LM2500 Start Sequence

Question 1

Ready To Start Permissive

Answer 1

1. Most remote bearing lube oil pressure greater than 13.5 psig.
2. Ngg less than 3500 RPM.
3. MRG Turning gear disengaged.
4. UEC Plus system reset.
5. Throttle at idle.
6. Motor Reg Valve in the start position and not being used by another engine.
7. Clutch cover in place

Question 2

Once all start permissives are met is the first timer

Answer 2

5 second timer, for the motor air regulator and bleed air transfer valves shift

Question 3

Once Starter On is displayed What are the three timers?

Answer 3

1. 20 second timer
2. 45 Second Timer
3. 90 Second Timer

Question 4

What are the parameters on the 20 second timer?

Answer 4

The Ngg must reach 1200 RPM within 20 second or auto-shutdown. “GTM FAIL TO REACH IGNITION SPEED SHTDN” Alarm.

Question 5

What are the parameters on the 45 second timer?

Answer 5

The GTM lube oil pressure must reach 10 psig within 45 seconds or Auto-Shutdown. “GTM LUBO SUPPLY PRESS LOW SHTDN” alarm

Question 6

What are the parameters on the 90 Second Timer?

Answer 6

The Ngg must reach 4,500 +/- 200 RPM or Auto-Shutdown. “GTM FAIL TO REACH START/IGNITION OFF SHTDN” alarm

Question 7

What is ignition Speed?

Answer 7

Ngg 1200 rpm

Question 8

What occurs at 1200 RPM

Answer 8

1. Ignitors are commanded on.
2. Fuel Valves are opened.
3. 40 Second Timer is started.

Question 9

What are the parameters for the 40 second Timer at 1200 RPM?

Answer 9

1. GTM Power inlet temp (T5.4) must reach 400F (ignition temp)
2. Fuel Manifold Pressure (FMP) must be greater than 50 PSIG
3. If failed to meet, Auto-Shutdown and motor for 60 sec.

Question 10

When T5.4 >= 400F and FMP >= 50 PSIG what occurs?

Answer 10

1. “GTM FLAME ON” is displayed
2. Engine Time meter is started.
3. Engine Start counter is advanced.

Question 11

What is sustaining Speed for the GTM?

Answer 11

Ngg 4500 (+/- 200 RPM)

Question 12

What occurs at 4500 +/- 200 RPM?

Answer 12

1. Igniters off
2. Start Air Valve closed
3. The bleed air transfer valve will shift back to masker position.
4. Low L/O alarm and auto shutdown circuits are enabled.

Question 13

What is Idle Speed?

Answer 13

Ngg 5000 RPM +/- 100 RPM

Question 14

What occurs at Ngg 4900-5100 RPM

Answer 14

1. “GTM AT IDLE” is displayed.
2. UEC commands Vent Damper Open and Module Cooling Fan On.
3. Icing alarm enabled.

Question 15

If engine hasn’t been started in 15 days what should be done prior to start?

Answer 15

Motor GTM

Question 16

What reasons should you abort start?

Answer 16

1. No lube oil pressure prior to 1100 RPM
2. Fail to reach 1200 RPM in 20 Seconds (UEC initiated)
3. Fail to light off, T5.4 fails to reach 400 F and FMP fails to reach 50 PSI in 40 seconds after fuel valve opened. (UEC initiated).
4. Compressor Stall
5. T5.4 rapidly approaches or exceeds 1350F during start
6. Time to idle exceeds 90 seconds. (UEC initiated)
7. GTM L/O pressure fails to reach 10 psig 45 seconds after start

Question 17

What is the Motor Duty Cycle?

Answer 17

1. 5 min on 2min off any number of cycle

2. 5 min on 18 min off in any 30 min cycle

Question 18

What is the Starter Duty Cycle

Answer 18

1. 45 sec on 2 min off any number of cycle
2. 2min on 5 min off
3. 2min on 21 min off within 30min period.