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Off field landing at KSGH


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Another factor that can lead to high engine stress is sudden power acceleration. Unlike stress at constant speed when the engine is quickly accelerated it has to overcome its own inertia force that is greater than at constant speed. This force burst  can initiate a crack on the connecting rods, cylinder or bearings that may develop into a fracture later on. This why is important that on take off to push the throttle slowly and verify full RPM before brake release. 

José

 

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Just now, Piloto said:

Another factor that can lead to high engine stress is sudden power acceleration.

José, I agree again.  In round motors there is also a danger in pulling the power back too suddenly.  Many cases of engine failure when the pilot reduced power from takeoff power.  The sudden deceleration is apparently hard on the rotating parts.  I don't know if the same phenomenon is present in square motors....  However, I think sudden power changes are, in general, not as good as small, slow power changes.

But I'm a dinosaur.

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51 minutes ago, Mooneymite said:

Jose', I agree with you.  Having started out with round motors,  high power settings were considered stressful on the engine and high power settings were time-limited.

However, it seems to be in vogue on Mooneyspace to climb at high power settings and the POH recommended reduction to 26"/2600 is poo-poo'd by most of the experts who post here.  The thought is that such a reduction is an OWT and that the engine is certified at max power to TBO.

It just seems intuitive to me that reducing power will produce less stress on the engine.  Less stress=longevity/reliability.

I guess I'm a dinosaur.

 

If you're a dinosaur, I must be, too.  My POH calls for 25"x2500RPM when climbing, to include climbing after takeoff.  Once I have comfortable ground clearance, I dial back to those settings and still regularly see 800 FPM or better.  If i'm staying in the pattern, I have to climb at about 20" once i start crosswind, or I will be both too high and too fast when I turn to downwind.

 

Climbing full WOT and max RPM seems like a good way to add to engine wear without any significant gain.

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17 minutes ago, Mooneymite said:

José, I agree again.  In round motors there is also a danger in pulling the power back too suddenly.  Many cases of engine failure when the pilot reduced power from takeoff power.  The sudden deceleration is apparently hard on the rotating parts.  I don't know if the same phenomenon is present in square motors....  However, I think sudden power changes are, in general, not as good as small, slow power changes.

But I'm a dinosaur.

I'm a fan of "if the engine is making power don't touch anything below 1000".  I read some study somewhere (quoted by Richard Collins) that said many engine issues happen immediately after power adjustments. Consider it your stage 1 climb for the jet jocks. 

-Robert

Edited by RobertGary1
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Its easy to generalize engine failures but I'm not sure they are often mechanical failure modes that are so easily classified.

In my case the nut on the piston end cap backed off after 1,000 SFNEW. Its not a function of how the engine is run or how often the oil is changed, etc. 

Paul Loewen's  engine failure was a result of a fuel hose backing off as I recall.

 

-Robert

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1 hour ago, ShuRugal said:

If you're a dinosaur, I must be, too.  My POH calls for 25"x2500RPM when climbing, to include climbing after takeoff.  Once I have comfortable ground clearance, I dial back to those settings and still regularly see 800 FPM or better.  If i'm staying in the pattern, I have to climb at about 20" once i start crosswind, or I will be both too high and too fast when I turn to downwind.

 

Climbing full WOT and max RPM seems like a good way to add to engine wear without any significant gain.

When I stay in the pattern, I level off at 1000 agl on the crosswind leg, and reduce power to maintain altitude and 90 mph. It's less than 20" even after I turn downwind and drop Takeoff Flaps.

One benefit of WOT/2700 to altitude is improved engine cooling. Do it once each way and watch both Oil Temp and CHT, they should be lower for the higher power climb because you get more air flow from the increased speed. The climb is also for a shorter time, further reducing the heat stress on the engine.

I am much less of a dinosaur, having only flown behind round engines as a passenger in the back, and nothing smaller than a C-117 [a stripped down, dressed up DC-3].

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2 hours ago, Mooneymite said:

However, it seems to be in vogue on Mooneyspace to climb at high power settings and the POH recommended reduction to 26"/2600 is poo-poo'd by most of the experts who post here.  The thought is that such a reduction is an OWT and that the engine is certified at max power to TBO.

It just seems intuitive to me that reducing power will produce less stress on the engine.  Less stress=longevity/reliability.

That's because with normally aspirated engines, the power goes down as you climb whether you want it to or not. You only stay at 100% power for a minute, then 98% for a minute, then 95%, etc. You're down to 85% by the time you reach about 4000ft and you couldn't make more than 75% (cruise) power by 8000ft if you tried. The amount of time spent at above cruise (75%) power is only about 10 minutes and it is perpetually decreasing as you climb. On the other hand, climbing at reduced power takes forever, forward speed is slower so a net greater tach time, higher EGTs, higher CHTs, waste more fuel, get to destination later, and more work adding throttle as MP reduces with altitude. It takes excess power to climb. Not making much excess power if you power back. The IO360 is not the kind of engine that needs a power reduction or affords much of a power reduction in the climb.

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2 hours ago, Mooneymite said:

However, it seems to be in vogue on Mooneyspace to climb at high power settings and the POH recommended reduction to 26"/2600 is poo-poo'd by most of the experts who post here.  The thought is that such a reduction is an OWT and that the engine is certified at max power to TBO.

I guess I'm a dinosaur.

I'm pretty sure dinosaurs were still roaming the earth back when my POH was printed...

I'm of the belief that knowledge has likely advanced since...

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2 hours ago, ShuRugal said:

  If i'm staying in the pattern, I have to climb at about 20" once i start crosswind, or I will be both too high and too fast when I turn to downwind.

 

Climbing full WOT and max RPM seems like a good way to add to engine wear without any significant gain.

Climb at full power and then level off at pattern altitude, wherever that occurs. Then throttle back to 16” to maintain 90 knots on downwind. 

There is no evidence that climbing at full throttle and 2700 RPM causes any more wear than normal  cruise operations.  We have ran our airplane for long periods of time (hours even) at full throttle and 2700 RPM, and extended periods of cruise at 83% power as well at sea level density altitude and the oil analysis is consistent with periods where we don’t. What does ruin engines is sitting. 

And Jose, those connecting rods are about twice as strong as needed. I am convinced by evidence, and I’ve also never seen a broken connecting rod or crank from firewalling the throttle. In fact, the most abused engines I have ever flown were on a travel air. Fuel cutoff and feathered from full power at 1500’, cowl flaps still open, shut down for 2 minutes then restarted and immediately back to full power.  Sometimes shut down, feathered, and unfeathered,  full power, then another cycle all in half a minute.  Sometimes the student tried to feather the engine still running at full power. Anyways, I remarked these engines must break often and he remarked this particular set had 8,000 hours since last overhaul. 

So let’s worry about actual causes of engine failure and damage rather than non-evidence opinions backed only by feelings.  

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4 minutes ago, jetdriven said:

So let’s worry about actual causes of engine failure and damage rather than non-evidence opinions backed only by feelings.  

I think it would be both interesting and profitable to study how engines that failed had been operated prior to failure.  I've seen several cases where pilots were strong advocates of one technique, or another right up to the point where things went awry.  In many cases we are operating engines that may have been abused long before we took possession of them; tracing history to connect up the dots from operating technique to TBO, or premature failure would be tough.

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Just now, ShuRugal said:

You know, I was with you right up until you said this. My manual says "Climb at 25"x2500 RPM". This, by you, is only feelings? Bite me.

 

No, but the opinion that not following this recommendation leads to premature engine failure IS based on feelings... because it's certainly not data.

I used to fly a 1964 M20C as well. In the 52 years since that manual was published, real data driven knowledge of our engines, has increased significantly. This is due not only to the last 52 years, but increases in measuring and testing technology, data logging engine monitors, and a very large sample size.

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José, I agree again.  In round motors there is also a danger in pulling the power back too suddenly.  Many cases of engine failure when the pilot reduced power from takeoff power.  The sudden deceleration is apparently hard on the rotating parts.  I don't know if the same phenomenon is present in square motors....  However, I think sudden power changes are, in general, not as good as small, slow power changes.
But I'm a dinosaur.


Smooth is almost always better...flying planes, driving cars, racing motorcycles...now if only l could execute a smooth golf swing.


Sent from my iPhone using Tapatalk
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29 minutes ago, Mooneymite said:

I think it would be both interesting and profitable to study how engines that failed had been operated prior to failure.  I've seen several cases where pilots were strong advocates of one technique, or another right up to the point where things went awry.  In many cases we are operating engines that may have been abused long before we took possession of them; tracing history to connect up the dots from operating technique to TBO, or premature failure would be tough.

Problem with that is that it is an example of a retrospective study (taking a target event and looking backwards to identify statistically associated factors).  This is considered less powerful than a prospective study (identifying factors and waiting to see if they are statistically associated with target events), because retrospective studies are vulnerable to far more investigator biases. 

Retrospective studies are also frequently misused to identify cause/effect, when in fact they do nothing of the sort, since they ignore all the non-event data.  For example, a study might note that WOT/max RPM was found more frequently before engine failures, but that might simply be the result of more operators using the WOT/max RPM procedure, not because of cause and effect.

So better way of doing things would be to follow a bunch of operators who climbed out according to two different procedures (WOT/max RPM vs partial throttle/reduced RPM), and then seeing which results in more engine failures over time.  The problem with that is that it takes much more time, people and money to do a study like that.

TL,DR: studies like that probably have been done, but take the results with a big grain of salt (and also consider who did the studies)

Edited by jaylw314
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You know, I was with you right up until you said this. My manual says "Climb at 25"x2500 RPM". This, by you, is only feelings? Bite me.

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My manual permits either WOT or reduced power climb. Of course, decreasing air density reduces power automatically anyway, as has been pointed out.

Some aircraft have max power limitations, turbos are finicky and expensive, and many have prop speed concerns for noise abatement. While l have only my personal experience on my engine to support that, I’ve not seen data indicating that a normally aspirated IO360 shouldn’t be run WOT to top of climb. At many altitudes we fly, fast cruise will be WOT anyway.

To you guys setting power to 25” leaving the pattern - I always wonder: Do you just add an inch every thousand until you can’t? Or do you monitor it constantly and slowly come in and match the decrease in MP due to decreasing air density all the way up? Seems like work...

I’m not that precise, so I’m glad my POH justifies my inherent laziness. Gives me more time to watch for traffic (VMC) or correctly execute my clearance (IMC).
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43 minutes ago, ShuRugal said:


 

 


You know, I was with you right up until you said this. My manual says "Climb at 25"x2500 RPM". This, by you, is only feelings? Bite me.

Sent from my Pixel using Tapatalk
 

Well, the Lycoming engine operator's manual has no such limitations. So, since they built the engine, I would think that would be a better source of info than a POH from 1964  that lists recommended climb power settings, none of which are found on the aircraft limitations section. Further, the "Time fuel and distance to climb" charts in the M20J  POH list full throttle and 2700 RPM, all the way up to 18,000 feet,  and, further, it also lists 2700 RPM as a cruise RPM in the charts for all altitudes.  Its an interesting read.

 

Edited by jetdriven
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2 hours ago, jetdriven said:

There is no evidence that climbing at full throttle and 2700 RPM causes any more wear than normal  cruise operations.  We have ran our airplane for long periods of time (hours even) at full throttle and 2700 RPM, and extended periods of cruise at 83% power as well at sea level density altitude and the oil analysis is consistent with periods where we don’t.

I don't think high power operations in climb are frequent or long enough to do much harm but I think continuous high power operations still can't be good for your engine.

Edited by 201er
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It really is "just entertainment", since each of us will operate his engine as he sees fit.

Everyone has diffent goals in mind, be it "climb fast, go fast", or "make it last", or something else.  Having different goals will dictate different modes of operation.

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1 hour ago, jetdriven said:

 

And Jose, those connecting rods are about twice as strong as needed. I am convinced by evidence, and I’ve also never seen a broken connecting rod or crank from firewalling the throttle. 

My good old friend Gaston lost his M20F N6417Q due to a broken connecting rod. The broken rod puncture a hole in the crankcase that caused oil starvation. It happened immediately after take off. The plane ditched on a pond. https://aviation-safety.net/wikibase/wiki.php?id=36856

José

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3 minutes ago, Piloto said:

My good old friend Gaston lost his M20F N6417Q due to a broken connecting rod. The broken rod puncture a hole in the crankcase that caused oil starvation. It happened immediately after take off. The plane ditched on a pond. https://aviation-safety.net/wikibase/wiki.php?id=36856

José

you forgot to mention the loss of oil pressure, "to zero" in fact, followed shortly but connecting rod failure as the big end welded itself to the crank journal.  Okay, your statement proves nothing, other than to check the oil before flying. 

How about a real example. Again, data convinces me, not feelings or unrelated things.

https://www.ntsb.gov/investigations/current/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001208X08893&ntsbno=MIA97FA242&akey=1

According to the passenger, about 5-10 minutes after takeoff while climbing on a northerly heading through 1,000-1,500 feet with the landing gear retracted, he first observed that the oil pressure dropped to zero momentarily then returned to the normal green arc range. He inquired to the pilot about landing on the Sawgrass Expressway, but the pilot elected not to land there due to the amount of traffic. The pilot began orbiting the area, during which, he then heard a loud sound. The pilot then initiated a descent for a forced landing to an open field.

Edited by jetdriven
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17 minutes ago, jetdriven said:

you forgot to mention the loss of oil pressure, "to zero" in fact, followed shortly but connecting rod failure as the big end welded itself to the crank journal.  Okay, your statement proves nothing, other than to check the oil before flying. 

My oil pressure went to zero and I had 7 quarts of oil.

-Robert

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Yes, i shouldnt have implied he took off with no oil, but the oil pressure going to zero was before the connecting rod failure.  or maybe the rod bearing spun, then it failed, but none of this points to operator technique.

Edited by jetdriven
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I was at engine shop were the engine was inspected. The cause of oil pressure drop was due to the broken connecting rod intruding into the case oil passage. Even after the connecting rod broke the engine ran for a short time.

FAA AD on connecting rods:

The FAA says it has received 5 reports of uncontained engine failures and IFSDs due to failed connecting rods on various models of Lycoming Engines reciprocating engines listed in Table 1 of Lycoming Engines Mandatory Service Bulletin (MSB) No. 632B, dated August 4, 2017, that were overhauled or repaired using any replacement part listed in Table 2 of Lycoming Engines MSB No. 632B, dated August 4, 2017, which was shipped from Lycoming Engines during the dates listed in Table 2 of Lycoming Engines MSB No. 632B, dated August 4, 2017.

http://www.aero-news.net/index.cfm?do=main.textpost&id=60e85149-b4e2-41ea-a01e-7dc7a6bcf865#

José

Edited by Piloto
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FAA AD on connecting rods:

The FAA says it has received 5 reports of uncontained engine failures and IFSDs due to failed connecting rods on various models of Lycoming Engines reciprocating engines listed in Table 1 of Lycoming Engines Mandatory Service Bulletin (MSB) No. 632B, dated August 4, 2017, that were overhauled or repaired using any replacement part listed in Table 2 of Lycoming Engines MSB No. 632B, dated August 4, 2017, which was shipped from Lycoming Engines during the dates listed in Table 2 of Lycoming Engines MSB No. 632B, dated August 4, 2017.

http://www.aero-news.net/index.cfm?do=main.textpost&id=60e85149-b4e2-41ea-a01e-7dc7a6bcf865#

José

Edited by Piloto
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