O-290-D Alternator Conversion

[8359]

Thanks for the suggestions and information John and Edd.

I found an IA that i think will be able to help me out, we are working through it now then I have an appointment at the FSDO on the 27th. The IA did have a few questions, he asked if I had a maintenance manual for the airplane, I’m not sure if one exists for the 120/140? What he was trying to find was whether or not the prop needs to be rebalanced after it’s removed.

Can anyone point me in the right direction?

Thanks and Merry Christmas!

[6643]

There is no maintenance manual specifically for the 120/140. There is a lot of good, applicable information in the Cessna 100 series manual, but "back in the day" standard practices and service bulletins were the rule. Today, AC43.13 constitutes approved data for our purposes.

As to your question, the prop is normally balance at (its) overhaul. The only reason you might argue it needs to be rebalanced when removed is if it was dynamically balanced on the plane, but, even then, I've never heard of it being rebalanced after removal, much less requiring it to be rebalanced.

[4004]

Of course I agree with John C. Just a point, label/mark EVERYTHING as you remove each piece, including each washer and return to the exact location - some balancers use small items such as washers to achieve a precision balance. 2C

[8359]

Circling back here. I was able to do some testing over the weekend and narrowed the problem down to the voltage regulator.

However, I do have a question about getting a field approval vs just a 337. I was talking to my A&P and he mentioned that the O-290-D IPC lists an alternator (LW-14347) as a certified standard alternator for the engine. He thinks based on this and Service Instruction SI1154U I would be okay to install that alternator without a field approval.

Any thoughts/experience with this? If that's true, we'd still need to fill out and file a 337 as it's a major alteration, correct? Would it be possible to extend this to then use an alternator that is specified as a certified replacement for the LW-14371?

Thanks for the input guys.

[6643]

I'm not sure I follow...

First, there is not a 337 vs. a field approval. Form 337 is used to record a major repair or major alteration. Every major alteration or major repair must be recorded on a Form 337. Every Form 337 must be supported by Approved Data. There are 8 types of approved data. They are:
1. Type Certificate Data Sheets
2. Aircraft Specifications
3. Supplemental Type Certificates (STC's) (Note: Persons interested in using an STC must have approval in accordance with 49 U.S.C., section 44704, from the holder of the STC prior to it's use.)
4. Airworthiness Directives (AD's)
5. Manufacturer's FAA Approved Data (DOA)
6. Designated Engineering Representative (DER) Approved Data With FAA Form 8110-3, Statement of Compliance (Note: This type of data usually requires additional approval.)
7. Designated Alteration Station (DAS) Approved Data
8. Appliance Manufacturer's Manuals (Excluding Installation Instructions)

In addition,
AC 43.13-1, Acceptable Methods, Techniques, and Practices (Aircraft Inspection and Repair), may be used directly as approved data (for repairs only) without further approval only when there is no manufacturer repair or maintenance instructions that address the repair and the user has determined that it is:
• appropriate to the product being repaired;
• directly applicable to the repair being made; and
• not contrary to manufacturer's data.

AC 43.13-2, Acceptable Methods, Techniques, and Practices – Aircraft Alterations may be used as approved data for major alterations when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337 when the user has determined that it is:
• appropriate to the product being repaired;
• directly applicable to the repair being made; and
• not contrary to manufacturer's data.

FAA FIELD APPROVAL (FAA FORM 337) issued for duplication of identical aircraft may be used as approved data only when the identical alteration is performed on an aircraft of identical make, model, and series by the original modifier. (I recall the form 337 used to have a block you could check if you were applying for multiple approvals, sort of like a personal STC.)

FAA Form 337s approved in 1955 or earlier may be used as approved data.

Previously approved 337s from 1956 and later can be used as acceptable data in support of a field approval.


Note that alternators and Generators are considered Airframe parts. While a particular appliance must be approved for installation on your powerplant, it must ultimately be approved for installation on the airframe.

I don't see any issues with installing the alternator on the engine, but you still need approval to install it in the airframe. Depending on the properties (output) you may be able to piggyback off of an existing STC (for the Cessna) that allows installation of a similar alternator. Whatever the STC calls for you'll have to duplicate, like overvoltage protection, alternator ventilation, instrumentation, etc.

[8359]

Thanks for the clarification John, I apologize this is all new to me, so I'm still trying to get it all straight in my head.

I think the A&P was hoping this would be approved data that would avoid having to get a field approval. I was in the process of getting the approval from the FSDO, but because of the shutdown that's at a standstill. I suspected his method wasn't right because I thought it had to be tied to the airframe somehow, which the two documents he provided do not.

I think I would still prefer to go with the B&C BC400 Kit. It comes with all the required brackets, voltage regulator, etc, and is the same price as the "approved" Lycoming alternator. I think I have solid supporting documentation for this conversion kit, I just need to wait for the FSDO to reopen.

Here is what I was going to present to the FSDO, if you have a moment to look it over and give me your opinion, I would appreciate it:

-STC for the kit, listing Piper PA-20, PA-22. (the TCDS for those aircraft list the O-290-D as an approved engine).
-An approved 337 for a Cessna 150 with the same alternator conversion kit (O-320). (This is the closest I could find to a 120/140 w/O-290)
-A filed out 337 listing my airplane, using the approved one noted above as a template, with updated drawing numbers, part numbers and dates.
-Installation instructions, Parts List

I guess based on your response above it may be helpful to also present the STC for the 120/140 C85,C90,O200. However that STC uses a different alternator kit, so I think it may muddy the waters?

Thanks for the help.

I think I'll also take Edd's suggestion to get in contact with that Lycoming employee and see if I can find any other route to do this.

As much as I'd like to fix the generator and be on my way, I'd like to pursue this as an alternate just in case.

[6643]

If the B&C alternator in the kit has the same electrical properties as the one in the 120/140 kit then the data in the Cessna STC would be worth presenting. I'm a little rusty; is the B&C alternator the one with the spinning outer housing?

[8359]

Here’s a link, when you say electrical properties, you mean same volt/amp rating? Or something else?

http://www.bandc.aero/alternatorbossmou ... pma-1.aspx

[6643]

Yeah, same amp rating. If they use the same regulator, better still. It could be that the only real difference is belt drive vs. gear drive.

That's the good one, not the one with the spinning housing.

[8359]

Yeah, same amp rating. If they use the same regulator, better still. It could be that the only real difference is belt drive vs. gear drive.

That's the good one, not the one with the spinning housing.

I'll have to see what I can find. That STC currently isn't online in the members section.

Thanks for the help John.