Weight of GFC 500 installed?

[Hakan Andersson]

Hi all,
I'm thrilled to be a co-owner of a PA-28-151.
We just got the plane and started to think about upgrades.
It's something about boys and new gadgets...

One of the things we are discussing is a new autopilot and we are looking to get a Garmin GFC 500.
In addition to the GFC 500 we also need two G5 to be mounted.

Looking at the additional weight for this package, each servo for the GFC 500 weighs 1.4 lbs according to Garmin, but that is all I can find.

Have anyone done a complete installation of this type of package and noted how much the Basic Empty Weight increases?

If anyone could help me with this one, I would be really glad.

Thanks.

All the best / Hakan

 

[Low Level Flyer]

From my installation 1.5 years ago in a 1968 Piper Arrow:

GMC 507 (GFC 500 control head)—0.82 lbs
Roll servo—1.73 lbs (I think includes mounting shelf)
Pitch servo—1.73 lbs (again, I believe includes mounting shelf)

I didn’t have the trim or yaw servos installed.


Sent from my iPad using Tapatalk

 

[WannFly]

trim servo - approx same weight
a whole bunch of wires - i would estimate ~ 3 lbs or thereabouts

 

[Racerx]

If you're removing the vacuum pump I think its all pretty negligible. I'd be more concerned with cost vs weight

 

[Hakan Andersson]

Thanks for your replies. Now I have something real to work with.

 

[BryanAV8R]

Hi all,
I'm thrilled to be a co-owner of a PA-28-151.
We just got the plane and started to think about upgrades.
It's something about boys and new gadgets...

One of the things we are discussing is a new autopilot and we are looking to get a Garmin GFC 500.
In addition to the GFC 500 we also need two G5 to be mounted.

Looking at the additional weight for this package, each servo for the GFC 500 weighs 1.4 lbs according to Garmin, but that is all I can find.

Have anyone done a complete installation of this type of package and noted how much the Basic Empty Weight increases?

If anyone could help me with this one, I would be really glad.

Thanks.

All the best / Hakan

After all is said and done...just went through this, and between removing the vac pump, NSD360, SigmaTec AI, vac gauge, regulator, filter, assorted hoses and installing 2x G5s, GFC500 control head, 3 servos (go for the autotrim...it's basically just the cost of the extra servo, some wire and a couple extra hours of labor..believe me, I was on the fence, and after springing for it...glad I did...!!!), and re-weighing the airplane, the useful load loss was 2 lb in a cessna 172 (I know, not a warrior...but, equivalent) and the CG shifted a little under 1" rearward mostly due to the 2 servos in the tail and probably the fact that the plane was physically weighed, not just a paperwork drill to adjust based on listed values in the install manuals (my IA and I agreed that with the extensive changes made...basically started with a stripped out bare instrument panel..it was worth putting it on scales and starting from a measured (rather than inferred) value).

You will be ok. Don't overthink it...it's not like you're going to loose the ability to use the rear seats...the weight and CG change is negligible and can be accounted for.

 

[MooneyDriver78]

My stec servos are like 4lbs, so I will be getting some extra useful load. The specs say GFC 500 servos are 1.4lbs, so that’s extra 2.6lbs not counting wiring harness, I wonder if they weigh it or if the harness weight is listed somewhere.

 

[Der Fliegermeister]

My stec servos are like 4lbs, so I will be getting some extra useful load. The specs say GFC 500 servos are 1.4lbs, so that’s extra 2.6lbs not counting wiring harness, I wonder if they weigh it or if the harness weight is listed somewhere.

Great autopilot! Looking forward to hearing how you like it. The harnesses for the GFC series autopilots are rather minimal (power, ground, can). But if they're to do all that work for you, might as well just have them do a fresh weigh on the bird. And make sure they actually update your equipment list!

Cheers!

 

[MooneyDriver78]

But if they're to do all that work for you, might as well just have them do a fresh weigh on the bird.
Cheers!

No way! First of all, they never do it correctly (empty fuel tanks), they either fill the tanks and subtract full fuel weight or they use fuel gauges to figure fuel weight and subtract from scale weight.
Either way it’s not going to be accurate.
I have created a spreadsheet sheet with all the changes since delivery, I found about 20 errors out of 100: bad math, missing entries, incorrect arm or weight….after all that, the logged W&B is within about 1lb.

 

[Der Fliegermeister]

No way! First of all, they never do it correctly (empty fuel tanks), they either fill the tanks and subtract full fuel weight or they use fuel gauges to figure fuel weight and subtract from scale weight.
Either way it’s not going to be accurate.
I have created a spreadsheet sheet with all the changes since delivery, I found about 20 errors out of 100: bad math, missing entries, incorrect arm or weight….after all that, the logged W&B is within about 1lb.

So they don't know how to do a w&b correctly but they're going to install an autopilot for you??...you might need to find a better shop, my friend!

 

[MooneyDriver78]

So they don't know how to do a w&b correctly but they're going to install an autopilot for you??...you might need to find a better shop, my friend!

Avionics shop will do the autopilot and w&b, but you recommended to weigh the plane (that’s an AP job) , not the same thing.

 

[Der Fliegermeister]

Avionics shop will do the autopilot and w&b, but you recommended to weigh the plane (that’s an AP job) , not the same thing.

So the installation of an autopilot under an STC is a _____ alteration? Answer: major; requiring a 337...to be signed by an IA or authorized repair station personnel. To hold an IA you have to hold A&P privileges on a mechanic certificate. Are you asserting that nobody there is an A&P? When I worked for an avionics shop, everyone had an IA (including me). We weighed airplanes after upgrades many times for our customers.

I think you may have missed my point. Sure, maybe that shop doesn't have load cells or scales. But if they're going to do a serious job like this and they aren't, by your own estimation, competent enough to weigh the airplane I reiterate: find a new shop.

I've got my fingers crossed for you that the proverbial can of worms doesn't open up on your installation situation. But I'd be willing to bet you're leaving weight savings on the table if the airplane hasn't been weighed in 20 years. Moreover, I would bet you a beer there are errors and/or omissions on the equipment list and that your empty CG is not accurate. (Or precise for you diehard physics nerds out there. I know the difference)

 

[MooneyDriver78]

So the installation of an autopilot under an STC is a _____ alteration? Answer: major; requiring a 337...to be signed by an IA or authorized repair station personnel. To hold an IA you have to hold A&P privileges on a mechanic certificate. Are you asserting that nobody there is an A&P? When I worked for an avionics shop, everyone had an IA (including me). We weighed airplanes after upgrades many times for our customers.

I think you may have missed my point. Sure, maybe that shop doesn't have load cells or scales. But if they're going to do a serious job like this and they aren't, by your own estimation, competent enough to weigh the airplane I reiterate: find a new shop.

I've got my fingers crossed for you that the proverbial can of worms doesn't open up on your installation situation. But I'd be willing to bet you're leaving weight savings on the table if the airplane hasn't been weighed in 20 years. Moreover, I would bet you a beer there are errors and/or omissions on the equipment list and that your empty CG is not accurate. (Or precise for you diehard physics nerds out there. I know the difference)

I assume they are just avionics techs, probably wrong about that but I know they are a repair station.
As I said there were many errors or omissions, but they mostly canceled out.
I’ve had plane weighed once with horrible results, they used the fuel gauges to determine weight of the fuel, one of which read low due to a fuel sender issue, so the weight was ~125 lbs heavier than it actually was.
Two other shops wanted to weigh it instead of doing a w&b recalculation, their attitude was the same as yours. When I asked how they would do that I quickly said no thanks.

 

[Bell206]

No way! First of all, they never do it correctly (empty fuel tanks), they either fill the tanks and subtract full fuel weight or they use fuel gauges to figure fuel weight and subtract from scale weight. Either way it’s not going to be accurate.

FYI: While I know of no legit weighing procedure that permits the use of partial fuel levels, there are acceptable methods to use full fuel. Some OEMs primary method is full fuel like Mooney with defueling aircraft as an optional method. Regardless, the only way to accurately correct any previous EWB calculations errors is with an actual weight and balance. Why you have had so many issues with people performing actual W&B I can not answer as the process is pretty straight forward given most OEMs provide a procedure.

I assume they are just avionics techs, probably wrong about that but I know they are a repair station.

The responsibility of correcting the aircraft empty weight and balance record (to include the equipment list) after an alteration or repair falls to the installer whether under repair station certificate or a A or P certificate. However, some installations are very difficult to mathematically calculate and the only accurate method is to weight the aircraft.

 

[MooneyDriver78]

…there are acceptable methods to use full fuel.

I don’t see how you can do that, you are assuming the specify capacity of full tanks is accurate, at least with my aircraft it is not, actual was 67 vs 64 in POH. So that would result in an extra 18lbs of weight added to my empty weight.
I would think all aircraft would under report their full tank capacity…can you imagine the lawsuit if they said your capacity was 64 gals, but found it was only 63.5?
Mooneys can be useful load challenged, so I am sensitive to loosing it , even if it’s “only” 18lbs.
And then how do you know the scales are accurate, aren’t they supposed to be calibrated every year? I’m sure that doesn’t happen.

 

[Bell206]

I don’t see how you can do that, you are assuming the specify capacity of full tanks is accurate, at least with my aircraft it is not, actual was 67 vs 64 in POH. So that would result in an extra 18lbs of weight added to my empty weight.

I believe the issue here is your understanding of usable vs unusable fuel. As I recall the 64 gallons in the POH is usable fuel. The remaining 3 gallons of your “actual” capacity is the unusable fuel that is required to be included with the empty weight. So the 18 pounds you are sensitive to is actually a feature of your aircraft that must be included when determining the certified empty weight. A quick look to Note 1 on your specific aircraft TCDS should detail how much unusable fuel must be included for the empty weight. I believe some Mooneys can have up to 30+lbs of unusable fuel included into their empty weight.

I would think all aircraft would under report their full tank capacity…can you imagine the lawsuit if they said your capacity was 64 gals, but found it was only 63.5?

No lawsuits required. Part of the certification process is to determine the usable and unusable fuel quantities which is listed in the TCDS and other documents. Hopefully you are not flight planning with those extra 3 gallons in mind. In that case the only law suit would be against you for using that 3 gallons as usable.

And then how do you know the scales are accurate, aren’t they supposed to be calibrated every year? I’m sure that doesn’t happen.

I'm quite sure that does happen. When someone performs a certified weight and balance and doesn’t ensure the scales are calibrated then they violate the performance rules in Part 43.13. If you are in doubt ask to see the calibration record. Whether the scales need calibration every 12 months depends on the type of equipment. The scales I used required calibration every 6 months.

 

[MooneyDriver78]

I believe the issue here is your understanding of usable vs unusable fuel. As I recall the 64 gallons in the POH is usable fuel. The remaining 3 gallons of your “actual” capacity is the unusable fuel that is required to be included with the empty weight.

We used the electric boost pump to drain the tanks through the fuel pickups, so the unusable fuel was left in the tanks. Then I added fuel (we were calibrating JPI fuel readings), and I added 33.5 gallons into each 32 gallon tank. So that’s how I am sure of my tank capacity.

 

[Bell206]

We used the electric boost pump to drain the tanks through the fuel pickups, so the unusable fuel was left in the tanks. Then I added fuel (we were calibrating JPI fuel readings), and I added 33.5 gallons into each 32 gallon tank. So that’s how I am sure of my tank capacity.

Was the aircraft properly leveled when you defueled it? If not then I doubt you left the required unusable fuel. I believe the Mooney procedure states when you defuel as you indicated with the boost pumps you must add the unusable fuel back into the tanks. Regardless, the only accurate means I'm familiar with when determining unusable fuel onboard is to defuel the aircraft completely and add unusable fuel by placing the prescribed amount of fuel to each tank, adding the weight amount mathematically , or, in the case you use full fuel subtract the weight amount of the usable fuel.