Question on indicated Oil Temp and Oil Pressure

[iWantWings]

Can anyone help me with some guidance/recommendation related to the questions below?

1.) Does the POH for Cessna 172 (carburated version) N model have any text where a flight is not recommended because the outside air temperature is too hot? (and I do not mean references to tables of density altitude and its impact on aircraft performance). But more like "if the OAT is X*Celcius, then your engine might not be cooled well enough to prevent overheating". Is there such thing in the C172 POH, or anywerhe else?

2.) In a situation where, during flight, the oil temperature indicator is in the red zone and the oil pressure indicator is no longer in the green zone (but not in the red zone either), what can be done to continue the flight safely, as planned? Or should a descent to nearest airport be considered? In other words, how should such a situation best be managed?



To put the 2 questions above into perspective, here is a summary

• student pilot on 2nd solo cross country
• It was a hot day with over 100*F (some areas in the region reported 107*F)
• Run-up was all within limits
• By the time I was climbing through 4,700 indicated altitude, the indicated oil temp was well into the red zone.
• Also, indicated oil pressue was no longer in the green zone (to the left of green, but still far from red).
• Prior to engine indicator being in red for oil temp and left of green for oil pressure, I was climgbing at full throttle at an attitude that got 85Kts.
• I tried a few things but they did not get the engine guages back into green zone, so I returned to home field. The things i tried were
  • lower the nose but maintain teh full power during climb through 4,700 indicated altitude. This increased KIAS and reduced climb rate.
  • full mixture rich hoping it would cool the combustion chamber, at the risk of fouling the plugs (I did this after I had already leaned the mixture due to high density altitude).
  • Before reaching my target of 5,500 feet, at 4,700 i began a cruise at 2,300 RMP for not more than a few minutes, hoping I'd see a change.
  • After all these, temp was still in red and oil pressure left of green, but nowhere near red.

A mechanic flew the plane with me thereafter; he confirmed that the oil temp was climbing at a fast rate and would have continued into the red zone if the brieft test flight to 2000 feet would have gone on, but there was nothing wrong with the plane.

So I have some questions about managing indicated oil temp and oil pressure when they exceed the normal range:

1. Did I overeact to the oil temp being into red and oil pressure just slightly out of the green zone (but still far from the red zone?).
2. Could I have climbed at less than full RPM? (I did lower the nose to get about 85-90knots in the climb, at reduce rate, but I sitll had full throttle). I didnt' try climging at less than full RPM- not sure if that's a good idea?
3. Could I have continued the climb to 5,500 even while oil temp was on red and oil pressure left of green, but once at 5.5K cruise at 2300 RMP and maybe a longer duration at that reduced RMP and cruise attitude would have gotten the oil temp and pressure back into normal green?
4. Could I have kept the mixture full rich during the climb to 5,500? I nkow that will help cool the combustion chamber, but what would it do the spark plugs? Is the trade off okay if temp is reduced and oil pressure increased back in normal range?
5. Oil Pressure indicator has a region that is Green, a narrow section for Red, and a section between the green and the red that is Black. How does one interpret the region that is black?
6. For how long is one willing to run an O320 engine in filght when oil pressure and oil temp are out of the normal operating range? How long until possible engine damage might start occuring?
7. Anything else I could have done?

I appreciate any info, and if screwed something up I'm sure I'll hear it. Thanks.
Edit:
- the engine oil had just been changed; i was the first flight after that.
- after i decided to turn back home, during the descent from 4,700 at 1,500 RMP, both oil temp and oil pressure indicators had returned to well within the green normal operating range
- others have flown the plane since and I have not heard (nor asked) about any issues being reported.

 

[BurtM]

Can anyone help me with some guidance/recommendation related to the questions below?

1.) Does the POH for Cessna 172 (carburated version) N model have any text where a flight is not recommended because the outside air temperature is too hot?

No. If you're flying one, you should know that, too. The POH is about 5 inches wide and 7 inches tall. It has about 48 pages. You should know that, too, unless you're a troll. BTW, there is no reason to specify the "carburated version" of the 172N because that's how they all were manufactured!

2.) In a situation where, during flight, the oil temperature indicator is in the red zone and the oil pressure indicator is no longer in the green zone (but not in the red zone either), what can be done to continue the flight safely, as planned? Or should a descent to nearest airport be considered? In other words, how should such a situation best be managed?

If oil temp is high and oil pressure is low, unless your CFI was a complete doof, you know what to do. If you don't, ask your CFI. Or ask another CFI that has a clue.

 

[murphey]

Any time you're worried about something amiss, it's NEVER a mistake to land or ifa close by, go back home and find the A&P.

 

[Rigged4Flight]

that was helpful.

 

[denverpilot]

1.) Does the POH for Cessna 172 (carburated version) N model have any text where a flight is not recommended because the outside air temperature is too hot? (and I do not mean references to tables of density altitude and its impact on aircraft performance). But more like "if the OAT is X*Celcius, then your engine might not be cooled well enough to prevent overheating". Is there such thing in the C172 POH, or anywerhe else?

You can answer this question yourself. Now is a good time to find time to read the POH cover to cover. If you had, you wouldn't be asking.

2.) In a situation where, during flight, the oil temperature indicator is in the red zone and the oil pressure indicator is no longer in the green zone (but not in the red zone either), what can be done to continue the flight safely, as planned? Or should a descent to nearest airport be considered? In other words, how should such a situation best be managed?

You have some ideas further down that are accurate, so why are you asking as if you don't know? Ask if there are any OTHER ways. Are you that unsure of them?

To put the 2 questions above into perspective, here is a summary

• student pilot on 2nd solo cross country
• It was a hot day with over 100*F (some areas in the region reported 107*F)
• Run-up was all within limits
• By the time I was climbing through 4,700 indicated altitude, the indicated oil temp was well into the red zone.
• Also, indicated oil pressue was no longer in the green zone (to the left of green, but still far from red).
• Prior to engine indicator being in red for oil temp and left of green for oil pressure, I was climgbing at full throttle at an attitude that got 85Kts.
• I tried a few things but they did not get the engine guages back into green zone, so I returned to home field. The things i tried were
  • lower the nose but maintain teh full power during climb through 4,700 indicated altitude. This increased KIAS and reduced climb rate.
  • full mixture rich hoping it would cool the combustion chamber, at the risk of fouling the plugs (I did this after I had already leaned the mixture due to high density altitude).
  • Before reaching my target of 5,500 feet, at 4,700 i began a cruise at 2,300 RMP for not more than a few minutes, hoping I'd see a change.
  • After all these, temp was still in red and oil pressure left of green, but nowhere near red.

A mechanic flew the plane with me thereafter; he confirmed that the oil temp was climbing at a fast rate and would have continued into the red zone if the brieft test flight to 2000 feet would have gone on, but there was nothing wrong with the plane.

I respectfully disagree with your mechanic and would want a second opinion. 100F+ is difficult on a weak cooling configuration but not impossible. If you did all the things you mentioned and the needle stayed in the red, I would suspect that there's a problem with the baffles, the temperature thermostat on the oil cooler, or the darn thing is bunked up internally and flow through it is awful, or the instrument is jacked and needs repair. Maybe even the wrong oil, wrong filter, or something equally stupid. It's far more common to see Cylinder Head Temp off the scale on a hot day first before oil temp. If the aircraft had a CHT gauge, what did it say? If it didn't, did the mechanic suggest or discuss the possibility that cylinder damage may have occurred? I don't like a summary dismissal of the indication without getting to root cause. It screams "mechanic has a monetary interest in not finding a problem with this aircraft" to me. Maybe (s)he's right, but I wouldn't like that simple an answer. Especially if they agreed the temp was climbing too rapidly.

So I have some questions about managing indicated oil temp and oil pressure when they exceed the normal range:

1. Did I overeact to the oil temp being into red and oil pressure just slightly out of the green zone (but still far from the red zone?).

1. 
   
   That's your judgement call. I say no. The aircraft powerplant isn't designed to operate (for long) above redline and real damage can occur if the instrument is correct.
   
   

   [*]Could I have climbed at less than full RPM? (I did lower the nose to get about 85-90knots in the climb, at reduce rate, but I sitll had full throttle). I didnt' try climging at less than full RPM- not sure if that's a good idea?

   
   Yes but...
   
   Most carbureted engines provide a slightly richer mixture at Wide Open Throttle depending on the design of the carb. Pouring less fuel on any controlled fire is certain to create less heat and less available work from the engine. If you could hold altitude with reduced power, it was certainly another option.
   
   

   [*]Could I have continued the climb to 5,500 even while oil temp was on red and oil pressure left of green, but once at 5.5K cruise at 2300 RMP and maybe a longer duration at that reduced RMP and cruise attitude would have gotten the oil temp and pressure back into normal green?

   
   There are plenty of Skyhawks that take off well above that altitude even if you factor in your calculated Density Altitude at my home airport KAPA, every day in the summertime. They don't do what you're describing unless they're broken.
   
   

   [*]Could I have kept the mixture full rich during the climb to 5,500? I nkow that will help cool the combustion chamber, but what would it do the spark plugs? Is the trade off okay if temp is reduced and oil pressure increased back in normal range?

   
   If a cylinder destroys itself in flight, you won't care much about a spark plug. At WOT full rich, you're not going to foul a plug.
   
   The real trade off is fuel consumption. You might run out of gas before you reach your destination.
   
   

   [*]Oil Pressure indicator has a region that is Green, a narrow section for Red, and a section between the green and the red that is Black. How does one interpret the region that is black?

   
   I don't have a good description for you other than "out of operating limits".
   
   

   [*]For how long is one willing to run an O320 engine in filght when oil pressure and oil temp are out of the normal operating range? How long until possible engine damage might start occuring?

   
   Long enough to turn toward an airport and land. You don't know what's wrong and there is no point in flying any further. If nothing else, continue the flight later when it's cooler, even if that means the next day, after getting a competent answer from a mechanic who isn't just as puzzled as you are.
   
   

   [*]Anything else I could have done?

   
   Find the root cause problem on the ground.
   

I appreciate any info, and if screwed something up I'm sure I'll hear it. Thanks.
Edit:
- the engine oil had just been changed; i was the first flight after that.

I really really really don't like our of spec gauge numbers fresh out of work being done under the cowl. It would have been an even bigger warning to my way of thinking than if the aircraft always "ran hot" and I was trying to find a cause on cooler days

- after i decided to turn back home, during the descent from 4,700 at 1,500 RMP, both oil temp and oil pressure indicators had returned to well within the green normal operating range

Next time, level flight, full rich, reduced power. See if it comes down into spec. If so, it's not your day to climb quickly. Or maybe it's so hot you need to step-climb and cool the engine at intermediate level-offs with reduced power.

- others have flown the plane since and I have not heard (nor asked) about any issues being reported.

Sadly in today's rental environment this is almost meaningless. I've watched pilots in T182T aircraft with fancy G1000 panels equipped with all the blinking obnoxious warning lights for engine operation blinking away in the red, and they never noticed it until I said something about it. There's lots of pilit's who have blinders on when it comes to the engine gauges and rental fleet aircraft. They're paying by the hour, and don't have to replace or repair the engine if it sustains damage. They drive it like it's a rental car.

Congrats on noticing and caring, but don't hang your hat on anyone else giving a damn in a rental. The owner would have different feelings.

I'd say at least you tried. Next time, the flight is over. Land and put it away. Even if that mechanic is right and there's nothing wrong, there's no point in continuing flight in an aircraft in conditions that won't allow the temperature gauges not to be off the scale. Playtime can wait. I might but only MIGHT change my mind if you were carrying the cure to cancer or something, but you still would be running an unplanned and unnecessary risk. Level off and cool it off.

If it won't cool off, flight's over. Fly when it's cooler outside.

 

[NineThreeKilo]

Can anyone help me with some guidance/recommendation related to the questions below?

1.) Does the POH for Cessna 172 (carburated version) N model have any text where a flight is not recommended because the outside air temperature is too hot? (and I do not mean references to tables of density altitude and its impact on aircraft performance). But more like "if the OAT is X*Celcius, then your engine might not be cooled well enough to prevent overheating". Is there such thing in the C172 POH, or anywerhe else?

2.) In a situation where, during flight, the oil temperature indicator is in the red zone and the oil pressure indicator is no longer in the green zone (but not in the red zone either), what can be done to continue the flight safely, as planned? Or should a descent to nearest airport be considered? In other words, how should such a situation best be managed?



To put the 2 questions above into perspective, here is a summary

• student pilot on 2nd solo cross country
• It was a hot day with over 100*F (some areas in the region reported 107*F)
• Run-up was all within limits
• By the time I was climbing through 4,700 indicated altitude, the indicated oil temp was well into the red zone.
• Also, indicated oil pressue was no longer in the green zone (to the left of green, but still far from red).
• Prior to engine indicator being in red for oil temp and left of green for oil pressure, I was climgbing at full throttle at an attitude that got 85Kts.
• I tried a few things but they did not get the engine guages back into green zone, so I returned to home field. The things i tried were
  • lower the nose but maintain teh full power during climb through 4,700 indicated altitude. This increased KIAS and reduced climb rate.
  • full mixture rich hoping it would cool the combustion chamber, at the risk of fouling the plugs (I did this after I had already leaned the mixture due to high density altitude).
  • Before reaching my target of 5,500 feet, at 4,700 i began a cruise at 2,300 RMP for not more than a few minutes, hoping I'd see a change.
  • After all these, temp was still in red and oil pressure left of green, but nowhere near red.

A mechanic flew the plane with me thereafter; he confirmed that the oil temp was climbing at a fast rate and would have continued into the red zone if the brieft test flight to 2000 feet would have gone on, but there was nothing wrong with the plane.

So I have some questions about managing indicated oil temp and oil pressure when they exceed the normal range:

1. Did I overeact to the oil temp being into red and oil pressure just slightly out of the green zone (but still far from the red zone?).
2. Could I have climbed at less than full RPM? (I did lower the nose to get about 85-90knots in the climb, at reduce rate, but I sitll had full throttle). I didnt' try climging at less than full RPM- not sure if that's a good idea?
3. Could I have continued the climb to 5,500 even while oil temp was on red and oil pressure left of green, but once at 5.5K cruise at 2300 RMP and maybe a longer duration at that reduced RMP and cruise attitude would have gotten the oil temp and pressure back into normal green?
4. Could I have kept the mixture full rich during the climb to 5,500? I nkow that will help cool the combustion chamber, but what would it do the spark plugs? Is the trade off okay if temp is reduced and oil pressure increased back in normal range?
5. Oil Pressure indicator has a region that is Green, a narrow section for Red, and a section between the green and the red that is Black. How does one interpret the region that is black?
6. For how long is one willing to run an O320 engine in filght when oil pressure and oil temp are out of the normal operating range? How long until possible engine damage might start occuring?
7. Anything else I could have done?

I appreciate any info, and if screwed something up I'm sure I'll hear it. Thanks.
Edit:
- the engine oil had just been changed; i was the first flight after that.
- after i decided to turn back home, during the descent from 4,700 at 1,500 RMP, both oil temp and oil pressure indicators had returned to well within the green normal operating range
- others have flown the plane since and I have not heard (nor asked) about any issues being reported.

Pres low with temp high, I sure as hell would land ASAP. Keep in mind flying isnt "paint by numbers" you need to know your aircraft and (in this case) have some common sense.

 

[iWantWings]

DenverPilot,

Lots of thanks for having taken your own time to answer my questions (and tell me hit the POH).

I have read the POH and do not recall reading anything related to outside air temp limitations - i guess it was not the best way to introduce the scneario and the other genuine questions. But I was not reffering to the POH only; part of my first question I mnetioned I wanted to know if there is any other printed info (i was thinking maybe other documents or placards) that would supplement the POH with the OAT limitation? No I take it there is not, so now i know.

The things that I have tried I was certainly not sure of. I was not sure if I should waste my time trying, or if should give them more time to take effect in helping cool the engine? But I chose not to get any farther from the airport, so all this happened rather "quickly".

No one has told me in details what I should or should not do to manage an instance where oil temp and pressure are indicated to be out of range. I was, however, told that "If the oil temperature is high and oil pressure is low, it is likely that there is not sufficient oil". In the case I described above, that was not the case.


What made this a bit more nebulous for me was that in prior flights with more than one CFI, the oil temp and oil pressure were at the exact limit of the normal operating range (on much cooler days though). I pointed the "at limit" out to the CFI and the calm response was that it was "normal" and that's they way the airplane ran. The differences in this solo flight were the 100+ OAT and that this time the guages crossed the boundary from their normal operating range limit into the red zone (for temp) or black zone (for pressure) without any hesitation, during my climb.

You've been very helpful, gave me some good tips that might save my a$$

In hindsight, this was an experience beyond the staged, simulated stuff. But to make it a "learning" experience I'm asking the questions I'm not sure of.

 

[denverpilot]

Nate, I have to give you major points for a well-crafted and beautifully laid-out response. But I think you've been trolled.

Just like I was when I answered this jagoff...

Maybe, maybe not. I figure there's probably someone reading along who may learn something from the questions anyway, and I'm bored tonight and enjoying the distraction/diversion of PoA. Or it's good for the archives and search engines. If I'm not answering badly that is. It's the Internet. Opinions are free and worth what the OP paid for them, after all.

I'm people-watching at the (almost) all-night Starbucks.

Too many ghosts at the empty house tonight with Karen away and the doggie gone. Kinda sucks being a severe night-owl on a night like tonight.

Probably about time to hang it up and head home to bed anyway.

It's been a week of fitful rest if any, so I'll "pay" for staying out late tomorrow. But I cancelled my engagements this weekend to stand watch for the dog anyway, so sleeping in tomorrow is "approved".

I'll probably then check the honey-do and project lists and pick off something tedious. If nothing else there's some weeds to pull and maybe I'll hear news about the stupid car. Ha.

And maybe I'll set up the new printer if I can lift it onto the desk alone. It arrived in its enormous box in the middle of all this crap and is sitting in the main floor hallway, awaiting the unboxing and stewn packaging all over the floor. Holy crap it's huge.

Then maybe see if dad was serious about wanting the Samsung laser and thinking about a job/home for the HP.

Karen would be happy if I had the scanner up and going and the other printers gone by the time she gets home later in the weekend.

Airplane is somewhere in Oklahoma this weekend, taking co-owner and nephew off to far flung places. And I probably wouldn't venture too far if it were here anyway. Brain may not be emotionally firing on all cylinders yet.

 

[SCCutler]

Well now.

I challenge the notion that there is anything "normal" about an engine which cannot maintain temperature and pressure in the normal ranges, even in the heat. Problem is, high temp and low pressure could be associated with failed bearings.

In this same heat, I have rock-solid oil pressure on my 2,000 hour-plus IO520, and oil temp never gets close to red zone. I do climb at a higher airspeed to protect my cylinders but, of course, they are MY cylinders.

JOOC, what oil are they running?

 

[Henning]

You did exactly correct, although I would have put the nose down and reduced power sooner. Once Oil temps get excessive on a hot day, it's very difficult to get them to come down again without serious and extended reductions in power. I also suspect the plane has an issue with the vernitherm (the thermostatic valve in the oil cooler) but that's nothing you can deal with. On a hot day I reduce power and climb at the highest speed/minimum rate I can get away with.

 

[Geico266]

You might want to consider using the "stair step" approach to climb. Climb until oil temps reach high yellow then lower the nose and reduce power to allow the engine to cool. Then climb some more, repeat.

Operating the engine oil temp in the red is not a good thing. Avoid it.

 

[poadeleted20]

I think Nate pretty well hit it -- high oil temp plus low oil pressure is a combination which should be dealt with ASAP lest your airplane become a bad glider. The low oil pressure pretty well confirms that the oil temp really is up there, and if you keep running it that way, you're just asking for loss of power. Get the power back to reduce heat and the nose down to increase cooling flow, and start looking for a good place to land.

As for that mechanic telling you nothing was wrong with the plane, that sends shivers up my spine. If operated within the normal speed and power limits, the engine should not overheat like that. If it does, there is probably something wrong, perhaps with the baffling, or maybe the oil cooler, or the vernitherm, or a lot of other things including magneto timing. If it happens again, I'd give it back to mainenance and tell them I'm not flying it again until they get it fixed, because something is definitely wrong.

 

[DouglasBader]

If your outside air temperature was hot, then your air cooling wouldn't be particularly effective. You need to minimize your ground time running the engine, especially the sunup.

You need to get in the air and get airflow over the engine, and you need to climb at higher speeds.

If you took off and climbed at the speed you've probably been taught to use by your instructor, then you were probably climbing too slowly.

If you were climbing at Vy, that was too slow. Climb at 100, and see how that does.

Once your oil temperature gets up there, it's going to be hard to get back down. If oil pressure begins to suffer, then it's time to cut the flight short.

If your oil temperature is over limits, you're going to begin to experience thermal breakdown of the oil, as well as damage to the engine. Get back on the ground. Oil is the lifeblood of our engine; it's critical. If you see a problem with pressures or temperatures, get back on the ground.

 

[jnmeade]

If you see a problem with pressures or temperatures, get back on the ground.

To each his own. Low pressure, I'd get it on the ground. High temperature, I'd watch it like a hawk to see if the reading was confirmed by other indicators or responded to varying the environment. I would have it checked when I landed but would not necessarily divert a flight if an oil temp reading was high and everything else said it was a liar. Sensors break like other things and a high temperature reading that is not substantiated is a cause for interest but not necessarily action.

But, again, to each his own.

 

[Henning]

To each his own. Low pressure, I'd get it on the ground. High temperature, I'd watch it like a hawk to see if the reading was confirmed by other indicators or responded to varying the environment. I would have it checked when I landed but would not necessarily divert a flight if an oil temp reading was high and everything else said it was a liar. Sensors break like other things and a high temperature reading that is not substantiated is a cause for interest but not necessarily action.

But, again, to each his own.

True, but when you have corresponding indications from both, it's not likely 2 sensors failed.

 

[bobmrg]

DenverPilot,

Lots of thanks for having taken your own time to answer my questions (and tell me hit the POH).

I have read the POH and do not recall reading anything related to outside air temp limitations - i guess it was not the best way to introduce the scneario and the other genuine questions. But I was not reffering to the POH only; part of my first question I mnetioned I wanted to know if there is any other printed info (i was thinking maybe other documents or placards) that would supplement the POH with the OAT limitation? No I take it there is not, so now i know.

The things that I have tried I was certainly not sure of. I was not sure if I should waste my time trying, or if should give them more time to take effect in helping cool the engine? But I chose not to get any farther from the airport, so all this happened rather "quickly".

No one has told me in details what I should or should not do to manage an instance where oil temp and pressure are indicated to be out of range. I was, however, told that "If the oil temperature is high and oil pressure is low, it is likely that there is not sufficient oil". In the case I described above, that was not the case.


What made this a bit more nebulous for me was that in prior flights with more than one CFI, the oil temp and oil pressure were at the exact limit of the normal operating range (on much cooler days though). I pointed the "at limit" out to the CFI and the calm response was that it was "normal" and that's they way the airplane ran. The differences in this solo flight were the 100+ OAT and that this time the guages crossed the boundary from their normal operating range limit into the red zone (for temp) or black zone (for pressure) without any hesitation, during my climb.

You've been very helpful, gave me some good tips that might save my a$$

In hindsight, this was an experience beyond the staged, simulated stuff. But to make it a "learning" experience I'm asking the questions I'm not sure of.

Google "Key Reprints from the Lycoming Flyer;" find it, download it (or bookmark it...it's a big file), and read it.

Bob Gardner

 

[iWantWings]

Well now.

I challenge the notion that there is anything "normal" about an engine which cannot maintain temperature and pressure in the normal ranges, even in the heat. Problem is, high temp and low pressure could be associated with failed bearings.

In this same heat, I have rock-solid oil pressure on my 2,000 hour-plus IO520, and oil temp never gets close to red zone. I do climb at a higher airspeed to protect my cylinders but, of course, they are MY cylinders.

JOOC, what oil are they running?

For that particular airplane I think that the oil being used is W100 Plus.
Not including the instance I wrote above, this airplane's oil temp indicator I noticed was alwasy in the green but very near the upper limit, close to red.

Problem for me is, there is really no "transition" between green and red regions of the oil temp. It's sort of binary: in the green, or a few milimeters to the right the needle is fully in red. I'm a bit puzzled. A few mms to the left it is normal operating region, then suddenly it's on the red a few mms to the right - and all bets are off?

So now im looking for the rate at which the oil temp climbs and oil pressure drops.

 

[iWantWings]

You did exactly correct, although I would have put the nose down and reduced power sooner. Once Oil temps get excessive on a hot day, it's very difficult to get them to come down again without serious and extended reductions in power. I also suspect the plane has an issue with the vernitherm (the thermostatic valve in the oil cooler) but that's nothing you can deal with. .

Even after I decided to return back at the aiport and had begun a descent at 1500 RMP, it took some time for the oil temp indicator to get out of the red zone. But eventually it did and continued into the green, normal op. zone.

On a hot day I reduce power and climb at the highest speed/minimum rate I can get away with.

I should have been more conservative in that regard, and also start it as soon as i reached TPA. Instead, I continued climbing at about 80-85 KIAS. By the time I leveled off and reduced to 2,300 RMP, it was probably too late and too little to make a difference quickly.

 

[iWantWings]

You might want to consider using the "stair step" approach to climb. Climb until oil temps reach high yellow then lower the nose and reduce power to allow the engine to cool. Then climb some more, repeat.

Operating the engine oil temp in the red is not a good thing. Avoid it.

The stair step approach is a good advice which I did not consider. At the end of my "first step" at 4,700 feet I leveled off and shortly thereafter I decided i was going to start a descent towards home.

(By the way, as i wrote in another post, there is no "yellow" transition between normal range green and red zone for this oil temp indicator. The Oil presure indicator, however, has a larger black area between the green and the left-most red zone, so there's some transition there).

 

[iWantWings]

I think Nate pretty well hit it -- high oil temp plus low oil pressure is a combination which should be dealt with ASAP lest your airplane become a bad glider. The low oil pressure pretty well confirms that the oil temp really is up there, and if you keep running it that way, you're just asking for loss of power. Get the power back to reduce heat and the nose down to increase cooling flow, and start looking for a good place to land.

As for that mechanic telling you nothing was wrong with the plane, that sends shivers up my spine. If operated within the normal speed and power limits, the engine should not overheat like that. If it does, there is probably something wrong, perhaps with the baffling, or maybe the oil cooler, or the vernitherm, or a lot of other things including magneto timing. If it happens again, I'd give it back to mainenance and tell them I'm not flying it again until they get it fixed, because something is definitely wrong.

Good advice. I guess i was wrong in hoping that I could get both oil temp and pressure back in the normal op zone, once they were out of it. But eventually I turned back.

I'm a bit dissapointed though, both my decisions and the plane. I've got some more questions to ask though

 

[iWantWings]

If your outside air temperature was hot, then your air cooling wouldn't be particularly effective. You need to minimize your ground time running the engine, especially the sunup.

You need to get in the air and get airflow over the engine, and you need to climb at higher speeds.

If you took off and climbed at the speed you've probably been taught to use by your instructor, then you were probably climbing too slowly.

If you were climbing at Vy, that was too slow. Climb at 100, and see how that does.

Once your oil temperature gets up there, it's going to be hard to get back down. If oil pressure begins to suffer, then it's time to cut the flight short.

If your oil temperature is over limits, you're going to begin to experience thermal breakdown of the oil, as well as damage to the engine. Get back on the ground. Oil is the lifeblood of our engine; it's critical. If you see a problem with pressures or temperatures, get back on the ground.

I wanted to respond to a good remark you've made (highlighted above).
I think I started it all wrong by not expediting the run-up while temps were on the ground over 100*F.

I took my time more than usual since i had to get all my frequencies for the cross country right, check and double check certain items. Although i made an effort to point the nose into the 13knot wind, I did not expedite the run up as i should have.

Something else I did not bother to write: Because I knew the oil change had just been made and I was going to be the first to fly it, I wanted to do 1 or 2 landings in the patern and see how it all worked before I started the x/c. With that said, both landings in the pattern were full stop, which meant I had to taxi at relatively slow speed, downwind. So now I think that that must not have helped either?

 

[iWantWings]

To each his own. Low pressure, I'd get it on the ground. High temperature, I'd watch it like a hawk to see if the reading was confirmed by other indicators or responded to varying the environment. I would have it checked when I landed but would not necessarily divert a flight if an oil temp reading was high and everything else said it was a liar. Sensors break like other things and a high temperature reading that is not substantiated is a cause for interest but not necessarily action.

But, again, to each his own.

I'm trying to figure out what "low pressure" really is on the oil pressure indicator for this aircraft.
Green Zone: all good.
Black Zone, to the left of Green: what is this? it's outside of normal operating zone, evidently, but is it an indicator that there will be an imminent engine failure? Or is it more like "don't let it linger in this area - do someting", but not necessarily land off airport?
Red zone: I guess i think point the engine will no longer run.

Anyways, i've got some reading to do

 

[iWantWings]

Google "Key Reprints from the Lycoming Flyer;" find it, download it (or bookmark it...it's a big file), and read it.

Bob Gardner

Thank you Bob. I've just looked at the table of contents for the PDF you mentioned. Wow, wish I had known about this before.

Thank You.

 

[X3 Skier]

Personally, having had the engine fail on me (Broken Exhaust Valve) anytime something out of the ordinary happens in the power plant arena, I am spring loaded to land. Not immediately but any sign of abnormal ops means heading for home or a field with a FBO that can check things out.

I am impressed with your desire to learn all you can and keeping a good eye on the thrashing around things under the cowling is a really good idea. :wink2:

Cheers

 

[Skip Miller]

Keep in mind that although these engines are air cooled, the bottom end of the engine is cooled by oil flow. The heat of course ultimately goes into the air courtesy of the oil cooler. The key is that low oil pressure can mean inadequate oil flow through the bottom end. Which can lead to very hot oil very quickly.

Regarding the black area on your pressure gauge: Mid to high time engine, time since last oil change getting long, hot engine (just landed), you may well see pressure in the black area at idle power after landing. I would call this normal for an engine as described, but it certainly is not desirable.

-Skip

 

[Dan Thomas]

Old airplanes often have oil coolers that are varnished up internally, sometimes sludged up, and they can't keep the oil cool on warm days. The 172 has its cooler oriented horizontally, with the inlet and outlet halfway between top and bottom, so that outgoing oil doesn't carry the bits of solids out with it and it settles in the cooler after shutdown and hardens there. Stupid design.

That airplane might also have a broken ground wire between the crankcase near the oil temp sensor and the back of the oil temp gauge. It's a small wire intended to eliminate the alternator's tendency to send a few electrons up the oil temp wire via the sensor itself, usually due to a poor engine/airframe ground. The extra electron flow drives the oil temp indication way beyond the truth.

In any case, the mechanic was avoiding responsibility by saying that there was nothing wrong.

Dan

 

[somorris]

If the airplane you are flying is getting that hot, there is something wrong. We had an issue like that, it was looked at by mechanics, and one of them checked the timing. It was off. After it was corrected, the engine (while still on the high side of green) is not running overly hot. I fly out of Memphis area, and it gets hot here too. It is not good for the engine to run that hot.

 

[DouglasBader]

The question has been asked several times now if there's some magic or evil that takes place the moment that the indicator crosses from green to red, or when the oil pressure or temperature bumps the red limit line.

Yes, there is.

It's an aircraft limitation, and it's part of the certification of the aircraft. When the indication has exceeded a limit (high temperature, or high or low pressure), then it's not airworthy, and is not within the prescribed, certified limitations of that type design.

It's not uncommon to find that the actual temperature is not what's indicated. It's common to test a thermocouple or probe, for example, and find that it's not truthful in what's indicated. Perhaps you're a lot hotter than you think.

Thermal breakdown of oil leads to loss of lubricity, changes in viscosity that aren't necessarily linear, and engine damage. It results in less cooling of the engine on critical parts such as crank journals and bearing surfaces. Oil is very much the lifeblood of your engine.

If the oil temperature is high but other indications (pressure, for example) look okay, it's still not okay to ignore the problem and continue flying. It's time to get on the ground.

It's not uncommon to have a problem with oil bypassing a cooler: a vernitherm or thermostat gets stuck open, a bypass valve gets stuck, often just a small piece of debris, and the system isn't work as it should. Oil pressure can work the same way. Regardless, one should visit the issue on the ground, not in flight.

 

[denverpilot]

In any case, the mechanic was avoiding responsibility by saying that there was nothing wrong.

I still say it screams that he has a monetary interest in no downtime, and he probably signed off on it as being airworthy with previous reports of the heat problem if the instructor said, "it's always done that".

 

[iWantWings]

Thanks!

Since I discontinued my x/c flight, I did not get to speak at length with CFI - That I will do soon, prior to the 2nd try (this would have been the "long" versin of the x/c).

But I've gotten good advice, info and refereces (things that could help me stay out of trouble).


So I undersntand

• If the engine guages are out of normal operating range (especially both oil temp and oil pressure), land at the nearest airport and do not consider making the planned flight.
• There are some things that can be done to help slow down the rate of increase in oil temp and rate of decrease in oil pressure. But these are no guarantee to work and should really only be used while flying the plane to the neareset airport (and not used to make it through the planned flight).
• I've got to learn better how an (Lycoming) engine works. Thank you for the link to the online Lycoming PDF.

My CFI, I am very happy with. If there's anything I dont know, it's becasue I didn't ask. So I'll make sure I ask the things in this thread.

Regarding the maintenance of the school's airplanes: I always had the impression that maintenance (of the school's aircraft) was a priority. The mechanic was very helpful - he did not hesitate to take me along for a brief flight so he could see for himself what I was talking about. I will just have to ask more detailed and directed questions. I know now (at least based on the repllies) that OAT alone does not cause an airworhty engine to exceed oil temp and oil presure operating range. So I need to know why OAT (as well as the things I did) pushed the indicated temp and pressure out of bounds for this particular 172.

My x/c is recheduled for this week - I feel a better informed so I'll see how it goes.

 

[denverpilot]

One question in case I missed it, is it an up-engined 172? 180HP? Those have cooling issues.

 

[Rigged4Flight]

Google "Key Reprints from the Lycoming Flyer;" find it, download it (or bookmark it...it's a big file), and read it.

Bob Gardner

My google clicker isn't working correctly. All I'm able to find are links to purchase the paper copy. Do you have a link to a downloadable version?

 

[DouglasBader]

I know now (at least based on the repllies) that OAT alone does not cause an airworhty engine to exceed oil temp and oil presure operating range.

Not so. Absolutely a high ambient temperature can lead to overheating your engine and an excessive oil temperature.

It's for this reason that ground run time needs to be minimized, and higher climb speeds are necessary for judicious engine cooling.

 

[MoltenLava]

I fly a Cessna 172M off LVK in NorCal regularly where the ambience temperature goes to 90-100 F most of the summer. After the take off and climbing for a few minutes the oil temperature gauge is usually pegged to the right most end of the green arc right at the red bar. The oil pressure should still be in the green arc. Others who fly carburetored C172 in hot region could chime in.

 

[DouglasBader]

How fast are you climbing?

Are you aware of the enrichment feature of your throttle/carburetor? Are you climbing at full power, with mixture rich?

 

[bobmrg]

My google clicker isn't working correctly. All I'm able to find are links to purchase the paper copy. Do you have a link to a downloadable version?

www.[B]lycoming[/B].textron.com/support/tips-advice/​key-reprints/​index.htmlhttp://www.bing.com/search?q=lycomi...m=QBLH&pq=lycoming+flyer&sc=2-14&sp=2&sk=AS1#

 

[iWantWings]

I didn't quite want to resurect the thread, but I do want to say that I completed the 2nd solo cross country in the same C172 type N that I wrote about in this thread.

All 2.5 hours were non-eventful and the instruments for oil temp and oil pressure never exceeded the "green" normal operating range.

The only thing buzzing is my head - have not been aloft for so long with the headset volume near max so that I would not miss a beat from ATC (the hardest thing about flying for me was making sure i don't screw up the communication with ATC).






So what was different this time around?:

1. The temperature was no longer over 100*F; at the start of the flight it was just under 90*F and aloft at 5,500indicated altitude the OAT indicator pionted to 81*F (a bit higher on the return on a different route).
2. I follwed the advice given to me (thanks again for that)
   1. Reduce the run-up time; that is, i did not unnecesarily waste time with the engine running on the ground (i didn't cut corners either). So i was rolling for takoff before the indicated oil temp was past the "1/2 way point".
   2. Once out of the pattern, I climbed at about 400 fmp at 90KIAS. Since the oil temp was not nearing the limit, I didn't have to do the "step-climb". I just kept it under 500 FPM and it worked well.
   3. I really made a effort to be coordinated in the climb and not "drag" my way thourgh the air while climbing. Stepped on that right rudder every time I rememberd .
   4. Edit: and I cruised at a power-setting of 2250-2300 RPM.
   5. Edit: and I intentionally did not lean as much as I normally would have. I didn't do a mag check after landing to see if the spark plugs were affected, but the engine performed very well (but what do I know).

One question in case I missed it, is it an up-engined 172? 180HP? Those have cooling issues.

No, this plane didn't go throught he "pimp my ride" (yet) . It's the 160hp 320 engine. (the school does have a C172 N with a 180HP engine that that thing is soooo smooth - new engine).

My google clicker isn't working correctly. All I'm able to find are links to purchase the paper copy. Do you have a link to a downloadable version?

This is the same link that Bob Gardner posted:
http://www.lycoming.textron.com/support/tips-advice/key-reprints/index.html

Not so. Absolutely a high ambient temperature can lead to overheating your engine and an excessive oil temperature.

It's for this reason that ground run time needs to be minimized, and higher climb speeds are necessary for judicious engine cooling.

Followed your advice and went well. Thank you!

I fly a Cessna 172M off LVK in NorCal regularly where the ambience temperature goes to 90-100 F most of the summer. After the take off and climbing for a few minutes the oil temperature gauge is usually pegged to the right most end of the green arc right at the red bar. The oil pressure should still be in the green arc. Others who fly carburetored C172 in hot region could chime in.

Thank you for sharing that. My goal now is to avoid flight during temps that near 100*F.

 

[DouglasBader]

Glad it went well for you.