BCS-12D-85 to a model 12D-4 HELP

[louiswp]

I need any accurate help on the following, A customer of mine has a BCS-12D-85 and wants to put an STC'd alternator system on his plane. The alternator is only approved for the 12D-4-85.

Now this is my question, his aircraft has all the upgrades and stc's that makes it a 12D-4 similar to how an ercoupe mods change a C to a D. even though he has all the mods his aircraft I don't believe would ever change to a -4 on the airworthiness certificate, data plate etc. I think it would only be on paper by upgrading the 337 forms stating that it meets the requirements and listing all the pertinent 337 changes.

I have done ercoupes changing from a C to D but it never changed the airworthiness certificate. Also this aircraft a few hours after being built was changed at the factory by adding the float kit and also adding the 85 engine.
has anyone gone through this with your taylorcraft. and is there other alternator systems approved for the BCS-12D-85

[Pearson]

Re: BCS-12D-85 to a model 12D-4 HELP

Both of those models are on the same type certificate. If the FAA will allow a type certificate as approved data, you could see if they will approve a one time STC using the TCDS as the approved data. I would point out the note just below the list of models in paragraph VII, (Same as Model BC12D-85 except for engine, baggage compartment , side windows and sky-lights)

[barnstmr]

Re: BCS-12D-85 to a model 12D-4 HELP

Louis,
I am not sure which Alternator STC you are talking about, unless it is the Classic Aero one. Is it a B&C or Plane Power alternator? It sounds to me like you must have the C85 engine STC # SA1-210. As the holder of that STC, I can help you sort this out. It seems you just need a DER approval finding that the two STCs are compatible. Give me a shout on email or by phone and we can work through this pretty easily.

Regards,

[louiswp]

Re: BCS-12D-85 to a model 12D-4 HELP

Louis,
I am not sure which Alternator STC you are talking about, unless it is the Classic Aero one. Is it a B&C or Plane Power alternator? It sounds to me like you must have the C85 engine STC # SA1-210. As the holder of that STC, I can help you sort this out. It seems you just need a DER approval finding that the two STCs are compatible. Give me a shout on email or by phone and we can work through this pretty easily.

Regards,

I have to check with the owner to see which alternator system he wants to put on. I am not concerned with the STC or field approval for the alternator since I can reference all the STC's which will allow the alternator.
My question or concern is he wants his airworthiness certificate and data plate to be updated to show its a -4.
I don't think the FAA would change it even though he has all the mods. I am trying to get all the facts before I check back with him and also get the feds involved. I am doing my research first.
Thanks