231LV

Hate to be the bearer of bad news but whenever mine started "twitching" or swinging wildly, my coupler was slipping. I have replaced a coupler maybe 3-4 times in my 20 plus years of ownership. My A&P chased down everything else it could possibly be (including everything mentioned in this thread) before pulling the coupler. Now, we just go straight to the coupler and the problem is solved.

If you pick a top paint shop, none of your concerns are necessary. The best shops do superb prep including straightening, filling, cleaning, ect. Pay a bit more for all new stainless steel screws which go on after the paint and prevent the paint seam from being broken when a screw has to be removed. The quality of paint, at a top shop, will easily last in all but the harshest environments. I had my plane painted three years ago and the shop did a superb job.

As a 20 plus year 231 owner/operator, I can say everything previous posters have said is correct. A 252 lets you set it and forget it as they say but the 231 requires a bit of "finesse" on the throttle. The Merlyn is a great wastegate but it will allow you to easily over boost the engine if you are too aggressive on the throttle. I like to use a whip analogy to describe the way a Merlyn works. Think of the difference in distance traveled between the handle(throttle) of the whip and the tip(engine boost). That is how the Merlyn reacts to throttle input. Hence, I added a vernier throttle which makes fine tuning the engine much, much easier. An intercooled turbocharged engine requires different MP settings...so you will not be able to get 40 inches without risking a head separation. Most 231 drivers will admit(under duress) a 252 is a better engine/airframe combo but you pay for that and the 231 gets you pretty close to the 252 on a significantly reduced budget.

turn on the Master and throw the speed brake switch....if they work, they are electric, if not, vacuum-driven

It is absolutely your coupler...my voltage would start fine then slowly slide lower and lower as the coupler heats up and starts slipping. Finally, there was no voltage at all except what was coming off the battery. Get it replaced and have some happy, worry-free flights. If you haven't had the alternator rebuilt in a while, this would be a good time to get it done (or purchase a yellow-tagged unit).

Good points...yes, the voltage is steady at 13.7v during flights and I'm glad to understand how the minders work so I am not terribly worried...didn't mean to hijack the thread...apologies

My 231 runs on the 14v system with all the standard electronics including an Aspen 1000 glass panel...I find that after I fly (no low volt annunciator light at anytime unless I drop below 980 rpm) my battery minder says the battery is discharged by more than half...it's a new battery so I can only surmise that the alternator can't put a charge into the battery as fast as the electronics are pulling the volts out...too bad Mooney never got an STC for a higher load alternator for the K models (and any others)

Yes it was the wombat I was thinking of and yes, it has been discontinued. Sadly, it seems, no other company sees a market for this type of a device. Using my phone as a hotspot is an alternative but the bandwidth is pretty small compared to the download so I suspect I would be sitting up there quite awhile waiting for it to download the updates....thanks all for the suggestions...

Most of us remember the days when paper plates were updated by hand every month...searching through thick binders to find the obsolete plate and replace it with a "new" plate that looks identical to the old. Then magic came along and we went digital. Gone were the paper plates (some here probably still carry them as a backup, I bet) and our e-devices became our plate holders and we could update them digitally. However, to do so, at least in my situation, requires me to go up to the airport and pull the navdata chip or card, if some prefer, and bring it back home and plug in the Garmin adapter into my laptop and download the files for the update and then return the chip to the plane. I know a second chip can make this task a bit easier but a second WAAS orange card is insanely expensive when bought from Jeppesen and buying them online may or may not work depending on the chip. A while back, I recall reading about a portable device (can't recall the company name) that allowed me to go to the airport and simply using my phone, could update the chip as I sat in the airplane (of course the chip must be removed and slid into this device.) Does anyone know of anything like this?

Its almost impossible to trundle a Mooney with a flat main gear unless the two gear doors are first removed. It's cheap insurance to avoid damaging one or both.

LOL...great training melody!! Thanks

This is a first in over 20 years of flying my 231. I have had my share of really bad landings but today took the cake. Coming in a bit high and fast, I got sloppy and overconfident and instead of popping the speed brakes (which I actually thought about for a moment) I let the plane float...one bounce, two bounce then down but too far down the runway and too fast so instead of executing a go-around, I stomped on the brakes and was told I was smoking the tire for several hundred feet before it blew pulling the plane to the right. I was fortunate that all I appear to have damaged (beside my ego) was the tire. Warning to all out there, don't get overconfident...no matter how long you have been flying and if you believe you need to go around....GO AROUND!

As others have said, there are many variables to consider when setting these engines up. I had my GB overhauled to an LB and had a Merlyn installed at the same time. The original engine came with an intercooler.....so...setting up FF with the intercooler was a bit more complicated than simply referring to a chart since the book had the FF set too low causing CHT's to go over 400 before rotating. Bottom line, my FF ended up at 23 gph at 37 MP. The intercooler requires a reduction in MP to avoid overboosting the engine. Prop RPM is limited to 2700 but I usually see 2650 at 37 MP which is my "max power" setting.

One of the great reasons this forum works so well is follow-ups on previously reported problems. I reported a frustration I was having with my volts on start-up well over a year ago. To recap, I would start up and the volts would hover around 12.3 volts before it would climb to 13.7v. Many opinions were offered from a voltage regulator issue to an alternator. One respondent offered that this was normal and the charging system was designed this way to prevent a voltage spike on start-up. The problem turned out to be a slipping coupler on the alternator. I suspect it had been slipping this whole time and progressively got worse which was verified when my last flight saw voltage sit at 12.0 volts. I now know that after replacing the alternator and using a solid state voltage regulator (either works or it doesn't), the most likely culprit is a slipping coupler. Hope this helps save some time troubleshooting a similar issue.

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.

The newer model Aspen?

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.

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?

I was flying my bi-annual with my CFI when we practiced an engine out landing. I dropped the gear as I would in a simulated off-field landing and then executed a go around. The gear wouldn't retract...nothing. I used the emergency pull cord and got the gear down for a safe landing at my mechanic's field. He jacked it up, pulled the belly panels and found the problem...bad and corroded leads which he cleaned up and tightened....problem solved....check for loose connections and or a short due to corrosion....that is the low hanging fruit and relatively cheap to solve before moving to the more expensive stuff.

Agreed! Engine management is more an art than science (though it's based on science). I ran a flight yesterday (with dog and wife so stayed low) at 11,000. 2480 RPM, LOP, 7 gph, TIT at 1550, highest CHT at 320, highest EGT at 1520, 22 MP with cowl flaps closed....TAS was way low at 104 kts but had a push so GS was 140 kts.....engine setting combo's seem pretty limitless based on the mission at hand.

Why aren't you using full power during climb? If you have an intercooler, you are limited to 36-37 inches of MP but that is a lot better than pulling back to 30 inches. I climb at full power with full open cowl flaps, full rich and maximum RPM. The TIT sits in the higher 1400's. Only after hitting the lower teens will you see your temps start to climb but with fully opened cowl flaps, you should not exceed 380 on CHT's unless you are climbing through 20,000 ft where the turbo has to work really hard and throw off lots of heat. Once level, I go LOP and dial in 2500 RPM. I will stabilize at 9 GPH around 30 inches of MP with my hottest CHT at 320 . Cowl flaps can be reduced to trail although temps will climb a bit but usually not above 360. TIT usually sits around 1580. Temp management is what the K is all about which is why the 252 and Encore came along to simplify engine management. I don't fly with fully closed cowl flaps since temps go higher than I want but flying them in trial works albeit at slightly higher temps.

Don't run an intercooled turbo at 40 MP, you are overboosting the engine. My typical max climb power is limited to 37 inches due to intercooling. Usually, I cruise at 10 gph running the engine LOP. Hottest CHT's are around 320 unless I am in the higher teens where the turbo is really working and glowing cherry red...then I can see 365-375 on the hottest. Enjoy your K...it is a great traveling machine!

Thanks all for the thoughtful responses. Having read through these a couple of times, it seems that my desired objective can be accomplished but would be less than ideal and not elegant. I failed to mention that both headsets are running off ships power with the Bose pin connectors. We do have jacks side by side with the pin connectors but also like the "no battery required". The X is outdated but still a nice headset and worth more than the $250 credit Bose offers against a $1200 pair of A20's. Ideally, a wireless cockpit would be the gold standard and we are getting there slowly. I think I will wait for the next iteration of wireless technology implementation and see what might fall out in a new generation of over or in-ear communication devices. Thanks again for a great discussion!

I have a pair of Bose X and Bose A20's for my wife and myself. I have been trying to find a link for the bluetooth upgrade and have not had any success. Does anybody have a link or can direct me to a website? We are tired of cords, in general and one less for the audio input from my phone would be worth the money for the upgrades.

Thanks Art...has anyone else used them and if so, what was your experience?