Whats a hot start?

[jrpilot]

Can someone tell me what a hot start is, in a video I am watching the pilot (who is in a B 747-400 simulator) does a regular start and a hot start.  I know what the outcome is with it over heating and what not...anyways I watched the video twice and cannot figure how he caused the hot start, in other words how does a hot start happen???
Thanks

[beefhole]

A hot start is, I believe, when it is very hot outside.  I've often heard to starting an engine in January as a "cold start", so I'm assuming it's the same the other way around.

Then again, come to think of it, this is probably completely wrong since it doesn't make any sense.  Hurray for those of us who just made an ass of themselves!

[jrpilot]

Actually, I did a search for pictures of it, and it seems you are correct, but I wonder how it happens, does the pilot wait for the N1 to turn longer or something???...in my video it seemed he did everything the samew way as the previous engine, yet the engine which he hot started produced overheating engine temperartures.

[Nexus]

A hot start is when the engine ignites and reaches self-sustaining RPM, but the combusiton itself is unstable and the exhaust temperature (EGT) rises rapidly past its max. limit.

A hot start can happen if you add too much fuel during start up (throttles aren't at idle), air intake/exhaust are blocked.
But a hotstart can even happen when starting the engines in sever tailwind, which causes the compressor to run backwards.

[jrpilot]

Nexus is it true that some airlines do hot starts in extreme cold?

[Rocket_Bird]

A hot start is basically when you introduce fuel before you have enough air for cooling and combustion.  Its like spraying fuel into your combustion liner and then lighting it, and well, burning it to crisp.  It can happen in any temperature pretty much