The International Cessna^® 170 Association

So I have a question for you all knowing cessna owners. Why does a 170 need a fuel pressure gauge being a high wing aircraft? Saw it in the IPC and got real confused. Thanks

IdahoPilot

Was this fuel pressure gage on a straight C-170 which requires a fuel pump?

The straight 170's have a fuel pump and pressure gauge do to the routing of the fuel lines.
I believe that it was thought that these were needed at high angles of attack to keep fuel flowing.
Later A & B models had the fuel lines routed differently and don't have the pump.

KAP has it correct. The "straight" 170 has an engine-driven (automotive type) fuel pump and a fuel pressure gauge to confirm pressure. Due to the CAR3 requirement that the fuel system deliver 150% of required fuel to the engine, and the straight 170s routing of fuel lines down the forward doorposts...in a takeoff/climb configuration insufficient head-pressure exists to meet the certification requirement. The pump assures that requirement, and is REQUIRED EQUIPMENT, along with the associated gauge and check-valve.
The A and B models re-routed the fuel line down the aft doorpost eliminating the problem.

I have heard of a few airplanes which were field-approved to switch to an electric pump, but have not personally seen one and do not know if that is a feasible mod anymore. I have also heard of straight 170 airplanes operating without a pump at all, but that is not legal. I would rather modify my straight airplane's fuel system routing down the rear doorpost, if possible if I wanted to get rid of the pump.

gahorn wrote:KAP has it correct. The "straight" 170 has an engine-driven (automotive type) fuel pump and a fuel pressure gauge to confirm pressure.

Ah Ha! It is all making sense. Guess I will start looking for a fuel pressure gauge. Thanks so much George.

gahorn wrote:KAP has it correct. The "straight" 170 has an engine-driven (automotive type) fuel pump and a fuel pressure gauge to confirm pressure. Due to the CAR3 requirement that the fuel system deliver 150% of required fuel to the engine, and the straight 170s routing of fuel lines down the forward doorposts...in a takeoff/climb configuration insufficient head-pressure exists to meet the certification requirement. The pump assures that requirement, and is REQUIRED EQUIPMENT, along with the associated gauge and check-valve.

SO, Does this mean the airplane does not have a problem with engine quitting without the pump? Just not 150% pressure?
Only reason I ask is the owner says it never had one on it the whole time he has owned it. And since it is required, are the lines available. Or will we be forced to build them. Sorry for all the questions. Thanks

IdahoPilot

You need the engine driven pump and the one way valve. All other lines can be built.

It has been reported the plane will run just fine without the pump. But it is not legal and you would be a test pilot for every flight.

George,

If you had a C-170, how would you go about getting approval to move the fuel line to the rear door post and remove the fuel pump? Take it to Alaska???

blueldr wrote:George,

If you had a C-170, how would you go about getting approval to move the fuel line to the rear door post and remove the fuel pump? Take it to Alaska???

I'd first get the Cessna drawings for early and late airplanes and take them to my FSDO and ask PRIOR to altering the airplane if they'd approve it. I'll bet they would.
If they wouldn't, I get the DAR in Austin to do so for about $500...which is about what it'd cost to do install missing pump/ck-valve/plumbing/etc...but without the future potential failures.

Well, I know this is an old thread but, I thought I would update this. We were able to get a fuel pump ($600) which will be installed after we get the engine reassembled the rest of the way (Waiting on cylinder to come back in). Thanks so much for the help. Now hopefully we can just find the correct check valve and get the lines routed correctly!

Thanks again everyone for your input.

IdahoPilot
K. Nimer

Cessna now makes that check valve...for a PRICE, of couse.

(The Andair check-valve is just as good, IMO.)

gahorn wrote:Cessna now makes that check valve...for a PRICE, of couse.

(The Andair check-valve is just as good, IMO.)

Is the Andair check valve legal?

Regarding the '48 170, in addition to the routing of the fuel lines problem, was there a difference in the ID of the fuel lines?

170C wrote:Regarding the '48 170, in addition to the routing of the fuel lines problem, was there a difference in the ID of the fuel lines?

No.