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Weight Reduction by removing vacuum system?


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I recently purchased an M20K. It has a Garmin 600 PFD/MFD but also still has the vacuum system intact with an artificial horizon. How much weight would I save by removing the vacuum system?

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HC,

You might get...
 

  • Near nothing if it is just the vac pump....
  • a big chunk if you have the back-up pump system in the tail...
  • A pain if you have vac powered speed brakes...
  • An opportunity if you can add a Second alternator...

What do you have in mind?

A few people have gone all electric over the years...selecting the proper back-up AI will be dependent on your primary AI... (G600)...

PP thoughts only, not an instrument guru...

Best regards,

-a-

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Check the weight of all the components and add ... I am guessing probably ball park would be around 7-8 lbs between the gyro, the pump, the air filter / regulator , hoses and low vac warning 

in my opinion , the biggest benefit is less clutter behind the instrument panel and in the engine accessoires compartment 

 

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26 minutes ago, OR75 said:

Check the weight of all the components and add ... I am guessing probably ball park would be around 7-8 lbs between the gyro, the pump, the air filter / regulator , hoses and low vac warning 

in my opinion , the biggest benefit is less clutter behind the instrument panel and in the engine accessoires compartment 

 

Mine was ~5lbs saved (total) by removing vac pump, standby vac system (manifold pressure based), and adi (gyro).  Had to add back in the weight of the new electronic ADI and whatever components it needs.

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An AI like a 52D56 is 2.7 lbs 

A 215CC pump is 3 lbs 

the vacuum regulator would be 0.5 lb if I was to guess (you probably have one ) 

the 5/8 hose is 0.25 lbs per foot ... I am guessing between the hose going from the pump to the firewall , and the two hoses from the back of the AI , you have about 3 ft or about 0.75 lbs

the low vac system is mostly wiring so maybe 0.1 lbs ?. The AN fittings probably 0.1 lbs 

add it all and probably around 7-8 lbs 

 

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1 hour ago, Hank said:

I picked up 25 lbs useful load in my C by reducing the size if the pilot's belly . . . . Time to do it again!

The same 25, or another 25?:rolleyes:

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1 hour ago, amillet said:

The same 25, or another 25?:rolleyes:

What goes around comes around. The same 25 need to go again. Two layoffs, three job changes and a 600 mile relocation caused many lifestyle changes, not all for the better.

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13 hours ago, OR75 said:

Check the weight of all the components and add ... I am guessing probably ball park would be around 7-8 lbs between the gyro, the pump, the air filter / regulator , hoses and low vac warning 

in my opinion , the biggest benefit is less clutter behind the instrument panel and in the engine accessoires compartment 

 

I would have to go back and look but about 7 lbs sounds right when I put in the G5's and removed the vacuum system. 

However, the biggest benefit was not the weight but how easy it is now to get to the oil filter without the vacuum pump in the way or the hose coming off it to the firewall. Also like you say there is a lot more room behind the panel. 

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5 hours ago, Hank said:

I picked up 25 lbs useful load in my C by reducing the size if the pilot's belly . . . . Time to do it again!

I gained about 30 lbs useful load over the last two years but managed to see 5 of it come sneaking back (I like ice cream...) Working on getting rid of those five again. 

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That is a sweet setup.  It seems optimally the G600 should be integrated with the autopilot and its seems unlikely that someone would spend that much money and not have that done.   One way to tell if, the 337, doesn't say is on a nice VFR day, pull the breaker on the the GRS77 or solid state AHRS while the autopilot is engaged.  If the autopilot disconnects it seems likely the vacuum ADI is no longer required for the autopilot.

The next question is: does the G600 require a backup attitude indicator?  I read it doesn't have a battery backup for when the alternator fails.   There are others that have these systems better prepared to answer this question.

You could gain a few pound in useful load having the stuff removed and lose a few pounds out of your wallet.

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13 minutes ago, skykrawler said:

That is a sweet setup.  It seems optimally the G600 should be integrated with the autopilot and its seems unlikely that someone would spend that much money and not have that done.   One way to tell if, the 337, doesn't say is on a nice VFR day, pull the breaker on the the GRS77 or solid state AHRS while the autopilot is engaged.  If the autopilot disconnects it seems likely the vacuum ADI is no longer required for the autopilot.

The next question is: does the G600 require a backup attitude indicator?  I read it doesn't have a battery backup for when the alternator fails.   There are others that have these systems better prepared to answer these system.

You could gain a few pound in useful load having the stuff removed and lose a few pounds out of your wallet.

I believe the autopilot does not rely on the attitude indicator as it flys approaches that are couple with the 650............but I am not certain. I will ask the former owner to clarify.

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The old BK APs used both references to the AI and the HSI...

These can be found easily, used to be found easily... in the BK literature that was on line...

The set of instruments was fully integrated and came with options like Alt hold...

 

Economics wise... somebody left the BK AI in place... it costs another box to translate Garmin signals to the BK AP...

When the BK AI goes expect a box to be needed...

When getting the GFC500 AP, no translation box will be needed...

 

The biggest savings you are going to experience... is the ease of integration amongst al the Big G boxes...

Big G isn’t perfect... updates keep coming...

As the days go by... the mechanical gyros are just taking up space...

Have you seen the GI275s in Mooneys?

To get all the available data found in one device... used to be 50 LBs...   :)

PP thoughts only...

Best regards,

-a-

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Hub cap...

Find one of these...

a back-up device that has been used with G1000 panels...

Mid Continent MD-302 SAM...

Not only can you run from the vacuum... you can run towards the tried and true...

PP thoughts only, This device was on sale around here recently...

Best regards,

-a-

 

CB7AA487-BF98-476D-926D-E9DB080E004F.jpeg

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33 minutes ago, hubcap said:

Could the artificial horizon be replaced with a G5?

Most likely, but...

The place to read that detail is the install manual for the G600... there will be a list of eligible back-up devices and what the requirements are...

The glass panel displays are a bit more complex with regards to separate power supplies, and batteries required...

It helps to start with the most recent version of the install manuals, because the eligibility list continues to grow... over time...

 

Also... the same thing applies to what device is sending attitude info to the AP...

G5s probably don’t talk to BK APs... The GI275 seems to be better at that...

Do you have a favorite installer to work with?  Some of the details that may be required may be down to the level device updates, firmware, and software...

The added challenge of the multi-step upgrade starts to show up...

The added challenge of different device manufacturers is ever present...

The Mid Continent device is like an accepted middle man by many companies...

BK and Gary/Min haven’t gotten along since they parted ways in the 90s...

Best regards,

-a-

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Replaced the ki256 with a gi275 to talk to kfc150, removed vacuum system... then speed brakes didn’t work. Engine driven vacuum pump went back on, speed brakes worked again. Left the heavy electrical stby vac pump out of the plane. 

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10 hours ago, Speed Brakes said:

Left the heavy electrical stby vac pump out of the plane.

This is what will give you the most weight reduction. If you still have the "Standby Vac" switch in your panel, you most likely have the standby pump in the rear of the plane. When I put in my Aspens and redid the panel, I left the engine pump in for the speed brakes only (older Precise vacuum-operated) and pulled the standby pump, wiring, and tubing. Gained 12+ pounds just with pulling it out.

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11 hours ago, Speed Brakes said:

Replaced the ki256 with a gi275 to talk to kfc150, removed vacuum system... then speed brakes didn’t work. Engine driven vacuum pump went back on, speed brakes worked again. Left the heavy electrical stby vac pump out of the plane. 

That's an ironic series of events considering your screen name  :D

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On 1/10/2021 at 2:04 PM, hubcap said:

This is the panel presently. It does have a King 200 AP but I do not know if it gets input from the artificial horizon. 

Pull the King Attitude Indicator’s circuit breaker and you’ll find out.  

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