500 hour alternator inspection

[carusoam]

Great first post Scott.N!

Welcome aboard.

Best regards,

-a-

[Dave Morris]

On 4/18/2020 at 8:59 AM, Matt Ward said:

For now, is there anything you'd recommend to diligently keep an eye to try and spot deterioration of the alternator?  I keep a good eye on the JPI and make sure it's 14v in flight.  What else could I be doing?  

My 68C just got out of annual and on the first flight afterward, on climbout, my EI voice annuciator said the dreaded "Check Bus Voltage", and a quick glance showed 11.7V which meant my alternator quit. The JPI started resetting, and my Aspen also showed 11V and switched to internal battery power. I have had a generator fail in flight on my M20A over Santa Rosa NM and I flew just fine to Double Eagle II and had the mechanic replace an el-cheapo ring terminal that was probably original equipment, and I was on my way again. I wasn't at all stressed because I had been performing battery load tests and had a small chart with the current draw of each item in the cockpit, so I knew I had plenty of battery to make it to the airport. On this 68 C model however the alternator has about 600 hours on it since overhaul in 2007, so I'm thinking it's going to be more serious than just a flaky terminal. TO answer the original question, no I don't think you'll get any warning or indication of reduced voltage or anything like that. It may be a 500 hour inspection or replacement of the brushes and bearings may be the best preventive maintenance.

[Ragsf15e]

5 minutes ago, Dave Morris said:

My 68C just got out of annual and on the first flight afterward, on climbout, my EI voice annuciator said the dreaded "Check Bus Voltage", and a quick glance showed 11.7V which meant my alternator quit. The JPI started resetting, and my Aspen also showed 11V and switched to internal battery power. I have had a generator fail in flight on my M20A over Santa Rosa NM and I flew just fine to Double Eagle II and had the mechanic replace an el-cheapo ring terminal that was probably original equipment, and I was on my way again. I wasn't at all stressed because I had been performing battery load tests and had a small chart with the current draw of each item in the cockpit, so I knew I had plenty of battery to make it to the airport. On this 68 C model however the alternator has about 600 hours on it since overhaul in 2007, so I'm thinking it's going to be more serious than just a flaky terminal. TO answer the original question, no I don't think you'll get any warning or indication of reduced voltage or anything like that. It may be a 500 hour inspection or replacement of the brushes and bearings may be the best preventive maintenance.

I wouldn’t jump to a new alternator too quick… they usually go a long time.  Definitely worth the troubleshooting, especially at the field and power terminal attachment at the alternator.  I’m very suspicious of a complete system failure on the first flight after annual.

Did they capacity check the battery though?  I wouldn’t have expected to have it that low right away.  Was it charging at takeoff?

[A64Pilot]

This is almost or just like the don’t overhaul your engine on a time interval, wait until it starts making metal.

Issue is with most things if you wait until it quits, most likely your not repairing or overhauling, your buying new as the internals are chewed up, brushes wear until they chew into the armature or slip ring, bearings wear until spinning parts make contact with parts that don’t etc.

If you plan on running the engine until it starts making metal best to plan on buying an exchange overhaul from the manufacturer as it’s likely to cost you that to overhaul by the time you replace all those hard parts the metal cam from and damaged.

If you choose to do the alternator inspection it’s most likely you’ll catch things before they break and can repair the thing before it’s eaten up.

But if you have something that’s old and heavy and you really want something new and lightweight, run it until it quits, but that may strand you somewhere away from home too.