15.21 Flashcards
What are some circumstances where maintenance personnel are required to operate a GTE
• Confirming a flight crew reported fault
• Post maintenance basic engine or aircraft system checkout
• Deterioration of engine performance
• Aircraft control linkage wear
• Moving an aircraft from one maintenance location to another
• To taxi-check an aircraft system
What should be done prior to positioning aircraft for ground engine operation
Check tech log to see if ac is servucabelfor ground run
Inform atc
Check engine oil levels and sufficient fuel for engines to run on ground
Position ac into the wind
Ensure area around ac is clear
Why should both engines be run at same time when doing engine runs
To prevent asymmetry
Why should engine power not be increased above idle on ground
As the more the engine is heated and cooled down the shorter it’s operational life will become
What’s trimming
A term applied to idle speed, variable throttle settings and max thrust adjustment during engine performance testing
What’s required to get accurate trim data
OAT and barometric pressure/airfield altitude is measured
When must all engine adjustments be carried out during ground run
At idle rpm
Why’s idle trim adjusted
To ensure that the engine idles at lowest rpm
What should be used as the reference point when carrying out acceleration checks
The oldest engine to ensure all engine accelerate at same rate
On completion of an engine ground run how long should the engine idle for
3 mins
Before closing HP cock
What can an n1 indication on high bypass engines also be used as
A thrust indication
What does the fuel flow indication do
Shows amount of fuel consumption during flight and used for trend monitoring
What’s exhaust gas’s temp indication used for
To recognise ans prevent critical condition of overheat
How do centrifugal compressor engines measure engine power
Why can’t axial flow compressors use this
By comparing relationship between engine rpm and jet pipe temp
As there’s no relationship between engine rpm and thrust
What percentage of thrust is produced by fan in large fan engine
90-95%