[GMAs]

I thought we went over this issue with the alternator stuff written in great depts before... but, as to the two couplers... the cont one is much better... why because it doesn't have the rubber potting problem that is caused by the heat and oil impregnations...

also the alignment problems is not as great as one would think.. Bob... as the gear is held by the bearings on the alternator thru the shaft and a bushing that controls movement... and while I agree its kinda a flakeie design... their are millions of cont engines out their from 0-200s on that are using them... and they have a good life expectancy...

No rather because your breaking the shaft... something else is happening... which can range from the cam gear and its bearing in the case being worn out... to the alternator its self and the instanious power loading... and these range from the bearing in the alternator.. the reason we say change them ever 500 hours... to the gear motor in the plane spiking it when you flip the gear handle... it is this spike that will demand that the alternator go from a low current setting to a high one suddenly.. and requiring more hp in a instant... which puts a larger load on the coupler and invertenly on the gear...

Also engine RPM... plays a part.. after all if your crusing along.. the alternator mass is real happy at what ever RPM its spinning at... but, if you go to a lower RPM.. and demand the same power thru the shaft... it gets to vibrating by the gear tooth messhings and not...

Now as to the issue again of the larger alternators... 65 amp... the engine was never designed for it... the gear is at its max when you put it in.. and that includes the shaft from the alternator.. unless they change their dia and design ... they will have quite a large loading on the little shaft... and with the gear hanging almost 3 inches off the nose of the alternator... think of the stress that the little gear is putting on the shaft... when your demanding all that power... kinda wants to make the cam gear force the alternator gear out of mesh.. reason for the gear vibration and groan...

Another thing we have found is that the shiming and locking nut on the end of the shaft... is incorrect... in other words some bozo... cranked it down until it bound up the whole mess... when in fact he didn't put the gear assembly on the shaft correctly and check its seating... the gear is supposed to have some play in it... (rotary) If it doesn't then something is binding and yes you can snap the shaft off...because the coupler can't do its job of dampning the vibrations... and load spikes...

Most mechanics don't even know that their is a overhaul manual... that specs out the tolarances for assembly of the drives... actually cessna sells it.. yep it a charging system manual.. even covers the regulators and the changes that took place... and shows the design of the highly reguarded 400 series... which we have covered before... you don't need it.. never will and its a bandade for the real problem that is happening...

Oh and one last thing to check... is contenuity... of the connections... ya we found one that the output post/stud was lose on... because again some bozo over tightened (actually the owner did it himself and was real proud that he found it lose and thus cranked it down with his little wrench)... and cracked the plastic insulator... it was bouncing around and this caused a lot of problems in the system that one would not think the stud was.... and yes he changed the regulators thinking that everyone else knew what was right for him... besides the regulator change... and the new overhauled alternator... it was a cool 3 grand... and the system was finally back where it should have been.... smile...

so before you leap into ... lousy design... you might want to go check the connections... 90%of what we find... it connections that have gone bad.. not the mechanical equipment...

And a few simple rules... replace alternator bearings and have it overhauled every 500 hrs.. for the high flyers.. more often...

Use a battery in line with your voltmeter to check connections... that way you can see the IR drop... otherwise the connection could look good... and really be bad when the current demand flows...

Don't jump to conclusions.. early.. on...

their is nothing wrong with one altenator taking the load... as you need more.. it will bring the other one on line to suplement the output demand... and actually the offset will keep them from doing something else that will break shafts and shear couplers... called alternator bounce... where they oscilate back and forth with the output... that is not good... resulting in both of them tripping off line eventually.... so for you all who want the alternator balanced... beware of the alternator bounce/osclation... it can damage your engine/drives and alternators... but, as we mentioned before... the fact that their is a differance in the cable IR drop/lengths... this hasn't been as much of a problem as one would think...as cessna engineers lucked out on the position of the engines... etc... smile...

What ever happened to the articles that were written on this subject... does anyone have a copy of them that they could repost... I see that their were only two people who want to have a siminar on the alternators and charging system.. so I guess we won't schedule anything for it... must not be a topic of interest... Hmmmmm

AC in a plane has no place... except in the wet hot state of florida.... I kept hearing the words... we should give it back to the indians... but, they probably took the money and ran to the north... thinking the settlers were stupid and would want their money back onece they lived their a while... why... we fond that just lifting your glass to drink water you swett...more than you drink.... smile... GMAs