voltage reg/alternator conversion

[James Mathias]

I would like some input. My pa 30 is having some electrical issues. We believe the voltage regulator is causing the problems. Here is my delemma my engines have 1700 hrs on them and relatively new generators. I would like to convert to a pa 39 when engines are redone, can I do an alternator conv.now and use the same ones when I switch rotation on the left engine? Or would it be best to change out the voltage regulator now and wait for the alternator conv at a later date when engines are replaced or rebuilt?

[N3322G]

James,

I don't know enough to answer this question but I can share that we replaced the voltage regulators on the 39 with Zeftronics stuff and have been very happy with the PMA'd (can't recall which they were) products.

[Zach Grant L1011jock]

James,
I would really think twice about converting your right engine to the LIO configuration. With this change in basic rotation comes a change in stall strips, a change in rigging, a change in prop blades, magnetos, governor, vacuum pump, starter, and yes rotation of the alternator/generator. It is not a small thing to do (read expensive), and for what gain? Vmc on a normal Twinco is really only 80, even though they raised it artificially to 90 to keep the less qualified people safe. If you pop the right engine you are exactly the same as a C/R airplane anyway, and thats with 50/50 odds (which I would kill for in most casinos). I like the fact that all the parts and accessories are interchangeable rt to left on a normal twin, it makes trouble shooting much less expensive. I also like not spending 3 times as much or more on internal engine parts at overhaul (cams/cranks etc). The C/R is slower, doesn't climb as well, and overall is what it is, a marketing stunt by Piper to try and salvage the reputation of the TwinCo, after it was tarnished by totally unrelated actions of the stupid training practices of the day. I have had both C/R and Normal Twincos, and have flown all sorts of light and medium twins in both configurations. At the end of the day, you do what you need to do to control any aircraft. I never once have thought about which way the prop is turning when I have had to shut one down. You push in on the rudder, and fly the plane, period, or you will be a headline in the local paper. Those results are the same regardless what configuration you have.

As for doing the alternator conversion, you have two very good choices. Interav is the tried and true solution (I have had great luck with this system on both singles and twins), and the Plane Power system, that is a newer system, and has some nice features. Short of that, if your gens still have the carbon pile regulators, I would highly suggest getting solid state replacements from Zeftronics.

Zach

[steen]

Hi, James.
If your engines only have 1700hrs. smoh and are in good shape, you probably have 600-800hrs. before overhaul, as the IO-320's if properly maintained are good for much more than 2000hrs. I usually run mine to 2500hrs. (not for hire) and upon teardown find the lifters are showing beginnings of spauling and the front main bearing is nearing limits. Oil consumptions is usually up to 1qt./10hrs. at that time also.
Long way of saying I would replace/repair the voltage regulator and fly on....assuming the engines are in good shape, of course.

My '66B is CR and I could not be happier with it. Zach is correct, of course, that when an engine quits you don't (shouldn't) say "Gee, the (l)(r) engine just quit" You merely step on the rudder and fly the plane...end of story.

The only way I use the lower VMC of the CR is when deciding how short a runway I will use. There are no published documents re balanced field lengths for the Twinkie, CR or normal, but there are some charts for TO and stoping distances and by combining that data and calculating the distance covered during my senility-long reaction time I came up with 2600' at sea level/standard conditions as my personal balanced field, with the usual density altitude adjustments for other conditions. By balanced field I mean acceleration to 80mph, 1 second to realize I've lost power on one side, and a full effort abort to a stop on the runway. Using the worst case scenario for the normal rotation with the higher VMC the distance is nearer 3000'.

Of course I still occasionally go into shorter strips but I do so knowing that in event of an engine failure I am for all practical purposes in a single and must just act accord lingly.

I don't entirely agree with Zach on the costs, altho' he is correct to a certain extent in that you can't re-use your old vacuum pumps, starter, mags, etc. on the new CR, but when I overhaul I overhaul all and I get accessories done too, so not much change. The engine internals are the same except for the cam, which is, as Zach says, three times the cost of the normal rotation cam, but crank, pistons, etc. are the same. The prop, of course, must be entirely different, but, again, you weren't gonna fly that old prop on a brand new engine anyway, were you? so the expense of a used rebuilt CR prop is somewhat offset as you would have had your old prop refurbished anyway. And, a new CR prop is more expensive (40% last time I bought two new props)
than the normal rotation.

Just some thoughts...let us know what you find and decide.

By the way, I still fly generators with all their shortcomings because on two occasions over many years I have been in nowheresville ready to return home and found a dead battery (yes, once I left the master on 'cause I flipped it back on to reset the Shadin after fueling and forgot to flip it back off.....the other time we never figured out what happened as when arriving back home the battery was charged and never caused any other problems). With generators I could do this but with alternators I could not as the alternator requires battery voltage to excite the field so it can make electricity, thus would be dead as the battery. The generator, like me, is always excited and ready to go.

Steen

[James Mathias]

Thanks Pat,Steem and Zach It is great to get this feedback. It really helps for a newbie like me.
Jim

[Zach Grant L1011jock]

Steen,
Check the Lyc. parts book. The crank for the LIO is different. The oil capilaries are drilled opposite angles from a normal rotation engine, and the crank is over 10K alone if one is available (learned this by personal wallet impact). As for the time since overerhaul, I agree, 2500 hrs should be a good number for an engine that has flown regularly and doesn't have more than about 15 yrs since it was opened up last. If it has been longer calendar time, then the operating time is reduced significantly due to inactivity.

As for the gens vs alternators, absolutely, correct in the fact a plane with a totally dead battery can get the generators to charge, where an alternator equipped aircraft will not. This assumes that the battery relay can be pulled, and that the power being generated can get to the battery (otherwise you have a hot bus, but no battery in the circuit as a capaciter, and it can also cause mayham on radios and other electronic devices). Different airplanes are wired differently, and as such, getting a jump in a B or later, and some 4 window models are also this way, won't bring the battery online. If you have a generator equipped plane, they will continue to produce power. If something happenes to the alternator charge (over volt etc) and it kicks off, with no charge in the battery, total electrical failure. Even if it is as simple as pulling the battery, and hooking it up to some jumper cables from a running car, and let the car charge the battery for a half hour or so, it is much more desireable to getting a jump on a flat battery, and then trying to go fly, regardless of the charging system in the airplane. Its all about acceptable risk, and to me, Ill find a courtesy car and some jumper cables and delay an hr.

All, here is a special treat, since acel/stop distance came up, attached are the charts! All that is fine and good IF you actually keep the plane on the ground to 90 mph (which is very difficult to do). Once airborne, all bets are off. Since most of the time twincos like to come off at 80-85 (especially at lighter weights) regardless what you do besides a wheelbarrow event, I tend to look at the time period between 80 and 90 as the ground effect time, and by the time you exit ground effect, the gear is coming up, you have 90+ mph and are accelerating to 105 very quickly. 90 is actually Vxse so the plane will continue to fly and accelerate if it isn't too hot, heavy or high, as long as it is clean! I say all this for the point that using the 90 mph accel/stop chart is optomistic to say the least. The 90mph chart should be about 500' longer minimum in my opinion for real world ops, but at that point you are flying and all bets are off anyway! The 80 mph chart is much more realistic, as most have not left the ground by 80 unless on a max effort, and that is a whole different discussion! Enjoy.

-Zach

[steen]

Thanks, Zach, for the info.
My majors replace everything (or overhaul accessories) except the case( which I have align bored), the crank and the oil pump as it usually shows no wear. Thank goodness I did not have to replace the crank on either engine so far, but the LIO is something to look forward to, isn't it? Wow! By next overhaul if they go full time the cranks will have 5000+ hrs. on them so I might as well start that operating fund now.
Some cranks are becoming tough to find....the rebuild of the O-235 in my restored PA-12 was ridiculously expensive as those cranks are disappearing (I restored it authentically and kept the same dash number and original crankcase and this ran the price up a bunch.
Once more, thanks.
Steen

[Kristin Winter]

My experience mirrors Zachs in many respects. I have been partners in a PA-39 and now own a PA-30C. On balance, I think that safety argues for normal rotation engines. The PA-30 stands a better chance of climbing out on one engine if the airspeed is above 90 mph. So the only scenario were I would be happier to have a CR would be if the aircraft rotated below 85 mph and the left engine failed completely, at just that instant. Two seconds longer, and the speed would be over 90 with the gear coming up and I wold be happier to have the improved climb performance of the normal rotation.

I also have experience with Navajos which come in C/R and normal versions. When Piper decided to market a C/R Navajo, they had to bump up the power by 30hp to keep the performance in the same range as the normal C model. The C/R is a marketing gimmick, pure and simple. Even if I thought that the C/R was a bit safer, I would have to think long are hard about spending the money to go with counter-rotating engines. There are a lot of ways to put that money to better use to improve safety. Airbags, better autopilot, more training, or just more flying all come to mind as worthwhile safety expenditures that would likely give more bang for the buck than going the C/R route.

[Ray B]

Interesting note-----Have you noticed that the P-38 has C/R props but they turn the "wrong" way! They both turn outward. I ask Tony LeVier about this, back in my younger years, and he said they leaned during testing that it gave them the highest airspeed for that design. So the question is if you swapped a PA-39s engines to the opposite side would it go faster? Anyone out there with a supper computer that could do this in theory? --------If it is faster who will be the first to go experimental and swap engines just to go faster than Hans? Ray B

[9089P]

Maybe this is the Last Great Mod that Hans has planned!:-)

Don

[James Mathias]

We tracked down the problem. The left generator was not putting out anything and the parallel relay failed so apparently the generator was using the battery to run like a motor. We have ordered a new gen and Zefronics parallel relay.

[Zach Grant L1011jock]

Ray,
Piper also went contra rotation on the aerostar 700P for the same reason as the P38. It's faster, and by definition, doesn't have a " critical engine" either....

James, glad you found your electrical issue.

Zach

[15384]

Since forking out some major bucks to up date my original 1963 panel in my PA30 I have now been thinking about alternators verses the generators I now have.

The reason being is because the updated panel has some glass items. Problem is with the generators not producing output until at least 1350+ rpm and being at a large airport where I have to taxi quite a ways. If I don't keep the rpms up in order to keep the voltage up to keep the glass items happy then I'm getting flags saying Low Voltage. The voltage will dip to 12 and keep heading south in short order. Glass doesn't like this, then wants to go on their back up batteries. Hassle.

So the altenative is to try and taxi making turns etc. with 2 engines making 1500 rpm and if I do that then I'm riding the brakes for 10,000 foot runway plus the real estate from the hanger to even get to the taxi way for the runway. I'd be doing brake pads twice a year.

So since my generators work fine, are in excellent condition, I have the Zeftronics regulators, what my solution is, is to taxi out to the Hold Line at normal rate, wait until I've done my Pre Take Off list routine, up the rpms, stand on the brakes then I turn on the glass gadgets, let them go through their warm up routine, make my inputs then go. This is about a 5-10 minute ordeal.

I would be nice to have alternators because of this issue but oh well I'll just keep what I have, not ride the brakes and use the money it costs to convert for fuel money as I continue IFR Training or to hire a personal Tutor for this blasted IFR Ground School.

John