Re:Boeing 787 Suffers Rare Dual Engine Failure on Landing
by cm2187 on Wednesday January 30, 2019 @01:39PM
(#19037852)
But why not throttling instead of switching off then?
Re:Boeing 787 Suffers Rare Dual Engine Failure on Landing
by t0mas88 on Wednesday January 30, 2019 @01:51PM
(#19037987)
Good 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.
Re:Boeing 787 Suffers Rare Dual Engine Failure on Landing
by sbradford26 on Wednesday January 30, 2019 @02:56PM
(#19038750)
Overspeed 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.
Re:Boeing 787 Suffers Rare Dual Engine Failure on Landing
by metalliqaz on Wednesday January 30, 2019 @04:28PM
(#19039704)
Adding on to this... things inside an engine happen FAST. Too much energy can spin up the turbines to the point of failure in milliseconds.
Re:Boeing 787 Suffers Rare Dual Engine Failure on Landing
by CamperBob2 on Wednesday January 30, 2019 @05:19PM
(#19040186)
Yep, as anyone who has ruined a fan by shooting a canned air duster at it can attest. :(
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.