Fuel Systems

Fuel Systems • Purpose • Requirements • Components o Fuel Quantity Gages  Mechanical  Electrical  Electronic  Atomic o Visual Or Mechanical  Sight Gauge  Dip Stick  Drip  Float Stick

1

 Stick With Prism  Floating Cork  Mechanical Float o Electrical  Resistive System o Electronic  Capacitive Probe Type System o Atomic o Flowmeters – Measure Fuel Flow In Lbs.  Vane Type  Mass-Flow Type  Pressure Gage • Pressure Warning Mechanism o Fuel Tanks – Far 23.963 Through 23.977  Internal

2

• Rigid (Metal) • Bladder (Flex Balloon)  Integral Tank (Wet Wing  External Tank • Removable Tip Tanks, Belly Tanks, Pylon Tanks  Testing - Far 23.965  Construction Characteristics • Surge • Baffles • Jet Pumps  Regulations • Required Tank Expansion Space • Min. Tank Capacity • Fuel Tank Location • Survival Under Adverse Conditions 3

 Tank Components • Fuel Tank Vent • Fuel Tank Cap • Quantity Gauge • Tank Outlet Screen • Tank Sump • Tank Sump Drain o Valves – Far 23.995  Selector Valves • Disk Type • Poppet Type  Shutoff Valve  Check Valve • Flapper Valve • Ball Check Valve 4

 Pressure Relief Valve  Pressure Regulating Valve o Fuel Pumps – Far 23.991  Types • Hand • Main o Engine Driven • Auxiliary  Other Pump Source  Purpose  Positive Displacement Or Constant Displacement Pump  Positive Pressure Pump  Single Stroke Primer Pump  Double Stroke Primer Pump • Simplified Double Stroke Primer Pump 5

 Solenoid Pulse Pump  Diaphragm Pump  Gear Pump  Vane Pump  Centrifugal Pump  Wobble Pump  Jet Pump • Aircraft Fuels o Terminology  Volatility  Vapor Pressure  Gasoline - A Blend Of Hydrocarbon Compounds That Have A Wide Range Of Boiling Points And Vapor Pressures  Iso-Octane  Heptane

6

 Tetra-Ethyl Lead (Tel)  Octane Rating • Dual Number Octane Rating • Low Number - Octane Of Fuel At Lean Cruise • High Number - Octane Of Fuel At Rich Takeoff  Detonation o Jet Fuel  Jet A (Kerosene),  Jet B (Kerosene And Gasoline) o Fuel Color Code  80-87 Octane - Is Red In Color  91-96 (100LL) - Is Blue In Color  100-130 - Is Green In Color  115-145 - Is Purple In Color  Jet Fuel Is Clear/Straw In Color

7

o Fuel Contamination  Water  Rust Or Scale • Magnetic (Black) • Non-Magnetic (Red), Al, Brass, Mg, Rubber  Dirt  Other Fuels  Sediment, Particulates o Water  Entrained : Separates Out Over Time  Suspended : Suspended Within The Molecule, Does Not Separate Out  Water Testing Kits • Gray Filter System • Straw-Colored Filter o Problems With Water 8

 Freezing  Microbol Growth o Mixing Fuels – Jet A And Avgas  Turbine – Tel Forms Deposits On Turbine Blades  Recips – Just A Little Jet A (0.5%) In The Avgas Lowers The Anti-Knock To Dangerous Levels  Two Sizes Of Filler Holes And Nozzles • ~2.5” For Avgas; ~3.0” For Jet A • Components Of A Typical Gravity Feed Fuel System o Fuel Tank o Fuel System Sump Drains (Far 23.971 And Far 23.999) o Fuel Selector Valve  One Per Engine  Any Tank To Any Engine o Main Fuel Strainer (“Gascolator”) – Far 23.271 And Far 23.997

9

o Firewall Fitting  Flex Hose - Used From The Firewall To The Engine o Fuel Head o Fuel Flow Requirement (Gravity Feed Systems)  Far 23 : 150% Takeoff Fuel Requirement (Far 23.955)  Far 25 : 100% • Components Of A Typical Multiengine, Low Wing Fuel System o 1 Tank o 2 Vent o 3 Fuel Cap o 4 Fuel Quantity Gauge o 5 Tank Screen o 6 Tank Sump - If Required o 7 Wing Tank Drain o 8 Fuel Selector 10

o 9 Main Strainer Or Filter - Lowest Part Of The System o 10 Firewall Fittings o 11 Flex Hose o 12 Primer Solenoid o 13 N/A o 14 Engine Driven Pump (Edp) o 15 Auxiliary Pump o 16 Firewall Shutoff Valve(S) o 17 Fuel Dump Valve o 18 Standpipe o 19 Cross-Feed Valve / Isolation Valve / Transfer Valve o 20 Isolation Valve o 21 Scupper o 22 Scupper Valve Or Drain o 23 Fuel Pressure Gauge

11

• Manifold Type System - Single Point Refueling o Multiple Tanks, All Connected To A Common Manifold • Fuel Jettison – Far 23.1001 o Be Able To Dump The Prescribed Amount Of Fuel:  Within 10 Minutes For General Aviation  Within 15 Minutes For Transport  Fuel Must Discharge Clear Of Aircraft • Troubleshooting o Use Of Flow, Pressure, Consumption, Etc. o Leak Detection o Leak Rates  Slow Seep – ¾” Diameter  Seep – 1 ½” Diameter  Heavy Seep – 3” Diameter  Running Leak

12

 Also By Drip Rate o How To Check  Clean And Dry The Area  Check After 30 Minutes  Can Dust With Red Dye Talcum Powder To See The Area Better

13