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We’ve run some of the diagnostics tests suggested (couldn’t do more because my A&P is busy on something else).
1. Gear doors were opened with the hand pump, the master was then turned on and the doors closed swiftly in 1 or 2 seconds. Powerpack performance seemed perfectly normal.
2. Nose gear was jacked up, the oleo came out smoothly and the squat switch clicked to the “closed” position. We didn’t actually confirm a closed circuit, but the switch clicked each time the test was repeated.
3. Voltages were measured as GMAs suggested and all was found normal. Specifically, there was negligible voltage drop across the master solenoid. (Also, it seemed from the wiring that current to the starter solenoids flows first through the master solenoid; since both engines are starting normally, that suggests that the master solenoid is OK.)
4. While not strictly a test, an IA who was with us when we were discussing the problem said that it sounded to him like an OVERVOLTAGE – not undervoltage – condition. He says the alternators may have dropped off, not because of excessive load current (which would have tripped the breaker), but because of an overvoltage. I seem to remember that the overvoltage light went on, but I can't be sure. Any thoughts?
Since I’m sure that in-flight not even the doors opened, seeing the powerpack work flawlessly in test 1 suggests to me that it may not be the powerpack. I’d like to continue diagnosing this, but my A&P is unable to get to my plane full time until Friday of next week, when he’s planning some retraction tests with the plane jacked up. He has, however, an hour here and an hour there. Are there simpler tests that we can do on the ramp to further diagnose this? I’d like to do the test suggested by Skyking (and I think also by GMAs and by Skymaster?) of jacking only the nose gear (to activate the squat switch) and try to raise the gear with the powerpack while the mains are on the ground, turning the master switch off as soon as the doors open and the nose gear starts to move. But I’m a little concerned of doing damage to the airplane and I want to get clear procedures on resetting everything back to normal-gear-down status. Is this safe? I take it that Skyking, GMAs and Skymaster have done this before? Any further thoughts on this – or on other tests – would be very welcome.
Thanks,
Ernie
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