Warming your engine?
Join Date: Jan 1999
Location: north of barlu
Posts: 6,207
Likes: 0
Received 0 Likes
on
0 Posts
The heart of the walming up problem is the "low tech " oils that aviation still uses most of you are using single grade oils such as W100 or W80 these are not good lubricants when they are cold and so to avoid damage to the engine it should be run at low RPM untill the bottom of the green arc on the temp gauge is reached.
The most common damage resulting from high RPM when cold is worn camshafts , normaly the lobes furthest from the oil pump are the first to have the case hardening worn through this distrbutes small steel particals around the engine , most of them seem to get embeded in the "softer! alloy of the pistons below the rings.
My recomendation is to use a multi-grade oil and warm the engine at low RPM not more than 1200RPM untill 40 C sounds good to me , thease are the numbers for the Lycoming O-540 an engine with a reputation for eating camshafts if ill treated.
The most common damage resulting from high RPM when cold is worn camshafts , normaly the lobes furthest from the oil pump are the first to have the case hardening worn through this distrbutes small steel particals around the engine , most of them seem to get embeded in the "softer! alloy of the pistons below the rings.
My recomendation is to use a multi-grade oil and warm the engine at low RPM not more than 1200RPM untill 40 C sounds good to me , thease are the numbers for the Lycoming O-540 an engine with a reputation for eating camshafts if ill treated.
Join Date: Aug 2001
Location: UK Work: London. Home: East Anglia
Posts: 306
Likes: 0
Received 0 Likes
on
0 Posts
Who Has - I believe you, but it does sound as if you have a weird typo in your POH. 0-540 = 6 cylinders and 235 bhp minimum. If it's 160bhp it must be a four-banger. How many cylinders do you have?
LnS - When I started flying the Yak I too imagined that in "standard" UK weather compared to the frozen wastes, the operation of the cooling gills would be pretty much "open fully and locked". In fact I was surprised just how much scope there is for using them. In this autumnal weather, standard cruising will be at a part-closed position, and in anticipation of a prolonged climb I would open them , then if descending a couple of thousand feet I would pull them closed a little more. Even if not making huge power reductions it still cools down quite noticeably when you're swooping down for an overhead join.
Another advantage is that when you stop for fuel (something you get LOTS of practice at), you can close the shutters after shut-down, and the engine stays nice and warm while you refuel, grab a cuppa, etc, so the restart is easier and you don't have to wait around for ages again for it to warm up before departure. Oh yes, and leaving it in the hangar with the shutters closed can only discourage little nesting creatures, and those peculiar individuals at air shows who seem to find the oddest places to dispose of put their crisp packets, Mars Bar wrappers etc.
So there's lots to do with those odd-looking levers on the right sill of the cockpit, but we make up for the workload by having automatic mixture control, no tanks to change, etc.
LnS - When I started flying the Yak I too imagined that in "standard" UK weather compared to the frozen wastes, the operation of the cooling gills would be pretty much "open fully and locked". In fact I was surprised just how much scope there is for using them. In this autumnal weather, standard cruising will be at a part-closed position, and in anticipation of a prolonged climb I would open them , then if descending a couple of thousand feet I would pull them closed a little more. Even if not making huge power reductions it still cools down quite noticeably when you're swooping down for an overhead join.
Another advantage is that when you stop for fuel (something you get LOTS of practice at), you can close the shutters after shut-down, and the engine stays nice and warm while you refuel, grab a cuppa, etc, so the restart is easier and you don't have to wait around for ages again for it to warm up before departure. Oh yes, and leaving it in the hangar with the shutters closed can only discourage little nesting creatures, and those peculiar individuals at air shows who seem to find the oddest places to dispose of put their crisp packets, Mars Bar wrappers etc.
So there's lots to do with those odd-looking levers on the right sill of the cockpit, but we make up for the workload by having automatic mixture control, no tanks to change, etc.
Thread Starter
Join Date: Oct 2001
Location: North Weald, UK
Posts: 357
Likes: 0
Received 0 Likes
on
0 Posts
Lowtimer - I'm inclined to believed your typo idea. Its only a 4 cylinder BUT there is a 235HP variant available.
One page in the POH states :- 0-320 4 cyl 160hp, but has been amended, the new sheet states:- 0-540 4 cyl 160hp.
A later chapter on engine limitations states :- engine : 0-320
So apart fom ripping the cowlings off to find the data plate, I think I'll accept its a 0-320.
Fortunately its the only mistrake I've found.
One page in the POH states :- 0-320 4 cyl 160hp, but has been amended, the new sheet states:- 0-540 4 cyl 160hp.
A later chapter on engine limitations states :- engine : 0-320
So apart fom ripping the cowlings off to find the data plate, I think I'll accept its a 0-320.
Fortunately its the only mistrake I've found.
Guest
Posts: n/a
Who has Control
You are right - the number doe smean cubic inches.
The 0-320 is usually 140-160HP, whereas the 0-360 is 180HP.
Both are 4 cylinder - I am not expert, but I believe that the 0-360 is basically a longer stroke 0-320.
The 540, as others have pointed out, is the big 6 cylinder 235-300HP block that hangs off the front end of the PA28-235/6 and the PA32 range.
If your a/c is a Koliber, it is available with a larger 0-540 engine as an option - giving 235HP.
Perhaps this is the explanantion - my original query was that an 0-540 giving 160HP seemed VERY de-rated - and as there is a 260HP carb version, I wondered if you had done a typo - but apprently someone else had!!!!!
BTW, I am a Squadron member and fly the Pup with 69 on the nose ... we may have bumped intp each other at some stage.
You are right - the number doe smean cubic inches.
The 0-320 is usually 140-160HP, whereas the 0-360 is 180HP.
Both are 4 cylinder - I am not expert, but I believe that the 0-360 is basically a longer stroke 0-320.
The 540, as others have pointed out, is the big 6 cylinder 235-300HP block that hangs off the front end of the PA28-235/6 and the PA32 range.
If your a/c is a Koliber, it is available with a larger 0-540 engine as an option - giving 235HP.
Perhaps this is the explanantion - my original query was that an 0-540 giving 160HP seemed VERY de-rated - and as there is a 260HP carb version, I wondered if you had done a typo - but apprently someone else had!!!!!
BTW, I am a Squadron member and fly the Pup with 69 on the nose ... we may have bumped intp each other at some stage.
Join Date: Oct 1999
Location: UK
Posts: 3,325
Likes: 0
Received 0 Likes
on
0 Posts
Agree with everyting Lowtimer says about the M14P in Yaks - in winter, it can be a very long wait before you can taxi.
I found the oil cooler flap didn't need much attention in flight, but those engine gills were something else, and an eagle eye had to be kept on the CHTs. After a while you could actually smell when the engine was getting hot enough to require a tad more opening of the gills; there was no such warning for overcooling.
But reading my car handbook, it says NEVER to warm up the engine by pre-drive idling. Start it and drive away immediately, it says (Omega V6). I wonder why? Is it something to do with not having cold and rich exhaust gasses soaking the catalytic convertor?
SSD
I found the oil cooler flap didn't need much attention in flight, but those engine gills were something else, and an eagle eye had to be kept on the CHTs. After a while you could actually smell when the engine was getting hot enough to require a tad more opening of the gills; there was no such warning for overcooling.
But reading my car handbook, it says NEVER to warm up the engine by pre-drive idling. Start it and drive away immediately, it says (Omega V6). I wonder why? Is it something to do with not having cold and rich exhaust gasses soaking the catalytic convertor?
SSD
SSD, sounds about right regarding the cat.
SSD & Lowtimer, pity there isn't an automatic option for the gills
who has control and QDMx3, looks like I got your posts mixed up in my befuddled mind
regarding the hp of QDMx3's engine and the type of who has control's engine.
Now that I'm straight again, what kind of system allows two different aircraft types with the same model of engine to have such different criteria for such an important part of their operations:
QDMx3 quoted from his POH (Super Cub)
who has control quoted from his POH (PZL Koliber)
Surely the operating criteria are unique to the engine rather than the airframe. I realise that different cooling capabilites in the cruise could be reflected in the POH but surely they will all start up/warm up the same! I don't recall seeing a Super Cub with a LoPresti style cowling with teeny weeny cooling air inlets
SSD & Lowtimer, pity there isn't an automatic option for the gills
who has control and QDMx3, looks like I got your posts mixed up in my befuddled mind
regarding the hp of QDMx3's engine and the type of who has control's engine.Now that I'm straight again, what kind of system allows two different aircraft types with the same model of engine to have such different criteria for such an important part of their operations:
QDMx3 quoted from his POH (Super Cub)
I believe my 0-320 handbook says you shouldn't run for more than four minues on the ground and that the engine is warm enough to take off when the throttle can be advanced without the engine coughing. It says nothing about having oil temp in the green.
Engine must be run at 1200 rpm or less until oil temp of 104deg F (40 degC) is attained.
Join Date: Jun 2002
Location: New South Wales
Posts: 1,794
Likes: 0
Received 0 Likes
on
0 Posts
Nope I didn't quote from the Super Cub POH, which is notoriously sketchy, but the engine handbook. But I've temporarily, er 'misplaced' it. I'll get back to you when I find it and quote exactly.
QDM
QDM
Join Date: Nov 2003
Location: Brazil
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
Just lean it after start
My procedure for engine warming is idle plus lean mixture. That way, I don`t get fouled plugs.
I strongly recommend everone to always lean the mixture after start until the run up. But if you pull the red knlb, pull it hard. You must have the mixture so lean that the engine will immediately quit when you apply takeoff power. It`s safer to pull hard than being timid and forget it leaned before the takeoff.
The mags check is much more valuable if you do it with the mixture leaned. With the mixture leaned, any ignition problem will show soon, before it gets worst. Doing this, I learned that, if a standard rich mixture mag check shows a discrepancy, you have a big problem. With the mixture leaned, the problem shows earlier.
I strongly recommend everone to always lean the mixture after start until the run up. But if you pull the red knlb, pull it hard. You must have the mixture so lean that the engine will immediately quit when you apply takeoff power. It`s safer to pull hard than being timid and forget it leaned before the takeoff.
The mags check is much more valuable if you do it with the mixture leaned. With the mixture leaned, any ignition problem will show soon, before it gets worst. Doing this, I learned that, if a standard rich mixture mag check shows a discrepancy, you have a big problem. With the mixture leaned, the problem shows earlier.
Join Date: Jul 2003
Location: N55' 56' and a wee bit west
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
poet that sounds like a katana or at least a rotax 912???
i usually find that start up then take your time taxying(which with its taxying abilitys aint hard) power checks then a back track usually gets it up to temp. it has however been drilled into me that you should never commence rolling until all gauges are reading normally
edited to say that i am pretty low hours so i normally take my instructers word as gospal but i shall be watcjing this thread with interest
i usually find that start up then take your time taxying(which with its taxying abilitys aint hard) power checks then a back track usually gets it up to temp. it has however been drilled into me that you should never commence rolling until all gauges are reading normally
edited to say that i am pretty low hours so i normally take my instructers word as gospal but i shall be watcjing this thread with interest
Join Date: Jan 1999
Location: north of barlu
Posts: 6,207
Likes: 0
Received 0 Likes
on
0 Posts
Two issues !
As far as I can see there are two issues to deal with the first is thermal shock this is best avoided by warming the engine at a fast idle speed untill the whole engine has had the chance to walm up to a point at which the rapid diferental expantion of the engine parts will be minimised.
The second issue is lubrication as we all know aircraft piston engine oil technology seems to be frozen in the 1940,s with most of us still using mono grade oils.
These oils do NOT work well untill up to near working temperature and will flow freely between the working parts , this is critical in the highly loaded parts of the engine.
This damage is most commonly seen on the cam lobes and cam followers and is known as "spalling" This is a direct result of lubrication breakdown usualy as a result of the engine being run to fast before the lubrication system has had a chance to build up the "splash lubrication " and the oil is to cold to flow freely.
As the cam and follower spall and small particals of steel are released into the engine , the particals that are not caught in the oil filter normaly embed themselfs in the pistons below the rings and score the barrels this leads to the release of more steel particals flowing around the engine and a rapidly increasing amount of engine damage.
There are two things that can be done to first and most important is to keep the RPM at or below 1200 untill the temp gauge starts to move and then dont do the run-up checks untill you have 40c oil temperature.
The other thing that you can do is use a multi grade oil , these provide better lubrication at low tempertures and some have an anti scuffing agent to help reduce spalling ( this is agent is required for the Lycoming "H" series engines)
The second issue is lubrication as we all know aircraft piston engine oil technology seems to be frozen in the 1940,s with most of us still using mono grade oils.
These oils do NOT work well untill up to near working temperature and will flow freely between the working parts , this is critical in the highly loaded parts of the engine.
This damage is most commonly seen on the cam lobes and cam followers and is known as "spalling" This is a direct result of lubrication breakdown usualy as a result of the engine being run to fast before the lubrication system has had a chance to build up the "splash lubrication " and the oil is to cold to flow freely.
As the cam and follower spall and small particals of steel are released into the engine , the particals that are not caught in the oil filter normaly embed themselfs in the pistons below the rings and score the barrels this leads to the release of more steel particals flowing around the engine and a rapidly increasing amount of engine damage.
There are two things that can be done to first and most important is to keep the RPM at or below 1200 untill the temp gauge starts to move and then dont do the run-up checks untill you have 40c oil temperature.
The other thing that you can do is use a multi grade oil , these provide better lubrication at low tempertures and some have an anti scuffing agent to help reduce spalling ( this is agent is required for the Lycoming "H" series engines)
Sliding slightly off topic:
A & C I've been thinking about using multigrade oil once my rapidly dwindling stock of 100W is finished. I have been led to believe that they provide better protection to engines that stand for a while (mine can be idle for at least a month at a time). What concerns me is that they might not be appropriate and / or approved for an ancient engine like a Cirrus Minor II with it's oil flinger front crank seal and ancient design oil seals.
Hopefully I am avoiding the spalling effect caused by overly viscous cool oil as I wait until the oil temp needle is off the stop (100F / 40C) before giving the engine any welly. However, I have seen my oil temp getting up to 180F during the summer when I was in a fast, for an Auster, cruise. I was surprised at how long it took for the oil to cool down to a more normal 150-160F after reducing the power. Would a multi grade help in these circumstances?
A & C I've been thinking about using multigrade oil once my rapidly dwindling stock of 100W is finished. I have been led to believe that they provide better protection to engines that stand for a while (mine can be idle for at least a month at a time). What concerns me is that they might not be appropriate and / or approved for an ancient engine like a Cirrus Minor II with it's oil flinger front crank seal and ancient design oil seals.
Hopefully I am avoiding the spalling effect caused by overly viscous cool oil as I wait until the oil temp needle is off the stop (100F / 40C) before giving the engine any welly. However, I have seen my oil temp getting up to 180F during the summer when I was in a fast, for an Auster, cruise. I was surprised at how long it took for the oil to cool down to a more normal 150-160F after reducing the power. Would a multi grade help in these circumstances?
Join Date: Apr 2001
Location: London UK
Posts: 231
Likes: 0
Received 0 Likes
on
0 Posts
Good tip - if you lean on the ground (in my view absolutely essential) then lean far enough so that you cannot get more than 2000RPM out of the engine; you can't damage the engine like that and you certainly can't take off with it leaned!
Has anybody ever seen REAL Russian oil? I have - I can tell you that all of the min temps for the M14 etc suddenly seemed very sensible. This was new oil. I can only describe it as a grey amorphus blob of cloying mush.The chap turned his glass jar upside down, counted to about five and the whole lot plopped to the bottom. The chances of that stuff lubricating below 40 deg C is NIL! The Russians are also very proud of their non-leaking engines. I wonder why they don't leak!
Koilber - 160hp O-320 (BZAJ at NW) but it is also available with an 0-540 pushing out 235hp.
Another contentious issue - Lengthy power checks cause much more harm than good on 'everyday' Lycs and Contis.
m
Has anybody ever seen REAL Russian oil? I have - I can tell you that all of the min temps for the M14 etc suddenly seemed very sensible. This was new oil. I can only describe it as a grey amorphus blob of cloying mush.The chap turned his glass jar upside down, counted to about five and the whole lot plopped to the bottom. The chances of that stuff lubricating below 40 deg C is NIL! The Russians are also very proud of their non-leaking engines. I wonder why they don't leak!
Koilber - 160hp O-320 (BZAJ at NW) but it is also available with an 0-540 pushing out 235hp.
Another contentious issue - Lengthy power checks cause much more harm than good on 'everyday' Lycs and Contis.
m
Join Date: Feb 2003
Location: uk
Posts: 76
Likes: 0
Received 0 Likes
on
0 Posts
LowNSlow,
There could be a small problem with multigrade oils not being approved for older out of production engines.The manufacture would usally approves a new type of oil for use with its engine after testing or making sure that it meets the required spec's MIL/SAE etc. by some other way.If its not approved then it can be regarded as using a non approved part with all the safty and legal problems that brings.Or the oil may just not work with the materials used in that engine.Check your POH/AMM.You could try the oil manufactures to.
You could try doing your oil/filter changes earlier and using a good quality oil.But warm up the engine before any high RPM.That is one of the best ways of reducing ware and tear on any engine.
There could be a small problem with multigrade oils not being approved for older out of production engines.The manufacture would usally approves a new type of oil for use with its engine after testing or making sure that it meets the required spec's MIL/SAE etc. by some other way.If its not approved then it can be regarded as using a non approved part with all the safty and legal problems that brings.Or the oil may just not work with the materials used in that engine.Check your POH/AMM.You could try the oil manufactures to.
You could try doing your oil/filter changes earlier and using a good quality oil.But warm up the engine before any high RPM.That is one of the best ways of reducing ware and tear on any engine.
Join Date: Jan 1999
Location: north of barlu
Posts: 6,207
Likes: 0
Received 0 Likes
on
0 Posts
low n slow
I would not use a multi grade in your engine , however Shell have now started to market "W100 plus".
This is W100 with the anti scuff agent and a corosion inhibiter added that I would think would be the best thing for your "old" engine.
This is W100 with the anti scuff agent and a corosion inhibiter added that I would think would be the best thing for your "old" engine.
Join Date: Nov 2003
Location: Australia
Posts: 126
Likes: 0
Received 0 Likes
on
0 Posts
On the 230hp IO-540 (C-182) i tend to leave the cowl flaps closed while getting up to temperature - every bit helps.
And on the topic of piston engine temperatures i've got a question re: shock cooling. I have no experience with water-cooled engines. On descent i tend to close the throttle and give the mixture a twist every 1000' or so to minimise any sudden temp changes. Am i right in saying this is unnecessary in water-cooled engines - could someone explain?
Rob.
And on the topic of piston engine temperatures i've got a question re: shock cooling. I have no experience with water-cooled engines. On descent i tend to close the throttle and give the mixture a twist every 1000' or so to minimise any sudden temp changes. Am i right in saying this is unnecessary in water-cooled engines - could someone explain?
Rob.
146fixer and A and C thanks for the advice. I don't think multigrades were in common usage when the POH for my 1946 Cirrus was written. I'll go for the W100 plus I think.
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Oil does several things in aircraft engines (cooling, lubrication etc) but if you have a TCM turbocharged engine, oil also assures that the wastegate operates properly.
For this to happen, the oil must be hot.
Watched in amazement some years ago as the president of Pacific Airmotive in KBUR taxied out for takeoff in a Cessna 402, did not bother with a runup( his usual forte)...and on takeoff, shoved the throttles full forward (recommended by the POH) only to find that three cylinders on the left engine, and two cylinders on the right engine separated from the case, leaving bits of metal all over the runway.
Hot oil was very necessary to ensure that the turbo wastegate operated properly, limiting the MP to the proper number.
For this to happen, the oil must be hot.
Watched in amazement some years ago as the president of Pacific Airmotive in KBUR taxied out for takeoff in a Cessna 402, did not bother with a runup( his usual forte)...and on takeoff, shoved the throttles full forward (recommended by the POH) only to find that three cylinders on the left engine, and two cylinders on the right engine separated from the case, leaving bits of metal all over the runway.
Hot oil was very necessary to ensure that the turbo wastegate operated properly, limiting the MP to the proper number.
LowNSlow, I see that many moons ago you asked about warming up big radials. The principles are the same as with any piston engine, but you do have to be very thorough with the procedures or significant mechanical damage will occur. My comments below relate to the PW R-1340 engine in the Harvard and the PW R-2800 engine in the Hellcat and Corsair. Other combinations, such as the Centaurus engine in the Sea Fury or R-2800 in the DC6, may be markedley different.
After starting with cold oil, the oil pressure will initially be very high, with a quoted maximum limit for most engines of 100 psi. With the PW R-1340 you can keep the pressure down to 100 psi by running at around 700 - 800 RPM then, as the oil temp increases, progressively increasing the RPM to maintain 100 psi until the normal warm up setting of 1200 RPM is reached. With the PW R-2800 you may see pressures as high as 200 psi after start. Pilots' Notes states that the RPM must not exceed 1000 until the oil pressure is less than 100 psi.
As with most engines, the RPM must not exceed the "warm up" setting (1200 R-1340, 1000 R-2800) until the oil temp reaches 40 deg C and the CHT reaches 120 deg C. This inevitably precludes taxying on grass but should allow you to taxy on hard surfaces if reasonably level. Also, although it may seem logical to warm up the engine with the cowl gills closed, in the Hellcat this can cause heat damage to the ignition harness so they must stay open on the ground.
Some engines have a lower maximum CHT limit on the ground than in flight, presumably due to the reduction in cooling airflow to certain cylinders without the airflow into the cowling.
Big radial engines do not like sudden large temperature changes. Therefore, you do not go straight from a display (continuous rich) setting to very low power for the approach. You always aim to spend a few minutes at a cruise power setting before an approach to land to let the engine temperatures stabilise at a lower value.
Prior to shutdown you run the engine at 800 - 1000 RPM for at least a minute to let the temperatures throughout the engine stabilise. Also, there is a maximum temperature for shutdown which is less than the normal ground maximum temperature. This is because the CHT initially rises after shutdown due to the loss of propwash over the cylinders.
So far on this thread, no-one has mentioned the problems of warming the engine in flight if the CHT cools below the minimum value. In the Harvard, this occurs easily during prolonged flight at idle (stalling, spinning, high speed dives), and I have often seen it with the IO-540 in the Beagle 206/Basset during descents and after engine shutdown during airtests and training. If you fly an aircraft that is prone to this and the POH does not tell you the power setting for warming up, you must use the minimum power that will give a CHT increase without losing too much altitude. Work it out in advance, remember it and use it!
I was somewhat alarmed when I first read this thread that minimum oil and cylinder head temperature limits were not being strictly adehered to. This comment is not a criticism of those who have posted here. In fact, it was heartening to find the interest in researching this field. However, it does raise two questions in my mind. Firstly, are POHs adequate in the promulgation of engine limits and advice on how to adhere to them? Secondly, is engine husbandry emphasised adequately during PPL training by flying instructor? I suspect that this might stimulate more debate!
Hope that this is of interest.
After starting with cold oil, the oil pressure will initially be very high, with a quoted maximum limit for most engines of 100 psi. With the PW R-1340 you can keep the pressure down to 100 psi by running at around 700 - 800 RPM then, as the oil temp increases, progressively increasing the RPM to maintain 100 psi until the normal warm up setting of 1200 RPM is reached. With the PW R-2800 you may see pressures as high as 200 psi after start. Pilots' Notes states that the RPM must not exceed 1000 until the oil pressure is less than 100 psi.
As with most engines, the RPM must not exceed the "warm up" setting (1200 R-1340, 1000 R-2800) until the oil temp reaches 40 deg C and the CHT reaches 120 deg C. This inevitably precludes taxying on grass but should allow you to taxy on hard surfaces if reasonably level. Also, although it may seem logical to warm up the engine with the cowl gills closed, in the Hellcat this can cause heat damage to the ignition harness so they must stay open on the ground.
Some engines have a lower maximum CHT limit on the ground than in flight, presumably due to the reduction in cooling airflow to certain cylinders without the airflow into the cowling.
Big radial engines do not like sudden large temperature changes. Therefore, you do not go straight from a display (continuous rich) setting to very low power for the approach. You always aim to spend a few minutes at a cruise power setting before an approach to land to let the engine temperatures stabilise at a lower value.
Prior to shutdown you run the engine at 800 - 1000 RPM for at least a minute to let the temperatures throughout the engine stabilise. Also, there is a maximum temperature for shutdown which is less than the normal ground maximum temperature. This is because the CHT initially rises after shutdown due to the loss of propwash over the cylinders.
So far on this thread, no-one has mentioned the problems of warming the engine in flight if the CHT cools below the minimum value. In the Harvard, this occurs easily during prolonged flight at idle (stalling, spinning, high speed dives), and I have often seen it with the IO-540 in the Beagle 206/Basset during descents and after engine shutdown during airtests and training. If you fly an aircraft that is prone to this and the POH does not tell you the power setting for warming up, you must use the minimum power that will give a CHT increase without losing too much altitude. Work it out in advance, remember it and use it!
I was somewhat alarmed when I first read this thread that minimum oil and cylinder head temperature limits were not being strictly adehered to. This comment is not a criticism of those who have posted here. In fact, it was heartening to find the interest in researching this field. However, it does raise two questions in my mind. Firstly, are POHs adequate in the promulgation of engine limits and advice on how to adhere to them? Secondly, is engine husbandry emphasised adequately during PPL training by flying instructor? I suspect that this might stimulate more debate!
Hope that this is of interest.
Join Date: Apr 2002
Location: Dorset
Posts: 902
Likes: 0
Received 0 Likes
on
0 Posts
Had an interesting one a couple of days ago, flying out of Perth in the club Fuji FA200 (IIRC, an O320 powered beast).
Ambient temperature at ground level was -3 deg C and the engine (aircraft had been in unheated hangar overnight) was run up very gently, progressively increasing revs to around 1500 whilst at the hold, waiting for oil temp to reach 40 deg C (bottom of yellow arc). After around 10 mins running, the temp was still only 30 deg C. The pilot I was checking out (as part of club currency rules) and I agreed to proceed with the power check as the temp had not moved at all in 3 mins. After the power check, the oil temp was still only 30 deg C. We then did a couple of circuits, during which time, the oil temp dropped to 25 deg C.
I then had the aircraft booked for an XC and flew at FL60 over the Cairngorms to Inverness and back (1 hr flight either direction). At cruise power, the oil temp never rose above 25 deg C and I estimate OAT at around -16 deg C.
On paper, the flights should not have proceeded - anyone think I was doing damage to the engine by continuing?? I felt that I'd done my best to warm the engine and that a transducer positioning error was causing erroneous readings.
Ambient temperature at ground level was -3 deg C and the engine (aircraft had been in unheated hangar overnight) was run up very gently, progressively increasing revs to around 1500 whilst at the hold, waiting for oil temp to reach 40 deg C (bottom of yellow arc). After around 10 mins running, the temp was still only 30 deg C. The pilot I was checking out (as part of club currency rules) and I agreed to proceed with the power check as the temp had not moved at all in 3 mins. After the power check, the oil temp was still only 30 deg C. We then did a couple of circuits, during which time, the oil temp dropped to 25 deg C.
I then had the aircraft booked for an XC and flew at FL60 over the Cairngorms to Inverness and back (1 hr flight either direction). At cruise power, the oil temp never rose above 25 deg C and I estimate OAT at around -16 deg C.
On paper, the flights should not have proceeded - anyone think I was doing damage to the engine by continuing?? I felt that I'd done my best to warm the engine and that a transducer positioning error was causing erroneous readings.