The International Cessna^® 170 Association

I just had work done on my 170b (new generator & muffler), and I looked under the cowling after the first flight back up today.

To my shock, there was an orange mess below the generator and on the side of the firewall and battery. The substance was a wax-like goo, as it hardened as the engine cooled down.

I took the cowlings off and did a thorough inspection, but found no areas where I saw it could have leaked, burned, or melted from. There was no damaged oil hoses or scat tubing. The engine also ran fine with no indications of a problem.

My only guess is it came out of the vent hole on the bottom of the new generator, but it looks like it splattered against the side of it, not coming out the vent.

Thoughts?

Firstly, that tube on the bottom rear of your generator is not an exit vent. It is a cooling air INlet. It should be plumbed to a source of fresh, cool air, such as via the aft engine-cooling-baffle bulkhead. Air enters your generator thru that tube, then travels forward inside the generator and exits the generator at the forward generator openings next to the engine accessory-case.

There is nothing inside your generator (at least that should be there) that would result in a waxy, orange gel that hardens.

It may be possible that some object such as packing-material your mechanic may have left inside your cowling or exhaust/muffler that heated/melted and blew aft to splatter on the firewall, gen, etc.

I’m guessing something inside your muffler-shroud such as packing materials, etc. What exactly was done to your mufflers?

GAHorn wrote:Firstly, that tube on the bottom rear of your generator is not an exit vent. It is a cooling air INlet. It should be plumbed to a source of fresh, cool air, such as via the aft engine-cooling-baffle bulkhead. Air enters your generator thru that tube, then travels forward inside the generator and exits the generator at the forward generator openings next to the engine accessory-case.

There is nothing inside your generator (at least that should be there) that would result in a waxy, orange gel that hardens.

It may be possible that some object such as packing-material your mechanic may have left inside your cowling or exhaust/muffler that heated/melted and blew aft to splatter on the firewall, gen, etc.

I’m guessing something inside your muffler-shroud such as packing materials, etc. What exactly was done to your mufflers?

Thanks for the tips about the genny. I've never had a tube installed on any generator I've had, but I'll ask my mechanic about it on Monday.

My RH muffler was replaced with a new one as the old one had cracks.

That is a mystery. Does it completely harden eventually?

What did your mechanic use as a gasket to install the generator. Hopefully only a new, complete gasket. By complete means he would have also had to remove and reinstall the tach drive as it has a shared gasket with the generator. Would he have used an orange silicone make a gasket?

If he used a orange silicone make a gasket I'd start to get real mad. I'd wonder about his work. And I'd probably have to have it done again this time by someone who knows orange silicone (or any color) is not necessary or called for in the maintenance manual in any application on the engine.

If you haven't, I'd be sending those pictures to the mechanic and asking him to identify the substance.

From the X30013 Overhaul manual for your engine:

You’ll have to let us know what the “orange goo” turns out to be. Looks just like something I’ve seen before…discovered on one of the main landing gear parts during post flight on the 550, we didn’t know what it was but thought maybe it could be remains of a bird strike. Turned out to be a large splatter of fresh grease left over from a recent gear inspection and lube.

reecewallace wrote:... I looked under the cowling after the first flight back up today.

To my shock, there was an orange mess below the generator and on the side of the firewall and battery.
Thoughts?

Reece,
Clearly a bird strike. Chicken À L'Orange. If it happened in the States the FAA would like you to fill out this form.

n2582d wrote:

reecewallace wrote:... I looked under the cowling after the first flight back up today.

To my shock, there was an orange mess below the generator and on the side of the firewall and battery.
Thoughts?

Reece,
Clearly a bird strike. Chicken À L'Orange. If it happened in the States the FAA would like you to fill out this form.

Didn't look like a bird strike to me. No indication of any strike (no feathers, bones, guts), and it's deep within the cowling. I've hit a bird before, and it was a lot different than this.

darhymes wrote:You’ll have to let us know what the “orange goo” turns out to be. Looks just like something I’ve seen before…discovered on one of the main landing gear parts during post flight on the 550, we didn’t know what it was but thought maybe it could be remains of a bird strike. Turned out to be a large splatter of fresh grease left over from a recent gear inspection and lube.

I'll let you know! My mechanic is going to look at it tomorrow and I'll post here about it once he does

Bruce Fenstermacher wrote:That is a mystery. Does it completely harden eventually?

What did your mechanic use as a gasket to install the generator. Hopefully only a new, complete gasket. By complete means he would have also had to remove and reinstall the tach drive as it has a shared gasket with the generator. Would he have used an orange silicone make a gasket?

If he used a orange silicone make a gasket I'd start to get real mad. I'd wonder about his work. And I'd probably have to have it done again this time by someone who knows orange silicone (or any color) is not necessary or called for in the maintenance manual in any application on the engine.

If you haven't, I'd be sending those pictures to the mechanic and asking him to identify the substance.

My mechanic used the proper gasket to install the generator, not silicone. My best guess is it was some type of grease or compound build up that splattered once I took off. The waxiness of it is odd though.

reecewallace wrote: My mechanic used the proper gasket to install the generator, not silicone. My best guess is it was some type of grease or compound build up that splattered once I took off. The waxiness of it is odd though.

Good to hear your mech didn't use silicone, but you know somewhere someone else has. To be honest it didn't really look like a splattering of silicone but I couldn't think of any other orange substance that would/could be found at that location. Kind of looks like Model 28 though that is more red.

UPDATE

Turns out, the substance was paraffin wax and it was coming from within my newly overhauled generator.

I took the cover off the generator and it was pooled full of wax. I used a heat gun to melt and clean all the wax off the firewall and surrounding areas, and it melted at a relatively low temperature.

The overhaul shop said it's now standard practice the cores are coated in wax during storage, and it melts off when it heats up. However, the technician told me it shouldn't melt off in winter temps (about 4°C), and usually melts during the summer. He said the generator may have been overworked (maybe a regulator issue?).

That said, the generator is attached to an extremely hot engine which I feel would melt the wax, even in the winter.

I ran a scat hose to the new generator that I installed on my O-300.I just felt better having something hooked up to that cooling fitting on the generator.

No idea if it helped, but it ran fine until I pulled it. Pretty easy to do from almost straight above the generator.

Reece….. exactly from WHOM (which Overhaul Shop) did you purchase that generator? I’m very curious who it is that is coating armatures with WAX. The only thing I’ve ever seen used for protective coatings of fields and armatures is shellac.

GAHorn wrote:Reece….. exactly from WHOM (which Overhaul Shop) did you purchase that generator? I’m very curious who it is that is coating armatures with WAX. The only thing I’ve ever seen used for protective coatings of fields and armatures is shellac.

I purchased it from Falcon Aero --> http://falconaeroparts.com/

Also, we looked in the 170b illustrated catalog, and the generator is not hooked up to a scat hose in this instance. My mechanic said in some planes it's illustrated to connect it, but not the 170b.