15.21 - Engine Monitoring and Ground Operation

Question 1

What is the purpose of the red stripe on the engine nacelle skin?

Answer 1

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.

Question 2

What are the additional hazards when testing reverse thrust?

Answer 2

Ground debris can be flung forward and sucked back into the engine as the thrust is increased.

Question 3

If there is a wind, where should the aircraft be facing when doing an engine run?

Answer 3

Into the wind

Question 4

Wind data of 220/15 means…?

Answer 4

Wind of a heading 220 degrees with an average of 15 knots (kts)

Question 5

When are icing conditions considered?

Answer 5

OAT less than 10 degrees C and visible moisture is present

Question 6

At what visibility level in nm can moisture be expected?

Answer 6

1 Nauticle Mile (1.852km)

Question 7

Why is it not practical to carry out engine power assurance tests/trim tests in severe icing conditions?

Answer 7

Using the anti-ice system will degrade the performance of the engine. Increased inlet and exhaust temperatures occur as bleed air is extracted.

Question 8

What happens to the density of air with increased levels of humidity?

Answer 8

It has a lower density with increased humidity which decreases thrust.

Question 9

Why should an engine be dry-cranked before starting if it has been stopped for a lengthy (specified) amount of time?

Answer 9

It allows a correct oil level to be determined due to syphoning.

Question 10

What are the AMM chapters 71 and 72?

Answer 10

71 - Powerplant
72 - Engine
Both have reference charts/tabled and procedures

Question 11

What should you do to the starter if the starter valve does not close, before shutting the engine down?

Answer 11

It must be isolated from any pneumatic source (engine/APU/ground cart) otherwise the starter or accessory gearbox drive can be severely damaged.

Question 12

What is a power assurance test?

Answer 12

The engine is run up to a specified thrust, observing that N2 and EGT still has the required margins to the specified maximum figures.

Question 13

What is the ECM program?

Answer 13

Engine condition monitoring. Trends can be calculated and viewed

Question 14

What is the ACMS?

Answer 14

Aircraft condition monitoring system.

Question 15

What is ACARS?

Answer 15

Aircraft communication addressing and reporting system.

Question 16

What are the three engine maintenance programs?

Answer 16

Hard time
On-condition
Condition monitoring

Question 17

What are examples of on-condition maintenance methods?

Answer 17

Borescoping
Visual examinations
Oil consumption rate monitoring
Engine vibration monitoring system
Spectrometric oil analysis program (SOAP)

Question 18

How is SOAP performed?

Answer 18

A sample of oil is burned between two graphite electrodes. Small metallic atoms and ions emit characteristic light spectra when vaporised.

Question 19

How is ferrography performed?

Answer 19

Detailed microscopic examination of a slide to determine the particle size, metallurgy, wear mechanism, component source of wear and identification of contaminants.

Question 20

What reading is a cause for concern when looking at vibration monitoring?

Answer 20

4-5 units and above. A fan balance check will be required.

Question 21

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?

Answer 21

It’s measured in gram-centimetres (g-cm)

Question 22

What is the three-shot plot method?

Answer 22

Three engine runs are completed which allows the imbalance location to be determined using only vibration amplitude measurement.

Question 23

What is the purpose of engine gas path cleaning?

Answer 23

Recovery of max thrust/power output
Recovery of EGT/N2 margin
Restoration of efficiency
Reducing exhaust pollution

Question 24

What is a compressor wash that only removes salt deposits called?

Answer 24

Desalination

Question 25

What is a compressor wash that removes baked-on deposits called?

Answer 25

Performance recovery wash

Question 26

What is the purpose of abrasive grit cleaning?

Answer 26

It uses nut shells or apricot pits whilst the engine is running at a specific speed to remove dirt and deposits in a more vigorous method.

Question 27

If a fault on the engine is detected by the EEC, what happens to the fault annunciator light, the fuel and trimming signal?

Answer 27

The light comes on and the trimming signal is downed immediately. The fuel is removed.

Question 28

If the engine fails to light up how is the starter cycle cancelled?

Answer 28

A time switch automatically stops the sequence

Question 29

What will you see if there is microbiological growth in the fuel tanks?

Answer 29

Brown slimy deposits

Question 30

During engine ground runs, what lights are required to be turned on?

Answer 30

Anti-collision lights only

Question 31

Dynamic balance testing can locate an unbalance in how many planes?

Answer 31

2 planes