INSIGHT INTO AVIATION TURBINE

FUEL

WILL BE COVERED IN FOLLOWING HEADS• INTRODUCTION• AVIATION TURBINE FUEL (ATF)• FUEL CONTAMINATION• PRESENT QUALITY CHECKS ON ATF CAN BE CARRIED IN FEILD

AVIATION TURBINE FUEL (ATF)

• ATF is specialized type of petroleum based fuel • ATF source of energy and powers most of modern

generation aero engine/ jet engine aircrafts

IMPORTANCE OF ATF• Aero engine has to function within pre determined

parameters within specified altitude and flight speed range. Hence Fuel Has To Be Of Consistent Quality and airworthy

• ATF acts hydraulic and lubricating medium for fuel equipments

WHAT IS AVIATION TURBINE FUEL ?

AVIATION TURBINE FUEL PROPERTIES

• IMPORTANT PERFORMANCE PROPERTIES OF ATF• Energy content :- predicted by fuel density• Combustion Characteristics:- combustion is

continuous in a jet engine• Stability :- Whose properties remain unchanged

Storage Stability Thermal stability

• Lubricity :- Lubricity is the ability to reduce friction between solid surface

AVIATION TURBINE FUEL

• Fluidity:- Ability of a substance to flowViscosity and freezing point are the physical properties

• Volatility :- Fuel tendency to vaporize

• Non-corrosivity :- essential that the fuel not corrodes

MAJOR CIVIL AND MILITARY JET FUEL GRADES

• JET A-1:- Most widely used Fuel for jet engine flash point minimum of 38°C , freeze point

maximum of –47°CUK specification DEF STAN 91-91

• JET A:- Available in U.S.A only has same flash point 38°C but a higher freeze point max – 40°C

ASTM D 1655 (Jet A) specification.• JET B:- Has higher flammability, alternate to JETA-1

an used in cold weather

MILITARY JET FUEL GRADES

• JP-4:- This is equivalent to JETB with addition of corrosion inhibitors

• JP-5:- High Flash point kerosene ,used on aircraft carriers

• JP-8:- Military equivalent of JET A-1

SPECIFICATIONS OF ATF• Product specifications is a mechanism by which

producers control the properties necessary for satisfactory and reliable performance

• The major jet fuel specifications are ASTM D 1655- US specifications for three commercial jet fuels JETA , JETA1 and JETB. Defence Standard 91-91-U K Ministry of Defence maintains this specification.GOST 10227 - Russian specification Joint Checklist - Group of oil companies have combined the most restrictive requirements from ASTM D 1655 and DEF STAN 91-91

SPECIFICATIONS OF ATF• International Air Transport Association (IATA) :-

publishes Guidance Material for Aviation Turbine Fuels Specifications.

• Indian Specification :- Q C Specification for Jet A-1 in India is IS No. 1571: 2001 -7th Revision

SPECIFICATIONS OF ATF- IATA AND ASTM

SPECIFICATIONS OF ATF- GOST (RUSSIAN STANDARD)

SPECIFICATIONS OF ATF- DEF STD 91-UK

FUEL PROPERTY AND SIGNIFICANCE • Indian specification:- IS No. 1571: 2001 -7th Revision

FUEL CONTAMINATION

• Every transfer of ATF from refinery to aircraft occurs, there is potential for contamination of the fuel

• Particulate matter and water are the most common fuel contaminants

• WHY FUEL CONTAMINATION CRITICAL Aero Engine fuel system has very precision

calibrated orifice/ fuel atomizer as components fuel burners. The contamination in ATF will affect stable engine operation

ATF FUEL CONTAMINATION• Fuel Contamination occurs due to fuel transfers from

refinery to Bulk Petroleum Installation.• Each time fuel transfer potential chance of fuel

contamination.• Particulate matter and water are the most common

fuel contaminants.• Particulate Matter

- Dominant source is solid corrosion - Airborne suspended particles - Solids from microbial infestation- Refinery processing materials ( Catalyst fine)

WATER CONTAMINATION

• Water comes in from Humid air, Rain water and due to condensation.

• Water occur in three formsDissolved Water :- Water is slightly soluble in ATF . With Increase in temperature water dissolves increases.

-ATF contains between 40 to 80 ppm dissolved water at 21deg C.Free Water:- Exists as a separate liquid phase. With influence of gravity forms a lower layer of fuel tank.

PARTICULATE CONTAMINATION

• Surfactants:- polar organic compounds can stabilize a fuel water emulsion by reducing the interfacial tension.

• Microbes:- Micro organism found in fuels includes bacteria and fungi. Solids formed by bio growth are very effective at plugging fuel filters.

PRESENT QUALITY CHECKS ON ATF IN FEILDS

• Visual Checks:- To check visually ATF sample is “clear and Bright” and also for any trace of sediments .

• Density Check:- To Check the density of ATF.

• Water Checks Finding water with help of water detection capsule

• Fuel sample from bottom of refuller tank checked for water

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