Certification of Fighter Class Aircraft Powerplants

7/29/2019 Certification of Fighter Class Aircraft Powerplants

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BY

C.JAGANATHAN

DEPARTMENT OF AERONAUTICAL ENGINEERING

EXCEL ENGINEERING COLLEGE


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Certification is a process by which the power

plant is recognized as Fit To Fly .

Certification process addresses following issues:

Flight within the acceptable mach no & altitude

combinations

Flights within the prescribed sorties

None of the flight duration exceeded prescribed time

limits

None of the flights exceeded any of the laid downacceptable parameters of the engine or aircraft

Permissible failures of the non critical components

of the engine .


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Driver documents for certification are

AIR STAFF REQUIREMENTS (ASR)

Aircraft designer documents, dictate the following

Single / double engine configuration

Typical type of sorties

Thrust requirements at various legs of sorties

Minimum SFC operation in DRY & WET

Unlimited throttle operation (no Embargo)

Life of the engine in TBO, CL, TTL, CYCLIC LIFE etc Weight of the engine not exceeded in ____ Kgs .

PRELIMINARY DESIGN DOCUMENTS OF THE ENGINE

COVERING THE ABOVE ASPECTS


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PRELIMINARY DESIGN REVIEW (PDR) of the

engine

Following documentary evidences to be

realized Technical specification of the engine

Performance documents of the engine

Performance deck to aircraft designer

Pedigree of all components subsystems usedalong with failure rates & boundary conditions

Design recognition vis vis accepted

specification for conformance


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Necessary to prove by test life & safety criticalcomponents

Zero max Zero cycles of 7000 for cold end

Zero max Zero cycles of 3500 for cold end

Boundary conditions while taking testing shouldmatch engine environment

For safety critical components cyclic loads may have

to be 1.5 times than the max cyclic load

Analysis of the component life has to be carried out

using the material property having (-) 3 values

All stress values (LCF & HCF) and creep properties

have to be arrived (-) 3 values

Castings, Forging properties have to be evolved from

specimens extracted out of castings & forgings


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Temp plates are evolved for various proposed

sorties to classify under benign, medium &

critical categories

Critically factors not to exceed 1.35, 1.8 &2.0 for benign, medium & critical categories

respectively

This is arrived by using conventional

proposals namely A+ B/4 + C/40 Before start off the tests, it is necessary to

finalize test procedure, test item,

measurements & failure criteria etc


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Tests have to be identified as safety level &

life tests based on single of multiple engine

configured aircraft Similarly, class A components under single

engine configuration may be downgraded to

class B components for a double engine

configured aircraftWrong identification can lead to unexpected

failure of component during operation


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Disk burst speed test at 122 % and dwelt for

10 seconds at this max rpm

Necessary to maintain boundary conditions as

that of the engine Blade off test (Both TURBINE & COMPRESSOR)

at max rpm and engine allowed to settle at a

lower rpm without much distress

Engine over speed test, wherein the shaft ismade to fail & turbine rotor spool should

lodge into its respective NGV


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ACCELERATED MISSION TEST (AMT) with a

severity factor of not less than 2.0. Ten hours

dedicated for hot air test

Failure definition is mandatory for theengine, subsystems, modules etc.

Single engine aircraft, fuel system test for

switch over from automatics to manual mode

& vice versa Single engine aircraft, oil interruption test

Casing, pipelines for pressure burst test


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ACCELERATED SIMULATED MISSION

ENDURANCE TEST (ASMET)

Engine endurance test

Altitude test with simulated altitudeconditions

Flying test bed

Subsonic platform

Supersonic platform

Performance of engine & its subsystems

Identification of critical speeds


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Ice inspection test

Sand ingestion test

Armament gas ingestion test

Corrosion susceptibility test Vibration test & its response

Gyroscopic load test

Water ingestion testCustomer air bleed contamination test

Blade & disc deflection test


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PRE FLIGHT RATING TEST (PFRT) Partial endurance test

Development endurance test (10000 Hrs)

Model specification of engine

Engine health monitoring proven system


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No major issues during & after first flightclearance, FINAL FLIGHT CLEARANCE (FFC) is

given.


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Thank you

Documents

Certification of Fighter Class Aircraft Powerplants