One would think that with so many SR22Ts flying, someone would recognise this… Also there are some SR22 owners here and they ought to know what output this alternator has, so they can shed any non-required loads. But maybe the existence of this system is not widely known?
Amazing that nobody with a Cirrus (apart from jxk’s post further back) has reported if they have this system… these systems need an AFMS so you would eventually become aware of it. Or it could be that the models sold to Europe rarely have it.
Anyway, having been in contact with the original designer of the B&C product line, which goes back about 25 years, I now know quite a bit more about how this all works.
The project is progressing. Here is the whole kit, with the original “mockup” unit (which they sent me 3 years ago to check for dimensional fit) shown in the pic
Well, 4 years late is better than never, and I am pleased to say that the “information” posted here is completely bogus.
The BC410 alternator outputs 15A net (18A with the 3A of field current) at 2400rpm engine speed and 18A net (21A with the 3A of field current) at 2575rpm engine speed. I believe the drive point is geared up by 1.3x from these figures. Its voltage regulator is set to 26V.
This is sufficient to power the whole of my TB20 in cruise, with things like lights turned off.
It is without cooling air going to the alternator, too.
Unfortunately I don’t think there is an easy route for approving these B&C alternators for EASA-reg aircraft. If anyone knows of one, it would be great to hear.
@Peter, I will completely remove my TB20’s vacuum system next week, after a vacuum pump fail.
I decided to put a Garmin G5 AI instead of the mechanical AI and since I don’t see where else the vacuum system would be used (I have an electric turn coordinator) I am tempted to use the pump panel to drive a backup alternator.
Can you please tell me if after all these years you found any 14V backup alternator that I can install in place of the vacuum pump (not the secondary accessory port that most probably is empty) on my FAA Socata TB20?
Thank you!
AlexTB20 wrote:
I decided to put a Garmin G5 AI instead of the mechanical AI .What A/P do you have? AFAIU the G5 AI can’t provide attitude information to autopilots. (Except possibly Garmin’s own autopilots.)
and since I don’t see where else the vacuum system would be used (I have an electric turn coordinator) I am tempted to use the pump panel to drive a backup alternator
DG/HSI…?
Alex – do you have a King autopilot which uses a vacuum horizon? Check this first.
The B&C alternators will do 14V also. The installation needs a Field Approval and this is hard to get done in Europe. I did mine via a guy in the USA for $1000. He would probably charge more this time because the FAA is making these harder. OTOH he will have less work to do… I can give you his details.
The standard TB20 fit has been a KI256 horizon / flight director and a King autopilot (later ones used the FD). There is no way to replace the KI256 other than EFD1000+EA100 or G500+GAD43 or G600 or…?
I am lucky enough not to have the King autopilot installed. It’s an S-tec 60-2, driven by the electric turn coordinator.
Is the G600 already approved for the TB20? Last time I checked for a glass panel solution there was only one STC issued for G500 only, by Daher/Socata, at around 45,000 euros per install.
Someone sent me this photo of a TB20 which did the backup alternator mod using a more radical approach
He removed the vacuum pump (for which there is a number of routes e.g. the old G500+GAD43 or EFS1000+EA100 and some recent ones) which freed up the drive pad. However the notes on the drawing say that the pump was moved to the lower accessory drive, but most IO540-C4D5D engines as built by Lyco don’t have a drive shaft there, which then makes sense in the following:
Incidentally to the alternator installation, you can see he also had the engine rebuilt to change the accessory gearbox to use two magnetos instead of the D3000 single shaft dual one. So the engine changed from a -C4D5D to a -C4D5. I think it must have been this guy.
An interesting note on such a project is that if you take such an engine to an EASA engine shop for say an overhaul, they will return it to you rebuilt as per the Lyco MM, not as you sent it to them! How do I know this? I’ve asked some 
So you need to be damn careful.
It’s a bit like taking a VW diesel (with the VW software cheat fix either not implemented or reversed) for a service; if they implement the cheat fix, despite a prior agreement not to, they can just laugh in your face because they merely followed VW policy so can regard the agreement as void. So most people who want to keep their diesel going nicely and not trashing the £1000 EGR valve every year avoid going anywhere near a VW dealer.
I finally updated my TB20 backup alternator article.
