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Switching off is much safer than a turbine overspeed past certain limits. Because an engine failure (one engine) is a situation all pilots are trained for and i
by t0mas88 8y ago
Switching off is much safer than a turbine overspeed past certain limits. Because an engine failure (one engine) is a situation all pilots are trained for and it has an almost certain safe outcome. Airplanes fly and land just fine on a single engine. We all train for engine failures all the time.
On the other hand, a runaway engine fire or uncontained turbine failure is much much more likely to cause a crash.
So almost all jet engines are designed to have a shutdown (sometimes helped by the built-in fire extinguishers) as a worst case outcome. The quick response drill for an engine overspeed or temperature past certain limits is to shut it down immediately and pull the fire extinguisher handle.
- cm2187 8y agoBut why not throttling instead of switching off then?
- t0mas88 8y agoGood question, you could theoretically throttle a runaway engine by reducing fuel flow (unlike a piston engine where you can limit air intake). But in 9 out of 10 cases you've already done that by pulling back the power levers. The next step is to cut off the fuel, because the throttles didn't get it under control.
- sbradford26 8y agoOverspeed protection takes place once everything else has failed. The engine controls have already attempted to throttle down and such. If that doesn't work then overspeed kicks in.
- metalliqaz 8y agoAdding on to this... things inside an engine happen FAST. Too much energy can spin up the turbines to the point of failure in milliseconds.
- CamperBob2 8y agoYep, as anyone who has ruined a fan by shooting a canned air duster at it can attest. :(