Expert: David Bidwell - 6/5/2008

Question
Hi David,

I hope this is the right category, if not I apologize.

I had a short flight on an airline this week. It was on a Jet aircraft, the type escapes me (small jet, used for short flights with the two engines mounted on the tail).

After the plane was pushed back from the gate, for some reason the pilot shut the engines down. I thought great, but a short time later (maybe 10 seconds or so) he started them back up and we started our taxi.

While taxiing, one of the engines was shut down. This time for only like 5 seconds, but he started it back up again.

We took off and made it without a hitch.

So why would they shut the engines down? I know that some planes will taxi with only one engine running to save fuel, but these shutdowns didnt last any longer than 30 seconds.

Any idea what they were doing, or am I mistaken in thinking that it was the engines shutting down?

Thanks for anything,

Answer
Hi Jim,
I wasn't on board so I can only guess what you were hearing.  I do not believe that the engines were shut down.  It takes a bit of time to spool up the fan on a jet engine.  I would guess that what you heard was similar to revving an engine on a car to get the power to move it. This would create the illusion that as the engine was winding down it was shut off.
Hope this helps.
Dave