REDUNDANCY

[Doc]

That's the word. Hope I spelled it correctly, but then, I have sell check, a redundancy of sorts for when I attempt to go over my head, using words I can't spell. Or when my fingers run off at the mouth on the keyboard.

Redundancy is HUGE in aviation. Two pilots, two electrical systems, two engines. Well, usually. Or sometimes.

Our Ornge thread turned into a wee bit of a one engine vs. two engine mud fling, so I thought I'd bring it over to it's own home? BTW, Ornge comes up on my spellcheck. Enough about Ornge. Okay?

Back to redundancy for a moment. The Caravan, while it has only one engine, has (if installed, and I've never seen one without it) a backup electrical system. Never been in a PC12, but I'm SURE it has one as well.

Obviously, I'm not a huge fan of, shall we say one fan. At least not in heavy IFR, or for long overwater or over mountain routes.

Some say they'd be more comfortable in a new PC12 rather than a "clapped out" King Air. If everything's still running, there would be no difference, except the PC12 would be prettier, and smell better. But even a sack of dung, clapped out POS King Air will bring you home IF GAWD FORBID, a PT6 goes south.

Cat asked a question regarding ferrying a single turbine or a twin turbine over the North Atlantic. Now ALL PC12's that we see on this side of the pond had to get here somehow. They were ALL ferried across that very same North Atlantic. They haven't lost a one. They are a VERY reliable aircraft. Obviously. But. There's always a "but", and that's where you, the pilot come in. It always comes down to choice. Yours.

REDUNDANCY

[Beefitarian]

*spell check

[iflyforpie]

Redundancy means SFA if you've got no gas. Ask the pilots of AC 143 or Transat 236. Avianca 52 had four engines, but you might need a seance to contact those pilots....

http://en.wikipedia.org/wiki/List_of_ai ... ed_gliding

[Beefitarian]

Wouldn't rubbing out of fuel be more of slack of planning issue? Or are you suggesting they get same fuel ration and can go farther feeding it to one engine?

[Beefitarian]

That should read "running out of fuel be more of a planning issue". Auto fill is horrible.

[Doc]

Redundancy means SFA if you've got no gas. Ask the pilots of AC 143 or Transat 236. Avianca 52 had four engines, but you might need a seance to contact those pilots....

http://en.wikipedia.org/wiki/List_of_ai ... ed_gliding

Means SFA if you forget to lower the wheels as well. That's not my point. A pilot can always find a way.....

[Beefitarian]

If you are not maintaining it or buying the fuel why wouldn't you want a back up?

[Cat Driver]

Doc, I pasted this from the Ornge thread as it in my opinion gets closer to the facts than just personal opinions.

I suffer from having the ability to examine a subject and using the information I gather and learn from that information then I can come to certain conclusions that are based on logic.

Ornge lost me in the logic arena when they decided to choose single engine aircraft to transport patients on emergency evacuations where bad weather and other critical issues will be encountered because emergencies are not time wise manageable.

Money can not be the reason they chose to forgo the added safety of two engines because they do not seem to be lacking for money within their bureaucratic structure nor their offices so there has to be another reason why they chose to deny their clients the added safety factor of twin engine airplanes....ignorance on the part of those in the power structure maybe?

And yes, I may have a personal reason to be concerned in this matter because I may someday be unfortunate enough to require a medevac in Ontario.....this outfit is not a charter company one calls at their own initiative.

[iflyforpie]

Redundancy means SFA if you've got no gas. Ask the pilots of AC 143 or Transat 236. Avianca 52 had four engines, but you might need a seance to contact those pilots....

http://en.wikipedia.org/wiki/List_of_ai ... ed_gliding

Means SFA if you forget to lower the wheels as well. That's not my point. A pilot can always find a way.....

A pilot can always find a way to cause a fuel leak?

http://en.wikipedia.org/wiki/Air_Transat_Flight_236

To have the fuel filters or heaters ice up?

http://en.wikipedia.org/wiki/British_Airways_Flight_38

To do the incorrect maintenance on all engines?

http://en.wikipedia.org/wiki/Eastern_Ai ... Flight_855

To hit a flock of birds?

http://en.wikipedia.org/wiki/US_Airways_Flight_1549

Three of those incidents I listed are on ETOPS aircraft, which have even more stringent training, safety, and maintenance standards than your run-of-the-mill King Air.

Compared to the small fleet size of SEIFR planes, the small number of passengers they carry, and all of the cons for twin engine aircraft (higher weight, higher fuel load, double the chance of engine failure, no back up FCU for the engines), the pros for twin engine aircraft are not quite as high as you would imagine. Sure twins are better and safer, but not to the degree you suggest.

Any King Air coming out of my field between July 1 and Aug 31 shares the same fate as a PC12 should they lose an engine on takeoff. That doesn't seem to concern too many pilots.

[teacher]

This is meaned with NO DISRESPECT AT ALL but a look at the most recent multi turbine accidents has proven that having 2 engines is not always safer.

[ScudRunner]

So whenever this debate comes up I take another angle on it that some people consider blasphemy.

Allow Single Engine Piston IFR (commercially). Up high above the crud, easy simple approach you see the runway you land you don't go missed and fly to the alternate. Something goes wrong you have time to react and trouble shoot. Or you could .. run the entire way "VFR" down low if something goes wrong look forward that's the impact site.

Trust me been there done that it, I know what I would rather be in ..................my Learjet. But seriously sitting above a layer at 6000 AGL etc or 1 mile clear of cloud down low.

Let the debate begin.

[wallypilot]

I think if you're going to compare single to multi engine aircraft, you need to discount multi-engine aircraft that don't have sufficient single engine climb performance. As Teacher pointed out, there are examples where having two engines didn't help the situation, although, in these situations, I'm sure PDM had as significant an effect on the outcome as does the fact that the multi engine aircraft cannot maintain altitude on a single engine. I'd take a king 350 over a 100 any day, all else being equal.

Point being, two engines on an aircraft that has good single engine performance is always better. Two engines on an aircraft that cannot climb on a single engine can be safer, but can also be less safe due to the perception of "two engines = safer". some solder light piston and twin turbine aircraft come to mind. Load up a king 100 to gross, and you're in a world of hurt if you lose one just after liftoff. Same with many cessna twins...these are just a couple examples.

It's all about knowing your airplane, the maintenance, your route, your weather, you experience, your ability level, good judgement and knowing well the capabilties of your airplane. Make good decisions with the tools you have, and any aircraft can be flown safely. Someone mentioned ferrying single engine a/c over the north atlantic. Sure, a PC12 ferry flight would less safe than a KA350 ferry flight. But with some mitigation techniques, the increased risk of the single engine can be reduced to a level where the flight crew feels the risk is acceptable. For example, in the event of a catastrophic engine failure, having a plan to trade off on the controls so you can don your immersion suit in the cabin before ditchin in the cold ocean.

Identify all the risks and make an assessment. I worked for a company that took over contracts from another company that was flying C208's IMC over the rocks. When we took over the contract, we looked at the route and told the client that we would only do those routes in that aircraft on days where weather allowed for flight in VMC conditions. NO IMC over the rocks in the 'van. within a few weeks, in order to get reliable deliveries, the client soon realized that they'd have to use a twin turbine to get any sensible crew to fly that trip on an IFR day.

Rambling over.

[flyincanuck]

@ teacher: true...but wouldn't you say that's just bad piloting? We're all trained to fly single-engine...even if it clunks out at a critical point.

By default you become a multi-tonne glider if you lose your only engine on a single.

edited for spell check...phew

[FlyGy]

Just wondering, on a twin engine helo, how many transmissions does it have? Two engines dont do a whole lot of good when the transmission fails.

[Nark]

Bob Hoover does more with two dead engines, than I ever hope to do with two good ones.

The idea of one versus two is ludicris. A large, large majority of accidents are pilot induced.
Perhaps we should debate, one pilots verus two?

[flyinthebug]

On Flying Wild Alaska this week...the 20 yr veteren pilot (forget his name, but has a beard) had to make a flight to a small island on the USA/Russia border. I believe it was some 100+ miles over water. Part of the show was about his decision to either take the Caravan or the 406. He decided he wanted two fans over water and went with the 406.

Now im not saying that means he was correct, nor am I saying he made the right decision. I am saying a 20 yr veteren pilot with years of experience, choose a twin over a turbine single to cross water. When a pilot with this gentlemans experience takes a "clapped out" 406 twin over a new Caravan... maybe we should pay attention to why?

For me personally, id take the "clapped out" twin over the single turbine any day.

Fly safe all.

[Beefitarian]

Other than if the twin is a plane like this.

I think if you're going to compare single to multi engine aircraft, you need to discount multi-engine aircraft that don't have sufficient single engine climb performance.

I don't know why anyone would have a plane like that. Goes faster?

My theory is if one engine stops, hopefully the other one can pull or push me to a safe landing.

[whipline]

I remember yrs back reading an article comparing fatality rates of small twin engine vs single engine aircraft. If memory serves the twin engines had a higher fatality rate. The good engine taking the aircraft to seen of the crash. For properly trained crews it shouldn't be an issue though. Personally I'll take all the engines I can get.

[old_man]

Just wondering, on a twin engine helo, how many transmissions does it have? Two engines dont do a whole lot of good when the transmission fails.

1 Transmission
1 Fan up top
1 Tail rotor + tail rotor drive.

[trey kule]

I have to agree with the problem of pilot error. While we can obviously make the case that when a twin engine loses one engine the AIRCRAFT IS CAPABLE of safely continuing the flight, the pilots, simply are not. Pilots dont like to admit that. And on smaller twins this is a big problem.

I can recall a PC 12 engine failure inLabrador years ago that should have been a total non event, and the pilot did absolutely everything wrong..which ended up in a wrecked airplane.
More recently perfectly good Navajos and King Airs being flown into the ground by incompletent pilots...

There is just so much more to it, than simple one vs. two engines.

[old_man]

While we can obviously make the case that when a twin engine loses one engine the AIRCRAFT IS CAPABLE of safely continuing the flight.....

Do not make this assumption with a twin engine helicopter.

[trey kule]

I was posting in general terms. There obviously is a difference , even in fixed wing aircraft about aircraft capabilty. Nit picking is fun though, isnt it?

[iflyforpie]

For me personally, id take the "clapped out" twin over the single turbine any day.

I won't.

Perhaps over water it would be debatable. Many piston twins when flying over long stretches of water will get your feet wet should you lose an engine because of the range reduction. Light twins on ferry flights it is pretty much a given that the aircraft will be lost with an engine failure and unless you calculate your single engine fuel range requirements (does anybody do that, do the manuals even have those figures) you probably wouldn't make it on a revenue flight where fuel is at the minimum required.

Perhaps it would be closer to help and give you more time to prepare when you go in or perhaps even make a diversionary field, but the failure rate of two piston engines is several orders greater than a single turbine with an alternate fuel control. Remember, it's not just the hours but the speed--with the exception of the Caravan, a single turbine will cover more distance per hour.

Over the rocks, I'll take a PC12 over a Navajo any day. Navajos don't have the required single engine performance to maintain some of the MEAs here and you would be stuck in the icing layers single engine and soon share the same fate as a PC12.

A PC12 will get me over the rocks higher, give me more options to avoid icing, get me there faster (less exposure to bad terrain), and more reliably.


The other issue is, why should we have to regulate common sense? You can depart an airport below approach minimums, do any of you do that? What would be the problem with ensuring you have a suitable ceiling for SEIFR to ensure you break out at a manageable altitude? Or restrict your operations to 'cloud busting' IFR instead of hard IFR? The number of days you wouldn't be able to fly would be quite few in most parts of the country.

[teacher]

I know you can twist facts and figures to prove anything however a while back I calculated and posted as well as found supportng documents stating without a doubt that yes, you are more likely to have a crash in a PC12 due to engine failure (we're talking in the low decimal percentages) BUT much more likely to survive. Engine failure crashes in light twin turbine aircraft actually have a lower survivability. There as of yet has not been a single fatality caused by a PC12 engine failure.

[who me ?]

The stats are flawed , this is because,
The REPORTED engine failures are the only ones which are recorded.
It is widely accepted that the number of unreported engine failures in light twins is some where in the 75 to 80% unreported. This is because, an engine fails, and nothing happens and that aircraft lands, no harm, = no foul.
This practice is very very high in privately operated aircraft and also happen in commercial operations at some levels.
When the manufactures and their agents were pushing the single engine turbines back in the early 90's
they saw these numbers and jumped on them ,and only reported in their stats, the numbers of fatalies after ( REPORTED ) engine failures. The unreported stats were covered up ( left out of the equation ). Even though it is stated in the US by the NTSB that the "vast majority" of engine failures in light twins are not reported.

I know that in my operation, in every sim session we re-enforce the aircraft capabilities, by simulating engine failures in all phases of flight and the REQUIRED climb performance which is required with one engine out.

I am sorry I just do not buy the single engine turbine stories.

Cheers Who me ?