Fuel System

TTP Cessna 172	Cat.B1	Level -3	ATA28	Fuel System
	Cat.B2	Level -2

Cessna 172 R has a wet wing fuel storage system with two integral fuel tanks (one in each wing), a three position selector valve, a fuel reservoir tank, an electrically-driven auxiliary fuel pump, a fuel shutoff valve and a fuel strainer.

Components forward of the fuel strainer include the engine-driven fuel pump, the fuel injection servo and the fuel distribution valve.
Fuel bays may need to be resealed if a leak has developed, or if the wing has been repaired. These procedures provide instructions for sealing fuel bays, classifying fuel leaks, and testing fuel bays after repair.

PTP Cessna 172	B1	LOC	FOT	SGH	R/I	MEL	TS
	B2	LOC	FOT	SGH		MEL

 282003 Fuel Selector Valve - Check controls for detent in each position, security of attachment, and for proper placarding. B 05-12-01 224

282005 Fuel Reservoir - Using quick drain, ensure no contamination exists.

282007 Fuel Strainer, Drain Valve, and Controls - Check freedom of movement, security, and proper operation. Disassemble, flush, and clean screen and bowl.

282010 Auxiliary (Electric) Fuel Pump - Check pump and fittings for condition, operation,

security.

Fuel System-Monitoring and Indication

TTP Cessna 172	B1	L-3	ATA 28A	Fuel System-Monitoring & Indication
	B2	L-2

                        

                

PTP Cessna 172	B1	LOC	FOT
	B2	LOC	FOT		R/I		TS

Float-type Fuel Level Sender Removal/Installation
NOTE: Fuel level sender removal/installation is typical for the left and right fuel bays.
A. Remove the Fuel Level Sender 
(1) Defuel the airplane. Refer to Chapter 12, Fuel - Servicing .
(2) Remove access panels 510DB and 510HB (left wing) or 610DB and 610HB (right wing). 
(3) Disconnect the wire ring terminals from the fuel level sender.
(4) Disconnect the fuel level sender ground wire from the wing rib.
CAUTION: Do not bend the fuel level sender float arm. A bent float arm will give incorrect operation
(5) Remove the screws that attach the fuel level sender to the bracket.
(6) Carefully remove the fuel level sender from the fuel bay
B. Install the Fuel Level Sender.
NOTE: If the fuel level senders are replaced, the system must be calibrated. Refer to Fuel Quantity Calibration .
(1) Make sure the fuel level senders operates correctly before the fuel quantity indicator is replaced.
(a) Carefully move the float arm by hand from the lower stop to the upper stop and back to the lower stop 80 times.
NOTE: The movement of the float will clean the contacts of the probe.
(b) Make sure the resistance is 3 ohms, +2 or -2 ohms when the tanks are empty.
(c) Make sure the resistance is 90 ohms, +5 or -5 ohms when the tanks are full.
(2) Install the new gaskets on the fuel level sender.
(3) Install the five bushings that come with the fuel level sender into the mounting screw holes with the shoulder to the outside of the sender.
CAUTION: Do not bend the fuel level sender float arm. A bent float arm will give incorrect operation
(4) Carefully install the fuel level sender in the fuel bay.
(5) Attach the fuel level sender with screws and torque the screws to 20 inch-pounds.
(6) Connect the larger ring terminal to fuel level sender center stud (stud #1). Torque nut to 12 inch-pounds.
(7) Connect the fuel level sender ground wire to the small stud (stud #2).
Print Date: Wed Mar 03 07:59:22 IST 2010 MODEL 172 MAINTENANCE MANUAL (Rev 17) 28-40-00 
(8) Install access panels 510DB and 510HB (left wing) or 610DB and 610HB (right wing). 

(9) Do a fuel quantity calibration. Refer to Fuel Quantity Calibration .