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The sample is in respect to Australian operations, in the USA there are far more PA31 used as private aircraft and the rate of accidents reflects this. There have been almost 300 PA31 in use in Australia throughout the years, not a small number by any means. They have been used in all sorts of commercial operations from Charter to RPT, Medical transport, target towing, Freight etc... Many hours have been accumulated and it is a proven workhorse.
A number of the shut downs on the list the aircraft continued to a destination passing suitable fields and at least one on arriving held for a while until emergency services arrived. Doesn't sound like struggling to fly to me. The Kingair enjoys a similar rate of accident including failures on take-off which have resulted in accidents due to lack of performance. But this is a turbine and newer so it must be safer... If the aircraft is maintained to an appropriate level and the flight crew trained there should be no issues. What was the accident rate of the RFDS Navajo fleet before pistons became unfavourable? |
Arnold E
As it was said in the "Castle", "tell 'im he's dreamin'" 43Inches There have been almost 300 PA31 in use in Australia throughout the years, not a small number by any means. I also have a hard time believing that there have only been 26 in-flight failures or shutdowns over the 43-odd years the aircraft will have been flying in Oz. That's, what, 1.6 failures every two years? A number of the shut downs on the list the aircraft continued to a destination passing suitable fields and at least one on arriving held for a while until emergency services arrived. Doesn't sound like struggling to fly to me. Nobody is saying that it always struggles with an engine out, of course it won't if it is reasonably light and the weather is good. It's when you are at max gross and there is bad wx or icing about that you have a problem. Just because pilots get away with emergencies most of the time, doesn't mean that the aircraft is as safe as it should be. I've flown the Chieftain enough to know that it's fine at reasonable weights, but near max gross in adverse conditions, it's not a happy aircraft at all on one engine. The Kingair enjoys a similar rate of accident including failures on take-off which have resulted in accidents due to lack of performance. But this is a turbine and newer so it must be safer... If the aircraft is maintained to an appropriate level and the flight crew trained there should be no issues. |
It was a mongrel aircraft when it was new and it just got worse from there. It came out of a desperate last gasp from the dying embers of the Piper company, if I recall correctly they only built 50. Even the RFDS on whom it was trying to be foisted jacked up. Bushy and others espousing the virtues of busted RRR's, bent and twisted old junk (most of you seem easily fooled by a schmick paintjob and new engines - hey, there is a bridge a couple of hundred k's south of here getting a new paintjob, I can let you have it for say, around three times what it is in reality worth....), as usual you are getting the words "able to" and "should" very badly mixed-up in relation to certified performance. To compare a 747 and a Pa31 in the same sentance draws a long bow as they weren't even built using the same criteria or for the same utilisation/cycle rate or even to carry the same design loads. They are as similar as a London bus and a mini in construction, design and intended use. I notice that no-one from your camp has the conviction to challenge the gauntlet I threw down about re-validation of the certified performance figures previous to the issue of each annual/MR. To expensive, or s#!t scared it wont make the grade? The truth of the matter is that many (not all) would possibly not make their certified performance due to a number of factors, engine age, gear/flight control rigging, bent and ill-fitting cowls/control surfaces, worn engine mounts enough to grind the crap out of the cowls - this alone will significantly change the thrust line of an engine, control cable rigging (despite the fact that they are supposedly checked each time I have seen so many huge splits in throttles/mixtures/pitches) - and the big one for a Pa31 - the bl**dy cowl flaps that some well meaning but brain dead engineer agreeing with the owner to rig them slightly open when indicating closed etc) etc.... And the list will go on and on ad infinitum. Krusty and Remoak raise great points about training. I have seen one Einstien leave the cowl flaps half open and run over rich in PA31s as he was under the impression he was looking after the engines/airframe to keep the CHTs down, which, of course he came up with himself. As a bit of a drama queen he got a little hot under the collar when asked by his Chief Pilot to explain why he was getting around 20LPH less economy and around 0.2 longer short sector times than all of the other pilots. It was pointed out to him that by allowing the airframe to accellerate that extra 10-15 knots the airflow would increase and running the engines at their designed FF/EGT then the rest took care of itself... There are similar stories all across the industry ranging from people with their own ideas on things like hot starting to descent power reductions and circuit patterns. Have personally experienced something as simple as a blown wastegate (the housing split and the controller blown fair off the side) cause a serious enough degradation of performance in a red legged Pa31 at just below MLW that I seriously thought about shutting it down as the drag was incredible from the prop on the engine that was delivering around 20". It certainly got my (and the 8 bums sitting behind me) attention as well. This happened in CRZ enroute from a mine in the Gulf of Carpentaria in the build-up to the wet. All I could get out of it was 5 thousand feet (at VYSE) by experimenting with airspeed back to VXSE (6,200'). Note: this aircraft was known for many many issues and in the end my company got rid it in the end. Why do you think that CASA want these dungers out of the sky and are doing their best to ensure that they are becoming more and more unsustainable? Is it because you think CASA is out to get you? I will make the point again that Andrew either ran out of luck/options/depth of knowledge or there is another issue that will possibly arise about the airframe or second engine or a feeder system to it. The real crux of the point I am making is that just because it has a second engine, does not mean that it is making either its rated power/torque or will deliver it at a crucial moment despite the fact it tests OK on the ground. There also seems to be a worrying trend for people to adopt VYSE in every situation (fine for enroute), why do you think there is a VXSE? Les. |
Remoak seems to do a lot of dreaming, but there is a lot of merit in his posts as well.
Remoak's suggestions, mixed with some reality would be good medicine for GA. Piston engined aeroplanes are an important part of Australia's transport system. Those who cannot accept that should go. |
I also have a hard time believing that there have only been 26 in-flight failures or shutdowns over the 43-odd years the aircraft will have been flying in Oz. That's, what, 1.6 failures every two years? All that tells me is that there are a bunch of stupid pilots out there. Nobody is saying that it always struggles with an engine out, of course it won't if it is reasonably light and the weather is good. It's when you are at max gross and there is bad wx or icing about that you have a problem. Just because pilots get away with emergencies most of the time, doesn't mean that the aircraft is as safe as it should be. I've flown the Chieftain enough to know that it's fine at reasonable weights, but near max gross in adverse conditions, it's not a happy aircraft at all on one engine. My point is that the aircraft is no more dangerous or marginal than any other aircraft in its class, including some turbo-props. The king-air comparision again was via a quick search of the ATSB site, three accidents occured relating to possible system failures which resulted in fatalities. One on take-off with an engine shut down and lack of performance due to a possibly unfeathered prop. The others were not engine related. There has also been a number of other fatal accidents during operations including the RFDS accident at Mount Gambier. One could say that given the amount of flights completed by the PA31 fleet to that of the King Air fleet in Australia that the King Air is more dangerous, but I don't have the actual data to support that. |
My point is that the aircraft is no more dangerous or marginal than any other aircraft in its class, including some turbo-props. Of course if you really want a good performance comparison... try comparing the performance of a Chieftain with a Cheyenne IV. That's more what I am talking about. In my admittedly utopian world, all PA31s would be scrapped and replaced with Cheyenne IVs (or Cheyenne 400LS if you are feeling generous). Basically the same fuselage as the PA31 but with proper reserves of power and performance, proper redundant systems and sensible automatic systems to assist in the engine failure case. |
I'm surprised no one else has seemed to considered this, what if the prop wasnt feathered, but seized with the engine failure? I'm thinking one engine performace would go out the window pretty fast, the report didnt confirm that it was feathered yet, just that one of the props wasnt turning from witness reports. Think about the force required to turn a prop (and the bits of the engine connected to it) with your hand. Now imagine the force required to turn the prop at windmilling speed. This is where the drag from a windmilling prop comes from, not the frontal area of the blades. The feather pitch position simply causes the airflow to cease driving the blades and turning the engine. |
Dangerous aeroplanes???
It's not aeroplanes that are dangerous, it's people. Aeroplanes are generally predictable. People are not.
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Still on the subject of vyse/vyxe Les;
Back in the early 90's the head of check and training at the company I worked for took us all out 2 at a time for some "training". No Jeopardy, no checking, lets just go out and explore some of the things that may catch us out. We spent half a day out in the central west (Bathurst) area and explored every thing from engine failure drills, to reduced performance when carrying ice (simulated by flying at reduced power), crucial decision making when faced with... "what do you think we should do if this happens?" etc, etc... One of the things I discovered, that wasn't covered in my initial multi-training, was that vyse in the PA31 (as in all multi-engined aircraft) was in fact a linear speed depending on A/C weight. Blue Line essentially was at MTOW and at lower weights (provided it was safe to do so of course) a (carefull) reduction to below it towards vyxe did in fact give significant improvements in performance! I can tell you now, I learnt more about my aircraft, it's capabilities, and my own limitations in that half day session than at anytime previously. There were plans to expand this program into regular structured sessions, and I for one (having experienced somewhat of a revelation) was excited about it. Unfortunately, management decided that it was too expensive, and the program was not proceded with! :sad: The check captain who conducted these sessions decided to move on, and our loss was certainly his next employer's gain. Just maybe, if more G/A pilots were exposed to this sort of "lateral training" rather than simply relying on the personal initiatives (the right stuff) of individual pilots, I believe they, and ultimately all of us, would all be far better off. |
Scavenger
I think this needs to be addressed before someone mistakenly takes it on board. Think about the force required to turn a prop (and the bits of the engine connected to it) with your hand. Now imagine the force required to turn the prop at windmilling speed. This is where the drag from a windmilling prop comes from, not the frontal area of the blades. Roughly speaking 3 x ~30" blades with an average chord of ~5" = 450 sq" (dimensions by eyeball guess) if this is presented to the airstream at 90 degrees it is pretty much equal to flat plate drag, (maybe slightly less). 450 square inches is 1.75 square feet. To drag a one foot square flat plate through the air at 100 kts creates ~26lbs of drag which requires about ~9hp, therefore 9 x 1.75 = 15.75 hp. That is approximately what you will rob from the available power of the good engine. Of the available 350hp on the good engine perhaps 270hp (guessing) is required to maintain L/D max or Vyse, leaving 80 hp for climb. 15.75 hp of that 80 is 20% so it will cost you around 20% of your climb performance if stationary and unfeathered. However the aerodynamic forces (drag) associated with a windmilling prop are huge. Consider how well an Autogyro (or a helicopter without power) would work with its rotating thingy stopped. Hope that helps. |
Given the reports that this aircraft had one engine shut down and other not delivering full power makes 95% of this thread irrelevant. Doesnt matter what profile, what aircraft or what training, without one good engine all bets are off. However i am sure someone like Remoak will tell us how much superior he is and how much better he would have done.
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I don't think so. Remoak is giving us his opinions, to which he is entitled to do. Freedom of speech is still alive in our "democratic" society. I thoroughly enjoy every post on Prune, some i question, a lot make me smile....its great to smile!
This accident is like a giant jigsaw puzzle. Each post just may have an input into putting that jigsaw back together.....maybe so we could all learn from this tragedy. |
Fair enough PA39, but the fact remains that you could be chuck yeager in a military jet but without one engine you have very limited options. BTW the company i used to work for operated a fleet of PA31's for 20 years with never more than a partial failure on one due to turbo failure.
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Demotronic. Nicely put on both counts.
If you graph the vertical profile of the aircraft (based on the ATSB timeline). The flight lasted about 760 seconds from first altitude loss to loss of radar return (about 300 ft AGL). Not much time, really. The flight had largely 3 segments. An initial loss of altitude to 5,000 ft which occurred at about 1200 ft/min which lasted about 100 seconds. Then a period of about 300 seconds where the speed was sort of stable at about 140 kt GS and a descent rate of about 740 ft/min. The final 360 seconds was marked by a reduced rate of descent (about 320 ft/min) with reducing airspeed (140 kt GS to 95 kt GS). It looks like he started to try and stretch the glide, which to a degree was successful. The aeroplane could have been flown slower than 140 kt GS which might have reduced the initial sink rate, but it looks like descending at 740 ft/min was what the aeroplane wanted to do with stable airspeed. This is not consistent with the LH engine producing much power at all. From the point of first altitude loss it needed a descent rate of about 350 ft/min to make Bankstown. It was never going to happen. However, the high initial descent, in my opinion. indicates that the pilot initially expected that the aeroplane would maintain height on one engine (which it should - easily). It was a reasonable thing to do, you need to come down sooner or later, ATC had cleared him to 5,000ft and at that height the Mojave should have been able to fly for hours. When did he figure out there was another problem that would drastically reduce his options? Was the second problem there all along, or did it manifest itself after he turned back? By the time the aeroplane returned to a stable speed (after the speed build up from descent) and the pilot could figure out that it would not maintain altitude, he was probably going through 4,000ft. At this point he was passing Richmond, which we know was in fog and less than 2 minutes later he reported to ATC that he was on top of a cloud layer, so its fair to assume that Richmond and its surrounds was completely obscured. What would you do? turn back to an unfamiliar airport that was not visible under fog / low cloud that required a bunch of frequency changes and mental calcs on approach intercepts? Or proceed to an airport that was straight ahead, that had emergency services waiting, was known to be visible and one which you had good local knowledge? I hope I'm never faced with these decisions. |
Les N
I notice that no-one from your camp has the conviction to challenge the gauntlet I threw down about re-validation of the certified performance figures previous to the issue of each annual/MR. As I have previously posted, - I have had a failure in a chieftain 700' high after takeoff with 6 pob, baggage and full mains in north west NSW in january in the rain, and the aircraft performed exactly as I expected. Once securing the engine, it was able to climb straight ahead until reaching 1000' where i returned for an uneventful landing. These aircraft are well within their design fatigue life and I can't speak for anyone else, but I have never flown one with flight control rigging, bent and ill-fitting cowls/control surfaces, worn engine mounts enough to grind the crap out of the cowls I am not an engineer, and I would be happy to be corrected if this is not the case, but I would suspect that the engine mounts are replaced, if not inspected for tolerances during an engine overhaul. The torsional forces at play on an engine driving that large a prop at MCP would be huge. A busted engine mount (I imagine) would be something easily identified. I broke on on my car sometime ago and everytime I took off I could feel the engine banging away in the engine bay. I dread to think of what would happen when you upscale that to aero engine specs. I doubt any maintence worker would be happy letting an aircraft go with a suspect engine mount. Why do you think that CASA want these dungers out of the sky and are doing their best to ensure that they are becoming more and more unsustainable? All that said, there are some s#@theaps out there that should have been retired 20 years ago, but in my experience they are becoming fewer and are not used for things as critical as aero-med. |
Aeromed only requires 'AIRWORK' on the MR.....which means you can run engines on condition and a myriad of other regulation loopholes.
Have a look at the TBOs on Kingairs running Aeromed... but in my experience they are becoming fewer and are not used for things as critical as aero-med. |
I'd love to know how many hours these engines had on them when Willow was at the helm. Odd that it didn't mention the TTIS for each engine though? I am sure it will be in the final report. |
desmotronic
Given the reports that this aircraft had one engine shut down and other not delivering full power makes 95% of this thread irrelevant. Doesnt matter what profile, what aircraft or what training, without one good engine all bets are off. However i am sure someone like Remoak will tell us how much superior he is and how much better he would have done. The problem is that it all got too difficult in the last minute or so, and the final desperate attempt to land on the street was never going to be the best option. Having the self-discipline to choose the safest option in the face of personal or commercial pressure is what distinguishes the professional pilot from the less competent one. Yes, the problems he had were difficult (although could have been much worse - he could have been IMC in bad weather), but there was the possibility of a safe outcome right up until the last minute or so. Sorry if professionalism offends you. |
Remoak,
You arrogance is amazing but at least you are consistent. If you want to speculate thats fine this is a rumour network after all. But if you want to denigrate the pilot who is not here to defend himself at least wait for the report so you can do it with the benefit of facts. That would be professional. Your self congratulatory drivel is not. |
"Having the self-discipline to choose the safest option in the face of personal or commercial pressure is what distinguishes the professional pilot from the less competent one"
There is a huge pressure, perceived or otherwise, not to have any accident or incident....and in this case the pilot may have felt that returning the plane to Bankstown was the "safest commercial" option. As I have said before there are many airlines that will not employ a pliot with any accident history. Just ask the poor BA 777 Captain that safely got his a/c on the groung at LHR that is now unemployable |
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