Intrinsic engine failure. A real concern or not?

[PTK]

 

I want to start this thread about engine failures in flight. I took a flight today and as it happens when I fly my mind started to think! The question I've been pondering is how paranoid are we about engine failure. Barring fuel starvation or impurities in the fuel just how likely is an intrinsic engine failure. Are we overly paranoid? Any studies out there?

 

[201er]

I think we are taught to be paranoid by instructors so that we are better prepared to handle the situation if it were to occur. Then pilots go out into the real world and fly without hiccup for many years and get complacent and are unprepared to deal with it if/when it does happen. I've spoken to several guys who have had engine failures to know that it is real and not just something you read about. Also the issue is that the symptom is the same but the causes can be so vastly different so it's a broader concern.

[jetdriven]

If your engine is over TBO calendar months or hours, then your engine can fail at any moment.  Climbing at 25 square makes it last longer.  

[PTK]

Quote: jetdriven

If your engine is over TBO calendar months or hours, then your engine can fail at any moment.  Climbing at 25 square makes it last longer.  

[bnicolette]

Good question Doc.  Where are those figures located at?  Like Byron pointed out it would be nice also to see what kind of time the engine had on them at time of failure.  We need some engines made by Honda maybe.  I had an old '86 Civic that had over 250,000 miles on it and I only did the timing belt every 75K miles and regular oil changes.  Never once did I have an issue with it!! Contrarily, I have a V12 Mercedes that is always needing some attention of some sort and it has 47K miles on it.  Hmmmmm???

It would be nice to see some sort of break down (no punn intended) of engine failures by make/model over the years.

[fantom]

Quote: allsmiles

Are we overly paranoid?

[Jerry 5TJ]

It is hard to get data on engine failure rates in GA.  You can get accident rates per 100K flight hours from the NTSB records.  Then you can parse those by cause, and try to cull out weather and pilot error from mechanical failures.  That does not tell you about failures that did not result in reportable accidents, so the NTSB records probably under-estimate engine failures.

Some engine manufacturers do provide data -- P&W Canada gives a figure for PT6A engines in terms of "uncommanded shutdowns per flight hour" which works out to about 1 per 300,000 hours per engine.  But that's a turbine.    

I'd guess the Lycoming 360 series failure interval is on the order  of 10,000 hours.    I had one in 1,800 piston hours, but that's just anecdotal, not statistically significant.  It was significant to me at the time, tho.

 

[garytex]

The Avaition Consumer does aircraft reviews in which they summarize the overall and fatal accident causes by make and model.  RLOC, Runway loss of control usually generates the most of the stupid pilot tricks accidents.  Fatals only occasionally related to engine failure as a usually 3rd or less frequent  cause.  Mooneys seem to have a slightly higher engine failure rate accident rate.  I wonder if the difficult (and thus less opened) cowl might have something to do with that.  In the 80's someone actually wrote a full size book drawn from NTSB stats.  I can not remember the title.  At that time VFR into IMC was the leading killer.  Safest transportation by category were Trains, then Busses, then commercial air, then cars, then light AC then motorcycles, and most dangerous: Horses with 1 hospitalization per 38 hrs riding.  They did caution that they thought that there were maybe some reporting errors in the horse numbers.  The fatal rate for the best of the ac, which was the 172  at 1.1 fatal for 100000 hrs was safer than cars by the mile.

But back to your question, engine failure shows up in the numbers as a non fatal cause, and an occasional fatal cause, and it does vary by make and model, just as we would immagine.  

 

[M20F]

Engine failure isn't really something I worry about that much.  If it fails there are only two scenarios and those are you die or you live.  In most cases people are kidding themselves as to their control over which of the two scenarios they are going to end up in.  While flying skills, pratice, good decision making, proper care to the airplane, etc. all help mostly what determines the winners/losers is luck.  By that I mean if the motor quits 200' AGL in a heavily populated area and you are going into somebody's house, not a lot you can do skillwise on that one.  The friends I have lost have for the most part been in situations which nobody was coming out of.

Thus I don't lose a lot of sleep over it but I am keenly aware when it is night in bad weather and the motor stumbles a little or I hit a little unexpected pocket of turbulence the heart jumps a bit and the mind races.

Be safe, be smart, and be proficent and you have nothing to worry about except the inevitability that we all go at some point.

[gregwatts]

I for one, am not the least bit paranoid about engine failure. Shit happens! All anyone can do is excersise diligence when taking care of their aircraft, and following recommended maintenance procedures, and being prepared for the possibility of a situation. Common sense plays a big part as well.

I fly at night. I fly over water. I fly in IMC. I support a Mooney mechanic!

I am more worried about being hit by by an errant driver in a car than I am about an engine out.

But that's just me.......

[Piloto]

Essentially there are two root causes for engine failure; material fatigue and improper assembly. When the engine was originally tested and certified the materials (metal and rubber) used were new and of good quality. Most likely the engine was assembled by the engineers that designed it. It is the deviations from these original conditions that causes the failures. A good engineer will take variations in material quality and design with allowances for this. Proper engine assembly is mostly a production responsibility. Most engine failures occurs during high power settings such as take-off and climbing. These failures are mostly due to material failure such as broken crankshafts, connecting rods and blown cylinders. These failures are hard to forecast but usually happens during the early life of an engine. Ironically you are better off overhauling your trusty 2000hrs engine (with original crankshaft and rods) than getting a new engine. A good old engine has proven itself. This is why most of the AD related to crankshaft, rods and other parts refer to newer engines but rarely to the old ones. Engine assembly either when new, overhauled or maintenance is another cause for engine failure. It only takes an improperly torque bolt such as those holding a connecting rod or a magneto to ruin your day, or the wrong piston rings. For this you have to trust your shop or mechanic. I found to never trust a mechanic with bad memory. Ask him how much cash he has on his wallet before working on your engine.

Overall well maintained aircraft engines are pretty reliable. The simpler the engine the more reliable would be. A four cylinder engine is more reliable than a six cylinder because there are less chances of having a failed connecting rod or a blown cylinder head. Same with normally aspirated engines. A normally aspirated engine would never have a turbo/exhaust failure. This is what makes the IO-360/O-360s so reliable. The above can also be applied to propellers. Two blade prop is more reliable than three or four blades props.

 

José

 

[jetdriven]

Actual mechanical failure is rare as a cause of accidents, barring experimentals. These have a far worse accident rate than certified aircraft.  When I hear someone bitch about the high cost of mainintaing a certified aircraft, remmeber there is a system in place that makes them 5, or 7 times safer.     this tidbit from the 2009 Nall Report:

In 2008, amateur-built aircraft had 27.29 accidents per 100,000 estimated flight hours, almost five times the rate of type-certificated aircraft, and their fatal accident rate of 7.00 was more than seven times higher.

I think largely this is up to the individual experimental aircraft and owner.  But still. I think the nall report for 2009 (non-commerical fixed wing)  has something like 18 mechanical caused fatalities in a whole year.  18 out of 19.78 million flight hours.

[jetdriven]

I dont think its that easy, Jose. For example, 90% of engine failures afe cause by fuel mismanagement, and thats more an airframe problem than an engine problem. Also, regarding 4 or 6 cylinder engines. A 6-cylinder Bonanza can blow a cylinder head right off, and still produce enough power to sustain flight for a while. A 4-cylinder engine cannot. So, a 6-banger is more complex, but also, has redundancy They probably wash out. I used to fly GTSIO-520 engines on a 421 and TIO-541-J2BD engines on a Chieftain (56" of manifold pressure for takeoff)  Argualby two of the most temperamiental and maligned engines in GA.  Their longevity depended solely on the actions of the pilot.  Ours lasted a long time, longer than many of the O-360s on people's M20C's, mostly becasue of how we flew them.

I dont think there is a difference in reliability that can be explained by how many blades a prop has on it.

Quote: Piloto

Essentially there are two root causes for engine failure; material fatigue and improper assembly. When the engine was originally tested and certified the materials (metal and rubber) used were new and of good quality. Most likely the engine was assembled by the engineers that designed it. It is the deviations from these original conditions that causes the failures. A good engineer will take variations in material quality and design with allowances for this. Proper engine assembly is mostly a production responsibility. Most engine failures occurs during high power settings such as take-off and climbing. These failures are mostly due to material failure such as broken crankshafts, connecting rods and blown cylinders. These failures are hard to forecast but usually happens during the early life of an engine. Ironically you are better off overhauling your trusty 2000hrs engine (with original crankshaft and rods) than getting a new engine. A good old engine has proven itself. This is why most of the AD related to crankshaft, rods and other parts refer to newer engines but rarely to the old ones. Engine assembly either when new, overhauled or maintenance is another cause for engine failure. It only takes an improperly torque bolt such as those holding a connecting rod or a magneto to ruin your day, or the wrong piston rings. For this you have to trust your shop or mechanic. I found to never trust a mechanic with bad memory. Ask him how much cash he has on his wallet before working on your engine.

Overall well maintained aircraft engines are pretty reliable. The simpler the engine the more reliable would be. A four cylinder engine is more reliable than a six cylinder because there are less chances of having a failed connecting rod or a blown cylinder head. Same with normally aspirated engines. A normally aspirated engine would never have a turbo/exhaust failure. This is what makes the IO-360/O-360s so reliable. The above can also be applied to propellers. Two blade prop is more reliable than three or four blades props.

 

José

 

[Piloto]

Byron

Fuel starvation is not considered an engine malfunction but an operator error. I just had a completely loose fuel injector line on my IO-360 (after an annual) and was able to maintain altitude running on three cylinders. BTW a blown cylinder top even if does not causes a jam it for sure cause an oil pressure drop thus seizing the engine. By simple probability math the chances of having a blade failure is greater on three blades than on two.

José

 

 

 

[jetdriven]

I call bullshit on a 4 cylinder Lycoming keeping an airplane aloft on 3 cylinders.  It is producing less than 50% power in flight. Probably less. You have only 3 cylinders producing power. OK, 75%. But thats at sea-level. At 5,000' altitude, thats like 56%.   math alone. But wait, you have a cylinder that is pumping compression with no power being produced.  So no we lose some more there.  What is the % of power you were producing?

Here is a Bonanza whch did blow a cylinder and produced power all the way till they shut it down in the parking spot:  http://www.csobeech.com/ECi-Head-Separation.html.'>http://www.csobeech.com/ECi-Head-Separation.html.   No oil streak.  A 4 cylinder Lycoming cannot do that.   http://www.csobeech.com/ECi-Head-Separation.html

Third, I have flown more in airplanes that have 4 blade props than two. In millions of hours, the Beech 1900 never had a prop failure that I can find.  So, there is no correlaton I can find either between number of blades and statistical chances of failure.  perhaps one on ten million vs. one in 15 million. But come on.  80-90% of accidents are caused by pilot error  And 90% of engine failures are caused by pilot error as well.  part 91 has a fatal accident rate infinitely higher than 135 in 2010, in which there were no fatal accidents for 135 operators.  The airplanes are the same.

Quote: Piloto

Byron

Fuel starvation is not considered an engine malfunction but an operator error. I just had a completely loose fuel injector line on my IO-360 (after an annual) and was able to maintain altitude running on three cylinders. BTW a blown cylinder top even if does not causes a jam it for sure cause an oil pressure drop thus seizing the engine. By simple probability math the chances of having a blade failure is greater on three blades than on two.

José

 

 

 

[johnggreen]

I've had two in my 51 years of flying.  I started at age eleven.

The first was in 1974 in a Cherokee 6.  Swallowed a valve, did some piston damage, set up incredible vibration.  Will be the subject of "I Learned About Flying From That" in the coming June issue of Flying mag.

Second was a broken fuel line on a Maule.

Fortunately, made it to an airport both times.

Had several other "issues" but could maintain altitude those other times.

I'm not paranoid, but I am always aware that it can happen.

Complacency is never appropriate in an airplane.

Jgreen

[bnicolette]

I have been very fortunate I suppose in my flying that I have never had an engine even cough on me.  My time in piston airplanes however is limited to the extent of only 1600 hours, but still in that time, I have had no engine/fuel issues.

Jgreen said it best............there is no room for compacency in an aircraft of any type.  To say that I am paranoid is not an accurate statement, but I am diligent in that an engine problem is always in the back of my mind from rolling out of the chocks to rolling into the chocks.  As I am flying over terrain that is not conducive to an easy off airport landing, then that engine failure scenario is on the forefront of my thinking.  For me anytime I fly any direction other than west, I have about :45 minutes where I am constantly weighing my options on where I'm going to go if things go bad.  I do have a lot of faith in my lil IO360 but not so much faith that the possiblity of an engine failure is negated.

It definitely happens and the best thing we can do for it is as Mike said......be ready for it.  Practice it when were out toying around and don't become complacent.

[201er]

Quote: jetdriven

[Piloto]

[fantom]

3 cylinders WILL definately fly a Mooney! I was elected to fly a Commander 112 after some maintenance. The mechanic had not assembled the intake air box correctly and at 200 ft. after takeoff, an aluminum spacer was sucked through a brand new cylinder. It was about 3/8 inch dia when it started and was reduced to pcs by the valves. Along the way impacting the sparkplug electrodes bending them shut.

After the initial shock and a scan of the gages  I flew a VERY close pattern and landed without problem. Climbed about 700 ft altittude with 2 people and full fuel in one of the most underpowered 200 hp lycoming aircraft built.

larry

[N9937c]

The above post was mine.

larry

[AlexR]

Quote: fantom

3 cylinders WILL definately fly a Mooney! I was elected to fly a Commander 112 after some maintenance. The mechanic had not assembled the intake air box correctly and at 200 ft. after takeoff, an aluminum spacer was sucked through a brand new cylinder. It was about 3/8 inch dia when it started and was reduced to pcs by the valves. Along the way impacting the sparkplug electrodes bending them shut.

After the initial shock and a scan of the gages  I flew a VERY close pattern and landed without problem. Climbed about 700 ft altittude with 2 people and full fuel in one of the most underpowered 200 hp lycoming aircraft built.

larry

[wrench]

Quote: Piloto

Essentially there are two root causes for engine failure; material fatigue and improper assembly. When the engine was originally tested and certified the materials (metal and rubber) used were new and of good quality. Most likely the engine was assembled by the engineers that designed it. It is the deviations from these original conditions that causes the failures. A good engineer will take variations in material quality and design with allowances for this. Proper engine assembly is mostly a production responsibility. Most engine failures occurs during high power settings such as take-off and climbing. These failures are mostly due to material failure such as broken crankshafts, connecting rods and blown cylinders. These failures are hard to forecast but usually happens during the early life of an engine. Ironically you are better off overhauling your trusty 2000hrs engine (with original crankshaft and rods) than getting a new engine. A good old engine has proven itself. This is why most of the AD related to crankshaft, rods and other parts refer to newer engines but rarely to the old ones. Engine assembly either when new, overhauled or maintenance is another cause for engine failure. It only takes an improperly torque bolt such as those holding a connecting rod or a magneto to ruin your day, or the wrong piston rings. For this you have to trust your shop or mechanic. I found to never trust a mechanic with bad memory. Ask him how much cash he has on his wallet before working on your engine.

Overall well maintained aircraft engines are pretty reliable. The simpler the engine the more reliable would be. A four cylinder engine is more reliable than a six cylinder because there are less chances of having a failed connecting rod or a blown cylinder head. Same with normally aspirated engines. A normally aspirated engine would never have a turbo/exhaust failure. This is what makes the IO-360/O-360s so reliable. The above can also be applied to propellers. Two blade prop is more reliable than three or four blades props.

 

José

 

[xftrplt]

Quote: flyingwrench

poster on the door to the ramp at a local airport I flew out of in the 80's, stating "85% of engine failures occur when powering back from takeoff power be ready for it if it happens".  I never did know its scource or it's accuracy but when departing airports from that day on I tried to scope out the best possible off field landing options.

[scottfromiowa]

I do not feel that my engine in my Mooney is "out to get me"...so no I am not paranoid about engine failure.  That said I listen to my engine (noise, vibration, oil use).  I installed updated engine management digital as primary and redundant indication to monitor condition in flight.  On return from my annual I took extra time in taxi and run-up.  I climbed to pattern and executed a left turn flying downwind to ensure it was running in green.  IO-360 is a reliable engine.  They almost always give fair warning before they go quiet without a mixture pull to initiate.  What me Worry?