SWAPPING VACUUM-DRIVEN SPEED BRAKES FOR ELECTRIC ONES IN M20K

[231LV]

Many first time Mooney buyers considering turbo models  are told to be concerned with the costs of running a turbo and the associated heat damage. I am here to tell you the real cost of running a Continental with direct drive accessories are the frangible couplers. Recently, my vacuum pump failed. I have already moved into the glass environment with an Aspen 1000 for my PFD. The ONLY thing keeping me from scrapping all the vacuum related stuff and going all electric are my speed brakes which are vacuum driven. Yesterday, I departed for a quick flight to my mechanic for a pump swap. Immediately after takeoff, I noticed my volts remained at 12.6. During the 20 minute hop, the volts varied between 13.8 and 12.2. Of course, My Aspen battery backup kept popping on and off. Meanwhile, I have the flashing Low Vac light  and the Low Volt light. Mechanic swapped the pump and tested and ordered a coupler. Took off for 20 minute hop back to home field and now the volts are pegged at 12.0. Low Volt light flashing so I shed the load and turn off the strobes then the Low Vac starts flashing and the gyro rolls over....replacement pump failed.  The Aspen is working great so no danger...clear VFR with the field 10 min away....then the Aspen goes TU with CHECK PITOT HEAT warning...If I had been in IMC this would have been serious (and yes, I realize the Aspen can only be certified for no vacuum with the Battery Backup unit which is yet to be procured). I'm now wondering if all of these flashing lights and red cross screens are inter-related. I can't turn on the Stand-by vacuum due to no electricity being generated so I can't get my vacuum-driven AH back and I hit the Pitot Heat on the off chance that somehow some moisture got into the pitot and froze and that worked, the Aspen came back. Then I realized that all these months when I started up the volts would slowly climb from 12.2 to 13.8 had to be a slipping coupler which was slipping more and more hence my first sentence. So after this lengthly description of my day, yesterday, I am back to the original question, is there an STC to replace vacuum-driven speed brakes with electric ones in the M20K model?

[stevesm20b]

The short answer is yes. I have the Monroe speed breaks on my 1981 231. It  uses an electric powered hydraulic pump to operate the spoilers. Works flawlessly and a lot less maintenance than the vacuum speed brakes.

[jlunseth]

I believe the answer is yes, the electric brakes come with an STC. Mine has electric. On the issue of the coupler though, I had a period where we (my A&Ps and I) were going through couplers like water. Put in a new one and it would not last more than two or three flights. The aftermarket couplers were just not worth the price savings. We ultimately went directly to Mooney and got the part. That coupler solved the problem and I have gone six or seven years without a new coupler and still going. The price was high, as I recall it was in the range of 3500 for the coupler, but that was cheap compared to the cost of constantly replacing low grade aftermarket couplers. At one point I had one installed by a non-Mooney A&P who failed to put the bushing in that goes on the drive spindle and inside the coupler where it can’t be detected by visual inspection. Coupler fell off into the running engine. Getting away from the cheap couplers solved the whole problem.

[N201MKTurbo]

I don’t get your logic. Your alternator drive is slipping, so you want to get rid of your vacuum system?

You can buy a lot of vacuum pumps for the price of a set of electric speed brakes.

[DCarlton]

I've often wished that Mooney had built a model with an LYC IO-540.  

[N201MKTurbo]

3 hours ago, DCarlton said:

I've often wished that Mooney had built a model with an LYC IO-540.  

Like a TLS Bravo?

[kortopates]

In order to upgrade the vacuum speed brakes you'll be purchasing brand new speed brakes from Precise - not upgrading. The earlier 1000 electric series are the closest you'll get to fitting the existing holes, the later 2000 series won't fit as nicely. Precise can share more details and availability of the 1000 series. You'll see its alot of work and expense to do away with the vacuum pump.

Personally I wouldn't even consider dropping the back up gyro instruments till you had new Aspen that didn't red x out entirely with loss of a single failure like air data. Neither a battery nor multiple Aspens makes any difference without the newer model. 

[Guest]

3 hours ago, N201MKTurbo said:

Like a TLS Bravo?

I thought the Bravo had a TIO-540?

[kortopates]

43 minutes ago, M20Doc said:

I thought the Bravo had a TIO-540?

details, details! IO-540, TIO-540!  

[Pinecone]

My 252/Encore had the vacuum speed brakes replaced with electric.

Something I did not realize before I picked it up. A nice $8000 GOOD surprise.

There is an STC for them in my files.

[231LV]

9 hours ago, N201MKTurbo said:

I don’t get your logic. Your alternator drive is slipping, so you want to get rid of your vacuum system?

You can buy a lot of vacuum pumps for the price of a set of electric speed brakes.

Yea....a bit of venting proceeded the actual issue. I would like to eliminate the vacuum system but want to retain speed brakes. I realize the cost of a vacuum pump is negligible compared to electric Monroe Speed Brake with R/R but want to explore all possibilities to make an informed decision. The coupler just added to the frustration of a newly installed vacuum pump failing 10 minutes after install.

[231LV]

2 hours ago, kortopates said:

In order to upgrade the vacuum speed brakes you'll be purchasing brand new speed brakes from Precise - not upgrading. The earlier 1000 electric series are the closest you'll get to fitting the existing holes, the later 2000 series won't fit as nicely. Precise can share more details and availability of the 1000 series. You'll see its alot of work and expense to do away with the vacuum pump.

Personally I wouldn't even consider dropping the back up gyro instruments till you had new Aspen that didn't red x out entirely with loss of a single failure like air data. Neither a battery nor multiple Aspens makes any difference without the newer model. 

The newer model Aspen?

[LANCECASPER]

49 minutes ago, 231LV said:

The newer model Aspen?

Max

https://aspenavionics.com/products/general-aviation/efd-1000-pro-max

[carusoam]

Precise flight is pretty good with their support…

Be on the lookout for the change in footprint between the old and newer speed brakes…

Also be on the lookout for change in mount location….

Some Mooneys got the brakes located in front of the spar, others are behind the spar….

Watch extra close to dimensions if your speed brakes are in a box, inside a fuel tank….

Electric speed brakes are nice to have.

PP thoughts only… Not a mechanic…

Best regards,

-a-

[DCarlton]

10 hours ago, N201MKTurbo said:

Like a TLS Bravo?

For me, probably without the T.  Just a simple IO-540.  At one point I googled all the aircraft that have been produced with that engine just to see if there was something I wasn’t aware of that I might want to own.  

[Guest]

48 minutes ago, DCarlton said:

For me, probably without the T.  Just a simple IO-540.  At one point I googled all the aircraft that have been produced with that engine just to see if there was something I wasn’t aware of that I might want to own.  

Might I suggest a Comanche?

[carusoam]

DC, Find the Missile…. They put a six cylinder, 300hp, Continental IO550… in a mid body M20J!

They, is Rocket Engineering…
 

The IO540 will only get you 3/4 of the way there…

You want the IO720… that is going the full distance!!!

 

Just remember…. If you go IO720… when it comes time for the OH…. You have to become one with your maintainer…. 
 

or something like that…

 

The IO720 is cool for one reason… it’s like a twin… yet, no matter what the failure is… you won’t get an extreme off center thrust situation…. 

Excess HP is everything…

Excess HP is even better at cruise altitude…. Go Turbo!

NA PP thoughts only, not a TC’d PP…

Best regards,

-a-

[Pinecone]

Or how about a TIO-540 at 350 HP ?????

 

[Guest]

2 hours ago, carusoam said:

DC, Find the Missile…. They put a six cylinder, 300hp, Continental IO550… in a mid body M20J!

They, is Rocket Engineering…
 

The IO540 will only get you 3/4 of the way there…

You want the IO720… that is going the full distance!!!

 

Just remember…. If you go IO720… when it comes time for the OH…. You have to become one with your maintainer…. 
 

or something like that…

 

The IO720 is cool for one reason… it’s like a twin… yet, no matter what the failure is… you won’t get an extreme off center thrust situation…. 

Excess HP is everything…

Excess HP is even better at cruise altitude…. Go Turbo!

NA PP thoughts only, not a TC’d PP…

Best regards,

-a-

If all goes well today I hope to get it outside and running again.

[stevesm20b]

6 hours ago, Pinecone said:

Or how about a TIO-540 at 350 HP ?????

 

I'm wondering why no one has an STC for this in a Bravo.

[LANCECASPER]

5 hours ago, stevesm20b said:

I'm wondering why no one has an STC for this in a Bravo.

Because 270hp in that version of the TIO-540 is wringing out about all you are going to get.

Before the oil-cooled heads (-B Bravo engine) people who were running that engine at 34/2400 and even 32/2400 were going through cylinders every few hundred hours. With a Bravo conversion and if you pull back to 29/2400 and keep the TIT 1600 or under you stand a decent chance of making TBO.

People make the mistake of looking at other Lycoming TIO-540 engines and seeing that some of them are rated to 350hp. To add to the confusion a magazine article back in the 90's said that the TLS engine was actually "de-rated" to 270hp, since other Lycoming 540s can produce 350hp. Definitely not true. In reality, the only parts that those two Lycomings share might be the same Spark Plugs. They have a different case, different crankshaft, camshaft and cylinders.

 

[231LV]

Thanks to all the responses to this thread. I now have a pretty clear understanding of where things stand. To summarize:

1) Electric speed brakes can be fitted to replace the original vacuum brakes.

2) They are expensive. Vacuum pumps are not.

3) If I elected to spend a lot of money to replace the vacuum with electric speed brakes, I would still have to spend more money to upgrade. my Aspen 1000 to an Aspen 1000 Max before I could completely scrap the vacuum system.   

4) Replacing the vacuum speed brakes with electric speed brakes would probably cost at least $20k ( including the upgrade to an Aspen         1000 MAX) but would get me a vacuum-less plane and an upgraded, stand-alone electric AHRS capable Aspen.     

5) I will stick with the vacuum system and replace the pump as needed.

[Guest]

40 minutes ago, 231LV said:

Thanks to all the responses to this thread. I now have a pretty clear understanding of where things stand. To summarize:

1) Electric speed brakes can be fitted to replace the original vacuum brakes.

2) They are expensive. Vacuum pumps are not.

3) If I elected to spend a lot of money to replace the vacuum with electric speed brakes, I would still have to spend more money to upgrade. my Aspen 1000 to an Aspen 1000 Max before I could completely scrap the vacuum system.   

4) Replacing the vacuum speed brakes with electric speed brakes would probably cost at least $20k ( including the upgrade to an Aspen         1000 MAX) but would get me a vacuum-less plane and an upgraded, stand-alone electric AHRS capable Aspen.     

5) I will stick with the vacuum system and replace the pump as needed.

A vacuum pump costs about $1.00 per hour to keep running.  They’re not as bad a people make them out to be.  Sadly parts for vacuum speed brakes are no longer available, I need wing cables for one.

[Z W]

Don't forget the cost of some sheet metal work and paint to fit the new electric speed brakes.  They are not the same size as the vacuum.

Our vacuum pump now just runs the speed brakes and the retractable step.  Would like to remove all that, but the cost is very high for the benefit while those systems are working.

[Pinecone]

The other issue with vacuum speed brakes is the bellows that actuates them.  Not available.  Jet Driven says he can patch them, but after a while, they will be too far gone.

I have an Aspen 1000 (not Pro Mx) but with a G-55 for backup.  No vacuum system'