Bravo Alternator Rebuild

[johnggreen]

Last week, I was flying my Bravo in solid IFR in steady, moderate rain when my master warning light blipped.  It happened so fast that I couldn't see what warning was illuminated on my annunciator panel.  I focused more attention on the panel and when it happened a second time, I saw it was my right alternator.  It happend once more and each time was so quick as to barely get the annunciator light illumninated.  Before, the day was over, I spent at least another two hours in light to moderate rain, but it never happened again.

I understand this might be a warning that the alternator is due a rebuild, so to be on the safe side, I'm going to rebuild or replace both with rebuilt units.  A rebuilt unit is about $1,000, but am told that the rebuild kit is less than a hundred dollars and that any good starter/alternator/motor technician can do the job and legally so if under the oversight of an A&P.

Any pointers as to the rebuild and sources for rebuilt exchange and rebuild kits would be appreciated.

Jgreen

 

[carqwik]

My right alternator failed after flying through heavy rain and moderate turbulence.  I simply replaced the Prestolite alternator (factory original) with a brand new PlanePower alternator.  The PlanePower alternator is more efficient, weights two pounds less, and fit perfectly although it does require some dismantling of the intake system to get access.  IIRC, it was less than $500 for the alternator plus 2 hours of labor. 

[AndyFromCB]

John,

The alternators are 4009ES, 70amp alternators, brand new from aircraft spruce at $560 a pop. Quality Aircraft Accesories is where I got mine for $570 but the shipping back and forth was cheaper for me. It took me about 2 hours under my A&P to take the old one off and install the new one, you need to take some other parts like baffles off to gain full access. For overhaul, they wanted $475.

Andy

[johnggreen]

Thanks for the info.  I'm taking it to the shop Monday to have the prop overhauled and at $550 range, I think I'll just have both replaced as they are at 1000 hours.  I am curious thought, does anyone know the mean time between failure for alternators?

Jgreen

[bbillb]

To carqwik

 

Just wondered if there was any issues with installing the PlanePower alternator in place of the Prestolite.

In the "Model Eligibility Fit Guide" on PlanePower's web site it says for M20M (single alternator installations only)

so they make it sound like its not allowed on the dual alternator Bravo.  Any thoughts on this as it seems

from other people's posts that the PlanePower may be the better alternator??

 

Thanks

Bob Byers

[carqwik]

Bob -

The PlanePower fit perfectly in place.  No shimming required, aligned perfectly with the belt.

Interestingly, I do not recall anything about "single" alternator M20M's...all of the ships came out of the factory with two alternators I believe.  However, there is a slight problem with the PP alternator in that it is so efficient that it "hogs" power production and my left alternator (original equipment) voltage idiot light flashes under lighter electrical loads. 

Apparently there is only one voltage regulator in the Bravo and it cannot be adjusted to balance the two alternators (at least this is what Top Gun told me IIRC).  So when the other alternator fails, I'll replace it with a PP alternator as well and that should bring things into balance.  That will lose a total of 4lbs at the far end of the moment arm too...a good place to lose weight in a Bravo!

I can say that I did read a lot of other posts (AOPA forum) and Mike Busch's comments (SavvyMX) about PlanePower and all were positive about them.

Ken

[johnggreen]

I contacted Planepower.  They do not have a replacement for both alternators so it was not an alternative for me.  The rebuilt exchanges cost me, I think, $625 each.  That may include a markup for the shop, I don't know, but my shop is always so reasonable in their overall billing that I won't be pinching pennies with them.

Jgreen 

[AndyFromCB]

Sounds about right with shipping costs. Mine were 570 plus about 40 in shipping to and cores back

[AndyFromCB]

There is actually two voltage regulators in a Bravo, Zeftronics, it just so happens they are sitting in a single box. However, they are not really load balancing voltage regulators, just a simple fail over connection from right to left chanel. Basically, the right channel is the master, with left only kicking in should the right side die. In order to trully balance, both channels would require a amp shunt pick up and our voltage regulators only have a sense voltage pick ups which BTW is a single point of failure as both channels get their sense voltage from Announciator Panel circuit breaker. If that one ever pops, there go your alternators. Or you can just turn on all your lights which will put enough load on them to limp home without exceeding about 30 volts. The G1000 Bravos, Ovations and Acclaims have a true load balancing voltage controller.

I have a plane power voltage regulator with a 9 pin plug sitting in my passanger wall pocket just in case the voltage regulator dies on me somewhere away from home. Total cost of about 200 in parts from PP and Moser. Plus it's great for tracking down issues.