Start switch

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Mwarmer
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Start switch

Post by Mwarmer »

At BGBW Narsarsuaq Greenland. :cry:

Last week we had a problem with our DA62. We were on BGBW Narsarsuaq in Greenland. We wanted to start the right engine, but nothing happened when I pressed the start button. Then started the left engine. The starter motor did not come to life. Then we connected to external power. Result: The right starter motor including relay burned. After consulting Diamond they sent a new right startmotor, which we mounted within 3 hours.
But at starting nothing happened. The right start motor with relay was installed properly. After consulting Diamond, Diamond thought of the start button switch. A new switch was brought along. The assembly was very simple. But we came to the conclusion that behind the button a switch is mounted of about $ 0,25. A wire had come off the switch, which meant that the relay on the starter motor was not receiving any control and therefore was not starting.
What surprises me now is that Diamond wants to receive $ 425 for this switch, while the quality of the switch is very very poor. :(
Does anyone also have experience with the problems of these switches?

Thanks for any comments. :)
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Boatguy
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Re: Start switch

Post by Boatguy »

Not with the starter switch (it's in the Electric Master in the 40NG), but in less than 600hrs I've had to replace a trim switch and a fuel pump switch.
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Steve
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Re: Start switch

Post by Steve »

Out of the Warranty period?
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Boatguy
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Re: Start switch

Post by Boatguy »

Steve wrote: Fri Aug 26, 2022 10:31 pm Out of the Warranty period?
Trim switch was under warranty, fuel pump was not.
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Steve
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Re: Start switch

Post by Steve »

Boatguy wrote: Fri Aug 26, 2022 10:53 pm
Steve wrote: Fri Aug 26, 2022 10:31 pm Out of the Warranty period?
Trim switch was under warranty, fuel pump was not.
Was wondering about Marcel's airplane mostly...
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Gordon
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Re: Start switch

Post by Gordon »

Thanks for the information Marcel - it maybe helpful one day when I'm in the Outback!

"But we came to the conclusion that behind the button a switch is mounted of about $ 0,25. A wire had come off the switch, which meant that the relay on the starter motor was not receiving any control and therefore was not starting."

If it happens to me, I might have to find the local town car thief to "hotwire" the switch ha ha.

I hope you weren't stuck in Bluie West to long.
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Mwarmer
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Re: Start switch

Post by Mwarmer »

Thank you for your comments.
I’m not happy with the switch. A key switch like in the DA42, is a better idea. Why did Diamond change this item?
Nevertheless I’m very happy with the airplane and it’s performance.
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Boatguy
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Re: Start switch

Post by Boatguy »

Mwarmer wrote: Thu Sep 01, 2022 5:08 pm Thank you for your comments.
I’m not happy with the switch. A key switch like in the DA42, is a better idea. Why did Diamond change this item?
Nevertheless I’m very happy with the airplane and it’s performance.
You said a wire had come off the switch. Is the wire integral to the switch, or could it have been reattached?

In other words, did the switch really fail, or was it sloppy assembly?
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ultraturtle
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Re: Start switch

Post by ultraturtle »

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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Colin
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Re: Start switch

Post by Colin »

That is valuable information hard won.

And, as usual, when I read the description of the relays I am sad I can't start both engines at once and pretend this is why I don't have a DA62.
Colin Summers, PP Multi-Engine IFR, ~3,000hrs
colin@mightycheese.com * send email rather than PM
http://www.flyingsummers.com
N972RD DA42 G1000 2.0 s/n 42.AC100 (sold!)
N971RD DA40 G1000 s/n 40.508 (traded)
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