BC12-D A65 to A75 Conversion

[CStence]

Re: BC12-D A65 to A75 Conversion

I'm not really following you on the problem. What ever this -14 engine is it still has a max continuous rating of 65 horsepower. The only increase is in take off power. It's still an A65 and shouldn't need any paperwork to justify the installation. Unless there is more to this story.
EO

The -14 engine actually makes 75HP at 2675RPM, which means whenever this engine is installed it probably has a higher operating RPM, just like an A75 does.
However, even if this was the same 65HP, it is still considered a major alteration because what is installed is different than what was originally installed (-14 as opposed to -8). That increase in HP (15%) makes it not only a major alteration, but one that can only be approved with an STC, according to the FAA. What I want to do now is de-rate the engine and operate it at 65HP (Not exceeding 2350 RPM in level flight). This should be straight forward since the engines are nearly one and the same (if operated the same).

Update: I have contacted a DER in Georgia who has been very helpful should approve the data for this (derated -14 installation) just as soon as I type it up for him. Then I'll just have to send the 337 to Oklahoma and we're home free.

[CStence]

Re: BC12-D A65 to A75 Conversion

Lots of people will install the A75 components as a reliability upgrade. The only way to get the power is to spin it at 2600 RPM. If your prop limits the engine at 2300 it only makes 65 HP.
If the plate says it's a 65, it's a 65, regardless of your letter.
EO

Oh yeah,...the plate is clearly stamped "A65-14" with the take-off HP listed at "75HP at 2675RPM." So really, it is even more surprising that it has gone all these years without catching the eye of an IA. Oddly enough, they have been operating it at A65 RPM ranges (per the prop pitch) so they weren't even getting the benefit of the higher HP.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

If it is stamped A65 that's what it is. The dash numbers are considered by Continental to be modification levels of the engine model. I believe the front of the parts manual describes this.
There is a Service Bulletin that covers the changing of the dash numbers with-in an engine family. You might be worrying about a situation that doesn't exist.
EO

[CStence]

Re: BC12-D A65 to A75 Conversion

If it is stamped A65 that's what it is. The dash numbers are considered by Continental to be modification levels of the engine model. I believe the front of the parts manual describes this.
There is a Service Bulletin that covers the changing of the dash numbers with-in an engine family. You might be worrying about a situation that doesn't exist.
EO

I don't think this is the case. The only engines that can be installed for the BC12-D are listed in the Type Certificate as: A65-8 (Taper Crankshaft), A65-8F (Flange Crankshaft) and A65-8J (Fuel Injection). Just as I can't install an A65-9 (different accessory case for starter) as a minor alteration since it is stamped "A65" on the data plate, I can't install other dash numbers because the engine family is A65.

You are right that Continental SB M47-16 talks about changing within the engine family. If it was simply a matter of changing from one engine dash number to the other, this can be done as a minor alteration since approved data exists for the change (ie SB M47-16). I've done this for C75 to C85 conversions. The issue at hand though is that no approved data exists for installing the -14 engine on the T-Craft.

[barnstmr]

Re: BC12-D A65 to A75 Conversion

Who is your DER in Georgia? Is it Bob Minnis? Tell him if he has any Taylorcraft compliance questions, to give me a call. He has my number.
Good Luck.

[CStence]

Re: BC12-D A65 to A75 Conversion

Who is your DER in Georgia? Is it Bob Minnis? Tell him if he has any Taylorcraft compliance questions, to give me a call. He has my number.
Good Luck.

Thanks Terry! It is Bob Minnis and I just heard from him today indicating that he was pleased with the data package I put together and would sign a Form 8110 in a week or so.

Terry, I see you are a DER as well. Question: What would be involved in approving the installation of the A65-14 engine NOT de-rated (75HP @ 2675RPM)? The most obvious thing I can think of would be answering the question of whether or not the engine mount structure can handle the extra torque. I was trying to work thru what that might be as I was typing up the report for Bob. Any thoughts?

[barnstmr]

Re: BC12-D A65 to A75 Conversion

I hold the STC for the conversion of BC12D to BC12D-85, also known as the "Gilberti/Harer STC". The nice thing about the STC is that it already contains approval for the structures aspects of the engine change up to 85 hp.

I have had some folks purchase the STC and then install a C75 or A75 engine instead. I provide DER approval of this as an STC deviation. I can do the same for you... The engine swap portion of the STC is $400. The weight increase is another $150 (increases maximum weight to 1280). If you only do the engine part now, the cost would be $450 including the extra approval for the deviation. Later, you could install a C85 and the wing mods for the weight increase. Check out the CAP web-log below for more information.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

I would disagree with the modification. Any engine of the A65 family would be acceptable for installation. Now if you wanted to install and make functional the accessories it becomes a different breed of cat. You can't go willie-nillie adding electrical systems just as you can't utilize 5 min full power ratings for continuous operation.
EO

[CStence]

Re: BC12-D A65 to A75 Conversion

I would disagree with the modification. Any engine of the A65 family would be acceptable for installation. Now if you wanted to install and make functional the accessories it becomes a different breed of cat. You can't go willie-nillie adding electrical systems just as you can't utilize 5 min full power ratings for continuous operation.
EO

What is your rationale? I.E. on what basis would you defend this position to the FAA?

[CStence]

Re: BC12-D A65 to A75 Conversion

Terry,

Thanks for the info. I'll pass it on to the owner to see if he would be interested.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

First, I wouldn't put myself into a position to defend.
The engine would have been modified per the approved Continental information as a minor alteration. Log book entry only.

The TCDS has information implying approval, mainly it has certification information.

[CStence]

Re: BC12-D A65 to A75 Conversion

I'm interested in what you're saying and would like to hear more. I follow you on the CAR's as opposed to the FAR's. I'm also with you on the engine change being a minor alteration per Cont SB M47-16. Where I get lost is where you say the TCDS implies that the A65-14 engine can be installed.

I also didn't see what you meant about the tailwheels - the current TCDS A-696 lists 8 different tailwheel models, so I would read this that those are the currently approved tailwheel models that can be installed as a minor alteration without the need for any other approved data (the TCDS IS the approved data for those 8).
I looked up CAR 4 and read thru it, but don't really see the point you are making. Could you elaborate?
Thanks.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

Continental considers all of the A65 engines a single model. Altering them per the service information would be a minor alteration. The dash number is nothing more than a modification level designator. If you choose to install a different dash number of the same model, so be it, but why would you install an electrical style engine on a non-conforming airplane? The manufacturers bought what they needed for the style of plane, either electrics or not.

[jim cooper]

Re: BC12-D A65 to A75 Conversion

What is gained by all of this? Certainly performance is not going to be much greater. Seems to me going to alot of trouble for very little reward. The Cont. 85 with a starter and Don Flowers mod to 0200 is the way to go if a change is wanted. (Humble opinion.)JC

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

I agree JC. The A75 is more "marketing HP" than something you can actually use. The C85 is by far the better choice.
EO