No, there are no keys. Smaller a/c like Cessna & Piper trainers have keys to turn on/excite the ignition system, but jetliners do not. Moving series of switches and levers in a perticular sequence spins the turbine, excites the ignition and adds the fuel. Once light off occurs, the engine is self sustaining and the ignition source can be turned off. (Shut down is caused by moving the fuel lever to cutoff.) You may find this site interesting: http://www.rolls-royce.com/education/schools/journey02/index.html

P.S.- Here is an additional link from ww.HowStuffWorks.com that explains: "How do they start jet engines on airplanes?" http://science.howstuffworks.com/question411.htm There are also several useful links at bottom explaining jet engine theory. :O)

No. The pilots go through a series of switches and levers to bring the engines to running conditions. Nowadays most modern aircraft just have one switch, and the computers will start the engines, but on an older aircraft, this would be an example of a startup sequence for a jet engine: 1. Preparation (fuel pumps, bleed air, electrical power, etc.) - One crew member will keep their hand on the fire lever for that engine, to shut it down and release extinguishers if there is a startup fire. During startup, RPM, exhaust gas temperature, fuel flow and oil gauges are constantly monitored. At the first sign of anomaly, the startup will be aborted. 2. Throttles to cutoff. 3. Air starter or starter motor switch on. Igniter units on. 4. Monitor engine RPM increase to (usually) 50 - 60% of maximum. 5. Throttles to idle (this starts fuel flow). 6. Watch for lightoff - Lightoff is when the engine fires up under its own power. This is indicated by a sharp spike in exhaust temperature which stabilises at normal levels. 7. Release starter switch. Continue to monitor exhaust gas temperature for fire or stall. From this point the engine will spool up to idle speed. That is a simple startup procedure, in a nutshell.