Caravan engine failures
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Redneck_pilot86
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Re: Caravan engine failures
Single engine turbines have an Emergency Power lever that bypasses the FCU and allows the pilot to meter fuel flow in the event of an FCU failure.
The only three things a wingman should ever say: 1. "Two's up" 2. "You're on fire" 3. "I'll take the fat one"
Re: Caravan engine failures
Ah, the old FTU lever....
Now, there are two ways of dealing with this... In the 15 seconds from the time the engines stops after you have pitched the nose down, feathered the prop, looked for the best landing space with about 5 seconds left, then start analyzing the problem. lets see Ng OK for a non starter assist air start? Ignition switch on...Crash..
Or have the luxury of all the time in the world to analyze a possible cause, and determine the
proper procedure..Engine failures dont happen at altitude like in flight training.
As I understand this it happened during or right after the departure..Particularily if there was a loud noise that would indicate to me that I had suffered a catastophic failure in the engine, I would be concerned about trying to keep it flying and get it down in the best place possible, not trying an airstart.
Now, there are two ways of dealing with this... In the 15 seconds from the time the engines stops after you have pitched the nose down, feathered the prop, looked for the best landing space with about 5 seconds left, then start analyzing the problem. lets see Ng OK for a non starter assist air start? Ignition switch on...Crash..
Or have the luxury of all the time in the world to analyze a possible cause, and determine the
proper procedure..Engine failures dont happen at altitude like in flight training.
As I understand this it happened during or right after the departure..Particularily if there was a loud noise that would indicate to me that I had suffered a catastophic failure in the engine, I would be concerned about trying to keep it flying and get it down in the best place possible, not trying an airstart.
Last edited by trey kule on Wed Oct 19, 2011 11:42 pm, edited 1 time in total.
Accident speculation:
Those that post don’t know. Those that know don’t post
Those that post don’t know. Those that know don’t post
Re: Caravan engine failures
Is it possible that in the event of an FCU failure that pilot attempted to use the emergency power lever? If the emergency power lever is advanced quickly you risk getting compressor stalls. When we did sim training in the caravan for our low level operation (consistently at or below 500' AGL), our emergency procedure in the event of an engine failure where a suspected FCU/P3 failure occurred was to right away get on the emergency power lever to try to get power ASAP (basically all levers to the firewall), and if that doesn't work then we would proceed to feather and secure the engine. However in practice one has to be very gentle with the emergency power lever otherwise you can risk doing a lot of damage to the engine.
Re: Caravan engine failures
Redneckpilot, the Emergency power lever on the Caravan and the PC-12 does not bypass the FCU. Both FCU's are normally controlled by P3 air from the engine. When you move the EPL you are directly controlling the metering valve in the FCU. If the FCU is the problem in the first place, you are going down no matter what you do with either of the levers. The ONLY reason for the EPL lever is if you have a P3 air line failure or a freezeover. The P3 air line to the FCU is normally heated. There is a CB for it. If that heater fails, then you may have an air line freezeover and have to use the EPL. The heater is there on all PT6 engines. Only on the single engine aircraft do they require an alternate method of operating the FCU.
The way that I always flew the Caravan was taking off with the separator in bypass and the ignition on. If I was in a mountainous area, immediately after takeoff I moved my hand over to the EPL just in case there was even a hiccup. For putting the separator back in, I reduced the power to take the load off the inlet vanes. The linkages are not that strong and I have seen sheared bolts and in one case where the arm that moves the vanes, the arm in the engine bay that is connected at the top to the handle in the cockpit actually snapped in two. That one was extremely dangerous as it was found it was swinging very close to the alternator belt. If you are putting 30 pounds of pressure on that handle in the cockpit, using some simple math and knowledge of levers, the pressure on the lower part of that arm is over 300 pounds and the smaller linkages you are getting close to 1000 pounds. Pulling it out at any point in flight is not nearly as bad as the airflow is pulling the bypass doors into the position you want.
Lilflyboy at what altitude are you guys putting the separator back in and about what airspeed. I've flown the van in Africa and there may be a precedent for what you are suggesting. Also, on the first accident, did they ever check to see if the doors on the separators were both working together?
Mr. North, you are bang on about the force required on the separator at high power sttings. If it is out after take off, you shoulnd't be pushing it back in until you are at least 1000 feet up and with the power back. If they pushed the separator back in right after takeoff with the power all the way up, i'm wondering if the door linkages broke and stalled/surged the engine that way.
This could just be a "normal" engine failure. Just because the first one failed for an unknown reason doesn't mean the second one did
The way that I always flew the Caravan was taking off with the separator in bypass and the ignition on. If I was in a mountainous area, immediately after takeoff I moved my hand over to the EPL just in case there was even a hiccup. For putting the separator back in, I reduced the power to take the load off the inlet vanes. The linkages are not that strong and I have seen sheared bolts and in one case where the arm that moves the vanes, the arm in the engine bay that is connected at the top to the handle in the cockpit actually snapped in two. That one was extremely dangerous as it was found it was swinging very close to the alternator belt. If you are putting 30 pounds of pressure on that handle in the cockpit, using some simple math and knowledge of levers, the pressure on the lower part of that arm is over 300 pounds and the smaller linkages you are getting close to 1000 pounds. Pulling it out at any point in flight is not nearly as bad as the airflow is pulling the bypass doors into the position you want.
Lilflyboy at what altitude are you guys putting the separator back in and about what airspeed. I've flown the van in Africa and there may be a precedent for what you are suggesting. Also, on the first accident, did they ever check to see if the doors on the separators were both working together?
Mr. North, you are bang on about the force required on the separator at high power sttings. If it is out after take off, you shoulnd't be pushing it back in until you are at least 1000 feet up and with the power back. If they pushed the separator back in right after takeoff with the power all the way up, i'm wondering if the door linkages broke and stalled/surged the engine that way.
This could just be a "normal" engine failure. Just because the first one failed for an unknown reason doesn't mean the second one did
Re: Caravan engine failures
Cat Driver wrote:I've had two.
any truth to that?
count me for one as well on the 208
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Brown Bear
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Re: Caravan engine failures
Just a thought, could they have had the fuel tank shut off warning horns disabled? They can be annoying. If so, the wee hopper tank would just enough fuel to die just after take off.
The best "Brown Bear" of them all!
Re: Caravan engine failures
Those are protected by a guarded circuit breaker and even then the FUEL SELECTOR OFF light on the panel would still come on. Possible but unlikely I think. You would really have to work at it to get the CB cover off and if a pilot was trying to do just that without a valid reason (of which I can think of none), that pilot has no business being in an aircraft. That also doesn't explain the bang that was heard.Brown Bear wrote:Just a thought, could they have had the fuel tank shut off warning horns disabled? They can be annoying. If so, the wee hopper tank would just enough fuel to die just after take off.
Re: Caravan engine failures
Just cruising through my FSI 'Van book.....I have NO idea what would cause this twice in a short span of time. However, I don't put much faith in the "bang" depending on who your witnesses were?Meatloaf wrote:Those are protected by a guarded circuit breaker and even then the FUEL SELECTOR OFF light on the panel would still come on. Possible but unlikely I think. You would really have to work at it to get the CB cover off and if a pilot was trying to do just that without a valid reason (of which I can think of none), that pilot has no business being in an aircraft. That also doesn't explain the bang that was heard.Brown Bear wrote:Just a thought, could they have had the fuel tank shut off warning horns disabled? They can be annoying. If so, the wee hopper tank would just enough fuel to die just after take off.
Re: Caravan engine failures
Like you Doc, I also went back to the FSI manual, as there was something bothering me about the whole Emergency fuel lever hypothesis,particularily as one poster mentioned flying low level and suspecting a FTU problem.
I think I found out what it was. When the FTU has a pneumatic problem (as someone correctly posted previously), the engine does not stop, but goes to idle. Here the engines apparently stopped, either quietly or not.
I still dont understand how some think that when an engine stops at such a low altitude
on a departure they are going to have time to do anything else but feather, fly, maybe tell
the pax's to brace........to much empahsis on the process and not on the objective. There simply is no time to attempt a restart if the engine calves at a few hundred feet. Better to concentrate on a controlled flight.
I think I found out what it was. When the FTU has a pneumatic problem (as someone correctly posted previously), the engine does not stop, but goes to idle. Here the engines apparently stopped, either quietly or not.
I still dont understand how some think that when an engine stops at such a low altitude
on a departure they are going to have time to do anything else but feather, fly, maybe tell
the pax's to brace........to much empahsis on the process and not on the objective. There simply is no time to attempt a restart if the engine calves at a few hundred feet. Better to concentrate on a controlled flight.
Accident speculation:
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Those that post don’t know. Those that know don’t post
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Redneck_pilot86
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Re: Caravan engine failures
I don't see where anyone has suggested there is time to attempt a relight. Three things that can cause you to lose power after takeoff are a flameout, a P3 failure in the FCU or a catastrophic failure. The process is simple. Power lever idle, ignition on, power back up. Did you get a response? Good. That was a flameout, your engine is running again, and you can now sort out why and what to do about it. No response? Emergency power forward. Did you get a response? Good, that was a P3 failure and now your engine is running and you can deal with it. No? Feather and land.trey kule wrote:I still dont understand how some think that when an engine stops at such a low altitude
on a departure they are going to have time to do anything else but feather, fly, maybe tell
the pax's to brace........to much empahsis on the process and not on the objective. There simply is no time to attempt a restart if the engine calves at a few hundred feet. Better to concentrate on a controlled flight.
The only three things a wingman should ever say: 1. "Two's up" 2. "You're on fire" 3. "I'll take the fat one"
Re: Caravan engine failures
That is why I am such a dummy.. You see, if you have a total power failure it is not the FCU...not sure why you would be dealing with that in this situation.....me....I'm going to get that nose down...now,....... before I stall the damn thing, feather the prop, and look for a place to land...idle cut off on the fuel, and fuel shut off if there is time...but I am going to fly the plane first....and under about 500 feet ,consider the forced landing as a done deal...not option B.
You didnt seem to mention about things like checking the Ng to make sure you have the minimum for a relight....and on thinking about it, that just might explain the bang.....All good in theory, but when you have a total of about 15 or 20 seconds to get the airplane in the right attitude(speed), pick a landing spot ,( just in case your plan A does not work), and while doing this check the Ng., turn on the ignition with your left hand, recheck the Ng, cycle the prop lever....yep..your a better pilot than me. On the other hand you could just put the nose down and go about trying a relight..If it works you will be a hero..If not....
You didnt seem to mention about things like checking the Ng to make sure you have the minimum for a relight....and on thinking about it, that just might explain the bang.....All good in theory, but when you have a total of about 15 or 20 seconds to get the airplane in the right attitude(speed), pick a landing spot ,( just in case your plan A does not work), and while doing this check the Ng., turn on the ignition with your left hand, recheck the Ng, cycle the prop lever....yep..your a better pilot than me. On the other hand you could just put the nose down and go about trying a relight..If it works you will be a hero..If not....
Accident speculation:
Those that post don’t know. Those that know don’t post
Those that post don’t know. Those that know don’t post
Re: Caravan engine failures
FSI has this wee drill. (FBI....fuel, boost, ignition) If the fire goes out, throttle to idle, ignition on, pumps on, back up with the throttle. If it catches, you're golden. If it don't, you're landing. (if low level) In the case of the emergency throttle lever, the engine has not quit (as Trey said) it's throttle to idle and VERY gently advance the emergency lever.
You can get all that done in a hundred feet or less, depending on how scared you are?
If the OP would keep in touch with us, and let us know what happened when they figure it out, I'd really appreciate it. Lot of Caravan drivers here.
Thanks
You can get all that done in a hundred feet or less, depending on how scared you are?
If the OP would keep in touch with us, and let us know what happened when they figure it out, I'd really appreciate it. Lot of Caravan drivers here.
Thanks
Re: Caravan engine failures
Everything else aside, we REALLY need to know what caused this. When you have a fatality that looks like it might be a mechanical problem, it's not like somebody flies it into the trees while .. running (we all know the cause of those accidents) but something has to be done to root out, and solve the mystery. Picture yourself in a PC12, departing in solid in solid IMC, and this happens? Somebody needs to bounce this one off Cessna and FSI. Something just isn't "sitting right" with me on this one.
I've got a few hours on PT6 equipped airplanes, and I can't come up with a plausible explanation.
I've got a few hours on PT6 equipped airplanes, and I can't come up with a plausible explanation.
Re: Caravan engine failures
It is exactly what Doc said. Fuel on, Boost on (you may have lost the engine driven pump) and Ignition on. Takes 2 seconds to do and it could save your ass. If your Ng has dropped to idle, forget putting the power lever to idle. It's already not working. Just get the EPL up. If FBI didn't work and your engine quit, you are landing, forget a restart.
Without more information, I can't think of what happened. I flew a Caravan that shed a power turbine blade on the next flight after I turned it over to another other pilot. I'd had the Maintenance manager and a rep from P&W on board my flight trying to figure out the numbers coming off the gauges. They had boroscoped it and found nothing and then while they were just starting to crunch the data, the turbine came apart. Pilot landed safely and everyone walked away. The PT6 is reliable but its had its share of failures. Flying around the salt pans in Botswana, I'm now wondering if compressor washes were done regularly enough and this is a turbine blade corrosion problem.
Without more information, I can't think of what happened. I flew a Caravan that shed a power turbine blade on the next flight after I turned it over to another other pilot. I'd had the Maintenance manager and a rep from P&W on board my flight trying to figure out the numbers coming off the gauges. They had boroscoped it and found nothing and then while they were just starting to crunch the data, the turbine came apart. Pilot landed safely and everyone walked away. The PT6 is reliable but its had its share of failures. Flying around the salt pans in Botswana, I'm now wondering if compressor washes were done regularly enough and this is a turbine blade corrosion problem.
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lilflyboy262
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Re: Caravan engine failures
Sorry on holiday at the moment, but wil write a detailed reply later on.
Basically both happened at around 300ft, the prop will pull itself into feather. You will have perhaps 40s to detect, react and respond, and then for the prop to pull itself out of feather again. By the you will be in the dirt. Specially when surrounded by 50ft trees.
In both instanes there was confirmed reports from reliable sources of a bang being heard.
The compressor washes are being carried here in accordance to recommendations for this environment. Maintenance is not an issue here.
basically all the information you have from here is all I have. A bang suggest either surge or catastrophic failure. The latter I can understand. It happens. If its an airframe/engine combo... Then well...
Basically both happened at around 300ft, the prop will pull itself into feather. You will have perhaps 40s to detect, react and respond, and then for the prop to pull itself out of feather again. By the you will be in the dirt. Specially when surrounded by 50ft trees.
In both instanes there was confirmed reports from reliable sources of a bang being heard.
The compressor washes are being carried here in accordance to recommendations for this environment. Maintenance is not an issue here.
basically all the information you have from here is all I have. A bang suggest either surge or catastrophic failure. The latter I can understand. It happens. If its an airframe/engine combo... Then well...
Re: Caravan engine failures
The bleed air valve begins to open when Ng goes below about 90%, if I remember right. When the inertial separator is pushed in it can be quite difficult to do at high power settings. Many people will ease back on the power to make it easier to close and save on knuckle skin. By doing this the Ng could drop below 90% where the bleed air valve should open. If the valve fails (which has been known to happen) this could cause a bang and a resultant compressor stall. Which could lead to an engine failure.
I'm not speculating this is what happened, however it is a very possible scenario, I know its happened before.
I'm not speculating this is what happened, however it is a very possible scenario, I know its happened before.
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lilflyboy262
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Re: Caravan engine failures
No other ideas? The more i read into it, the more I am beginning to lean towards bleed valves, compressor surge and then flameout.
What can cause them to stick? Can they become temporarily stuck and the resulting accident then "unstick" them? Does surge leave any telltale signs in the engine?
What can cause them to stick? Can they become temporarily stuck and the resulting accident then "unstick" them? Does surge leave any telltale signs in the engine?
Re: Caravan engine failures
the same engine out after TO happened to an aquaintenance in Central America a few yrs back
This makes 3 I've heard of now. What does P&WC say and Cessna say? P&WC WAS contacted ,right??? I'd be more interested in what they say rather than this hodge podge open to all who has a computer forum.
This makes 3 I've heard of now. What does P&WC say and Cessna say? P&WC WAS contacted ,right??? I'd be more interested in what they say rather than this hodge podge open to all who has a computer forum.
Re: Caravan engine failures
Give Cessna a call? Or maybe FSI can shed some light on it?kilpicki wrote: What does P&WC say and Cessna say? P&WC WAS contacted ,right??? I'd be more interested in what they say rather than this hodge podge open to all who has a computer forum.
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lilflyboy262
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Re: Caravan engine failures
As far as I'm aware, the engines get brought back to the maintenance facility here and checked out. If no cause can be found, then the engine gets shipped back to P&W and they go through it.
I brought this subject to Avcanada, while there is some who think they know more than everyone else, there is actually guys on here that DO know what they are talking about. Slightly dissappointed at the lack of response in the maintenance forum though.
No futher developments but I have only just got back from holiday so haven't been able to talk to those concerned.
Again I pose my question. Is it possible for a bleed valve to stick, and then unstick in the accident, leaving no trace of the problem? Or does the engine need to be operating for them to operate?
And does surge leave any trace throughtout the engine?
I brought this subject to Avcanada, while there is some who think they know more than everyone else, there is actually guys on here that DO know what they are talking about. Slightly dissappointed at the lack of response in the maintenance forum though.
No futher developments but I have only just got back from holiday so haven't been able to talk to those concerned.
Again I pose my question. Is it possible for a bleed valve to stick, and then unstick in the accident, leaving no trace of the problem? Or does the engine need to be operating for them to operate?
And does surge leave any trace throughtout the engine?
