REFLECTOR: Interesting Gotcha this morning

Fri Nov 5 18:59:34 CST 2004

I had put a shot of spray foam in each duct on each end. Easy to get out or punch through if you need to run something else through there but quick and eay way to keep the water and cold air out. 

Rob

-------------- Original message -------------- 

> After fixing the leak in my sump tank, I decided I would clean off my 
> engine and reinstall my dip stick tube as it had become loose. 
> 
> I used the spray on engine degreaser and hosed it off afterwards. It took 
> two applications to get it really clean as the loose dip stick tube had 
> been leaking oil. Rinsed it down real good and let it sit for an hour 
> before taxing back to the hanger from the wash rack. 
> 
> Fired her up this morning and taxied out to RW 13. About half the way 
> there I started getting a pop corn sound in my headset! It was pretty 
> loud. I turned the ANR off and on, no change. Tried EI or right mag, no 
> change. Changing the rpm did seem to increase the rate of popping but not 
> as much as the rpm was changing. Turned off the intercom, slightly less 
> volume. Turned off the strobes, no change.. changed comm's the quality of 
> pops changed but still there. 
> 
> All indications voltage and amperage looked within norm. 
> 
> I sadly taxied back to the hanger... Damn, and we were planning a trip to 
> Mesa Verde tomorrow..... 
> 
> At the hanger I cycled electrical power and no change. Cycled again(I'm 
> stubborn) and it stopped!! Hmmm... Now thats good and 
> bad... Intermittents can be real buggers.. I could not get it to come back. 
> 
> I got out , looked at the alternator wiring, as much as I can see with out 
> de-cowling.. Popped the nose door and canard hatch. Nothing obvious??? 
> 
> My friend the local A&P/AI wandered by, he said he got worried as he heard 
> me taxi out but not take off. I told him the story and he didn't have much 
> more to suggest, except that it may have been an external source, some 
> local transformer or something. that got my hopes up a bit, but not much... 
> 
> I decided to fire up and see if it would come back by taxing 
> around. pushed out of the hanger, "prop clear!" and started the 
> engine. He got this funny look on his face and gave me the kill signal 
> while pointing back at the engine. I stopped it and bent out and looked 
> back. There was a puddle under the engine. I had not primed or ran the aux 
> fuel pump. 
> 
> I jumped out and went back, stuck my finger in the liquid, smelled, 
> tasted, it was water?? Wow, it was coming out of he gap in the cowling 
> where the vent and fuel whiffle valve lines are. 
> 
> It must be from washing the engine I said. Strange it didn't drain when 
> the cowling was off.. I went to the nose and lifted. Water gushed 
> out!!! Must have been 1/4 gallon or more! 
> 
> Then I realized there are gaps where the oil lines and wires go into the 
> two ducts on either side of the fuselage. In my quest to really rinse down 
> the engine and firewall to insure I got all the degreaser out I had sprayed 
> a bunch of water into the ducts! Who knows how many BNC and other 
> connectors are in there getting soaked. Not to mention the main big ol 
> wires for the starter/alternator. The shape of the fuselage is like a 
> banana and any liquid put in the firewall end of the duct would migrate to 
> the center of the fusalage... 
> 
> In fact I had noticed one time after I had changed the oil and really 
> bothched catching the oil from the filter, its mounted right above the left 
> duct. The oil poured all over that spot. A couple weeks later I had the 
> back seat out and there was an oil stain where there is access to the duct, 
> the pilled oil that got in the duct it had migrated up the duct to the 
> middle of teh fusalage. 
> 
> I held the nose up for about 5 minutes until all dripping stopped. 
> 
> Fired up and flew around for half an hour with no popping noise. Now I 
> don't know for sure if it was the water that caused the popping noise, but 
> I do know I don't want to get that water in there again! It could also 
> freeze and do who knows what? 
> 
> Scott 
> 
> "Those who sacrifice freedom to get security, deserve neither." 
> - Benjamin Franklin 
> 
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