737-300 start switch modes

[jason_beall]

Hi all,

Not sure if this should be asked here or in the wannabe's section. I'm doing the home study for my 737 type rating and was hoping for some clarification. My question relates to the CONT and FLT positions of the 737-300 Engine Start Switches. When do you use each mode in real world ops. I understand CONT is selected for takeoff and landing. What about FLT?

Whats going on systems wise when each is selected?

Thanks,

-Jason

[4Screwaircrew]

FLT-Use for air starts, severe turbulance, moderate to severe icing, moderate to heavy precipitation, hail or sleet.

[Rumbo de Pista]

The screwy one is right...

The switches go onto 'CONT' for take-off and landing and when the engine anti-ice is on.

I used to ask for 'Start switches to FLT' whenever it looked as though flameout might be even an anorexic possibility, ie, hail, heavy rain, significant turbulence, etc.

As to what it costs, you'd need to join Bluecoat and search some recent threads on igniters, costs, and life.

[aztruck]

Cont will give you continuous ignition on the selected igniter(L OR R), FLT will give you ignition on BOTH automatically. 1st flight of the day use the right igniter to start engines. Why? Cos its powered by the AC standby bus, and therefore could be the only chance you have to start an engine at altitude in the event of a double engine flameout. ie if the right igniter wont work, you aint got no spark plugs if the ac power fails.
If this happens at 37000 feet, its a long way down before you can start the APU and get power back on the busses

[QAVION]

"As to what it costs, you'd need to join Bluecoat and search some recent threads on igniters, costs, and life."

Haven't got a value for a 737 plug handy, but I've just checked our computer records and a B747-400 (Rolls Royce) ignitor plug is Australian $415.27 (circa U$ 245)... P/N YA211-25. Not quite as expensive as I first thought.

According to my sources, high energy General Electric ignitors may only last 200~300hrs.

Regards.
Q.

[HugMonster]

1st flight of the day use the right igniter to start engines. Why? Cos its powered by the AC standby bus, and therefore could be the only chance you have to start an engine at altitudeAz, do you fancy rephrasing that? :D