Cessna Cardinal 177 Fuel Sender Design Process

Can we offer a Retrofit CiES Fuel Sender for your aircraft. 

What are the steps we need to take: 

New Cessna 177 Cardinal Fuel Level Sensors 

• Obtain a a set of old fuel level sensors from the aircraft we are considering.  If the part numbers for the senders match the aircraft they are on, we are good to go.

• Ideally this aircraft should have a strong user base with an owner base that demonstrates their willingness to embrace new technology with their pocketbook.

• Discuss the compatibility with commonly installed MFD components or instruments.  CiES  Fuel Level Senders now has the capability of driving even old analog gauges in the aircraft (Universal Fuel Level)..

• Our market is the pilot / customer that is more concerned with fuel level issues and wants the required fuel level instrument in the panel to have the  capability of multiple point calibration.

Old Cessna 177 Stewart Warner and Leigh Fuel Sensors 

• Evaluate the existing sensor design -  For example the bends in these sensor arms are either to assist in installation and removal of the fuel sensor or to clear aircraft structure in the fuel tank.

• As our sensor design allows for an easily detachable arm - these bends might not be necessary and simplify the design greatly.

• We then proceed to manufacture a prototype sensor with our best guess for geometry.

Cessna 177 Cardinal Fuel Tank - Internal Shot

• Check the sensor in the aircraft fuel tank.  As you can see in the illustration - in this case the simple arm design works better in the tank and sweeps a better fuel volume being closes to the Spar and maximum chord point.

• At this point we qualify the design with drawings and procedures for the completed unit so that we can send these files to the FAA to have this configuration added to our TSO.

Fuel Tank with Prototype Sensor Installed 

• Once we have approved drawings we can can produce the required sender with a TSO Tag attached.

• The fuel tank is then drained, the aircraft leveled and braced only then is the zero fuel amount added.  There should be movement of the sender to be able to record an accurate zero fuel level, this is an absolute requirement.

• Fuel is then added to the tank incrementally and accurately to obtain data points for calibration.  We direct the installer to take special caution to insure tabs fuel value is accurately recorded by the fuel display.

• Equally the installer needs to insure full fuel level per the POH is also accurately displayed.   

Note:  All aircraft fuel tanks are built with expansion volume - Full fuel per the POH may or may not be to the neck on the filler plate.  This is very important as the aircraft will probably be fueled in the future on a ramp -

Varying fuel tank angles caused by imbalanced fuel filling - filling one side before the other

or 

The angle of the ramp typically created to drain water from the ramp surface.

Both of the above have an effect on apparent aircraft fuel level from simple visual observation.  

• A confirmation of entered fuel level and actual fuel level when the aircraft is in stable cruise flight may allow the pilot to correct for an erroneous starting fuel level value. 

• The final result is a happy customer with a new fuel sender design that has hundreds of data points to describe the fuel tank contents on their new MFD display or instrument.

Note:  While this seems to be an involved procedure - accurate fuel display on an aircraft requires this level of detail otherwise you might not get the information you need.