SB for: Composite Design manufactured control panel for all UL engines

Time of compliance: Before next flight

Reason for this bulletin:

Several customer have had a loss of ECU power due to an undetermined issue with the 20A ECU breaker. Stress analysis on several breakers indicated that the breakers performed per manufactures specifications using a static DC load. In actual operation with the engine several of the 20A breakers tripped causing loss of engine power. The breakers in question are from Tyco electronics - model# W28-XQ1A-20.

A revision to the UL control panels several years ago has mitigated this issue. Many of the panels fitted with the W28 series breakers are still in the field or in aircraft under construction. The new breakers have been supplied with the UL control panels for the past two+ years with no operational problems. The newer breakers are Klixon (Sensata) series 7277 or 7274 series, easily identified as having a pullable knob type actuator.

It is highly recommended that all existing control panels with the W28 series circuit breakers be refitted by Composite Design with the new breakers. This is a factory modification only.


If you have a subject control panel, it will need to be refitted. Contact Composite Design via the above email to schedule service or answer questions.

There is a temporary interim fix that can be used prior to modifying current panels by installing a jumper on the terminal block.

The addition of the jumper is meant to be a short term fix to avoid the possibility of an ECU shut down due to a tripped breaker.

It will bypass the breaker in the Emergency Power Mode. This jumper addition to the panel does not require any additional wiring changes.


Herman Eshuis

Wheels and Wings, LLC

Zenith builder assist and completion center

ULPower sales and service dealer

Lake City, FL


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Big thanks to Herman for the posting.  I'm good,  But check yours.

Thanks Dave!  Mine is good now!

Today I received my power panel back from Comp.Dsn. It was modified not only with new C/B's but also new type indicator lights and faceplate with new labeling for the pump switches. All the latest and gretest.

I am perplexed by the new switch position on the modified power panel from manual pump to ecu+aux pump.

I just sent mine off for the mod a couple weeks ago. I discussed at length with Wayne Lanza the changes and switchology. I believe he said the both pumps are on in the lower position. Just the “main” pump on in the upper “normal” position. If the main pump should fail, you need to manually select the switch to the lower position to activate the aux pump.

I can't figure out why it would be necessary to run both pumps at once except maybe for takeoff . And then I wouldn't want to switch back in flight either.


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