Start switch

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Mwarmer
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Re: Start switch

Post by Mwarmer »

Hi all,
The three cable are scolded at the switch. Really unprofessional.In my opinion there should be an AD in which Diamond will replace the switch in different more solid stable switches.
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CFIDave
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Re: Start switch

Post by CFIDave »

ultraturtle wrote: Sat Sep 03, 2022 6:05 amYears of throwing parts at the problem resulted in the unnecessary and very expensive replacement of perfectly fine components, most of which were verified to work just fine after removal:
  • Battery
    Main Start Relay
    Man Start Relay (again)
    Left engine start motor
Neither of my engines would start in the winter when it was really cold, so I also wasted money by installing a brand new battery, thinking that was the problem. When that didn't work, I replaced the main start relay, which -- fortunately in my case -- fixed the problem. (I found a "good home" for my lightly-used original Concorde battery by selling it to a DA40 XLS owner on the field who needed to replace his. The DA62 and DA40 both use the same battery.)
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Former DA40XLS, DA42-VI, and DA62 owner
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dakota1111
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Re: Start switch

Post by dakota1111 »

I fly a diamond DA 62. Thank you very much for providing this information and troubleshoot. Based on my cold-weather issues, starting my left engine, I am hopeful that the "start switch assembly" is the culprit I have been trying to locate. With that said, you mentioned the "start switch assembly". What is the part number that you are referring to exactly? Please kindly advise.

Thank you in advance.
K.C.
ultraturtle wrote: Sat Sep 03, 2022 6:05 am
Mwarmer wrote: Fri Aug 26, 2022 6:53 pm Does anyone also have experience with the problems of these switches?
I had a similar problem, but the fix took years, and many thousands of dollars to fix. I wish it was only $425.

Fast forwarding to the end of the story, the start switch assembly probably needs to be replaced again if you are still having start problems.

Now, the long version...

It is helpful to understand the logic of the DA62 starting system. There are 3 start relays, a main (normally open) starting relay that feeds power to the L and R individual engine (normally closed) relays that, when energized, allow power to the start motors. When a start button is pushed, the main start relay closes, and power is sent downstream to both individual engine start relays, but that same start button signals the opposite engine start relay to open, preventing its start. Power flows only to the selected engine, it starts, and the world is wonderful.

If one of the diodes that control this logic, (located behind the start button assembly, and part of it) fails or the signal path is otherwise grounded, both individual engine starter relays open, and neither engine starts. Open both front doors as you attempt a start, and you will hear both relays click, breaking the circuit, and preventing a start on either engine.

Years of throwing parts at the problem resulted in the unnecessary and very expensive replacement of perfectly fine components, most of which were verified to work just fine after removal:
  • Battery
    Main Start Relay
    Man Start Relay (again)
    Left engine start motor
In my situation, the problem was worse in cold weather. For my ferry flight to finally get it fixed, I wrapped hand warmers around the start switch assembly to warm it up, and after about 20 tries, the diode mush heated into an operational position and I finally got one of the engines started. Second engine start was never a big deal.

After finally convincing a maintenance shop to replace the start switch assembly (hard to do), I have had no problems whatsoever getting it to start on the first try for almost a year now.

Finally threw a part at it that worked...
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ultraturtle
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Re: Start switch

Post by ultraturtle »

dakota1111 wrote: Sat Mar 11, 2023 5:36 amWhat is the part number that you are referring to exactly?
I believe that the part number that you circled in your PM (AV24LC404) is the correct one. I'm a couple of days away from my maintenance records, and will try to verify when I get home.
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