Major versus minor alteration; voltage regulator

[FlyingDude]

48 minutes ago, Shadrach said:

I did not address it specifically, however I “assumed” compatibility after referring to the TCDS (see my earlier post.)

Sorry Ross, I wasn't aware of your previous post.  I saw the first one and the final ones on field approvals.

I second @A64Pilot's comment below.  

On 8/27/2024 at 9:10 AM, A64Pilot said:

As I said, give the FSDO a call and ask them, as a 40 yr A&P and 15 year or so IA I feel sure I know what their answer would be. It might just possibly start with wondering why the manufacturer didn’t include your model Mooney in with the others.

Using your logic I’d be able to use engines, props and all kinds of other things on my Mooney, because they are approved on other Mooney’s.

the control loop needs to be fast enough to keep up with load and rpm fluctuations (which I am sure the solid state R1244 can keep up with the buzzers (VR414/4 and DGR-2) but compensated enough to prevent jitteriness or instability.  The field current required by the alternator needs to be within the expectations of the regulator in terms of output voltage and load current combinations, both for corner cases and for the steady state.  You can't have a 70A alternator that wants 4A field at 1500rpm and a regulator that maxes at 2A, for example.  You might get instability and oscillations, or it might just not be able to provide the highest current (leading to voltage crash) or the lowest current (leading to overvoltage, which will then make the alternator zero the field current).

I have an R1244.  When I bought my kit, they didn't ask me if I had an alternator in my Mooney and if I wanted to keep it.  They shipped me an overpriced automobile alternator together with the regulator...  Let's go over your findings:

M20J/K models can use TCM alternators and VR414,DGR2 regulators; all interchangeably.  That's fine per TCDS.

M20J/K models can be fitted with Planepower alternators that use R1422.  That's per STC.

What OP @Jetrn wants to do is to match the TCM alternator with an R1422 because both TCM and Planepower alternators are approved for Mooneys.  Just because those 3 alternators are approved for an airframe does not mean that the accompanying regulators are also all approved, all interchangeably.

You need some data to show that TCM - R1244 combo was made and it supported the required load conditions at the same engine rpms.  If you have this data, as an engineer, I'd be OK with the combo.  What FAA will do or say ... other dudes here are more knowledgeable in working with FAA.

Otherwise, all rest is debate, conjectures and refutations (i.e. futile).

I'd still recommend the OP to get a complete Planepower kit.  

 

[Yetti]

Textron shows a VR415F to be listed in the catalog....    https://ww2.txtav.com/Parts/PartSearch/PartsDetail/VR415F

Which should be acceptable from the TCDS point of view.

[FlyingDude]

1 hour ago, Yetti said:

Textron shows

care to explain how Textron TCDS is relevant to Mooney?  For my education.  Thanks.

[Yetti]

1 hour ago, FlyingDude said:

care to explain how Textron TCDS is relevant to Mooney?  For my education.  Thanks.

Page one of this thread at the bottom says that the VR415 is on the Mooney model m20K TCDS.

 

Edited August 28 by Yetti

[Shadrach]

7 hours ago, FlyingDude said:

Sorry Ross, I wasn't aware of your previous post.  I saw the first one and the final ones on field approvals.

I second @A64Pilot's comment below.  

the control loop needs to be fast enough to keep up with load and rpm fluctuations (which I am sure the solid state R1244 can keep up with the buzzers (VR414/4 and DGR-2) but compensated enough to prevent jitteriness or instability.  The field current required by the alternator needs to be within the expectations of the regulator in terms of output voltage and load current combinations, both for corner cases and for the steady state.  You can't have a 70A alternator that wants 4A field at 1500rpm and a regulator that maxes at 2A, for example.  You might get instability and oscillations, or it might just not be able to provide the highest current (leading to voltage crash) or the lowest current (leading to overvoltage, which will then make the alternator zero the field current).

I have an R1244.  When I bought my kit, they didn't ask me if I had an alternator in my Mooney and if I wanted to keep it.  They shipped me an overpriced automobile alternator together with the regulator...  Let's go over your findings:

M20J/K models can use TCM alternators and VR414,DGR2 regulators; all interchangeably.  That's fine per TCDS.

M20J/K models can be fitted with Planepower alternators that use R1422.  That's per STC.

What OP @Jetrn wants to do is to match the TCM alternator with an R1422 because both TCM and Planepower alternators are approved for Mooneys.  Just because those 3 alternators are approved for an airframe does not mean that the accompanying regulators are also all approved, all interchangeably.

You need some data to show that TCM - R1244 combo was made and it supported the required load conditions at the same engine rpms.  If you have this data, as an engineer, I'd be OK with the combo.  What FAA will do or say ... other dudes here are more knowledgeable in working with FAA.

Otherwise, all rest is debate, conjectures and refutations (i.e. futile).

I'd still recommend the OP to get a complete Planepower kit.  

 

So my error was in assuming that @Jetrn wanted to replace his stock voltage regulator with a voltage regulator that was an approved replacement for his stock voltage regulator but only in other Mooney models. I now understand that the rr1244 is part of the plane power STC. I agree more information is needed. I still don’t think this is a major alteration. Indeed it may not be compatible at all, though I think that unlikely.

[Jetrn]

Initially I reach out to consolac.com as I did recall kortopates mention this company in other threads. They do not have the drawings for the voltage regulator. Eventually, I got an answer for International Avionics and shipped the part in this case both voltage regulators which are separate units but one assembly. Today I did reach out again to consolac and spoke with the repair representative, he suggested that I request the schematic, exploded drawing, parts list, and testing procedure from International Avionics as they are required by the FAA to provide them as the owner of the plane. I am not aware of this regulations but plan to call back tomorrow to see if he could provide it and if they would be willing to repair it without the documents.  I did send an email to International Avionics requesting the documents. The representative from consolac suggested if a DER was needed it would be about$1000. Here is a picture of the regulator assembly

Edited August 29 by Jetrn

[EricJ]

There are a few ACs that offer guidelines on replacement parts for aging airplanes, and the Owner Produced Parts regulations allow for a fairly wide variety of options in replacing parts.   It might also be possible to find a suitable replacement part that meets the specs of the old part (i.e., is a suitable functional equivalent of the old part), and then applying for a VARMA letter to vouch for the installation in the aircraft.   A VARMA letter would provide the basis for IAs to sign off subsequent annuals with the part installed.

[Aerodon]

Here is a picture of one of the two ACU's installed in my 252.

It was probably made by Zefronics for Mooney, but maybe they have a secret stash somewhere?

Alan Fox is parting out a 252 and probably has two for you, along with the mounting bracket?

And there are a couple of service bulletins around the ACU's.  One is to splice an additional ground near the ACU, another is to relocate the 'field V' sense wire away from the field breaker.  This one makes sense, if the field breaker trips there is no way for the ACU to provide the warring light, when you really need it.  But Mooney went about it in a really convoluted way with wire splices to the annunciator panel and the hi/lo vacuum switch.  It's much easier to relocate this ring terminal from the field breaker to the annunciator and hi/lo breaker. 

 

 

 

Don

[Marc_B]

@Jetrn One other option that may be applicable.  Mooney had a retrofit VR that for a while was offered by LASAR that I believe was the field adjustable replacement for the IAI regulator 800270-503.  The downside for this was the cost.  When I did my panel upgrade, I just had IAI service my VRs.  But given that you're running into issues this may be an available albeit pricey solution.

https://lasar.com/electrical-instruments/voltage-regulator-retrofit-replaces-800270-503-940170-503?rq=940170-503

From Mooney Retrofit Kit List:

The Mooney Service Manual is pretty parsed about the VR other than giving specs for max voltage (28.3 +0.2/-0) and saying that the Mooney voltage regulator wasn't field adjustable.  Although from the pic on LASAR website it looks like retrofit was also made by IAI...any chance they have one on the shelf and given the issues might give you a discount??

[shawnd]

4 hours ago, Aerodon said:

It was probably made by Zefronics for Mooney, but maybe they have a secret stash somewhere?

The Zeftronics folks are pretty nice to talk to. When I ran into alternator trouble back in 2021, they didn't seem to have a product for the 252. But things may have changed now. At the time, I chose to send it to https://www.consolac.com to get it repaired and they did a fine job.