Finally! I'm getting the GFC 500 installed next week

[donkaye]

I spent a lot of time trying to find someone to install a GFC 500 in my airplane without feeling like I was being robbed.  I had several good bids, but they were for installs in either September or December. Another was for a June installation, but for too much money.

Today I flew out to Minden and was happy with what I saw.  A reasonable bid, not the lowest, but reasonable.  They could start near the end of the month after the parts arrive.  They were ordered yesterday, and the job should be done before MooneyMax in June.  I'll give a pirep when the job is done.

[Cruiser]

I take it the GFC 500 is not subject to the new CANBUS wiring requirements.

[ragedracer1977]

They changed back. Rev 18 goes back to shielded twisted pair MIL-C-27500

[donkaye]

9 minutes ago, Cruiser said:

I take it the GFC 500 is not subject to the new CANBUS wiring requirements.

A number of ways around it, but that won't be necessary, since Garmin announced a fix for the issue today.

 

[ilovecornfields]

@donkaye, if you were in Minden you should have stopped by to say hi!

 

 

 

 

[flyingcheesehead]

Silly question: Are you going to do 2, 3, or 4 servos?

I never thought about doing the yaw damper in the R, but with the way people rave about it when they have it, maybe I will. I'm just curious if it'll ask to trim, or just sit there with the servo pushing the rudder one way or the other. I don't like the thought of a constant force on the servo, but I don't think they ask to trim all the force out either. Maybe someone who has one already can elaborate?

Edited April 19, 2019 by flyingcheesehead

[aviatoreb]

On 4/17/2019 at 10:49 PM, donkaye said:

I spent a lot of time trying to find someone to install a GFC 500 in my airplane without feeling like I was being robbed.  I had several good bids, but they were for installs in either September or December. Another was for a June installation, but for too much money.

Today I flew out to Minden and was happy with what I saw.  A reasonable bid, not the lowest, but reasonable.  They could start near the end of the month after the parts arrive.  They were ordered yesterday, and the job should be done before MooneyMax in June.  I'll give a pirep when the job is done.

Are you able to share what is the expected cost of the install?  Or if not publicly could you pm?

[donkaye]

5 hours ago, aviatoreb said:

Are you able to share what is the expected cost of the install?  Or if not publicly could you pm?

I had quotes ranging from $24,200 to $36,000 for the 4 servo installation including the required G5 and GAD 29b. Mine will be several thousand more than the low bid.  However, after the expected sale of my ESI 500 with SVT and NAV, the KC192, and 3 servos, I think the net installation price will be between $19,000 and $20,000 for the 4 servo installation.

[donkaye]

4 hours ago, flyingcheesehead said:

Silly question: Are you going to do 2, 3, or 4 servos?

After reviews of the Yaw servo, I wouldn't consider doing my install without it.  The added cost isn't that much.  DEFINITELY wouldn't get the 2 servo installation where YOU act as the pitch trim servo.

 

[81X]

On 4/19/2019 at 6:37 PM, donkaye said:

 

I would say that 3 servos are all but mandatory; adjusting trim when your G5 tells you to would get pretty old pretty fast, especially in an airplane that needs a lot of trim with flaps, approach speed changes, etc.  

The YD is just the bees knees and a really cool add on if you have the money. 

[bradp]

Don Trek responded to me over on beecthalk that the Carlisle wire would be required for G3X and GFC 500 installations, but that you wouldn’t need to rewire an existing G5 if you add a new G3x or GFC. 

 Any news from the avionics shop on the latest revision to the GFC manual.  I really wish I could get my hands on one 

[Jerry 5TJ]

On 4/19/2019 at 2:30 PM, flyingcheesehead said:

Silly question: Are you going to do 2, 3, or 4 servos?

I never thought about doing the yaw damper in the R, but with the way people rave about it when they have it, maybe I will. I'm just curious if it'll ask to trim, or just sit there with the servo pushing the rudder one way or the other. I don't like the thought of a constant force on the servo, but I don't think they ask to trim all the force out either. Maybe someone who has one already can elaborate?

Once stabilized manually trim the rudder then engage YD.  

 

[flyingcheesehead]

31 minutes ago, Jerry 5TJ said:

Once stabilized manually trim the rudder then engage YD.  

 

RIght... But then when you level off in cruise, which normally takes a healthy amount of left rudder trim, will it tell me "TRIM L" or will I have to disengage the yaw damper, trim, and re-engage?

[Jerry 5TJ]

My KFC225 does not signal YD servo force.  The YD does hold the ball in the center by itself.  I prefer to take the static load off the servo. 

Also you want YD off for landing...Some installations (KFC150) have a YD that does not decouple via the autopilot cut off.  

[flyingcheesehead]

On 4/26/2019 at 4:36 PM, Jerry 5TJ said:

My KFC225 does not signal YD servo force.  The YD does hold the ball in the center by itself.  I prefer to take the static load off the servo. 

Also you want YD off for landing...Some installations (KFC150) have a YD that does not decouple via the autopilot cut off.  

I'm just wondering what the behavior of the GFC500 is. Like you, I'd prefer to take the static load off the servo... I just don't know if it'll be signaled or I'll have to disengage the yaw damper manually trim, and re-engage when I enter a new phase of flight. If I do have to do that, IMO the yaw damper has a lot less value.

Interesting about the KFC150 - Mine doesn't have YD so I wasn't aware it didn't cut off.

[Jerry 5TJ]

Re the use of YD — perhaps you’re overthinking this. 

I’ve never turned off the YD and seen the ball skid to the corner.   YD authority isn’t overwhelming.  

In cruise as the P46T accelerates more L trim is needed.  If the YD is on and the rudder trim was set to neutral (as it is for takeoff) by the time the plane is level and stable at cruise power the yaw is about 1/3 ball off with YD holding about another 1/3 ball worth of rudder.  Switch off the YD,  set rudder trim, YD back on.  

So I tweak YD once per flight and check it is off as pre-landing flow.  

I suspect, but don’t know, that the system is tuned to dampen the faster yawing motions that sicken a passenger in the back    Steady yaw offsets are not as rigidly corrected.  

Since there is no electric rudder trim you may leave the YD engaged as you trim the yaw.  Works ok, but the YD action slows the response a bit.  

My habit is to turn it off.  My CFII (8,000 hours In PA46) scolds this as an unnecessary action to be avoided in single pilot IMC.   He has a valid point.  

If you wish you could leave the YD on full time.   The 3 planes I’ve had with King YD never had a problem with the yaw servo or the yaw gyro listed in the logs.  

(The pitch servos, now that’s a different story entirely)

The KFC150 system YD switch is separate from the control head.   The plane I owned with that AP system had the usual AP cut off buttons on the yokes, BUT that switch did not sever power to the YD.   A separate button on the panel ran YD.  

A crosswind landing with the YD engaged was ‘interesting’ as the YD is attempting to center the rudder pedals.   You can overpower the yaw servo but it isn’t fun to discover on short final.

 The KFC225 and GFC500/600 YD are integral and AP cut off switch cancels all including YD.  

Suggest if you can you do get YD as it does stabilize your plane in the third axis.  

Edited April 28, 2019 by Jerry 5TJ

[MIm20c]

I notice the tail wagging all the time in the short body. I seldom notice it in the long body. Still not convinced it’s worth the upgrade price. 

[flyingcheesehead]

11 hours ago, Jerry 5TJ said:

I’ve never turned off the YD and seen the ball skid to the corner.   YD authority isn’t overwhelming.  

In cruise as the P46T accelerates more L trim is needed.  If the YD is on and the rudder trim was set to neutral (as it is for takeoff) by the time the plane is level and stable at cruise power the yaw is about 1/3 ball off with YD holding about another 1/3 ball worth of rudder.  Switch off the YD,  set rudder trim, YD back on.  

So I tweak YD once per flight and check it is off as pre-landing flow.  

I suspect, but don’t know, that the system is tuned to dampen the faster yawing motions that sicken a passenger in the back    Steady yaw offsets are not as rigidly corrected.  

Since there is no electric rudder trim you may leave the YD engaged as you trim the yaw.  Works ok, but the YD action slows the response a bit.  

 The KFC225 and GFC500/600 YD are integral and AP cut off switch cancels all including YD.  

Suggest if you can you do get YD as it does stabilize your plane in the third axis.  

Interesting.

In my M20R, there's a "T/O" range on the yaw trim that's about the right-hand 1/3 of the full travel. I generally take off with full right rudder trim and still have to give the right rudder pedal a good shove on liftoff (65-70 KIAS) but it steadily drops down as I get through gear up (~85 KIAS), flaps up (~95 KIAS), and at Vy (105 KIAS) the trim takes care of everything. I normally climb significantly faster, around 130-135 KIAS, and by the time I accelerate to that speed a couple thousand AGL I trim the rudder maybe 1/4 of the way over (halfway between neutral and full right) and then in cruise it's pretty close to neutral, maybe just a hair to the right.

My rudder trim is electric ONLY - No wheel. But it's not an autopilot-related servo, I have no YD currently, so my questions are solely around the GFC 500 that I hope to install, not the KFC 150 that I currently have. 

Looking in the G5/GFC500 manual and the M20R AFMS for the GFC 500, the annunciations don't show anything like TRIM R or TRIM L, only TRIM UP and TRIM DOWN. It also looks like if you disconnect the autopilot by pushing the AP button on the GMC 507 controller, or by pushing the manual electric trim, the yaw damper will stay engaged, while if you disconnect the autopilot via that AP DISC button on the yoke, that will disengage the yaw damper as well. A handy thing to know, and kind of a handy way of having it work!

[flyingcheesehead]

11 hours ago, MIm20c said:

I notice the tail wagging all the time in the short body. I seldom notice it in the long body. Still not convinced it’s worth the upgrade price. 

Yeah, I had no desire at all for a yaw damper until someone came along here and raved about it.  

I have a long body (M20R) and it's normally pretty stable in yaw, all I do is make a couple of adjustments to the yaw trim per flight. But, when it starts to get pretty turbulent, even when I'm standing on both rudder pedals to help the yaw stability... Well, it'd be nice in those instances, maybe. 

[carusoam]

FCH...

Something to consider...

Unfortunately, I can’t put my finger on it...

There is an SB(?) For when the rudder trim has been pulled too hard... causing it to slip?

Something can get out of alignment for some reason... some how...

Long Body rudder trim adjustment...

your description of not having enough trim to match the requirement sounds like something may have slipped out of adjustment...

 

My O1 uses the same trim setting as marked...

The SB that I am trying to describe, may be a couple of years old....

Let us know if you’re not familiar with this one... we can find it, or ask the Doc...

Best regards,

-a-

[flyingcheesehead]

28 minutes ago, carusoam said:

FCH...

Something to consider...

Unfortunately, I can’t put my finger on it...

There is an SB(?) For when the rudder trim has been pulled too hard... causing it to slip?

Something can get out of alignment for some reason... some how...

Long Body rudder trim adjustment...

your description of not having enough trim to match the requirement sounds like something may have slipped out of adjustment...

 

My O1 uses the same trim setting as marked...

The SB that I am trying to describe, may be a couple of years old....

Let us know if you’re not familiar with this one... we can find it, or ask the Doc...

Best regards,

-a-

Not familiar with that, no... It's been this way since I've had the plane (~7 years) and since I'm off the pedal before Vy I figured it was OK. Most of the rudder I use is right at rotation and in the first few seconds of climb while the gear is still down. (Hmm, maybe my left gear doors are rotated into the wind... )

But, if you can point me toward that SB I'd appreciate it.

How exactly does one "pull the rudder trim too hard"?

[flyingcheesehead]

12 hours ago, carusoam said:

There is an SB(?) For when the rudder trim has been pulled too hard... causing it to slip?

Something can get out of alignment for some reason... some how...

Long Body rudder trim adjustment...

your description of not having enough trim to match the requirement sounds like something may have slipped out of adjustment...

Thanks to @Deb for providing the SI... And now that I have a copy, I'm pretty sure I've seen it before.

Two things: 

1) It does not apply to my airplane. It says it applies to M20R s/n 29-0412 and on. 29-0412 is a 2006, possibly the first one with the GFC 700? The part number they list for the SI is 740196-003, my parts manual shows 740196-001. Do Mooney parts have a "version" after the dash, where a -003 should be used to replace a -001, or does that mean that other parts have been updated as well (such as the capstan) such that the new part isn't correct when surrounded by older parts? (Upon further review, the capstan mentioned in the SI is the same one in my parts manual... So maybe a bad example.)

2) My plane already meets the standard specified for the check flight: "The rudder trim shall center the turn coordinator ball with no pilot application of rudder during full power climb at 105 KIAS."

Given that - Is this actually a problem for me that I should be chasing? I had previously decided it wasn't. 

[Browncbr1]

On 4/28/2019 at 10:05 AM, Jerry 5TJ said:

Re the use of YD — perhaps you’re overthinking this. 

I’ve never turned off the YD and seen the ball skid to the corner.   YD authority isn’t overwhelming.  

In cruise as the P46T accelerates more L trim is needed.  If the YD is on and the rudder trim was set to neutral (as it is for takeoff) by the time the plane is level and stable at cruise power the yaw is about 1/3 ball off with YD holding about another 1/3 ball worth of rudder.  Switch off the YD,  set rudder trim, YD back on.  

So I tweak YD once per flight and check it is off as pre-landing flow.  

I suspect, but don’t know, that the system is tuned to dampen the faster yawing motions that sicken a passenger in the back    Steady yaw offsets are not as rigidly corrected.  

Since there is no electric rudder trim you may leave the YD engaged as you trim the yaw.  Works ok, but the YD action slows the response a bit.  

My habit is to turn it off.  My CFII (8,000 hours In PA46) scolds this as an unnecessary action to be avoided in single pilot IMC.   He has a valid point.  

If you wish you could leave the YD on full time.   The 3 planes I’ve had with King YD never had a problem with the yaw servo or the yaw gyro listed in the logs.  

(The pitch servos, now that’s a different story entirely)

The KFC150 system YD switch is separate from the control head.   The plane I owned with that AP system had the usual AP cut off buttons on the yokes, BUT that switch did not sever power to the YD.   A separate button on the panel ran YD.  

A crosswind landing with the YD engaged was ‘interesting’ as the YD is attempting to center the rudder pedals.   You can overpower the yaw servo but it isn’t fun to discover on short final.

 The KFC225 and GFC500/600 YD are integral and AP cut off switch cancels all including YD.  

Suggest if you can you do get YD as it does stabilize your plane in the third axis.  

I agree with turning off the YD as part of GuMPs.  Maybe not a big issue on smaller planes, but if in any kind of heavy cross wind landing situation, the YD fights you as you slip upwind wing down to keep straight on the center line.   Bigger the plane, the bigger the issue.   Very big PITA trying to land a twin in heavy cross wind with YD engaged.   YD is off below 1000agl when I’m flying. 

[carusoam]

FCH,

Glad you were able to find the service letter, and not be affected by it...

 

On the topic of known causes for yaw, and cases for having a YD, and the economic reason they might not become very popular...

 

1) The reason for using rudder during rotation on T/O. 

During rotation... this is a laws of physics / dynamics kind of thing...  more rotating mass, faster rpm, the faster the nose gets raised... the stronger the nose is going to yaw... so the expected extra bit of rudder gets applied at the same time...

 

2) The reason for using rudder during the climb...

This is the aviation 101 we all train for... the AOA combined with relative wind and rotating prop, causes a bit of yaw... the LBs got the rudder trim and a setting to begin the balancing act...   keeps your right leg from getting tired...

The rudder trim setting will be very dependent on weight, speed, power setting, and climb angle...

 

3) in cruise... rudder trim levels the wings with the change in fuel level...

4) There is always a subtle use for trim in the descent as well... opposite of the climb, but much milder, because power used is less, and the angle of descent is not very strong...

 

Using the rudder trim to keep the ball centered for climb, cruise, and descent... is icing on the LB cake. 

 

Now for how a YD gets used... Above, is listed the usual known sources of Yaw... we encounter on every flight... they are pretty well known.  But, they disappear into the noise every time the weather gets bumpy...

 

Weather seems to be a significant cause of yaw... and airplane design is a significant source of minimizing the response to the initial yaw...

Large tails mounted further from the Cg, have a stronger tendency to dampen the tail wagging response...

V-tails are known for their natural tail wagging response....  because of the missing vertical component...

Using a Yaw Damper isn’t going to cut out the bumps, but with a fast computer, with a strong sensor, and a quick acting servo... the side effect of tail wagging will be greatly reduced...

The YD May be helpful for some people that are sensitive to sea sickness.  Unfortunately, my passengers are sensitive to the bumps themselves.  Eliminating the tail wagging would allow the flight to be extended another 15 minutes...

 

I typically fly high enough to be In smooth air above the bumps... 

PP thoughts only, not a CFI...

Best regards,

-a-

[PT20J]

On 4/28/2019 at 7:45 PM, flyingcheesehead said:

But, when it starts to get pretty turbulent, even when I'm standing on both rudder pedals to help the yaw stability

This is a really good point - stick-fixed stability is generally better than stick-free stability, so blocking the rudder pedals to keep the rudder from floating will improve the ride in turbulence. 

One of the tough problems in designing an airplane without some sort of stability augmentation system is getting the balance of lateral and yaw stability right. Too much one way and you get spiral divergence, and too much the other way and you get dutch roll. Dutch roll is more annoying and difficult for the pilot to counteract and so the nod is usually to decreased spiral stability. The J (the only one I've tried this with) actually has great spiral stability -- slowed down and trimmed to around 90 KIAS straight and level hands off it will eventually enter a descending turn. But as the airspeed builds, the nose comes up as the inherent longitudinal stability kicks in. Around two and a half oscillations of the phugoid and it will settle out in about a 45 degree bank at a constant 90 KIAS or so. This, of course, assumes that it's rigged right and there is no fuel imbalance. So, because of this characteristic, the M20J has a bit of tail wag in turbulence. (This is all likely due to making the vertical stabilizer as small as possible as was discussed in another thread - in aerodynamics, you don't get something for nothing). I can easily see the advantage of the yaw damper if you are going to fly a lot in turbulence.

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Edited May 5, 2019 by PT20J