Loss of power after takeoff

[ArtVandelay]

53 minutes ago, Shadrach said:

That's a good practice. Perhaps check with your IA on VR settings.

This is what Concorde Battery recommends depending on temp. Do consider the OAT that you spend the most time in. I think that most N/A aircraft operate In OATs between 32 and 59 degrees hence my recommendation.

 

 

These are charging voltages, not voltages when the batteries are nearly charged.

im assuming we have 2 stage voltage regulators, so stage 1 is charging, and stage 2 is after its reach a nearly full charge, it drops the voltage to maintain the full charge and complete the final charging, continually charging at above voltages would cook your batteries.

If you had a 3rd stage there would be a PWM step to get charge to full charge between 1 and 2 stages.

[N601RX]

A modern regulator like Plane Power will proportionally reduce or increase the current to the field to always keep the charging voltage at the set point which is adjustable and should be set to the voltages in the chart above.  They are not multi stage, the battery normally does not deep cycle and is normally operated in the upper end of its charge capacity.

Multi stage chargers are normally used in deep cycle application where a bulk charge is needed as well as a final top off charge.  We design them into the solar powered equipment at work.

 

 

[Shadrach]

1 hour ago, Hyett6420 said:

To my mind the telling line is the line that says "I did mag/ignition check". Then you took off. There is nothing that said you moved the oil around the propeller again.ie exercised the prop.  SO even though you had warm oil in the governor you may not have had sufficient pressure (next time you do a warmup and exercise the prop, look how your oil pressure drops as well then climbs back up again).  I know nothing of the ED series of instruments so I can't comment on the readings but from what you and others have said so far, I don't think it has anything to do with the fuel or you would have had a rough engine, but a combination of flaps and gear down (Js don't climb too well like that anyway) and slightly out prop from fully fine will give you what you saw.  

 

Question:-

when you taxied out for the ill fated climb out did you run the WHOLE checklist again including exercising the prop three times by 599 revs each time?  Ie 2000 down to 1500 then back up again. No more than 500 is ever needed unless it is a DC3 type radial thingy. 

Do expand on how "exercising" the prop affected pressure on take off or how a failure to do so would cause a loss of performance...especially a loss of performance with no change in RPM?  

Also, who or what has given you the idea that multiple pulls are needed? It's a hydraulic pisto operated by the governor. It's either full of oil and moving freely or it isn't. Multiple prop cycles on the ground are fairly useless and because people were taught to do them, not because they actually do anything( other than suck in any loose gravel, that they do pretty well).

 

[carusoam]

Initial training focused on three prop pulls.  Looking at oilP, drop in rpm and The response time for the govenor oil pressure to rise.  They were unusual, deep and deliberate...

Once becoming an owner, two become enough and not so deep.  

Same attention to detail with the mag check gets learned as well.  Enough rpm to show a drop, but not so high to run a million stones through the prop...

I have not yet experienced a rubber prop seal leak yet.  But I have seen pictures around here of them. I have had the internal aluminum disc get dislodged from the crank shaft.  Prop failed to high rpm on run-up and wouldn't come off the stops until the prop got removed and the 50 cent seal got hammered in place.

Best regards,

-a-

[kevinw]

3 hours ago, Hyett6420 said:

To my mind the telling line is the line that says "I did mag/ignition check". Then you took off. There is nothing that said you moved the oil around the propeller again.ie exercised the prop.  SO even though you had warm oil in the governor you may not have had sufficient pressure (next time you do a warmup and exercise the prop, look how your oil pressure drops as well then climbs back up again).  I know nothing of the ED series of instruments so I can't comment on the readings but from what you and others have said so far, I don't think it has anything to do with the fuel or you would have had a rough engine, but a combination of flaps and gear down (Js don't climb too well like that anyway) and slightly out prop from fully fine will give you what you saw.  

 

Question:-

when you taxied out for the ill fated climb out did you run the WHOLE checklist again including exercising the prop three times by 599 revs each time?  Ie 2000 down to 1500 then back up again. No more than 500 is ever needed unless it is a DC3 type radial thingy. 

No I didn't. I figured the oil was hot, it had already been done when I first took off. Because the stop was very brief I just taxied back out and did the normal pre-takeoff check without cycling the prop. I will watch the oil pressure next time. I've never been taught to do that but it makes perfect sense. 

[Shadrach]

32 minutes ago, kevinw said:

No I didn't. I figured the oil was hot, it had already been done when I first took off. Because the stop was very brief I just taxied back out and did the normal pre-takeoff check without cycling the prop. I will watch the oil pressure next time. I've never been taught to do that but it makes perfect sense. 

I would bet $10,000 that this issue had nothing to do with not cycling the prop on your already warm engine. 

[cnoe]

I tend to agree more with the John Deacon theory of prop cycling on runup...

PROP CYCLING (see http://www.avweb.com/news/pelican/Pelicans-Perch-77-Startups-and-Runups-186619-1.html)

Don't wear the poor thing out, especially on the single-engine aircraft. Many do three or more cycles, often to very low RPM. Not necessary, and probably not desirable, it just prolongs the whole event, making the engine hotter, and going to full low RPM may be hard on the prop and engine mounts as the blades flail the air. Repeated cycles are probably a carry-over from the old radials.

The big old radials do often need several cycles to flush all the really cold oil out of the prop system. This can be clearly seen on cold starts after the engine has been at rest for a time. During the first cycle, the RPM will drop much more slowly than usual, and it will probably even drop erratically, from "slugs" of oil sludge going through. I've had to exercise them as much as a dozen times to get a nice smooth drop. It's also required to cycle them to the low RPM stop at least once to make sure the system has been adjusted properly; the minimum governor setting is generally 1,200 RPM. These prop systems are somewhat different from those on most GA aircraft.

GA props on single-engine GA aircraft do not keep a lot of oil in the prop hub when at rest: There's a big, strong spring that pushes the blades "flat," and it takes engine and governor oil pressure to get any oil in there at all. A single cycle is sufficient to check function, and frankly, this check is unlikely to find any problems. I frequently skip it entirely. If the RPM comes up to nominal takeoff RPM (on the takeoff run), and stays there, that's function check enough.

(You know, I think there are probably people out there who want to put the airplane up on jacks before every flight so they can roll the wheels to make sure they rotate before they taxi. We tend to do a lot of "checking" in aviation that is really doing nothing more than wearing things out prematurely.)

On the other hand, light twins usually have the spring pushing the prop into feather, and the dome will be full of oil at rest, so they may benefit from a few cycles on a cold day. But modern oils don't sludge up as much as the old straight 60-weight in the radials and the GA props should be well-oiled with one or two short RPM drops on the check. If I owned a twin, I'd probably do a feather check once a month in the air, for real. Certainly before and after the annual, and let it go at that.

In summary, start the engine gently when cold. Lean past "peak power" right after the start, enrich only as much as needed for the runup. After the runup, either go full rich or lean back again. Perform a short runup as a function check, and get on with the show. Skip the prop check on the singles, once or twice on the twins, and as needed on the big radials. Do the mag check leaned out, watching the engine monitor for an EGT rise, ignoring the large RPM drop.

Next month I hope to address the "Prop driving the engine." This old fable is causing enormous danger in the warbird community, is not as well understood as most pilots think, and is probably near-total nonsense in the "flat" engines.

Be careful, up there!

Sent from my iPad using Tapatalk

[Hank]

In warm weather, a single pull of the prop lever, with 200-300 RPM drop, is usually sufficient.

On cold days, or if I haven't flown in a while (especially if I haven't flown in a while AND it's cold), I can pull the prop lever all the way back and nothing will happen for 2-3 seconds. Then when it starts to come down, I push the lever forward again. The second cycle is faster, and the third is normal speed.

So I guess the real answer to how often to cycle the prop, or if it's even needed, is "it depends."

[jlunseth]

It wasn't the prop.  Go back and look at the data on the first page.  The RPM's were a little over 2650 and stable.  

Edited March 12, 2016 by jlunseth

[carqwik]

Were there any clouds above with lots of vertical development? 

[DonMuncy]

As others have and are suggesting, I wonder if you experienced wind shear. Once on the way to California, I was rocking along at 150 KIAS, when suddenly I felt I was slowing. I looked down and saw I was doing about 120. I started checking things and pushing knobs. Then the airspeed came back up slowly. If seemed like forever, but I'm thinking perhaps this was about the same amount of time you have described. You also said and you made a 180 turn, your performance came back up. This seems to fit. Can anyone see anything inconsistent with this theory.

[carusoam]

I reviewed the data again this morning...

The following thoughts are from a PP perspective.  Not a CFI or mechanic.

I have a couple of questions.

1) The JPI has collected and recorded speed and altitude data.  Is this data from the GPS?  Where does the FF, MP and RPM data come from?  Is it real calibrated data from a JPI900?  Does the speed and altitude come from an air data system or is that all GPS derived as well?

2) What were the wind conditions at the runway?  (Headwind component, please)

3) How flat is the runway?  Is it uphill at all?

4) did you use up a lot more runway than normal?

5) did you rotate in the same spot you normally do?

6) was the runway at 1200' MSL?

 

What I am seeing is 

1) very consistent EGT and CHTs.  Nothing standing out as changing or odd or detonating.  The FF matches the throttle position,  not really lean or really rich

2) rpm is not full 2700 rpm, a touch low at 2660.(?)  can't check the data and write at the same time.

2.5) the HP calc is saying 73 %hp.  Compare the POH power tabled to this.  MP, rpm, and FF will back up your power calculation.

2.6) At full power, all knobs forward, at 1,200' MSL.  I would be expecting a number a lot closer to 100%.  In NA planes, 65% is normal up to around 7-8000' MSL...

3) if the data is from the GPS, we need the headwind component too get a feeling for what the air speed really was.

4) if the runway is really flat at 1200' MSL, the take-off starts with the first change of altitude.

5) speed of rotation is indicating around 55kts, climb becomes noticeable six seconds later at 60kts

6) climb continues for many seconds at 76 kts where a few hundred feet of climb have been achieved.

Please verify...

1) the headwind that day.

2) the flatness or uphill nature of the runway.

3) The POH power chart for the FF, MP and RPM you were using.  Was it really only 73%? What is 100% hp FF, MP at 2700rpm?

4) The thoughts I presented.  Unfortunately I can't write and look back at the data at the same time.  That's a lot to remember.  I have probably made some errors...

 

Worst case scenario that I see....

1) Runway is flat, not uphill.

2) No headwind.  GPS data will mimic airspeed pretty closely

3) T/O initiates at a pretty low speed 55kts and proceeds through 65kts and then climbs out at 76kts.

4) This would be typical of a short field departure.

5) T/O FF is usually 2X cruise FF.  But the data is not showing a number anywhere near 20gph when typical cruise is around 10gph.  

6) The source of the JPI's data is critical to this analysis. Air data vs GPS data.  POH data vs JPI calculated %hp.

Putting all these hints together,  It appears like the throttle never went full open, when the knob was pushed in.  Doing a normal take-off, but not having normal horse power can be confusing at best.  At worst, it could include trees in the flight path.  The MP looks lower than normal.  The FF looks lower than max.

If the plane was rotated at the same spot on the runway as usual, but not making usual hp,  this could lead to being behind the power curve from the beginning.

70% hp is a lot for cruise.  But it takes excess power to climb.  There is not a lot of excess available at 70%

let's check the data, and compare to these thoughts line by line.

Are you able to graph the FF, CHTs and EGTs during the run-up?  A graph really makes the data easy to interpret.

 

Hoping this helps discover what is going on for this particular flight...

Best regards,

-a-

[carusoam]

Asside from that...

when you sense something not right, keep climbing.  Altitude is energy in the bank.

If not climbing, leave the throttle in. Speed is energy in the bank.

the data indicates that you reduced throttle when you reached TPA.

If the throttle was broken, it could be made worse by adjusting it.

It may be better to leave the throttle where it's at until lined up on final approach.

See what I mean?

If My writing seems harsh... I think you did a good job.  Trying to pull the logic together with all the data is more challenge than I have skills...

PP Thoughts, not a CFI.

Best regards,

-a-

[Shadrach]

14 minutes ago, jlunseth said:

It wasn't the prop.  Go back and look at the data on the first page.  The RPM's were a little over 2650 and stable.  

Agreed. It's a point that has been made several times. There is no change in MAP or RPM. Any change in prop pitch would show up in RPM and also in MAP.  Looking at the data, this appears to have been a some other event external to engine/prop performance.

[carusoam]

Ross,

do you have IO360 Full throttle MP and FF at 1,000' and 2700rpm handy?

Best regards,

-a-

[Shadrach]

1 hour ago, carusoam said:

Ross,

do you have IO360 Full throttle MP and FF at 1,000' and 2700rpm handy?

Best regards,

-a-

Sea level and 2000' for the 20J. 

I don't trust Mooney's numbers though. Why does the engine burn 15.8gph to make 85% at 26.2" @ sea level and 13.8gph to make 85% at 26" @ 2000'. If the mixture and RPM remain constant and mass airflow remain constant, why does FF drop by 2gph in mere 2000'?

[ArtVandelay]

3 hours ago, Shadrach said:

Why does the engine burn 15.8gph to make 85% at 26.2" @ sea level and 13.8gph to make 85% at 26" @ 2000'. If the mixture and RPM remain constant and mass airflow remain constant, why does FF drop by 2gph in mere 2000'?

It's because you have excess fuel, it provides cooling but doesn't burn, when you lean you reduce the fuel flow, till the point of perfect proportion, peak EGT, and a little more gives you LOP, gives you a little extra air, but insures maximum fuel efficiency because all the fuel is burned.

The engine doesn't burn the 15.8gph, probably more like 12, the rest is going out the tail pipe.

 

[jetdriven]

14 hours ago, cnoe said:

I tend to agree more with the John Deacon theory of prop cycling on runup...

PROP CYCLING (see http://www.avweb.com/news/pelican/Pelicans-Perch-77-Startups-and-Runups-186619-1.html)

Don't wear the poor thing out, especially on the single-engine aircraft. Many do three or more cycles, often to very low RPM. Not necessary, and probably not desirable, it just prolongs the whole event, making the engine hotter, and going to full low RPM may be hard on the prop and engine mounts as the blades flail the air. Repeated cycles are probably a carry-over from the old radials.

The big old radials do often need several cycles to flush all the really cold oil out of the prop system. This can be clearly seen on cold starts after the engine has been at rest for a time. During the first cycle, the RPM will drop much more slowly than usual, and it will probably even drop erratically, from "slugs" of oil sludge going through. I've had to exercise them as much as a dozen times to get a nice smooth drop. It's also required to cycle them to the low RPM stop at least once to make sure the system has been adjusted properly; the minimum governor setting is generally 1,200 RPM. These prop systems are somewhat different from those on most GA aircraft.

GA props on single-engine GA aircraft do not keep a lot of oil in the prop hub when at rest: There's a big, strong spring that pushes the blades "flat," and it takes engine and governor oil pressure to get any oil in there at all. A single cycle is sufficient to check function, and frankly, this check is unlikely to find any problems. I frequently skip it entirely. If the RPM comes up to nominal takeoff RPM (on the takeoff run), and stays there, that's function check enough.

(You know, I think there are probably people out there who want to put the airplane up on jacks before every flight so they can roll the wheels to make sure they rotate before they taxi. We tend to do a lot of "checking" in aviation that is really doing nothing more than wearing things out prematurely.)

On the other hand, light twins usually have the spring pushing the prop into feather, and the dome will be full of oil at rest, so they may benefit from a few cycles on a cold day. But modern oils don't sludge up as much as the old straight 60-weight in the radials and the GA props should be well-oiled with one or two short RPM drops on the check. If I owned a twin, I'd probably do a feather check once a month in the air, for real. Certainly before and after the annual, and let it go at that.

In summary, start the engine gently when cold. Lean past "peak power" right after the start, enrich only as much as needed for the runup. After the runup, either go full rich or lean back again. Perform a short runup as a function check, and get on with the show. Skip the prop check on the singles, once or twice on the twins, and as needed on the big radials. Do the mag check leaned out, watching the engine monitor for an EGT rise, ignoring the large RPM drop.

Next month I hope to address the "Prop driving the engine." This old fable is causing enormous danger in the warbird community, is not as well understood as most pilots think, and is probably near-total nonsense in the "flat" engines.

Be careful, up there!

Sent from my iPad using Tapatalk

Don't forget the IO-360-A3B6 variants have a counterweight crankshaft which doesn't like sudden 300-400-500 rpm changes.  It can detune the counterweights. 

[Shadrach]

4 hours ago, teejayevans said:

It's because you have excess fuel, it provides cooling but doesn't burn, when you lean you reduce the fuel flow, till the point of perfect proportion, peak EGT, and a little more gives you LOP, gives you a little extra air, but insures maximum fuel efficiency because all the fuel is burned.

The engine doesn't burn the 15.8gph, probably more like 12, the rest is going out the tail pipe.

 

 TJ, I have a fairly robust understanding of combustion science.  ROP and LOP something I've studied extensively.    However, what we are discussing is full rich operation at low altitude.   All other things being equal, I don't believe the engine should require any more extra fuel at sea level and 26 inches of manifold pressure then it would require at 2000 feet and 26 inches of manifold pressure. 

 Also, as an aside. The extra fuel doesn't really cool anything other than the EGT's. What the extra fuel actually does is slow the combustion event, lowering peak ICPs, lower CHTs and increased detonation margins. 

[carusoam]

Ross, Thanks for supplying the power tables.

Mooney may have used some fuzzy numbers for FF back in the day when FF was more of a test stand instrument.

From the table at Sea Level and the one at 2,000' we can interpolate numbers for MP at 1,000'...

FT at SL... MP = 30.2”

FT at 2k'... MP = 28.1"

Roughly Interpolating MP at 1,000', MP should be 29"

Actual recorded MP is only 26.9".  note: I did not include the OAT in my calculations...(important for density altitude performance determination)

Overall, actual MP Seems a little low to me.  

To see how important this 2” difference in MP is...

Use the Rule of thumb for power settings (remember this one?) for climb and descent.  1" of MP for each 100 fpm climb or descent.  If you are traveling along level at pattern altitude you can start a 500fpm descent by pulling out 5" of manifold pressure.  (Fuzzy memory, but somebody can fill in some better detail)

If I was expecting a 500 fpm climb and was missing 2" of MP, a 300 fpm climb is going to be more likely.

pulling back on the yoke to increase the rate of climb has resulted in a pretty slow air speed.  This starts up the discussion of being or getting behind the power curve.

Adding in the missing 50 rpm to the discussion...  100% hp is achieved by using 2700 rpm, only 94% is available at 2600. Interpolating for 2650rpm, another 3% hp has gone missing...

This is PP thoughts and ideas.  I am not a CFI or mechanic.

Consult somebody with this knowledge....

Best regards,

-a-

[kevinw]

10 hours ago, carusoam said:

I have a couple of questions.

1) The JPI has collected and recorded speed and altitude data.  Is this data from the GPS?  Where does the FF, MP and RPM data come from?  Is it real calibrated data from a JPI900?  Does the speed and altitude come from an air data system or is that all GPS derived as well?

2) What were the wind conditions at the runway?  (Headwind component, please)

3) How flat is the runway?  Is it uphill at all?

4) did you use up a lot more runway than normal?

5) did you rotate in the same spot you normally do?

6) was the runway at 1200' MSL?

1. Yes, I believe this comes from the GPS

2. I used rwy 31. Winds were about 270-280 at 12-14 knots. What's interesting is I took off an hour earlier from rwy 21 and winds were 240 at 14. Over the course of an hour they moved to 280.

3. runway is relatively flat

4. Perhaps a little more. It almost felt like I took off with no flaps but they were in takeoff position.

5. Yes

6. Yes, the runway is at 1202' MSL.

One other thing, The EDM830 is new and I'm not exactly sure how it calculates %HP or how accurate this is. I suppose from RPM and MP. The throttle was 100% fully in. I looked at data from previous flights and it is consistent. The sky was clear so there was no vertical developing clouds. It was windy and as I mentioned in #2 the direction was changing fairly quickly. 

...and Anthony I don't take your writing harsh at all. I appreciate all the comments and input. I'm learning a lot from this post.

[Cyril Gibb]

18 hours ago, cnoe said:

I tend to agree more with the John Deacon theory of prop cycling on runup...

Me too.... or even moreso.

I don't get an RPM drop on the runup unless it's greater than 1850.  I recently got a stone ding deep enough to almost need a new blade on my ramp.  What's worse, the prop has just been overhauled.  No more runups at that rpm for me again.... ever.  Most everything else can be checked at a lower rpm.  I also do an oil pressure, manifold pressure and airspeed check on the takeoff roll.

The prop fails to the fine pitch stop on the governor which doesn't depend on the prop control, so I think the worst that can happen is terminating the flight and coming back or continuing the flight at 2700 rpm.  That assumes the limit is set correctly at the governor as opposed to depending on prop cable travel limit.

[Shadrach]

12 minutes ago, Cyril Gibb said:

Me too.... or even moreso.

I don't get an RPM drop on the runup unless it's greater than 1850.  I recently got a stone ding deep enough to almost need a new blade on my ramp.  What's worse, the prop has just been overhauled.  No more runups at that rpm for me again.... ever.  Most everything else can be checked at a lower rpm.  I also do an oil pressure, manifold pressure and airspeed check on the takeoff roll.

The prop fails to the fine pitch stop on the governor which doesn't depend on the prop control, so I think the worst that can happen is terminating the flight and coming back or continuing the flight at 2700 rpm.  That assumes the limit is set correctly at the governor as opposed to depending on prop cable travel limit.

Cyril, if you lean the engine until just before roughness at taxi/idle RPM (1000rpm) you will see a drop and likely a noticeable one. I pull the prop out while taxiing and push it in at the first sign of RPM loss. I complete all of these continuity checks on my way out. I have not done a check list style run up in many years.

[Cyril Gibb]

5 minutes ago, Shadrach said:

Cyril, if you lean the engine until just before roughness at taxi/idle RPM (1000rpm) you will see a drop and likely a noticeable one. I pull the prop out while taxiing and push it in at the first sign of RPM loss. I complete all of these continuity checks on my way out. I have not done a check list style run up in many years.

I'll try that next time out... thanks

[ArtVandelay]

3 hours ago, Shadrach said:

 TJ, I have a fairly robust understanding of combustion science.  ROP and LOP something I've studied extensively.    However, what we are discussing is full rich operation at low altitude.   All other things being equal, I don't believe the engine should require any more extra fuel at sea level and 26 inches of manifold pressure then it would require at 2000 feet and 26 inches of manifold pressure. 

 Also, as an aside. The extra fuel doesn't really cool anything other than the EGT's. What the extra fuel actually does is slow the combustion event, lowering peak ICPs, lower CHTs and increased detonation margins. 

I think I see what your saying, just for 85% the sea level FF is higher for same MP, it's interesting the app I use for power settings keeps the FF the same for both altitudes, agreeing with the 2000' numbers, as expected.