Twins are No Safer Than Singles

[KLRDMD]

This is part of a post from today on the Twin Cessna forum. It perfectly illustrates why "twins are no safer than singles" in the accident database. This won't show up in the accident database. I'm not sure a single engine piston airplane would have fared as well under the same circumstances.

Was flying from MA to MN today, with a planned fuel stop in Michigan. First leg was planned for 3:15, flying at 12K. At one point during the flight the MP on the left engine dropped from 30" down to 26", then recovered. That occurred when I was near emptying the aux tank, so I wasn't sure if it was a fuel hiccup. Nearing the end of the portion of the flight over Ontario, the oil pressure dropped to 20PSI. (Red line is 10PSI, green arc starts at 30PSI.) Pressure was holding at 20 PSI, but I started looking for a diversion with a maintenance facility. My in-flight resources weren't particularly useful, so when I crossed back to the US with Cleveland approach, I asked if they could tell me if there was a maintenance facility at Flint. Controller made a call, then came back and said there was, so I asked to divert. My intended stop at RNP was just past FNT.

Somewhat after that, the oil pressure started to fall below 20 PSI, so I made the decision to shut down the engine. After securing, I let ATC know I had made the precautionary shutdown. Soon asked if I needed assistance and was I declaring an emergency. I said I may need assistance taxiing on the ground, and yes, declared an emergency. FNT was landing to the south but winds were only 6 knots, so they offered me a straight in landing to 27. Thought about it for a few seconds and realized the idea of not making any turns in the pattern sounded pretty good. On the approach, there was just a scattered layer below, so I had the airport in sight from fairly far out (20 mi+). Had the ILS dialed in, but it didn't show the glideslope, so I loaded in the RNAV approach. Left flaps up, and put the gear down at glideslope intercept from 3K. I ended up never putting any flaps in, so I was a bit fast over the threshold and used more runway than usual. But with 7K available it wasn't an issue. Emergency vehicles followed me down the runway and all the way to the shop on the field. Taxiing to maintenance required a bunch of right turns (into the good engine), but surprisingly that wasn't an issue.

[Davidv]

Sounds like you made some good decisions and had a safe ending!  As you point out in your story, one benefit of the twin is being able to shut down the engine before the issue (such a rapidly declining oil pressure), damages the engine beyond repair.  In a single we are going to try and keep the blades spinning no matter what to try and make a runway.

Interested to hear the cause of the issue once it's determined...

[KLRDMD]

10 minutes ago, Davidv said:

Sounds like you made some good decisions and had a safe ending! 

It was a post to the Twin Cessna forum, not me although I do own and fly a Twin Cessna.

[exM20K]

2 hours ago, KLRDMD said:

This is part of a post from today on the Twin Cessna forum. It perfectly illustrates why "twins are no safer than singles" in the accident database. This won't show up in the accident database. I'm not sure a single engine piston airplane would have fared as well under the same circumstances

It’s not obvious how this illustrates anything other than a competent multi-engine pilot executing a routine engine-out landing after a precautionary shut down.

in a single, this event is about half as likely to happen.

A competent single-engine pilot would divert to nearest suitable field when the OP starts going.

An engine-out in a single is not a death sentence, but rather is something to deal with. As with twins, many do not make it into the stats because no substantial damage or serious injuries.

I have quite a bit of multi time and may own a twin again some day (waiting on Bob Kromer to make me a smoking deal on a Blackhawk C90), but until I have substantial time in type, I am certain that I’m safer in my Acclaim.

We pilots are a link in the accident chain some 75% of the time, after all…. Especially we high-time studs that know it all :-)

-Dan

 

[Ragsf15e]

Sounds like having a twin gave him more options to shut down early to prevent further damage and to be picky with his divert airfield, but not necessarily the difference between living and dying.

[N201MKTurbo]

You say a single may not have faired as well. Only if the sick engine was the one on the front of the single. The chance of having a sick engine on a twin is twice as high.

The statistics are kind of skewed. I assume most twin engine failures go unreported. The only ones that are reported are when something bad happens. 

[Ragsf15e]

47 minutes ago, N201MKTurbo said:

You say a single may not have faired as well. Only if the sick engine was the one on the front of the single. The chance of having a sick engine on a twin is twice as high.

The statistics are kind of skewed. I assume most twin engine failures go unreported. The only ones that are reported are when something bad happens. 

Yeah, definitely.   We need one of our math geniuses to make sense of it though… twins have twice as many chances for something to fail, but a much lower chance of off field forced landing if a failure occurs.  In some instances (high DA, low alt), a twin with one engine might be as bad or worse than a single without an engine if the pilot doesn’t act exactly right.  Then there’s the fact that we’re lumping all twins together… an Apache and a King air should have a much different outcome for a takeoff failure, except there’s the KA that hit Flight Safety…. It’s pretty tough to make a reasonable comparison.

[PMcClure]

39 minutes ago, Ragsf15e said:

Yeah, definitely.   We need one of our math geniuses to make sense of it though… twins have twice as many chances for something to fail, but a much lower chance of off field forced landing if a failure occurs.  In some instances (high DA, low alt), a twin with one engine might be as bad or worse than a single without an engine if the pilot doesn’t act exactly right.  Then there’s the fact that we’re lumping all twins together… an Apache and a King air should have a much different outcome for a takeoff failure, except there’s the KA that hit Flight Safety…. It’s pretty tough to make a reasonable comparison.

I think the math has already been done. Check the cost to insure a similar valued twin to the mooney.

[KLRDMD]

Just now, PMcClure said:

I think the math has already been done. Check the cost to insure a similar valued twin to the mooney.

With similar experience, the insurance premium between a single and twin is similar.

[aviatoreb]

1 hour ago, KLRDMD said:

With similar experience, the insurance premium between a single and twin is similar.

The actuaries know their business.  Across a population is the twin more less or same likely to cost the insurance agency in a given year.  If a twin is safer then the twin should cost less on same hull value.

Great job by the way knock on wood and I don’t blame you for enjoying your machine.

[N201MKTurbo]

Let’s just look at a gear up in a 310 vs a Mooney. Everything in a 310 cost 3 times more than a Mooney. It has 3 times as many cylinders and uses 3 times as much fuel. For that you get 20% more speed and more useful load.

I would imagine a gear up will cost 3 times as much to repair. So even though the hull values are about the same, the repair costs are much higher.

 

BTW, I love flying 310s

Edited July 11, 2021 by N201MKTurbo

[Ragsf15e]

20 minutes ago, N201MKTurbo said:

Let’s just look at a gear up in a 310 vs a Mooney. Everything in a 310 cost 3 times more than a Mooney. It has 3 times as many cylinders and uses 3 times as much fuel. For that you get 20% more speed and more useful load.

I would imagine a gear up will cost 3 times as much to repair. So even though the hull values are about the same, the repair costs are much higher.

 

BTW, I love flying 310s

Using your example may indicate that the insurance folks think the twins are safer.  If same hull value costs the same to insure, but repairs cost double, they must be seeing less claims overall.  Or at least less big liability claims.

[hammdo]

I have personally experienced a single engine out (last May). My CFI and I followed the emergency procedures and when it was obvious she would not start up, we executed an off field landing. The biggest difference as mentioned would be a twin getting to an airport where I couldn't (we were still 5 miles from one).  Finding a good spot to land is key. Some places to land leave you with the lesser of two evils.

Just some context...

-Don

 

[Urs_Wildermuth]

3 hours ago, KLRDMD said:

It perfectly illustrates why "twins are no safer than singles" in the accident database.

I wonder what exactly you mean by this, for me this example shows exactly that in capable hands twins are a lot safer.

You loose an engine in cruise in a SEP, you are going down to ground level, no matter what. If you are lucky, you will reach an airport. If not, you will land whereever.

In a twin, no matter which one, you will also descend, depending on the airplane will determine how fast and to what level. Some of the 160-180 hp normally aspirated twins will descend to about 4000 ft DA at MTOW of 4200lb, which in cruise by definition it can't have. Most turbocharged twins will maintain anywhere between 10 and 17 k ft OEI.

I've flown some hours in Seneca I's and at the time we tried out what can be done and what not. At about 4000 lb, the Seneca I drifted down to about 5500 ft. If we put the Rajay Turbocharger to use on the "live" engine, we were able to hold almost 10'000 ft with one engine in the presecribed zero power setting. My FI at the time told me he had actually shut down engines before and the values improved slightly with the feathered prop.

A guy I know well used to own a BE95, the 180 hp powered Travel Air. He claims that in an actual shut down situation being about half ways in a trip from Switzerland to Algiers (long time ago) he was able to drift down to about 6000 ft, where the pane held altitude. I heard similar values from people with Twin Commanches, the Turbo version of that plane being one of my pipe dreams to own, and a lot higher values from the Turbo TC.

The Seneca II was a totally different beast. Not only will it climb quite high on one engine if it has to (about 13000 ft) it is generally a much better airplane than the Seneca I.

So in practice, if you have to shut one down in cruise, where also flying skills are not massively taxed OEI, I'd rate your chances of landing at some airport rather high. If you have to shut down over the sea, your chances of staying dry will massively improve. That goes for all of them with the possible exception of the original Apache, which I have never flown but am told that in some conditions may not hold any altitude above terra firma at all.

Even over mountains like the Alps and even on one of the 4000 ft OEI celing wonders your chances are bigger. If you fly at, say, 16000 ft and loose an engine in mid weights, you will descent at about 200 fpm to 500 fpm towards whatever altitude it will eventually manage to keep. Chances in todays age with GPS based terrain awareness e.t.c. are massively higher than they used to be to find yourself terrain where you can safely descend into the lower areas or to follow valleys e.t.c. No, it is not a out of jail card in all circumstances, but im most of them, I'd say with pilot competence it is much better than in a single to reach landable ground.

The most accidents twins do is either with EFATO where people loose control or simply fail to realize that below a certain height and before it is cleaned up, a twin is naught but a SEP and needs a straight ahead landing. Unfortunately, it has also happened that people lost control on approach or n the circuit OEI as they fell victim to the Vmca trap when increasing power on the good engine or when attempting a single engine go around, which most manufacturers tell you not to attempt anyway. But out of cruise, as this situation here was, a twin will give you that landing at an airport under most circumstances where a single would not.

If I were in the market for a light twin, I'd go either for a Turbo Twin Comanche or a Seneca II or III. But having said that, I saw a really nice Seneca I recently at a very low price but with new engines and props plus really good IFR cockpit (Aspen, dual GNS430W, 3 axis Ap and radar) which, had the owner bothered to return my mails, would have really have had me tempted, despite the measly range. The other one I saw recently which got me musing was a GA7 Cougar, also in excellent condition and with very low hours. But I have to say, the one thing which keeps me from making this step is that I own my C model Mooney for a reason: It is the one airplane with a decent performance I can afford. So no twins for me. But whoever can, should not get dissuaded by old wife's tales about people who mostly never flew one.

 

 

 

 

[A64Pilot]

A multi really comes into its own when over water or over the jungle, because a successful forced landing just isn’t possible.

‘So if you fly over a lot of inhospitable terrain, then a multi has more value than it does for someone who doesn’t and flies almost all their flights day VFR.

There are situations in a multi that an engine loss isn’t as benign as it is in cruise, and you have to be on the ball then, and not everyone has been.

Supposedly Lindbergh picked a single because of the likely hood of losing an engine was much less likely. I think what he could afford had a lot to do with it.

Same with modern pilots. I can’t afford a twin so for me it’s a mute issue.

There is an old saying and it’s that eventually all pilots end up with an airplane they can’t afford.

Went to breakfast with someone moving down here, he has a Widgeon and just replaced both GO-480’s as he was over TBO on both he had to buy new cranks and cams etc.

‘I can only imagine that cost much more than my Mooney did, but for him it may have been no big deal.

 

Edited July 11, 2021 by A64Pilot

[Jerry 5TJ]

 

I’ve been flying a new Tecnam P2006T recently.  It reminds me in some ways of my old M20E:  At 2600# gross, about the same weight.  Each has 200 hp, tho the Tecnam has it divided between two 100 hp Rotax 912s.  Cruise at about 140-145 knots is similar.  Fuel flow similar, around 9-10 GPH total for both engines.   Useful load and range, again, about the same.  Even the landing sight picture is similar: Both planes sit low on the ground.  

With one engine inoperative the Tecnam  doesn’t have much performance left, but it will slowly drift down to around 5-6000’ and maintain that altitude.   

[Ragsf15e]

15 minutes ago, Jerry 5TJ said:

 

I’ve been flying a new Tecnam P2006T recently.  It reminds me in some ways of my old M20E:  At 2600# gross, about the same weight.  Each has 200 hp, tho the Tecnam has it divided between two 100 hp Rotax 912s.  Cruise at about 140-145 knots is similar.  Fuel flow similar, around 9-10 GPH total for both engines.   Useful load and range, again, about the same.  Even the landing sight picture is similar: Both planes sit low on the ground.  

With one engine inoperative the Tecnam  doesn’t have much performance left, but it will slowly drift down to around 5-6000’ and maintain that altitude.   

They don’t have Fiki models do they?

[RobertGary1]

17 hours ago, aviatoreb said:

The actuaries know their business.  Across a population is the twin more less or same likely to cost the insurance agency in a given year.  If a twin is safer then the twin should cost less on same hull value.

Great job by the way knock on wood and I don’t blame you for enjoying your machine.

One factor is probably that when a twin has an issue is much more expensive to fix. But I’d really have to see data to support the previous posters assertion that multi insurance is no more than single with comparable time pilot. 

[carusoam]

Great info Ken!

Thanks for sharing all of the details…

Engine out decision making happens pretty quickly… with an added touch of pressure…

 

There is a cargo Boeing 737 at the bottom of the sea this week…. Started with an engine out after take-off.

Ended with both engines not producing enough power to stay aloft… 

Coast guard picked up the two man crew…

In the dark, over the ocean, the cockpit was torn from the plane… (Hawaii)

 

PIC has a lot to do with the successful outcome.

Nice decision making…

Best regards,

-a-

[KLRDMD]

Just now, carusoam said:

Nice work Ken! Thanks for sharing all of the details…

I just shared someone else's story. This wasn't me.

[Tim Jodice]

18 hours ago, N201MKTurbo said:

Let’s just look at a gear up in a 310 vs a Mooney. Everything in a 310 cost 3 times more than a Mooney. It has 3 times as many cylinders and uses 3 times as much fuel. For that you get 20% more speed and more useful load.

I would imagine a gear up will cost 3 times as much to repair. So even though the hull values are about the same, the repair costs are much higher.

 

BTW, I love flying 310s

A few things to be fair to 310s and twins in general,

Not all parts cost 3 times. in fact many of the parts are the same and when you get to the airframe they only have one. 

If all Mooneys had 4 cylinder engines then yes there would be 3 times the cylinders. At the other end of Mooneys a quick look on Airpower shows you can buy 2 factory IO-470s for a 310 or Baron for one engine on a Bravo. 

A small engine (IO-470) 310/baron usually burns 25-28 GPH ROP, I personally run a Baron at 22 LOP. compared to a J typical 10GPH Close to 3 only if you running the twins at a high power. 

20% faster in cruise but they climb at a much higher rate typically going faster as well.

Useful load is the big one and the only reason I fly a twin. Most Mooneys have around 900 useful load. yes there are the few around 1000 and some very rare examples like striped Eagles that approach 1100. Most small engine Barons 310s have 15-1600 Useful and some rare examples around 17-1800. They do need to use up some of it to carry the extra fuel needed but they still have a better useful load. 

At most twice the cost to repair from a gear up. while you do have 2 engines to fix you still only have one airframe to repair the sheet metal, flaps, etc and that can be a big part of the bill.

The reason I bring all this up is because someone reading MooneySpace my want to buy a twin and unless you are comparing a Mooney 201 to a turbo 310 or 340 it doesn't cost three times as much to run.

I learned all of this from  owning a 201, partner in a Baron along with other friends that own twins.

[aviatoreb]

5 hours ago, Jerry 5TJ said:

 

I’ve been flying a new Tecnam P2006T recently.  It reminds me in some ways of my old M20E:  At 2600# gross, about the same weight.  Each has 200 hp, tho the Tecnam has it divided between two 100 hp Rotax 912s.  Cruise at about 140-145 knots is similar.  Fuel flow similar, around 9-10 GPH total for both engines.   Useful load and range, again, about the same.  Even the landing sight picture is similar: Both planes sit low on the ground.  

With one engine inoperative the Tecnam  doesn’t have much performance left, but it will slowly drift down to around 5-6000’ and maintain that altitude.   

Those seem nice - very fuel efficient.

how is climb performance at sea level with one engine?

[Jerry 5TJ]

1 hour ago, aviatoreb said:

Those seem nice - very fuel efficient.

how is climb performance at sea level with one engine?

Poor. 

[KLRDMD]

3 hours ago, Tim Jodice said:

A quick look on Airpower shows you can buy 2 factory IO-470s for a 310 or Baron for one engine on a Bravo. A small engine (IO-470) 310/baron usually burns 25-28 GPH ROP, I personally run a Baron at 22 LOP. compared to a J typical 10GPH Close to 3 only if you running the twins at a high power.  20% faster in cruise but they climb at a much higher rate typically going faster as well.

Useful load is the big one and the only reason I fly a twin. Most Mooneys have around 900 useful load. yes there are the few around 1000 and some very rare examples like striped Eagles that approach 1100. Most small engine Barons 310s have 15-1600 Useful and some rare examples around 17-1800. They do need to use up some of it to carry the extra fuel needed but they still have a better useful load. 

The reason I bring all this up is because someone reading MooneySpace my want to buy a twin and unless you are comparing a Mooney 201 to a turbo 310 or 340 it doesn't cost three times as much to run. I learned all of this from  owning a 201, partner in a Baron along with other friends that own twins.

I've owned four Mooneys (C, F, M and K) and three Baron/310s so I too have real life experience owning and maintaining these airplanes. As mentioned, two IO-470s cost about the same to overhaul as one TIO-540. I pull the power back even more than the above and burn 10 GPH per side in cruise in my Baron/310s. I burned 19.4 GPH in cruise in my Bravo. I change the oil in turbos every 25 hours, every 50 hours in normally aspirated engines. So, the engine overhaul cost, fuel burn, oil changes, etc. are a wash. The hangar is the same. Insurance is dependent on hull value. My Bravo insurance premium was much higher than any of my twins due to the hull value. I had 900-1,000 lb useful load in my Mooneys. My 310 has 1,725 lb useful load plus about six times the cargo capacity of the Mooneys. The twins climb about twice as fast as the Mooneys and at a higher airspeed. My twins have cost right at 50% more to run than my singles, lumping all 18 airplanes I've owned together. Don't let anyone convince you it costs three times as much or even twice as much.

And the bottom line, if I lose an engine in cruise I have options. Each flight I have about three seconds of risk, when actions needs to be quick, not superhuman fast, just no delay in responding. For me, at this point in my life and flying career, I choose to own a fly a twin. It is OK if something else is right for others.

[KLRDMD]

I just got a text from a friend of mine who owns a Beech 58P (pressurized Baron). He had to shut down his right engine tonight and landed uneventfully at CHD. He would not have made the airport in a single engine. Would he have survived the landing, been injured, badly? Fortunately, we'll never know. There will be no accident/incident report.

He had a B55 Baron previously. In that airplane he also had to shut one down and landed uneventfully, this time at ABQ. That was less than 100 flight hours ago for him. Again, no accident/incident report was filed. In this case he would have landed out in the desert somewhere between Albuquerque and Phoenix. With his family onboard. If in a single engine would they have been injured, alive, who knows?

This was the last part of his text to me: "The guy in the tower at Chandler though was more frazzled than me because he was the controller when the Bonanza overran the runway yesterday. They had firetrucks out and everything."

Oh, and he is METICULOUS about every last thing on his airplane being perfect. No squawks ever. A completely open checkbook.

You can see the right prop feathered.

Edited July 12, 2021 by KLRDMD