C172 vacuum system 337

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Jaime

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JDias
Hello,

I've recently purchased a C172 with a Continental O-300-D. I will only be doing day VFR flights with it.
I would like to remove the vacuum system including the heading and attitude indicators. I would also like to remove the vertical speed indicator.
All these instruments are in the minimum equipment list.

Would it be possible to remove them with a 337? Would I need a DER's approval? Has anyone else done this?

Thanks.
 
Last edited:
Are you planning to replace them with glass instruments?


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FAR 91.205.

Here is the minimum you have to have to be legal for VFR Day flight. ATOMATOFlAMES!

A – airspeed indicator
T – tachometer (for each engine)
O – oil pressure gauge (for each engine using a pressure system)
M – manifold pressure gauge (for each altitude engine)
A – altimeter
T – temperature gauge (for each liquid cooled engine)
O – oil temperature gauge (for each air cooled engine)
F – fuel gauge
L – landing gear position indicator
A – anti collision lights (for aircraft certified after March 11th 1996)
M – magnetic compass
E – ELT
S – safety belts

Note: if your aircraft is not equipped for such ie: fixed gear or normally aspirated engine, those (the manifold gauge and gear indicator) would not be required.

If I may editorialize, when it comes time to sell this airplane, your removal of the vacuum system and instruments without suitable replacement will seriously and negatively affect the plane's value. Nobody wants a plane with no Attitude Indicator, heading indicator, or VSI. I suggest you search the accident databases for VFR Flight into IMC. But it is your plane....

-Skip
 
Skip Miller said:
FAR 91.205.

Here is the minimum you have to have to be legal for VFR Day flight. ATOMATOFlAMES!

Note: if your aircraft is not equipped for such ie: fixed gear or normally aspirated engine, those (the manifold gauge and gear indicator) would not be required.

If I may editorialize, when it comes time to sell this airplane, your removal of the vacuum system and instruments without suitable replacement will seriously and negatively affect the plane's value. Nobody wants a plane with no Attitude Indicator, heading indicator, or VSI. I suggest you search the accident databases for VFR Flight into IMC. But it is your plane....

-Skip
Click to expand...

Thanks Skip. The vacuum instruments and the vsi are not required for day vfr as per FAR 91.205, but are in the MEL.
If I can legally remove them, I would keep them, to reinstall in case of a future sale.
 
Skip Miller said:
Nobody wants a plane with no Attitude Indicator, heading indicator, or VSI. I suggest you search the accident databases for VFR Flight into IMC. But it is your plane....

-Skip
Click to expand...
I wouldn’t say nobody. It wouldn’t bother me too much for the way I would fly it.

Having said that, it would be highly unusual for a 172 to not have those things. If they are the old style gyros, they can be replaced with modern units at a significant weight savings.
 
Jaime said:
Thanks Skip. The vacuum instruments and the vsi are not required for day vfr as per FAR 91.205, but are in the MEL.
If I can legally remove them, I would keep them, to reinstall in case of a future sale.
Click to expand...

If you have an O-300 based C172, it's a fairly old C172. You have an MEL? Was this something requested and approved by the FAA? I'd be a bit shocked that your vacuum pump and vacuum instruments were listed as required equipment on the equipment list from the factory, even on my 1975 T210 they were optional.
 
^this. You don't have an MEL (a list of stuff that can be broken and you can still dispatch). You just have an equipment list

That said, my Citabria has no vacuum system. I've seen float planes with stripped panels for weight savings.

An O-300 powered 172 is not a rocket and would benefit from such weight loss.
 
Jaime said:
Hello,

I've recently purchased a C172 with a Continental O-300-D. I will only be doing day VFR flights with it.
I would like to remove the vacuum system including the heading and attitude indicators. I would also like to remove the vertical speed indicator.
All these instruments are in the minimum equipment list.

Would it be possible to remove them with a 337? Would I need a DER's approval? Has anyone else done this?

Thanks.
Click to expand...
No 337 needed. those instruments are not marked as (R) on the equipment list. This is an equipment list for weight and balance. not really used as MEL.
but your 0-300-D has a vac pump, and a starter drive, are you going to remove that too.??

IMHO a 15 -20 pound weight gain isn't worth the trouble. hopefully you'd never be that close max gross.
 
Tom-D said:
No 337 needed. those instruments are not marked as (R) on the equipment list. This is an equipment list for weight and balance. not really used as MEL.
but your 0-300-D has a vac pump, and a starter drive, are you going to remove that too.??
Click to expand...

I will check with my AP to confirm whether the plane has an equipment list or a MEL.
Yes, vac pump would also go.
 
Jaime said:
I will check with my AP to confirm whether the plane has an equipment list or a MEL.
Click to expand...
FYI: most likely it is an Equipment List you are looking at, considering there is no Master MEL available for a 172. If it was an MEL it would follow this format:
http://fsims.faa.gov/PICDetail.aspx?docId=M CE-208 R11a

FYI 2: each aircraft is required to have a current Equipment List along with it's current Weight &Balance report.
 
Jaime said:
I will check with my AP to confirm whether the plane has an equipment list or a MEL.
Yes, vac pump would also go.
Click to expand...
If you remove just the pump, that is one thing, no 337, but when you remove the starter adaptor and convert the 0-300-D to a 0-300-A. we will need authorization of some sort.. STC/ Field approval, or ?
this leads to your aircraft having the wrong engine installed = more paper work.
 
I think even the crankshaft is different between the O300-D model and the O300-A model. The D model has the damper on the rear where the A model does not. Tom can confirm.
 
Thank you all for you feedback! I only have an equipment list not a MEL after all.
 
Clip4 said:
Those must be some rather heavy instruments. You are going to lose about 10 lb.
Click to expand...
As I recall, ours had a wet vacuum pump that wasn't lightweight. I don't know about 20 lbs, but perhaps close to it, if he removes the pump/lines/filter/VSI/AI/DG. Still, not worth it! That airplane near gross on warm days will make you not want to get it close to gross on warm days.
 
Do the alternator conversion with the other stuff plus what you find while you're in there, and you'd likely hit 20 lbs.
 
I have a cessna 172F model. It has an o-300 D. It does not have a vacuum pump or the starter adapter. It has a pull starter. I think you could loose the whole starter adapter, and replace it with a light weight starter. I’d you do go with a geared light weight starter they are not compatible with the starter adaptor. The adaptor starter and pump are heavy. A geared starter would lose weight. Put in an electronic efis. Dynon makes a replacement with STC.
 
Tom-D said:
If you remove just the pump, that is one thing, no 337, but when you remove the starter adaptor and convert the 0-300-D to a 0-300-A. we will need authorization of some sort.. STC/ Field approval, or ?
this leads to your aircraft having the wrong engine installed = more paper work.
Click to expand...
If he removes the fuel pump, wings, and propellor, that would also be a bigger deal. Fortunately, he’s mentioned nothing about removing any of those things.
 
Patrick evans said:
I have a cessna 172F model. It has an o-300 D. It does not have a vacuum pump or the starter adapter. It has a pull starter. I think you could loose the whole starter adapter, and replace it with a light weight starter. I’d you do go with a geared light weight starter they are not compatible with the starter adaptor. The adaptor starter and pump are heavy. A geared starter would lose weight. Put in an electronic efis. Dynon makes a replacement with STC.
Click to expand...
The 0-300-D does not have a pull starter.
When you convert to a light weight starter, on a -A, the STC is included in the paper work.
The 0-300-D does not need a STC.
 
Salty said:
If he removes the fuel pump, wings, and propellor, that would also be a bigger deal. Fortunately, he’s mentioned nothing about removing any of those things.
Click to expand...
I think he's already missing the fuel pump...
 
what is the standard procedure for a vacuum pump removed? plenty of people seem to be doing it these days. I would’ve assumed a block off plate is installed on the mount?
 
Bacho said:
what is the standard procedure for a vacuum pump removed? plenty of people seem to be doing it these days. I would’ve assumed a block off plate is installed on the mount?
Click to expand...

There had better be a cover, considering many (all?) accessory pads have a lube oil port to feed oil to a wet vacuum pump or something similar. The covers are readily available.
 
Jaime said:
15-20lbs weight reduction. I only fly day vfr, so I have no need for these instruments.
Click to expand...

If you’re worried about exceeding the load limits by 15-20 lbs, just exceed the friggen limit and be done with it...unless you’re asking because you’re already so over the limit that you need to get safely closer.

I’m not suggesting you fly outside of the certified limits; You need to be safe and legal. But consider whether 20 lbs is going to make a difference to safety of flight vs the drastic move of dumping flight instruments that are the most basic part of an already basic machine.

Heck, run one less quart of oil, vacuum the dirt out of the carpet, wear shorts, pick the rocks out of your shoe tread, and poop before you fly. Lose some weight if you’re not skinny. Maybe you’ve already done these things.

What’s your typical density altitude?
 
Dan Thomas said:
I think he's already missing the fuel pump...
Click to expand...
The 1948 -170 Cessna is the only one of the type that needs one.

because of the different fuel system routing.
 
455 Bravo Uniform said:
If you’re worried about exceeding the load limits by 15-20 lbs, just exceed the friggen limit and be done with it...unless you’re asking because you’re already so over the limit that you need to get safely closer.

I’m not suggesting you fly outside of the certified limits; You need to be safe and legal. But consider whether 20 lbs is going to make a difference to safety of flight vs the drastic move of dumping flight instruments that are the most basic part of an already basic machine.

Heck, run one less quart of oil, vacuum the dirt out of the carpet, wear shorts, pick the rocks out of your shoe tread, and poop before you fly. Lose some weight if you’re not skinny. Maybe you’ve already done these things.

What’s your typical density altitude?
Click to expand...
Best advice yet.......especially if your typical American in which case you are, at least 15# over your healthy BMI.
 
Snowmass said:
Best advice yet.......especially if your typical American in which case you are, at least 15# over your healthy BMI.
Click to expand...

yup. During one of my annuals, I cleaned out all the mud daubbers nests out of the wings and cleaned out the inside belly of the play when it was all apart. Not sure what weight the plane lost, but made me feel better about not carrying around garbage.

You can pull the rear seat in a 172. That'll drop you 20-25lbs right there.

Maybe look at lighter interiors. You can remove all the carpeting and replace it with foam. Forget who sells it.

If you stripped off all the paint, the plane would probably loose 30-40lbs.
 
Jaime said:
15-20lbs weight reduction. I only fly day vfr, so I have no need for these instruments.
Click to expand...
You will certainly greatly diminish the value of the craft by doing so. Getting an extra 10 or 20 lbs. of useful load isn't worth it.
 
Just because you are planning only VFR doesn't mean you find yourself inadvertently in IMC. Keep those instruments and get some instruction on basic IMC flight such as a life saving 180 degree escape turn. You will never notice such a minuscule weight saving.
 
Snowmass said:
Just because you are planning only VFR doesn't mean you find yourself inadvertently in IMC. Keep those instruments and get some instruction on basic IMC flight such as a life saving 180 degree escape turn. You will never notice such a minuscule weight saving.
Click to expand...
I would assume it is a minuscule saving, 2 Narco 12s are about 25 pounds, and a ADF, audio panel. and all the wires and you will approaching 35-50 pounds.
you will still need transponder, intercom. the Com-2000 weighs 1.3 wiring included
convert the old 12vdc plug, to into a USB plug you are good to go.
 
many old aircraft do not have center stacked radios.
 
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