BC12-D A65 to A75 Conversion

[NY86]

Re: BC12-D A65 to A75 Conversion

I think you all are missing a point w.r.t. the A65-14. The engine is approved for 75 takeoff hp with a 5 minute limit. There is no way you can meet the RPM requirements for 75 hp while still meeting the static rpm requirements for the A65 in the airframe with a fixed pitch prop. You would need something like a Beech-Robi adjustable prop. If you install a fixed pitch prop that allows you to reach the 75 hp rpm you will not be able to reach 65 hp without exceeding the (65 hp) redline in level flight.

Your argument for installing the -14 in place of the -8 is that there is no hp increase as you are using the same prop and static limits as the -8.

[barnstmr]

Re: BC12-D A65 to A75 Conversion

Charles,
That's good news. You'll be glad you did this extra leg-work when the owner gets ready to sell the airplane. If you didn't get a DER approval, it would come back on you somewhere down the line.

[CStence]

Re: BC12-D A65 to A75 Conversion

Hey guys, just got my approved data from the DER, Bob Minnis. He was most helpful to work with and was prompt in his response time. His phone number is: (678) 494-0797. Email: [email protected]

Anyway, I've attached the engineering report and approved data form if anyone cares to see what it looks like.
Thanks for all the help!

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

Charles, keep up the good work and fly safe.
EO

[CStence]

Re: BC12-D A65 to A75 Conversion

Jim,

In this instance what is gained is that the fellow's airplane is airworthy again. If I could leave the engine as is, he would have a 10HP increase which would be something too. The original problem is that the aircraft doesn't conform to the Type Certificate. This is the easiest, legal path to do that, even though he ends up with, at best, a more reliable engine (due to the better cooling and lubrication) and a thicker logbook.

EO,

I completely agree with what you are saying about Continental engines. I've done this myself several times, per Cont SB M47-16. Again however, the question is not whether I need DER, STC or other approved data to change the engine. The question is why I would or wouldn't need such data to effectively alter the airframe by installing the changed engine.

As I understand it, the job of the IA is to determine that (1) the aircraft is conditionally airworthy and (2) that it conforms to the Design Type Certificate. Nothing in what you said clearly points to why if the T-craft Type Certificate A-696 calls for an A65-8, -8F or -8J I could just go ahead and install a -12, -14 or otherwise.

Regarding CAR 4a477, I see the reference you were referring to regarding tailwheels. However, I would argue that, like FAR 23, these are guidelines for the designer of the airplane, prior to final certification. Once the Type Certificate is issued by the FAA, the whole airplane is certified in whatever manner it was presented to the FAA. THEN as an IA, at each annual, it is my job to make sure the airplane still meets the design parameters in which it was presented to, and certified by, the FAA.

[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

[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

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.

[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

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

Terry,

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

[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?

[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

[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.

[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?