The International Cessna 170 Association

All~

I searched for several hours, but could not find an instance where a '48 C170 owner obtained a field approval to remove the mechanical fuel pump, check valve and fuel pressure gauge (by re-routing zither fuel lines down the aft door posts). If I have missed anything, please let me know.

In the meantime, I'm gearing up to present a case for removal to the local FSDO. If by some stroke of luck I am successful, I will certainly share the fruits of my labor with the group.

One thing I need to confirm before starting is whether the fuel lines for the A and B model C170's depart the fuel tanks in the middle before turning aft, as depicted in the IPC's. Could someone check on that for me? Thx.

Dave

Further to my earlier post, "zither" = late-night typo, not a type of fuel line.

Well good luck. My 48 had the pump removed sometime in the 70's, long before I owned it. Everything else is stock including the fuel line routing. The best I can determine is it has accumulated 1200 hrs in that configuration. I was preparing to reinstall the mechanic pump; however, to my surprise the cam has no lobe. The motor was overhauled in 2000 and the cam replaced. Going forward I'm piecing together an electric pump and associated hardware

However, it is my opinion only, but the fuel pump is a very conservative install. During certification Cessna engineering must have seen something they didn't like and opted for a mechanical assist pump. In a low fuel condition there might be an issue but I doubt it... I have not seen this or know of any such issue. Let us know

Thanks, Poncho. I had my first conversation today with the local FSDO and the reception was more positive than expected. So, onward and upward. In the meantime, I'm hoping someone here can confirm the exit point of the fuel lines from the main tanks in the A and B models (i.e., from the center of the tank).

Taken to show how the fuel gauge and float would be positioned in the tank but you can see the fuel outlet below and aft of the fuel gauge. Below center vertically and aft of center for and aft.

This is an A model tank but B models are the same.

By comparison here is a picture sent me by Tom Downey of a '48 wing laying upside down. You will note the fuel line exits the wing at about the same spot the A and B would but the fitting faces forward unlike the A and B routing.

Thanks, Bruce. This is exactly the information I was looking for.

I hope you are able to get that approved, because I am working on rerouting the fuel lines to conform with the A and B model, to remove the pump and check valve, Has any ever done this ?

As others here have reported many times, if you remove the fuel pump, fuel pressure gauge and check valve from your '48 170 without an FAA field approval, you will no longer be in compliance with the type certificate. IIdon't know about you, but I'm not willing to take the risk. That said, I've had conversations with the Seattle FSDO regarding this alteration and am optimistic it will be approved. I'm only a few days from submitting the Form 337 and hope to have a final decision by year's end. If this gets approved, I will gladly share my paperwork with the group.

Reiterating what's been said previously... it is the original certification rules which mandated the pump. The fuel flow must exceed 150% of engine requirement in the most demanding flight attitude, i.e., during takeoff/climb ....and the forward doorpost routing needed mechanical assistance to meet that rule.
There are anecdotal stories of engine performance problems without the pump, usually on balked-landing-climb and high angle of attack/climb situations.

'48 C170 Owners,

I have received from the FAA via field approval permission to remove the engine-driven fuel pump, check valve and fuel pressure gauge from my '48 C170 and to reroute the fuel lines aft from the main wing tanks down the rear door posts as designed for the A and B models. Thanks to those members who assisted with photos and other information.

I hope to start the project within the next week or so, though it will be tedious and will take several more weeks to complete.

Once the Form 337 is signed and filed with the FAA, I will be glad to donate copies of the paperwork (Form 337, AFM Supplement, placard for Owner's Manual, etc.) to the Association.

I will also have for sale an engine-driven fuel pump, check valve, fuel pressure gauge and associated fuel lines for anyone who would rather restore than alter.

Dave

C170B Owners:

Would it be possible for someone with a B model to photograph how the fuel lines are routed forward through the fore and aft gear box bulkheads? There are no lightening holes in those bulkheads and I'm curious to see the means used to penetrate them for routing. There should be an inspection hole in the floor just aft of the aft gear box bulkheads that can be used for taking photos. Thanks in advance.

Dave

Nice work on that. Now I can leverage my position.

Anyone do this on a Canadian registered aircraft. I'm looking for some help with the Canadian regulatory authority. Thanks

FYI, I spoke to Transport Canada today. No issue in converting to the A and B fuel system and deletion of the fuel pump and associated hardware. I will do it over the winter when the wings are off for recovering. I will post the progress over the winter/spring time.