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Generator not on-line for initial start

M

Mike Buettgenbach

Active Member
Sponsor
912iS, about 240 hours, no other symptoms that I've notices

Normal function: Start the aircraft, Amps show a small amount of consumption. Increase RPM to ~ 2400-2500 and it switches to Gen B, amps goes up to normal value of 9-12 amps and then tapers down as the batt charges.

Operation now (the problem situation): no generator output at initial start. Increase to 2400 RPM --> Gen B comes on and all appears normal. Run for a couple minutes; shutdown; restart --> function is normal (as stated above)
This has happened for the last 3 starts over about 1 month. The wx here is COLD, so that might be a part of the symptom/problem. . . . eventually it will warm-up here I HOPE.
All thought welcome
Thx much!
MikeB
 
I read your message a few times.. I'm not sure I understand. Under Normal function, that sounds correct. Battery is powering everything until the engine starts spinning. Then, Generator B (B for the big boy 30A generator) is powering the ECU & Fuel pumps; the battery is powering the avionics. Battery will be showing a discharge of about -5A depending on your avionics... until the switchover at about 2400rpm for a couple seconds. Then Generator A will power the ECU & Fuel pumps; Generator B is powering the avionics and recharging the battery. Alternator will show about 20A (indicating that power is flowing from the alternator to the main bus) and battery will show 5-15A [charging] (depending on how depleted the battery was).

Under Operation now, I don't understand because you shouldn't have any generator output (to the avionics / main bus) at initial start... ?
 
Hey Rob -
Under "normal" I should have worded it more accurately - Under Normal (prior to this fault situation) : After initial start, the Amp meter would show a small amount of charge - 4-5 amps . . . or so. Then after higher RPM it would switch to the other gen and show 8-10 amps charge.

Operation now: no amperage is showing at initial start (no charge or discharge) . . . just "0". Then at higher RPM, the other gen connects and shows the higher output - 8-10 amps.

Did that help?
Thx Rob
MikeB
 
Mike Buettgenbach said:
Hey Rob -
Under "normal" I should have worded it more accurately - Under Normal (prior to this fault situation) : After initial start, the Amp meter would show a small amount of charge - 4-5 amps . . . or so. Then after higher RPM it would switch to the other gen and show 8-10 amps charge.

Operation now: no amperage is showing at initial start (no charge or discharge) . . . just "0". Then at higher RPM, the other gen connects and shows the higher output - 8-10 amps.

Did that help?
Thx Rob
MikeB
Click to expand...
I looked back at my last flight.. and one from July (hot).. It seems that I have 0 amps until the switchover:

1740788265519.png
 
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