. No other avionic or electric component or system has expereicned vibration induced failure in 200 hours of operations. After inspection of the LSE boxes by myself and other Boeing mechanical and avionic engineers with over 50 years combined experience we found the following: 1. The PCB moves inside the enclosure (translates in all axes). There is no retention other than loose side rails. The packaging is not of a sufficient standard for any vibration environment (all possible applications). 2. The transistors mounted from the PCB to the enclosure will fail (and did twice). 3. The PCB component legs will fail. (A voltage regulator did fail).

I have modified my Plamsa III by soft wiring and strain releiving the transistors and have potted all components. I have mounted the unit on velcro inside the cockpit. Yes, some critical components are velcro mounted even in the cert world. I have screwed the PCB to the encolsure. I have added a mag and removed the Plasma I.

I will not fly in an aircraft with dual plasma ignition under ANY circumstances. If modded per above the lightspeed ignition systems are exceptionally good performers.

Last edited by longez360 : 08-31-2008 at 05:22 PM.
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  #8  
Old 08-31-2008, 06:05 PM
allbee allbee is offline
 
Join Date: Aug 2006
Location: spokane, wa
Posts: 805
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I finished mounting my plasmaIII about a week ago and went with the location just to the rear of the firewall on the pilot side. After reading this on vibration, I think I'm going to mount it with some rubber mounting as well. My thoughts on the failure in this thread may be more because of movement of the wire going to the box. When you mounted the box on the other side of the firewall you also end up mounting the wire stationary at the firewall (on the box)and the other end goes to the baffle. In other words the wire, the way you set it up, correct me if I'm wrong, goes through the baffle at the rear of the engine and right to the box? If so than the wire could have been moving or vibrating, thus causing intermittant connection. just a thought. Another thought on the situation could be just a bad connection when the wire and the connector was put together at the factory.
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  #9  
Old 09-01-2008, 06:49 PM
RVadmirer RVadmirer is offline
 
Join Date: Dec 2006
Location: Kalifornia
Posts: 466
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Wayne built one of the most beautiful and finely crafted composite airplanes in the world. Accusing him of hacking up anything is a huge mistake. If I didn't have a Lightspeed II, which appears not to need modifying, I would be asking him for instructions on modifying mine as he did to yours. You are probably missing out on a nice piece of equipment.
I have mounted my box inside the headrest on small rubber bumpers to help with vibration and it has never given me any trouble. I have had to remove and clean the 9 pin connector to the Hall Effect module and they have since upgraded that connector. I'll do all connections at Conditionals to avoid surprises.
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  #10  
Old 09-08-2008, 03:27 PM
RVadmirer RVadmirer is offline
 
Join Date: Dec 2006
Location: Kalifornia
Posts: 466
Default Another Lightspeed Failure

Well my 9 pin connector didn't make it 30 hours before it failed again. So it's obviously a bad part and of course I'm told I have to buy the proper component that should have been used in the first place! And the price went up since I was quoted three weeks ago. At least the P-mag guys are taking care of their customers and fixing their issues. No such luck at Lightspeed. Dig out the checkbook. That's three failures in less than 200 hours...... Consider that when you are shopping for ignition, or insist on two of them!

Last edited by RVadmirer : 09-08-2008 at 03:29 PM.
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