The Continental IO-520
Thread Starter
Join Date: Jul 2003
Location: Wherever I Lay my Hat...
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
The Continental IO-520
I've been sitting on this one for a while, might be a good time to pop the query up!
I've struck a few Pilots in Aus and NZ that (predominantly) seem to have spent time flying in Maun, Botswana. More than a few of them use a reduced-power take-off technique that seems to require the application of power only until the red-line on the oil pressure gauge is reached. I've only seen this done on cold-start, first flight of the day take-off's. On one memorable occasion the aircraft had a full load of tandem meatbombs on board and barely cleared the fence beyond the far threshold!
IMO, it is one of the stupidest things I have ever seen done with/in an aircraft. Despite extensive research, I can find no evidence of the technique being recommended in the POH for C206/210 airframes, nor can I find anywhere any evidence of it being thought 'a good idea'! I currently have queries in with both Continental and Lycoming seeking their opinion of the technique.
My concern with this practice is twofold:
It is my opinion also that my passengers have paid for and deserve the very best I as an individual and my aircraft can give them -all the time. I am not going to try to protect a few thousand dollars (OK -quite a few!) of metal whilst putting my pax and aircraft at avoidable and unneccessary risk.
I wonder how many others have seen similar, or are there any that could explain why this is perceived as being a good idea in some quarters?
I've struck a few Pilots in Aus and NZ that (predominantly) seem to have spent time flying in Maun, Botswana. More than a few of them use a reduced-power take-off technique that seems to require the application of power only until the red-line on the oil pressure gauge is reached. I've only seen this done on cold-start, first flight of the day take-off's. On one memorable occasion the aircraft had a full load of tandem meatbombs on board and barely cleared the fence beyond the far threshold!
IMO, it is one of the stupidest things I have ever seen done with/in an aircraft. Despite extensive research, I can find no evidence of the technique being recommended in the POH for C206/210 airframes, nor can I find anywhere any evidence of it being thought 'a good idea'! I currently have queries in with both Continental and Lycoming seeking their opinion of the technique.
My concern with this practice is twofold:
- If a proper engine-warm and run-up was conducted (commensurate with the prevailing ambient conditions) there would be absolutely no need to do anything like this in the belief of protecting the engine, and
- Passengers are being carried on Commercial operations during the practice of this technique.
It is my opinion also that my passengers have paid for and deserve the very best I as an individual and my aircraft can give them -all the time. I am not going to try to protect a few thousand dollars (OK -quite a few!) of metal whilst putting my pax and aircraft at avoidable and unneccessary risk.
I wonder how many others have seen similar, or are there any that could explain why this is perceived as being a good idea in some quarters?
Grandpa Aerotart
You're absolutely correct...this practice is stupidity of the highest order...period.
Reduced thrust takeoffs are the sole preserve of Jet engined aircraft...and even then only under specific circumstances.
The TBO on these engines is predicated on testing that uses max power for at least the proposed TBO. That means the engine should be easily capable of sustaining full throttle/redline RPM for 1700 hrs. MSL/ISA conditions obviously.
Equally stupid is reducing power just after takeoff...say at 500/1000' or some similar arbitrary altitude/time. Unless the POH has specific instructions to this effect, and the IO520/550 and like engines DO NOT then there is absolutely no requirement nor benefit in any way shape or form of doing so...NONE.
All you are achieving is minimising performance at the most critical time...just airborne....really, REALLY dumb in piston twins.
Well said...the really stupid thing is these idiots are NOT preserving the engine by 'babying' them in this way...they are not saving money in fact they are reducing engine life by this malpractice.
At lower speeds seen on takeoff with high power settings it is essential that at least redline RPM/Fuel flow are seen and
MP is appropriate for the ambient conditions. That means that 29.5 inches at MSL or 28.5 at 1000' DA etc...perhaps in the early part of the takeoff roll a 1/2 inch less for system innefficiencies like a less than perfect air filter...but that is really about it.
If MP is less than optimum you're not feeding enough air to the engine to allow it to produce full rated power.
If Fuel flow is less than redline then a/. there will not be the fuel to mix with the air to produce rated power and b/. there will not be the extra fuel which helps engine cooling by slowing the rate of combustion.
If redline RPM is not evident you're not achieving the required thrust and the peak combustion pressures will be happening too close to TDC causing CHTs to go through the roof possibly leading to pre ignition and/or detonation.
The absolute best way to 'baby' your engine and maximise life while minimising costs/hr is to use full power on every takeoff and NOT to reduce power at all after takeoff until setting cruise power. In a normally aspirated engine power is reducing as soon as you start to climb anyway. How silly is it to reduce power at 500' only to start inching it back up again as you climb and the MP falls away.
Even those engines with 5 minute (or similar) limits on takeoff power before reducing to METO don't require pulling MP/RPMs back at 1000'...that's about 2 minutes after applying takeoff thrust...why not take an extra minute and get up 2000' before reducing thrust if it is a POH requirement only.
Reduced thrust takeoffs are the sole preserve of Jet engined aircraft...and even then only under specific circumstances.
The TBO on these engines is predicated on testing that uses max power for at least the proposed TBO. That means the engine should be easily capable of sustaining full throttle/redline RPM for 1700 hrs. MSL/ISA conditions obviously.
Equally stupid is reducing power just after takeoff...say at 500/1000' or some similar arbitrary altitude/time. Unless the POH has specific instructions to this effect, and the IO520/550 and like engines DO NOT then there is absolutely no requirement nor benefit in any way shape or form of doing so...NONE.
All you are achieving is minimising performance at the most critical time...just airborne....really, REALLY dumb in piston twins.
It is my opinion also that my passengers have paid for and deserve the very best I as an individual and my aircraft can give them -all the time. I am not going to try to protect a few thousand dollars (OK -quite a few!) of metal whilst putting my pax and aircraft at avoidable and unneccessary risk.
I wonder how many others have seen similar, or are there any that could explain why this is perceived as being a good idea in some quarters?
I wonder how many others have seen similar, or are there any that could explain why this is perceived as being a good idea in some quarters?
At lower speeds seen on takeoff with high power settings it is essential that at least redline RPM/Fuel flow are seen and
MP is appropriate for the ambient conditions. That means that 29.5 inches at MSL or 28.5 at 1000' DA etc...perhaps in the early part of the takeoff roll a 1/2 inch less for system innefficiencies like a less than perfect air filter...but that is really about it.
If MP is less than optimum you're not feeding enough air to the engine to allow it to produce full rated power.
If Fuel flow is less than redline then a/. there will not be the fuel to mix with the air to produce rated power and b/. there will not be the extra fuel which helps engine cooling by slowing the rate of combustion.
If redline RPM is not evident you're not achieving the required thrust and the peak combustion pressures will be happening too close to TDC causing CHTs to go through the roof possibly leading to pre ignition and/or detonation.
The absolute best way to 'baby' your engine and maximise life while minimising costs/hr is to use full power on every takeoff and NOT to reduce power at all after takeoff until setting cruise power. In a normally aspirated engine power is reducing as soon as you start to climb anyway. How silly is it to reduce power at 500' only to start inching it back up again as you climb and the MP falls away.
Even those engines with 5 minute (or similar) limits on takeoff power before reducing to METO don't require pulling MP/RPMs back at 1000'...that's about 2 minutes after applying takeoff thrust...why not take an extra minute and get up 2000' before reducing thrust if it is a POH requirement only.
Last edited by Chimbu chuckles; 17th Apr 2007 at 14:27.
Bugsmasherdriverandjediknite
Join Date: Jul 2000
Location: Bai, mi go long hap na kisim sampla samting.
Posts: 2,849
Likes: 0
Received 0 Likes
on
0 Posts
The engine has a pressure relief valve in the oil system. Reducing the power to lessen the oil pressure is both a stupid and dangerous practice, and serves no purpose other than endangering the lives of the pilot and passengers.
why do people insist on being test pilots, by using methods other than those recommended by the manufacturer?. Dumb dumb dumb.
why do people insist on being test pilots, by using methods other than those recommended by the manufacturer?. Dumb dumb dumb.
Join Date: Nov 2006
Location: The Night Sky
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Agree wholeheartedly with the sentiments expressed so far. Sadly I don't think the old wives tales about engine handling (more often mishandling) will be exorcised any time soon. Having spent plenty of time behind an IO 520 I think they are a great engine. I don't know why there are so many knockers out there. Any "reputation" these engines have for not making TBO or failing prematurely is probably mostly bullsh*t or a direct result of ham fisted or misguided handling. In my opinion the equal and in some aspects the better of any Lycoming.
Unless the POH has specific instructions to this effect, and the IO520/550 and like engines DO NOT
EDIT: and back on topic.....any pilot who thinks 5-10mins (on an average day) to get the temps into the green i too long to wait, thenI wonder how they will go waiting for SAR to come and get them after an engine failure!
Last edited by Chadzat; 18th Apr 2007 at 06:16.
Thread Starter
Join Date: Jul 2003
Location: Wherever I Lay my Hat...
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Chadzat
...reduce power from a screaming 2850rpm back to the green band
UBE: precisely the point.
edit
Whoops, sorry I didn't note to which post you were commenting.
I don't think CC is advocating leaving the 520 turning at 2850 (the 550 however will happily turn @ 2700 all day) -as he states, in a normally aspirated engine, your power setting (MP) effectively starts reducing as soon as your wheels leave the ground. Winding the prop back to say 2700 for the climb has many advantages in performance, and is a 'good neighbourly' practice also. Those blade-tips going trans-sonic is bloody hard to listen to.
Last edited by kiwiblue; 18th Apr 2007 at 07:03. Reason: hmmm... hoist on my own petard
There seems to be general agreement that the original thread of this post is crap, but the topic of power settings for IO520s after TO is an interesting one.
While I would not challenge CC, cause he is generally right, I must confess that I am a 25/25 on climb kinda person. Maybe I am just a creature of habit, although CCs point on pulling the MP back and then having to shove it back in has got me thinking. At the weights I fly, 25/25 will generally get me to 10 k in 10 min in the V35B. Maybe pulling the RPM back to 2500 and letting the MP drop off in the climb makes more sense, but its not my aircraft so I tend to fly it by the POH.
I once lost a bet with a pilot who bet me that he could knock off my C210 over 50 nm (property near Muttaburra to Longreach) in his C185.
We agreed to fly at 5500 (the 185 drivers suggestion), and I foolishly gave him about 600 m (length of the runway) head start. He killed me in the climb and I never looked like overhauling him.
In the C210 I pulled the power back to 25/25 soon after take off and cruised 24/24. The C185 pulled the RPM back to 2500 in the climb and left the MP at TO setting. At 5500 it was on 25/25, where it (I suspect) it remained until finals.
I would not have believed a 185 could knock off a 210, if I had not been there. 20 years later I am still trying to live it down.
Dr
PS: Yes, I did remember to retract the gear!
While I would not challenge CC, cause he is generally right, I must confess that I am a 25/25 on climb kinda person. Maybe I am just a creature of habit, although CCs point on pulling the MP back and then having to shove it back in has got me thinking. At the weights I fly, 25/25 will generally get me to 10 k in 10 min in the V35B. Maybe pulling the RPM back to 2500 and letting the MP drop off in the climb makes more sense, but its not my aircraft so I tend to fly it by the POH.
I once lost a bet with a pilot who bet me that he could knock off my C210 over 50 nm (property near Muttaburra to Longreach) in his C185.
We agreed to fly at 5500 (the 185 drivers suggestion), and I foolishly gave him about 600 m (length of the runway) head start. He killed me in the climb and I never looked like overhauling him.
In the C210 I pulled the power back to 25/25 soon after take off and cruised 24/24. The C185 pulled the RPM back to 2500 in the climb and left the MP at TO setting. At 5500 it was on 25/25, where it (I suspect) it remained until finals.
I would not have believed a 185 could knock off a 210, if I had not been there. 20 years later I am still trying to live it down.
Dr
PS: Yes, I did remember to retract the gear!
I think you'll find that most of the published 5 minute limits exist only to reduce noise levels from departing aircraft to appease the neighbours.
As for a "screaming 2850" the only thing screaming is the prop tips.
As for a "screaming 2850" the only thing screaming is the prop tips.
The only action I take on an IO-520 after takeoff is to wind back the RPM to 2500 (2550 for the 210). That's it. By the time you reach 4000' the MP will be back to 25", 7000' it'll be 22" and when you get to 10,000' it will have dropped back to around 19".
You cannot and will not stress, harm or junk the engine using this technique. Leaning the mixture is per the POH. Oversquare intially the climb? A furphy. Everywhere I go in the Chieftan, it's always running oversquare.
If I have reason to be up in the flight levels in the A36 it's run at full throttle (of course) and the prop spins at 2700 RPM.
You can use the following scale as a guide to set engine power.
42 = 55% power, 45 = 65% power and 48 = 75% power.
You add together your MP and RPM to arrive at a particular number. 22"MP and 2300RPM gives you 22 + 23 = 45. At that MP and RPM setting, the engine is operating at about 65% power. 23" and 2500RPM gives you 23 + 25 = 48, or around 75% power. And so on and so on. Sorry about the topic creep.
Reduced power takeoffs? About the dumbest thing I've heard all year so far!
You cannot and will not stress, harm or junk the engine using this technique. Leaning the mixture is per the POH. Oversquare intially the climb? A furphy. Everywhere I go in the Chieftan, it's always running oversquare.
If I have reason to be up in the flight levels in the A36 it's run at full throttle (of course) and the prop spins at 2700 RPM.
You can use the following scale as a guide to set engine power.
42 = 55% power, 45 = 65% power and 48 = 75% power.
You add together your MP and RPM to arrive at a particular number. 22"MP and 2300RPM gives you 22 + 23 = 45. At that MP and RPM setting, the engine is operating at about 65% power. 23" and 2500RPM gives you 23 + 25 = 48, or around 75% power. And so on and so on. Sorry about the topic creep.
Reduced power takeoffs? About the dumbest thing I've heard all year so far!
" ... As for a "screaming 2850" the only thing screaming is the prop tips" ...
and if its a C185 with an 88" prop, "screaming" is not an apt decription of the noise ........ its more of a VERY, VERY, VERY LOUD CACKLE !!!!!!!
Dr
and if its a C185 with an 88" prop, "screaming" is not an apt decription of the noise ........ its more of a VERY, VERY, VERY LOUD CACKLE !!!!!!!
Dr
Thread Starter
Join Date: Jul 2003
Location: Wherever I Lay my Hat...
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by gassed budgie
Oversquare intially the climb? A furphy.
It's hard to forget the shocked expressions on some pilots' faces when they realised that I had absolutely no intention of pulling the throttles back on the BN-2A (O-540's) after take-off!!! They went all the way up once and stayed there 'till finals -unless there was a bloody good reason not to. Props back to 2450-2500, mixture back to the top of the R on the quadrant. Worked a bloody treat. Ran lean, good T's & P's, slightly LOP, good grey pipes, climbed her at 115-120KIAS, expected and got 135-140KIAS in the cruise. Nice flat attitude in the cruise, elevator neutral. That's where she liked to run
Those same pilots never did figure out how I could take so much time out of them in an identical aircraft
About the most you can expect to see on your MP gauge at sea level on a standard day for a N/A engine is 29". You lose around 1' of MP for every 1,000' gain in altitude as you're no doubt aware. Hence the 19" at 10,000". The A36 that I fly on quite a regular basis (110 hrs in the last 8 weeks) pulls just on 20" at 10K's. Some induction systems are more efficient than others. One of the worst is the 210. From memory (I'm sure someone will correct me if I'm wrong) 75% power is available only to around 6,500'.
How rude and crude can you get. The A36's and V35B's aren't a whole lot better.
By the way the scale I suggested above is only for engines that redline at 2700Rpm.
How rude and crude can you get. The A36's and V35B's aren't a whole lot better.
By the way the scale I suggested above is only for engines that redline at 2700Rpm.
Join Date: Nov 2006
Location: Enzed
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
In reply to original post...
As a C206/210 pilot based in Maun, Botswana let me assure you that the practice you(kiwiblue) describe is NEVER used by the pilots flying here.
1. I don't know if you have ever flown a C206 at 3100 ft AMSL in temps around 45degrees out of short, rough, dirt strips at MAUW, but if you don't push Throttle/pitch all the way to the firewall you're gonna be a lovely fireball at the end of the strip!
2. Even with the throttle open all the way we only can muster 25MP! So its staying all the way in bro, for takeoff, cruise and descent.
3. After 500hrs hours in a 206 i have never seen the oil pressure reach the red line on takeoff.
4. The only thing that gets wound back after takeoff is the rpm for the reason (as someone mentioned) to stop the prop screaming at 2850.
Cheers
As a C206/210 pilot based in Maun, Botswana let me assure you that the practice you(kiwiblue) describe is NEVER used by the pilots flying here.
1. I don't know if you have ever flown a C206 at 3100 ft AMSL in temps around 45degrees out of short, rough, dirt strips at MAUW, but if you don't push Throttle/pitch all the way to the firewall you're gonna be a lovely fireball at the end of the strip!
2. Even with the throttle open all the way we only can muster 25MP! So its staying all the way in bro, for takeoff, cruise and descent.
3. After 500hrs hours in a 206 i have never seen the oil pressure reach the red line on takeoff.
4. The only thing that gets wound back after takeoff is the rpm for the reason (as someone mentioned) to stop the prop screaming at 2850.
Cheers
Thread Starter
Join Date: Jul 2003
Location: Wherever I Lay my Hat...
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
Very pleased to hear it 206Dog. Why I raised the issue in that way: I have only ever seen it done twice myself, both were ex-Maun drivers, the one I challenged after watching his pax-carrying abortion of a take-off at reduced power, climbed straight on his high-horse, telling me all about all the hours he'd done in Botswana where he was taught the technique and how it was a standard practice. I don't know if he ever did get the idea -he left where he was working very soon after.
There's a very ggod friend of mine going to be in Maun in a few weeks too -she'll be flying with one of you guys at some point, so yeah I was hoping to provoke a reaction from Maun too
get some discussion going. Thanks I sure as all hell don't want her exposed to this crap.
But above all, it does happen. I've seen it. I've discussed it with the one I caught up to. As I have stated, I can think of few things sillier to do in an aircraft. There is a learning element in here for others that may at some stage have this bull**** foisted on them.
Oh. Yeah mate. Been there, done that.
There's a very ggod friend of mine going to be in Maun in a few weeks too -she'll be flying with one of you guys at some point, so yeah I was hoping to provoke a reaction from Maun too
get some discussion going. Thanks I sure as all hell don't want her exposed to this crap.But above all, it does happen. I've seen it. I've discussed it with the one I caught up to. As I have stated, I can think of few things sillier to do in an aircraft. There is a learning element in here for others that may at some stage have this bull**** foisted on them.
Oh. Yeah mate. Been there, done that.
Join Date: Mar 2004
Location: new zealand
Posts: 56
Likes: 0
Received 0 Likes
on
0 Posts
I agree with Mr 206
Hey Shiny one!!!! hows the old maun town treating you???
I worked there for a couple of years, Never did reduced thrust T/O, But i am aware that one of the companies there did do it, although I do stand to be corrected.
I never did it, Flying out of delta strip with 1 plus 9 or 10 locals at 45 degrees with5 knots on the tail, I dont think it would work that well! Although the boss was pretty stringent about us beinging the prop back as soon after T/O as possible, something to do with noise or something like that. If I was heavy I didnt, but light I had no problem doing it.
P.S. when I was there all the engines made time ex.
I worked there for a couple of years, Never did reduced thrust T/O, But i am aware that one of the companies there did do it, although I do stand to be corrected.
I never did it, Flying out of delta strip with 1 plus 9 or 10 locals at 45 degrees with5 knots on the tail, I dont think it would work that well! Although the boss was pretty stringent about us beinging the prop back as soon after T/O as possible, something to do with noise or something like that. If I was heavy I didnt, but light I had no problem doing it.
P.S. when I was there all the engines made time ex.
As I am currently doing some hours in a C210, with this engine, I took great interest in the instructor's engine management today.
His after-take-off check runs along the lines of
Gear Up
Power Back to 24
Prop back to 2500
Flaps up
etc
Now, it is true that the aircraft climbs very well at 24 inches, albeit a light fuel load and only 2POB, and indeed for flying circuits, which is what I was doing today, it was probably a good idea (for no one wants to be racing down downwind at 150 knots in a 210), but with this thread in mind I asked the instructor about regular take-offs when you were actually going somewhere. I figured, Take-Off power is limited to five minutes, and climbing at over a thousand feet per minute you'd be well over 5000' by the time you needed to throttle back anyway.
"No," says the instructor, "24 inches is Maximum Except Take Off, so after you've taken off, you throttle back to 24, then as you climb away, and you trickle the power back in to maintain 24 inches until you're at full throttle."
He then proceeded to explain the concept of Full Throttle Height to me, which I was already well aware of.
I asked, with apologies to Chimbu Chuckles, why we must reduce the power at 300' only to have to increase it again later?
"Because its METO - Maximum Except Take Off".
I postulated my theory about running the engine at full throttle for five minutes after take off, but he countered by informing me that although the manufacturer states the limit is five minutes, what they really mean is thirty seconds, otherwise you'd be "tearing the engine to shreds inside".
I decided there was nothing to be gained from pointing out that if the manufacturer says five minutes, then the manufacturer probably means five minutes, and if the manufacturer meant thirty seconds, they'd probably say thirty seconds...
We went inside and got a coffee.
His after-take-off check runs along the lines of
Gear Up
Power Back to 24
Prop back to 2500
Flaps up
etc
Now, it is true that the aircraft climbs very well at 24 inches, albeit a light fuel load and only 2POB, and indeed for flying circuits, which is what I was doing today, it was probably a good idea (for no one wants to be racing down downwind at 150 knots in a 210), but with this thread in mind I asked the instructor about regular take-offs when you were actually going somewhere. I figured, Take-Off power is limited to five minutes, and climbing at over a thousand feet per minute you'd be well over 5000' by the time you needed to throttle back anyway.
"No," says the instructor, "24 inches is Maximum Except Take Off, so after you've taken off, you throttle back to 24, then as you climb away, and you trickle the power back in to maintain 24 inches until you're at full throttle."
He then proceeded to explain the concept of Full Throttle Height to me, which I was already well aware of.
I asked, with apologies to Chimbu Chuckles, why we must reduce the power at 300' only to have to increase it again later?
"Because its METO - Maximum Except Take Off".
I postulated my theory about running the engine at full throttle for five minutes after take off, but he countered by informing me that although the manufacturer states the limit is five minutes, what they really mean is thirty seconds, otherwise you'd be "tearing the engine to shreds inside".
I decided there was nothing to be gained from pointing out that if the manufacturer says five minutes, then the manufacturer probably means five minutes, and if the manufacturer meant thirty seconds, they'd probably say thirty seconds...
We went inside and got a coffee.