The International Cessna 170 Association

I got to fly 8180A this morning after an 8 month restoration, overhaul, paint and many upgrades. The overhauled engine ran great. The initial flight was about 45 minutes until the rings seated and the cylinder temps started to come down and stabilize. My new CGR-30 kept a close eye on the temps. The plane was completely re-rigged and I was not quite sure what to expect. However the trim was very close. We rigged it according to the book and it flew hands off. Hopefully that is the case.

It was a little nerve-racking flying a new engine AND a plane that was completely re-assembled but it was non eventful. I didn't get many pictures as I found myself pre-occupied with preflight etc.

The only squak we had was the generator. It is a brand new OH Falcon 20Amp. The first part of the flight the system was charging fine. About half way through the flight I noticed the generator did not appear to be charging. Battery voltage showed 12.7v with all the systems on.

When we removed the cowl for inspection we noticed this red waxy stiff all over the firewall. It was coming from the generator. It must have got hot and melted the internal insulation material. We removed the generator and had it tested by a local shop and it is working fine. Since I had to remove the generator, I decided to dump the oil and have a look at the screens. The fine screen had some fiber like material. Small black strands. I have never seen that before. We will keep a close eye on that.

I am looking fore some advice from the collective here. Could the regulator not be working causing the generator to over charge and get hot? Wouldn't the volt meter show a higher charge if that was the case? The regulator is the original unit. I plan on re-reading the generator troubleshooting in the 170 electrical manual again this evening.

Here's a couple pictures.

That looks like the glyptal (http://www.eastwood.com/glyptal-red-brush-on-1-qt.html) that is used for insulation of the windings but it usually dries fast and does not sling out. If that is what it is I can't imagine how it sprayed out onto the firewall.

Yeah. That is exactly what it is. We have never seen this happen before. I am going to call them tomorrow and ask about it. I had the generator tested here at a local shop and it was ok so I cleaned up everything and re installed it.

I cleaned and checked the regulator using the C170 electrical manual as a guide and flew some more this afternoon. It appears to be working properly now. I'll keep a close eye on it.

If the generator is overcharging the battery, it should show up as a constant positive current on the ammeter. It's normal to show a positive charge to the battery immediately after a start, but it should go back to near zero in a few minutes.

cessna170bdriver wrote:If the generator is overcharging the battery, it should show up as a constant positive current on the ammeter. It's normal to show a positive charge to the battery immediately after a start, but it should go back to near zero in a few minutes.

Yep...and it wouldn't take long before you'd smell sulfur as the battery boiled (lead-acid battery.) A LONG period of heavy charge should be monitored with consideration in-flight of pulling the CB/fuse to prevent battery overheating. A volt-meter is invaluable in such cases and I recommend all owners consider installing one. They are cheap and in many cases more useful than an ammeter. An alternative for those portable Garmin GPS users is to use the menu to add "external power" to the "numbers" page. If you're running a portable GPS with that feature you can digitally monitor your charging system.

When I had a new (rebuilt) generator installed a few years ago it did the same thing. It spit that red stuff on the firewall for a few flights and then stopped. It has shown no signs of improper operation otherwise so I just keep flying it.

Maybe they brushed on too much insulation when they put it together I had mine tested and verified all the wires. It has been working fine ever since.

Just be glad it isn't throwing GREEN stuff.





I can't believe we went that many posts talking RED without it being addressed, so there you all go. Your welcome

counsellj wrote:Just be glad it isn't throwing GREEN stuff.





I can't believe we went that many posts talking RED without it being addressed, so there you all go. Your welcome

It's amazing what some overhaul shops will do in an attempt make their generators put out more....