15.21 - Engine Monitoring and Ground Operation Flashcards
What is the purpose of the red stripe on the engine nacelle skin?
It warns personnel approaching the engine at the safe entry/exit corridor. You shouldn’t move forward of this line when the engine is running at idle.
What are the additional hazards when testing reverse thrust?
Ground debris can be flung forward and sucked back into the engine as the thrust is increased.
If there is a wind, where should the aircraft be facing when doing an engine run?
Into the wind
Wind data of 220/15 means…?
Wind of a heading 220 degrees with an average of 15 knots (kts)
When are icing conditions considered?
OAT less than 10 degrees C and visible moisture is present
At what visibility level in nm can moisture be expected?
1 Nauticle Mile (1.852km)
Why is it not practical to carry out engine power assurance tests/trim tests in severe icing conditions?
Using the anti-ice system will degrade the performance of the engine. Increased inlet and exhaust temperatures occur as bleed air is extracted.
What happens to the density of air with increased levels of humidity?
It has a lower density with increased humidity which decreases thrust.
Why should an engine be dry-cranked before starting if it has been stopped for a lengthy (specified) amount of time?
It allows a correct oil level to be determined due to syphoning.
What are the AMM chapters 71 and 72?
71 - Powerplant
72 - Engine
Both have reference charts/tabled and procedures
What should you do to the starter if the starter valve does not close, before shutting the engine down?
It must be isolated from any pneumatic source (engine/APU/ground cart) otherwise the starter or accessory gearbox drive can be severely damaged.
What is a power assurance test?
The engine is run up to a specified thrust, observing that N2 and EGT still has the required margins to the specified maximum figures.
What is the ECM program?
Engine condition monitoring. Trends can be calculated and viewed
What is the ACMS?
Aircraft condition monitoring system.
What is ACARS?
Aircraft communication addressing and reporting system.
What are the three engine maintenance programs?
Hard time
On-condition
Condition monitoring
What are examples of on-condition maintenance methods?
Borescoping Visual examinations Oil consumption rate monitoring Engine vibration monitoring system Spectrometric oil analysis program (SOAP)
How is SOAP performed?
A sample of oil is burned between two graphite electrodes. Small metallic atoms and ions emit characteristic light spectra when vaporised.
How is ferrography performed?
Detailed microscopic examination of a slide to determine the particle size, metallurgy, wear mechanism, component source of wear and identification of contaminants.
What reading is a cause for concern when looking at vibration monitoring?
4-5 units and above. A fan balance check will be required.
When balancing an engine, the location of the imbalance must be known with its magnitude in terms of weight moment. What is it measured in?
It’s measured in gram-centimetres (g-cm)
What is the three-shot plot method?
Three engine runs are completed which allows the imbalance location to be determined using only vibration amplitude measurement.
What is the purpose of engine gas path cleaning?
Recovery of max thrust/power output
Recovery of EGT/N2 margin
Restoration of efficiency
Reducing exhaust pollution
What is a compressor wash that only removes salt deposits called?
Desalination
