Agusta Crash in Mexico City
Join Date: Feb 2005
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Standard for an overspeeding engine is to put it into manual, and back off the power to a useful level. Shouldnt have caused a crash unless the overspeed protection failed for some reason, and the engine oversped so much it had a catastrophic event.
Join Date: Dec 2001
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Note - there is a fair degree of supposition in the following, but it may be worth considering.
If the engine oversped to the point of the power turbine wheel bursting (but not the compressor turbine), with this engine there would be no indication of an engine failure, and hence no access to the contingency power ratings.
This has happened before - the power turbine wheel disintegrated, and the compressor ran up to maximum fuel flow in an attempt to get the N2 signal back to 100%. Needless to say, since the compressor was working just fine, there was no engine failure declared by the computers, and the 2 minute and 30 second power ratings would not automatically be avaiable.
In the earlier incident, the pilot had time to look inside and figure out something was wrong and selected the correct engine to shut down. This allowed the contingency power ratings to be used and he landed safely. But the cockpit indications would be very confusing -on 'bad' engine- N1 and TOT maximum, zero torque, zero N2. 'Good' engine would have N1 and TOT appropriate to torque and good N2 signal. Probably have both low rotor warning and overtorque warning on at the same time. (Could you figure this out if it happened to you??)
Like I said, quite a bit of supposition here, but it may help someone who is trying to sort this out.
If the engine oversped to the point of the power turbine wheel bursting (but not the compressor turbine), with this engine there would be no indication of an engine failure, and hence no access to the contingency power ratings.
This has happened before - the power turbine wheel disintegrated, and the compressor ran up to maximum fuel flow in an attempt to get the N2 signal back to 100%. Needless to say, since the compressor was working just fine, there was no engine failure declared by the computers, and the 2 minute and 30 second power ratings would not automatically be avaiable.
In the earlier incident, the pilot had time to look inside and figure out something was wrong and selected the correct engine to shut down. This allowed the contingency power ratings to be used and he landed safely. But the cockpit indications would be very confusing -on 'bad' engine- N1 and TOT maximum, zero torque, zero N2. 'Good' engine would have N1 and TOT appropriate to torque and good N2 signal. Probably have both low rotor warning and overtorque warning on at the same time. (Could you figure this out if it happened to you??)
Like I said, quite a bit of supposition here, but it may help someone who is trying to sort this out.
Shawn, that is an adept supposition, but it would be a rare thing, and SM is correct in that there would indeed be visible damage in the vicinity of the engines.
As you alluded; 'managing' (presumably shutting down) the correct engine would be crucial - there are enough examples where this procedure has been fouled-up even when the cockpit displays were blindingly obvious (or not .. as in the cases referred to!).
I would be keen if there was someone who could provide a brief overview of the mechanical (and other) factors which influence the onset of engine overspeed.
As you alluded; 'managing' (presumably shutting down) the correct engine would be crucial - there are enough examples where this procedure has been fouled-up even when the cockpit displays were blindingly obvious (or not .. as in the cases referred to!).
I would be keen if there was someone who could provide a brief overview of the mechanical (and other) factors which influence the onset of engine overspeed.
Join Date: Aug 2011
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What ever happened to GET the Collective DOWN on any low Rotor rpm?
Studied the history on the S-58. The single 1820 had a better survival rate than the PT 6 twinpac, Get back to basics & quit studing to death the engines & keep the rotors turnin. Rotor RPM is life.
Studied the history on the S-58. The single 1820 had a better survival rate than the PT 6 twinpac, Get back to basics & quit studing to death the engines & keep the rotors turnin. Rotor RPM is life.
Avoid imitations
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What ever happened to GET the Collective DOWN on any low Rotor rpm?
Having flown this sole type for the past five years I have to say that that the engine display (strip gauges) are not the clearest ones I know.
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Look at the damage as seen-No mistery-Even If you pulled pitch at the top of the trees the rotors show no rotational/inertial damage=Low or no Rotor rpm. It fell like a stone.Vertical crushing impact .Arrorgant? Belittling? Just looking at a wrecked Agusta with no post impact fire ,Vertical crushing , a rotor system with little if no leading edge damage. In any helicopter RPM is life-This example had None.
Avoid imitations
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In any helicopter RPM is life-This example had None.
