Tom 4536

45 minutes ago, whiskytango said:

I have noticed the same problem occurring intermittently.  It seems to occur after I get a new altimeter setting from ATC while in altitude hold mode.  The GFC500 will cyclicly hunt about 40 feet above and 40 feet below the previously set altitude over about a 5 second period.  I have not tried lubing the controls or testing with Alt Static (I will try those on next flight).  What does seem to make it stop is to temporarily use Vertical Speed mode, set to 0 FPM.  It will then hold selected altitude perfectly, until the next altimeter setting change.  Not sure how to interpret this. 

This is great info. I know that the autopilot corrects the altitude as soon as I reset the altimeter setting, but what I don't know is whether the oscillations start when the altimeter setting is changed. I haven't found any way to stop the oscillations. My plane is in for annual so I won't be able to check this for a while. Setting the Vertical Speed to 0 will be an interesting experiment. My GFC 500 software was updated in the past month and the update did not solve the problem. Thanks for the ideas.

10 minutes ago, PT20J said:

@Tom 4536, does it oscillate in all pitch modes or only ALT hold? That might eliminate the static source as an issue. You've already replaced the servos and checked the cable tensions. If all the setup parameters are correct per the STC, then it might be something with the airframe. You mentioned having to adjust the gain on the old autopilot. I'm not sure of the circumstances, but are you sure that it wasn't tweaked to overcome some other problem in the airframe? The GFC 500 servos are not as robust as some legacy servos. Ultimately this is a problem that will need to be worked out with your installer and Garmin field support which has direct access to engineering.

Skip

It oscillates only in alt hold. I mentioned the gain control in the old autopilot only to mention that the gain control was available if it needed to be adjusted. It didn't need to be adjusted. To my knowledge the GFC 500 doesn't have a gain control to reduce the oscillations. The old AP worked perfectly until it died. After two attempted repairs by Executive Autopilot I gave up on the old Century 41 AP and had the GFC 500 installed.

1 minute ago, PT20J said:

Bridle cables are the cables between the servo sheave and the control push-pull tubes that translate the rotational motion of the servo motor to the linear motion of the controls. If they are loose, there will be slop in the system, and, depending on time constants involved, it can cause an oscillation.

Those are the cables that were checked.

19 hours ago, PT20J said:

Mooney used a several different guides for the control columns. Later models use an eyeball made of nylatron which should not be lubricated. They do seem to get stiff over time but it’s the bearing surface between the ball and socket that wears and the only solution is to replace them.

That said, they would have to be very bad to affect the autopilot and you would surely notice it when hand flying. 

Did the installer check the bridle cables for proper tension? I would also check to see if the trim servo is hunting which would cause the trim wheel to rock back and forth. 

I think @donkaye had some issues initially — maybe he has some ideas. 

Skip

The servo cable tensions were checked. When the plane porpoises, the trim wheel does not move but the yokes move slightly. Not sure what the "bridle cables" are. Thank you for your input.

Somehow I missed 81X's post. Thank you. All my servos have been replaced, but the idea of trying alternate static source and also seeing what happens to the FD without the autopilot engaged is a great idea. As soon as my plane is out of annual I will try those ideas.

It does appear that the autopilot is overcorrecting. With my Century 41 AP, it was just a matter of adjusting a gain control.

12 minutes ago, StevenL757 said:

First - start by ensuring your firmware/SW versions are current across all your Garmin devices where applicable.  This is a best-practice that your installation shop should’ve done by default before releasing the aircraft back to service.  So, verify this with them first.

Second - I know it sounds crazy, but this has helped several people in the past.  Clean both control column shafts, and then lubricate both with silicone spray…and ONLY silicone spray.  Do not use Triflow LPS or anything like that, as it can cause buildup in the guide blocks under the panel that surround the shafts.  This will eventually cause increased sticking and friction.  Also, if you have any RAM mount or other device connected to one or both control columns, remove them temporarily and go fly again to test.  It’s possible - yet unlikely - that this is the culprit, but should be ruled out.  The added weight on the shafts by one or more devices is an excess force that an autopilot needs to counteract when in command of the aircraft.  Fly a multitude of headings - including with headwinds, tailwinds, and crosswinds during testing.  If the problem still persists in those scenarios, then notify your shop and make arrangements to have them look into it further.  Have them engage Garmin for guidance - don’t accept the shop’s “we don’t know” stance.

Steve

I tried silicone spraying the control column shafts and had all my Garmin software updated in the past month. I don't have anything mounted on my control columns, but my problem persisted after all these measures.

1 hour ago, Larry said:

I had a GFC500 installed driven by a G5 with a G500 (legacy).  I'm getting a slight porpoising of 1/2 degree up and down every +/-15 seconds in level flight smooth air. I believe that I'm also getting it during climb and descent.  The pitch change is reflected in the G5 and G500, but don't know if this is the cause or reflection of the autopilot's action.  The installer claims he can find nothing wrong.  Has anyone experienced anything of this nature?

My newish GFC500 does the same thing. I have GI275's rather than a G5. My installer doesn't know of a fix.

40 minutes ago, T. Peterson said:

Wow! That’s wonderful performance! I don’t have Gami injectors or an intercooler, though I do have the Merlyn wastegate. Therefore I cannot do the LOP, or so I have been told.

 Thank you for your input! Someday I hope to install those extras and achieve a little better performance. In the meantime my wife and I very much enjoy our new flexibility in being able to visit family! I have never before owned an airplane and it is a blessing notwithstanding a few glitches to overcome!

 I am going to try your power settings and see how that works out, 2400/30.0

Thanks again, 
Torrey

T. Peterson: FYI, my LOP cruise engine settings were based entirely on information provided by the very knowledgeable contributors to Moneyspace. The support here has been invaluable.

GAMIs are not expensive. They cost about 1amu and my MSC charged about 3 hours labor. My engine runs smoother and I can run LOP.

2 hours ago, T. Peterson said:

I have not had a problem with over-temp, but that may very well be due to the droop. Also hot summer has not yet arrived. Furthermore, since I am brand new to GA and piston airplanes, I am trying to be very conservative. I can’t get any better than about 12.4 gph at any altitude from 6000 to 13000 feet. My TIT is about 1550 and cylinder temp 340 to 380.  The belly of the airplane is filthy, but that is going to be remedied on the 28th. I thought that maybe the dirt and cowl flaps were costing me, but I guess not. TAS runs between 157 and 162.
The former owner said he got 11 gph at 11000, and I suppose if I pulled MP back I could do better. I cruise at 2500 rpm and 28 inches. 

T. Peterson: I have a 1979 M20K-231 with GAMIs, Intercooler, Merlyn and JPI-900. For the 12 months I have been running LOP in cruise mode. At 11,500, my cruise setting have been 30"MP, 2400RPM, 10.9-11.1gph. This results in TAS of 185-190mph, CHT 320-360, TIT 1580, oil temp 180 (winter) 190-200(summer). I live in Tucson.

My plane is at an MSC for annual. I asked the MSC to report back to me as to the engine health after 12 months (200hrs) of running LOP as described above. The MSC reported that the cylinders and valves look excellent and all the compressions are 77-79/80.

Hope this helps with your concerns regarding your engine settings.

A year ago when my Precise Flight speed breaks needed repair, Precise Flight overnighted "loaner" speed brakes to me to use. That way we could use their boxes to ship my speed brakes. When the repaired speed brakes were returned to me, I sent their "loaners" back to precise Flight. Worked fantastically.

43 minutes ago, flyboy0681 said:

Not the same issue I'm reporting. When this happens to me, the Connext button on the SYSTEM menu is disabled and grayed out. The result of this is that no traffic appears on the iPad. Then out of nowhere (anywhere from 10 to 40 minutes in the air), traffic suddenly appears and when I see it I immediately go to the Connext button and find that it's enabled.

Interesting, because my other problem in my 231 panel is that my Connext turns off after about 60 minutes. (Foreflight tells me the Connext status.) My avionics installer told me it is a quirk of the FS210. He told me to turnoff the Bluetooth/FS210 circuit breaker when Connext turns off. I find I need to leave the breaker off about 10 minutes before Connext will restart. It acts like it is an overheating problem.

8 hours ago, Tom Pegrume said:

I have exactly the same problem on a classic GTN750. Happened since the Avionics shop did a software update. I have an FS210. Did anyone get resolution to this problem?

 

Also VCALC utility has disappeared and replaced with VNAV which is asking for a barometric input!

I have started having the problem in my 231 that has a 430, FS210, GI275's and Foreflight with latest updates.

While flying with a friend in his 252 with a 430 & 530, FS210, GI275's and Foreflight with the latest updates, he had the same problem.

In neither plane did we have any avionics updates. On both planes we have been able to overcome the problem by re-booting the iPads and turning off the avionics master switch and re-booting the avionics. Maybe this is a Foreflight or iPad update problem??

I’ve been flying with a friend in his 252 with a new GI 275 engine monitor. When cruising lean of peak the EIS %HP does not change as fuel flow is changed. Is this an oversight by Garmin or are we doing something wrong? The Garmin Pilot Guide (Ver. H) does not mention that we have to tell the EIS that we are LOP.

The JPI 900 in my 231 requires that I tell it I am LOP to get the correct %HP.

Thank you.

7 minutes ago, N201MKTurbo said:

I personally hate vernier throttles. Spinning them is too slow and you cannot hold the button in and brace your hand on the panel. In turbulence it is almost impossible to do a non-spin throttle change. I think they are dangerous. I wouldn't do touch and go's with a vernier throttle. The strange thing is I find them mostly on 231s which is the worst place for them because you cannot accurately advance the throttle to full power except for spinning it. I don't know what people are trying to accomplish with a vernier throttle, I can set MP to within a 1/10 of an inch without a vernier.

My 1979 231 has a McFarlan vernier throttle that does not have a center button. My prop & mixture do have a button. I do not use the throttle's vernier during takeoff.

Rene (602-614-0504) owns a Mooney and is a CFI. 

27 minutes ago, PeteMc said:

Prop: Just as an FYI... I learned from Inst. and @ MAPA PPP to reduce the RPMs for the prop.  Better for the Prop & Governor not to do a full range test at high RPM.  I do the Mag check at the higher RPM, then reduce to about 1500 RPM for the Prop (min RPM where your plane still has full range on the prop).

This is the first time I have heard of using a reduced RPM for the prop test. I am curious what RPM other MS'ers are checking their prop at. Also how many times they are doing the check. Thank you.

On 11/24/2021 at 6:20 PM, Mac80 said:

After oil change and plane wash today I noticed that my flaps were not closing. I opened them so the FBO could access the snap connectors attached to the flaps to lower bottom cowl.

I want it closed to preheat the next time I fly and tried a couple times final got it closed but 2 amp breaker kept popping. I can fly this time of year without opening the cowl flaps as it unlikely to get warm again till spring here in Missouri.

Could putting push spring snap connection off 180 degrees backward cause excessive friction. I can fly with closed now as it is cool and am not really wanting to open it till I let the shop see the problem.

I cannot imagine that having an oil service would mess with the cowl flat electric motor other than the flap mechanical connectors that need to come off to drop the bottom cowl.

A short in cowl motor or connector may cause the breaker to pop out but why would that happen with just changing oil?

They also cleaned the engine. I believe they use some type of kerosene, and they also washed the plane and may have used a type spray wax.

Has anyone had problems with cowl flap breaker popping off and how was it resolved. Suggestions appreciated.

A friend with a 252 burned out a cowl flap motor twice after a recent oil change. Turns out the flap was catching on the new oil filter, which happened to be slightly larger than the recommended oil filter. Seems the correct oil filter is in short supply in some areas.

The 64oz Ocean Spray Cranberry Juice bottle has a large opening and works great.

4 minutes ago, A64Pilot said:

So long as the ball is centered, the fuel won’t move.

 

‘You can however move the full side to side with no turn

What keeps the fuel from flowing downhill toward the end of the left tank in a left turn turn? In your video he was able to pour the tea, which shows the fuel will flow from side to side in a turn. Seems that the fuel could flow away from the tank outlet.

20 minutes ago, M20F-1968 said:

I do not like the thought of fuel planning down to 1 gallon.  Knowing how much fuel is in the tank is essential and can be coupled with a fuel totalizer and paper and pen quite nicely.  CIES senders help as well.  But, a left hand turn to final with 1 gallon in your left tank will get your attention quickly.

John Breda

Does anyone know how much fuel we need in the left tank to make a left turn to final without running out of fuel?

Make sure you don't have the 3 inch rudder peddle extensions. The extensions give less leg room and put your knees higher. As others have stated, I find adjusting the seat back angle helps a lot.

When my Century 41 failed, it was a week prior to a panel upgrade to GI275s. So while the Century 41 was at Executive Autopilots, the old AI was being replaced with a GI275. The Century 41 had the same problem even with the new AI.

11 hours ago, peter west said:

have a 1979 mooney 201 which came with century 41 auto pilot from factory. auto pilot has issue with altitude hold, gets pitchy, only holds altitude for a few minutes at a time, then cannot hold the pitch at proper attitude, then it pitches down, the aircraft loses 300 -400 feet or so all at once, and at that point i have to uncouple auto pilot.  have had brain box sent to auto pilot central in tulsa, they say nothing wrong with brain box.  have no idea what to do about this, most shops will not work on this brand, aircraft based in denver,colo.  

Last year I had the same problem with my Century 41 in my 1979 231. We sent all the autopilot components to Executive Autopilots twice and never solved the problem. I gave up and had a GFC500 installed. Hope you have better luck than I had.

On 8/8/2021 at 6:42 PM, Hank said:

That formula only works for LOP. For ROP power, see your Performance Tables.

So, on my 231 if I am at 55% LOP and want to increase to 60%LOP do I change the FF with mixture control or by increasing MP?

When I got tired of the hassles with renting I bought a M20K-231. After the 10 hrs of training I felt comfortable and have never regretted my purchase. I can fly as slow as a 172 or as fast as a Mooney, all the time using less fuel than the 172. They say money can’t buy happiness. But money can buy a Mooney which can bring happiness. Maybe you shouldn't show this to your girlfriend or my wife!