IO-360-A3B6D to A3B6 Conversion

[MichMooney201]

https://mooneyspace.com/topic/15898-m20j-io-360-a3b6-conversion-experience/

I wanted to update the Mooney community with a new thread on the conversion process I am in the middle of going through on my 78 J switching to a A3B6 motor from a single drive A3B6D.  For anyone else considering this, I have reposted the above link from member dhc which has turned out to be an extremely valuable resource for the conversion.  My goal is to update the pricing for needed parts and share some of the issues that were a little different from dhc's conversion, even though both of us have converted a 78 J.

The first consideration for anyone is whether a field overhaul, factory overhaul or factory refurbishment is where you want to spend the money.  Time for any of these was not a consideration because a field overhaul takes the same amount of time as it does to have Lycoming do its job.  All quotes, including factory refurbished were 4-6 weeks, and I stopped flying my J when I started fouling the lower #4 cylinder plug on short final so waiting for an engine while continuing to fly was not an option.  2000 hrs had passed and it was time for a new motor.  The cost for a field overhaul from the reputable shops was $27-$29K which included Poplar Grove, Western Skyways and Penn Yan, (varied about $2K depending on factory new or refurbished cylinders).  Factory overhauled, (A3B6) from Lycoming was $32K and factory refurbished was $35,500.  Interesting to note, a A3B6D is more expensive to refurbish/overhaul than a A3B6 by about $1700.  So in looking at cost of ownership over the next 2000 hrs, (10-15 years based on how my plane flys now), the next overhaul would be cheaper on the A3B6 than the B6D.  So just in a motor comparison, switching to the A3B6 was about a $3500 upgrade if I look at the cost of the motors and potential future savings at overhaul, $5200 if I take out the next overhaul.  So for my plane partner and I, a ZERO time engine logbook, 80% brand new parts engine built to new limit tolerances as opposed to overhaul minimum tolerances, and a significant plane value increase completely made the cost of the factory reman worth the cost.

That all being said, there are some gotcha costs involved, including costs that one would bear during an engine change out/overhaul.  You will have to purchase some parts that won't come off the A3B6D such as the prop governor brackets and cable mounts, and the prop governor oil line.  Prices varied considerably among the shops out there for these parts and G&N was the best for me by far. The new oil line was $560 from LASAR, $452 from G&N for the same part.  $452 is ridiculous from Lycoming when it was $280 in 2014 when dhc did his conversion.  The cable brackets were another $50 and $75 a piece, and the prop governor brackets were $147 and $175.  Rebuilt prop governor is $1250 from West Coast Governor Service, highly recommend Dan there, btw, (former Navy Hydraulic mechanic so he knows his stuff).  So there is roughly $2100 in prop governor parts/conversion for the new motor, about $900 increase to change to the A3B6.  Oddly enough, there are two different control actuators that you could get on your prop governor which is differentiated by what side of the actuator the set screw is on.  This set screw placement will dictate if you need to use the $147 bracket from Mooney or not, we did not and the part was returned, (literally the only cost savings we had in this entire conversion).

The alternator that comes with the reman from Lycoming will not fit the baffling on the J so you will have to either use your existing or buy a new one.  I had just purchased a new alternator 100 hrs ago so I was good there.

New hoses are in order on an engine change and there are some differences because of the  oil filter placement on the A3B6 so Ashley from PHT in Tulsa was a great reference there, about $900 for a complete set of hoses.

Other than the prop governor costs, everything is the same between the two motors.  Lycoming now uses Slick mags and harnesses so the timing on the motor is at 20 degrees instead of the 26 degrees of the Bendix mag setup.  If you wanted to go to the Bendix setup you could, but we are installing a Sure-Fly electronic ignition as soon as they are STC'd so the advance timing of the Sure-fly negates the lost power from the Slick mags and is cheaper and better running than a Bedix mag setup.  $1250 for the Sure-Fly.

Total costs: 35500 motor, 450 shipping, 2100 prop gov and acc, 900 hoses, 150 two cases of oil, 600 motor mounts, 1550 new baffles.  $41250.00 to date. 

Ultimately, the cost of switching to the A3B6 has been worth every penny and because some of the trials detailed by dhc, the conversion has gone relatively smooth. The increase in costs to switch have been minimal because the only real headache is the prop governor, so plan on the extra $1000.

[carusoam]

Welcome out in the open, AU!

You win a prize for the most costly first post.  

Got any pics from your conversion experience?

Best regards,

-a-

[Luke]

Did you have any issues with fuel pressure on the A3B6?

Mine is above the 30psi airframe limit (operating correctly) which makes the JPI engine monitor go nuts. I'm having to get Lycoming to swap the fuel pump under warranty.


Sent from my LGUS997 using Tapatalk

[MichMooney201]

Luke,

I specifically called Lycoming on the fuel pressure issue because the A3B6 is also used on some Beech change outs and so the fuel pump, alternator and prop governor oil lines fit Beech set ups and then the marketing gurus at Lycoming decided to hit Mooney drivers with flyers and ads.  So, the mfg bill of materials at Lycoming is for the standard Beech layout, and we get to pay big bucks to buy the parts like the $560 oil line to make the engine fit our planes.  That being said, the tech guy at Lycoming checked the model number on the motor coming to me and he assured me the fuel pump on my motor would fall with POH operating specs.  We will fire the plane up this weekend and that will be one of the first things I check.  They are aware at Lycoming of this issue and have made the changes to a lower pressure pump so that one pump fits both Mooney and Beech builds, so they say. We shall see for sure this weekend.  

[carusoam]

Looking forward to the good fuel pressure results... this has affected a few Mooney owners recently...

Best regards,

-a-

[RobertGary1]

What type of approval did you get? Is this a 337 or did you find an stc?

-Robert

[MichMooney201]

7 hours ago, RobertGary1 said:

What type of approval did you get? Is this a 337 or did you find an stc?

-Robert

Robert,  what are you referring to specifically needing an approval or STC?  

[RobertGary1]

2 hours ago, 201AU said:

Robert,  what are you referring to specifically needing an approval or STC?  

Yes. Just curious what the approval process was. When I went to my a3b6 from a1a  modworks had an an stc but they’re not around now. 

Here is what I see for the type certificate today...

m20J

Textron-Lycoming IO-360-A1B6D or IO-360-A3B6D or IO-360-A3B6. (Bendix fuel injector, Model RSA 5AD1, P/N 2524054) See Note 12 and Note 20.

 

So maybe you’re still ok???

-Robert

Edited April 12, 2018 by RobertGary1

[jaylw314]

9 hours ago, RobertGary1 said:

What type of approval did you get? Is this a 337 or did you find an stc?

-Robert

The A3B6 is listed in the TCDS, so my understanding is it would just need a sign off in the logbook if it was just installation of a Lycoming reman?

[MichMooney201]

I will research tomorrow and verify the fuel pump that came on the reman and repost what I find out from Lycoming, etc.  type certificate clearly calls out the Dukes or Weldon fuel pump.  Somehow I overlooked this minor detail...even when I knew there was over pressure issues.  Good catch and thank you.  

Edited April 13, 2018 by MichMooney201

[MichMooney201]

So I took a photo and checked numbers on the fuel pump and it is model LW-15473 which is a Lycoming rebuild.  In looking online for additional info, this same part number crosses to a Tempest AF15743 which calls out a fuel pressure range of 25-30 psi.  The original on the type cert is AC products, which is now Lycoming so the LW-15473 is on the type cert and the part number has been superseded to 62B26931.  BTW, the Dukes or Weldon fuel pumps are the electric driven pumps, and the LW-15473 is the motor driven.  For others having issues, this pump is available rebuilt or new and pricing online was $259-$400 for the correct pump. This should solve over pressure issues, and Lycoming confirmed they are not putting the higher pressure pumps on the A3B6 in the future...at least that’s what the tech guy told me.

Edited April 13, 2018 by MichMooney201

[Alan Fox]

On ‎4‎/‎12‎/‎2018 at 6:15 PM, RobertGary1 said:

Yes. Just curious what the approval process was. When I went to my a3b6 from a1a  modworks had an an stc but they’re not around now. 

Here is what I see for the type certificate today...

m20J

Textron-Lycoming IO-360-A1B6D or IO-360-A3B6D or IO-360-A3B6. (Bendix fuel injector, Model RSA 5AD1, P/N 2524054) See Note 12 and Note 20.

 

So maybe you’re still ok???

-Robert

Your F came with an A!A  , the J is counterweighted , the f was not , they are not interchangeable without the STC , the J IS allowed in the TCDS to accept the newer engine..

 

[jetdriven]

On 4/12/2018 at 6:20 PM, jaylw314 said:

The A3B6 is listed in the TCDS, so my understanding is it would just need a sign off in the logbook if it was just installation of a Lycoming reman?

Thats what we did. log entry. Same with the bendix 1200 magnetos.  listed in the parts catalog for the engine. 

Edited April 15, 2018 by jetdriven

[Guillaume]

2 hours ago, jetdriven said:

Thats what we did. log entry. Same with the bendix 1200 magnetos.  listed in the parts catalog for the engine. 

In europe, each certified aircraft like the M20J has to comply with the design approval holder parts catalog.

For the engine, the M20J parts catalog says :
A1B6D for aircraft s/n from 24-0002 to 24-0377 excluding 24-0084
A3B6D for aircraft s/n from 24-0378+
A3B6 for aircraft s/n 24-3374+

It also says that A1B6D engines can be converted to A3B6D by complying with Mooney SB M20-206.
Mooney also says you can replace the old C212 (square tip) prop by the C214 (round tip) by complying with SB M20-214.

But I'm not aware of a Mooney SB providing the instructions to convert an aircraft equipped with an A3B6D to an A3B6 (ie replacement of prop governor bracket, change of hoses...) .

I'm surprised that in the US, you can install an engine not listed for your aircraft serial number (in the parts catalog) without any further approval .

In Europe, this wouldn't be possible for a type certified aircraft without a manufacturer SB, third party STC or major modification approval.

Edited April 15, 2018 by Guillaume

[MichMooney201]

20 hours ago, Guillaume said:

In europe, each certified aircraft like the M20J has to comply with the design approval holder parts catalog.

For the engine, the M20J parts catalog says :
A1B6D for aircraft s/n from 24-0002 to 24-0377 excluding 24-0084
A3B6D for aircraft s/n from 24-0378+
A3B6 for aircraft s/n 24-3374+

It also says that A1B6D engines can be converted to A3B6D by complying with Mooney SB M20-206.
Mooney also says you can replace the old C212 (square tip) prop by the C214 (round tip) by complying with SB M20-214.

But I'm not aware of a Mooney SB providing the instructions to convert an aircraft equipped with an A3B6D to an A3B6 (ie replacement of prop governor bracket, change of hoses...) .

I'm surprised that in the US, you can install an engine not listed for your aircraft serial number (in the parts catalog) without any further approval .

In Europe, this wouldn't be possible for a type certified aircraft without a manufacturer SB, third party STC or major modification approval.

I have done a fair amount of homework on this topic and a far as the FAA is concerned, the conversion is allowed without any additional approvals because there are three engines listed on the type certificate and all are approved engines for use, and there are no serial number limitations listed on the type certificate.  As further evidence, if you look on the type cert for K models, note 17 specifically calls out an engine replacement for the TSIO-360-GB series engine to a Lb series engine, because everything is called out as serial number specific on the K's in the type cert.  This is not so for the J's, or for any other instance where an air frame has a call out specific to a serial number.  Note 12 on the type cert also clearly spells out engine can be converted, for the A1B6-D to the A3B6-D.  We have not done an engine conversion, but a replacement.  Additionally, there is no conversion of the air frame to hang the A3B6.  When I talked to Mooney, there are no specific changes needed to be made to hang the motor as everything has already been spelled out in parts manuals for the  A3B6,(prop gov bracket and hoses), where service bulletins are issued with additional instructions if there has not previously been written communication from Mooney addressing the service needed to be spelled out.  Lastly, the type certificate is the enforcing document in the US, not the parts manual.  I was wary enough about the conversion to ask a ton of questions of the popular Mooney service centers before going down this road as they have done a ton of these conversions themselves, and they all responded with they did no additional paperwork or approvals because of how the type certificate is written.

[Guillaume]

2 hours ago, MichMooney201 said:

 I was wary enough about the conversion to ask a ton of questions of the popular Mooney service centers before going down this road as they have done a ton of these conversions themselves, and they all responded with they did no additional paperwork or approvals because of how the type certificate is written.

I understand you did ask MSC's but did you ask your FSDO ?

We also have MSC arround here and our CAA's (Civil aviation authority, our FAA equivalent) really don't care what MSC opinion's is on the regulations.
During ramp checks or airworthiness review, the CAA opinion is the one that matters.  

I'm surprised that in the US you can install/replace any parts which is not listed in the TCDS but then, did you update the POH pages yourself without any approval (to reflect the new engine configuration) ?
Everytime Mooney has released a SB for a new prop, engine, they would provide POH replacement pages for the aircraft updated configuration.

Edited April 16, 2018 by Guillaume

[Yetti]

IX.  Model M20J, 4 PCLM (Normal Category); Approved September 27, 1976

EngineTextron-Lycoming IO-360-A1B6D or IO-360-A3B6D or IO-360-A3B6. (Bendix fuel injector, Model RSA 5AD1, P/N 2524054) See Note 12 and Note 20.

 

http://67m20e.com/Mooney TCDS 2A3 Rev 52 dtd 9DEC10.pdf

 

Mooney the company has already approved with the TCDS  A3B6 is approved for the J

 

[jaylw314]

27 minutes ago, Yetti said:

IX.  Model M20J, 4 PCLM (Normal Category); Approved September 27, 1976

EngineTextron-Lycoming IO-360-A1B6D or IO-360-A3B6D or IO-360-A3B6. (Bendix fuel injector, Model RSA 5AD1, P/N 2524054) See Note 12 and Note 20.

 

http://67m20e.com/Mooney TCDS 2A3 Rev 52 dtd 9DEC10.pdf

 

Mooney the company has already approved with the TCDS  A3B6 is approved for the J

 

And I imagine that means it is technically a "minor modification" so only requires an A&P signature in the logbook (although an IA needs to sign off the new engine 100 hour anyway).  The logbook entry and IA signature in the logbook is all I have when the remanufactured A3B6 was installed at Dugosh in 2012

[EricJ]

On 4/15/2018 at 10:29 AM, Guillaume said:

It also says that A1B6D engines can be converted to A3B6D by complying with Mooney SB M20-206.

If I'm reading that right the only thing that "converts" an A1B6D to an A3B6D is moving the bushings to reclock the prop by 60 degrees.    I think my motor is still marked as an A1B6D (I'll have to confirm that), but during the last annual on my airplane (just before I bought it) there was a Big Deal about a previous PPI discovering that the prop was clocked wrong and the IA moved it.   I wonder if he moved it back or whether it's in the A1 or A3 position.

I'm half hoping it's wrong so that I can move it and it'll get smoother. 

[bradp]

My 77 J is a converted A3B6 that was installed with a logbook entry at Dugosh in 2006 ish. 

No STC needed - just a logbook entry.  It’s spelled out right in the TCDS. 

You guys definitely have different / more rules over on the continent. Especially all those time in service maintenance items - I think that would drive me nuts as an owner and I’d try to keep a plane in Europe on an N-reg if lived abroad.... 

[amillet]

On 4/11/2018 at 1:14 PM, MichMooney201 said:

factory refurbished was $35,500

Wow.  In Aug 2015 it was $29,963 for me. Inflation. 

[MichMooney201]

Hi everyone...update time.  First of all, the A&P/IA working with me on the changeout has indicated the POH for the A3B6D has the exact same operating parameters as the A3B6 and therefore, because the type cert spells out POH's by serial number, my A3B6D POH will cover all requirements of the A3B6 motor, which is spelled out and approved on the type cert without exceptions.  Seems we are in a circular reference for this thing, but its now a case closed and I have the documentation all in order and signed.

Second, the fuel pump that came from Lycoming works like a champ.  It sat right on the white line in the middle of the green arc indicating 25 psi.  NO overpressure at all.  For those who are experiencing over pressure indicated on the gauge, be sure to make sure both electrical leads are on the fuel pressure transducer, because if one is not, it will read past 30 PSI pegged wide open.  Found that out by experience.

Third, the prop governor was listed as the biggest PITA of this project and it hasnt disappointed.  Flew the plane Friday night for an hour and everything was working great.  ONLY problem was we only got 2550RPM on takeoff so we are still messing with that.  It could be a prop cable installation issue or a proper clocking of the prop gpvernor itself.  A&P is working on that tonight so hopefully that issue goes to bed.

Lastly, if anyone os considering doing this to their 201, I would recommend this process to all.  I know every nut and bolt and wire forward of the firewall and have a complete understanding of how all the systems come together.  This has been a fantastic learning experience!!

[carusoam]

Great detail, Mich!

Is the two wire connection specific to the new engine/sensor?

Many Mooney sensors use the plane as ground, often leading to challenges over the years...

I can see how that change effects the reading.

Best regards,

-a-

[MichMooney201]

On 4/24/2018 at 12:20 AM, carusoam said:

Is the two wire connection specific to the new engine/sensor?

No is the short answer.  Our wiring did not change and I was able to use the fuel pressure transducer off the old motor and everything worked out great, which was a 2 wire connection.  I concur I have chased gremlins on this plane related to the grounding we all seem to be fighting.  Interestingly enough, the factory ground location on mine was from the motor to an aluminum shroud on the starboard side, (sorry, I'm retired Navy), right side of the plane attached to the firewall.  There is another location where a threaded stud is mounted directly to the firewall that would also take the ground strap but my particular ground strap is not long enough.  My IA saw this and recommended I add an additional strap from the shroud to the firewall simply because of the grounding issues and gauge trouble  commonly experienced.  In addition, application of dielectric grease will help to combat other connection issues

[jetdriven]

On 4/23/2018 at 3:31 PM, MichMooney201 said:

Hi everyone...update time.  First of all, the A&P/IA working with me on the changeout has indicated the POH for the A3B6D has the exact same operating parameters as the A3B6 and therefore, because the type cert spells out POH's by serial number, my A3B6D POH will cover all requirements of the A3B6 motor, which is spelled out and approved on the type cert without exceptions.  Seems we are in a circular reference for this thing, but its now a case closed and I have the documentation all in order and signed.

Second, the fuel pump that came from Lycoming works like a champ.  It sat right on the white line in the middle of the green arc indicating 25 psi.  NO overpressure at all.  For those who are experiencing over pressure indicated on the gauge, be sure to make sure both electrical leads are on the fuel pressure transducer, because if one is not, it will read past 30 PSI pegged wide open.  Found that out by experience.

Third, the prop governor was listed as the biggest PITA of this project and it hasnt disappointed.  Flew the plane Friday night for an hour and everything was working great.  ONLY problem was we only got 2550RPM on takeoff so we are still messing with that.  It could be a prop cable installation issue or a proper clocking of the prop gpvernor itself.  A&P is working on that tonight so hopefully that issue goes to bed.

Lastly, if anyone os considering doing this to their 201, I would recommend this process to all.  I know every nut and bolt and wire forward of the firewall and have a complete understanding of how all the systems come together.  This has been a fantastic learning experience!!

Prop governor for the A3B6 is a different part number because the drive pad ratio of the A3B6 is different as well. Any given engine RPM the prop governor input RPM is different.. hence the need for the different governor model number.