Engine Start Sequence Flashcards
What does the engine start sequence look like in steps for a ground battery start?
- Push start button
- 8-10% N2 and N1 Rotation: Advance throttle to Start/Idle Position
- 45% N2 - Start Sequence Terminates
- 56.2% N2: Idle RPM
- Select Idle RPM on first engine before second engine start
What does the engine start sequence look like in steps for a GPU start?
Same as battery start except:
* Requires a 28 volt (29 maximum), 800-1100 amp GPU
* Generator switches should be in OFF position until both engines started and GPU is disconnected
What does the engine start sequence look like in steps for a Emergency air restart (without windmilling)?
- Battery powers the starter, while the operating engines generator powers the buses
- Essentially a battery start
- Generator assist is disabled via squat switch
What does the engine start sequence look like in steps for a Emergency air restart (with windmilling)?
- The windmilling engine supplies the starting power, while the operating engines generator powers the buses
- Starter button should not be used to rotate starter-generator
- A minimum of 240 knots of ram air through the engine is required
- Ignition and boost pump must be manually selected ON, not NORMAL since normal requires the use of the starter button to begin the sequence
Describe in detail what happens when you push the start button.
- Start relay closes
- Starter button illuminates
- Engine instrument floodlights illuminate
- Boost pump activates:
FUEL BOOST ON annunciator illuminates
FUEL LOW PRESS annunciator extinguishes - N2 rises
What is occuring when you see an 8-10% rise in N2 and the slight N1rotation
- Fuel flows to slinger
- Igniters activate (Green igniter light illuminates)
- Lightoff should occur within 10 seconds
- ITT rise
- Monitor acceleration and engine instruments
Rise in ITT
Rise in N1
Rise in N2
Rise in fuel flow
Rise in oil pressure
At 45% N2, describe in detail what is occuring?
GCU starter overspeed sensor automatically terminates the start sequence
* Starter button light extinguishes
* Generator comes on-line
* Ignition terminates (green igniter light extinguishes)
* Boost pump operation terminates (FUEL BOOST ON annunciator extinguishes)
* Engine instrument floodlights extinguishes
* Start relay opens
* Engine accelerates to idle RPM of 56.2% +/- 1.3% N2
At 56.2% N2, What are you expected to see?
- All warning and annunciator lights for that engine should be extinguished
- Generator should show charging
- All engine instruments should show idle limits
Idle fuel flow =
280 pph
If you intend on doing a Cross Gen start what should the RPM be at on the running engine?
56.2% N2: Idle RPM
After second engine start all warning lights / annunciators should be extinguished, except for
AC FAIL and FRESH AIR (if selected)
Which engine spools up faster than the other and why?
Left engine has slightly faster spool-up due to less line loss from
battery.
