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POOR PERFORMANCE SEEKING ADVICE

ALMARTON

Well Known Member
SEEKING ADVICE FROM RV COMMUNITY

I've got a RV7A in Brazil IO360 with Hartzell CS propeller only 140 hours from new Very well built but needing some adjusts I guess.

Guess that because currently it is doing only 151kts TAS (2400rpm) at 65% power at @ 8000 ft OR... 155 kts at 75% (2500 rpm -same altitude conditions). And it does that consuming a lot of gas... about 12 gals at 65% or 13,5 gals at 75% power! :( - best power ROP adjust -

I suspect the Fuel Injection System (AVSTAR) has to be regulated and the noozles clean because it is too rich and there is a difference in CHT and EGT to one cylinder, it also gets very rough on LEAN.

Another guess is that the Hartzell propeller may not be well set (angles of the blades not correct set in installation).

It does reach the 2700 rpm in take off run, and the correct MAP pressure (to be known - 1 psi maninfold less than static manifold of the day - QFE - )

I did purchase de aircraft ready , all NEW and tested, so I do not have knowledge of the assembling issues affecting speed and consumption neither adjusts I have to make to increase cruise speed and decrease fuel consumption.

Would you have any suggestions? Compression on all cylinders are OK (78/80 psi). I really suspect it is Fuel Injection adjusts (it may operate too rich choked as it is ) and something with the CS propeller.

Any help suggestions very welcome!
 
need more info

Which io360; parallel valve or angle valve? (20 HP difference for stock lycs of either configuration)

Fuel flow does sound high for cruise power, and if you have major egt spreads, that obviously needs to be addressed. Don't forget to check ignition timing; if it's set late it will raise egt's and reduce power. To check power output, measure max climb rate near sea level at full throttle and 2700 rpm. Compare to Van's climb numbers for your engine/airframe. If you're close to Van's climb number, you're likely making full power.

Having said that, realize that 75% power at ~8000 feet altitude is: properly leaned, with the throttle wide open and the c/s prop adjusted for 2700 rpm; not 2500. Find a copy of a Lyc owner's manual & study the power charts.

Properly leaned, assuming a 'stock' engine, a 180 HP engine should burn ~10.125 gph at 75% power, and a 200 HP engine should burn ~11.25 gph. Both numbers assume BSFC of .45 lbs per HP per hour. A bit better numbers if you have properly tuned and functioning electronic ignition, but not a really big difference.

Make sure you have all fairings in place and aligned properly.
 
Which io360; parallel valve or angle valve? (20 HP difference for stock lycs of either configuration)

Parallel valve IO 360 180hp

Don't forget to check ignition timing; if it's set late it will raise egt's and reduce power.

How to check ignition timing? Mag drop is ok though... 80 rpm drop on each mag...

To check power output, measure max climb rate near sea level at full throttle and 2700 rpm. Compare to Van's climb numbers for your engine/airframe. If you're close to Van's climb number, you're likely making full power.

Ok, I will check max climb sea level... will take a while though (cause I live in the mountains, gonna have to take time to travel )



Having said that, realize that 75% power at ~8000 feet altitude is: properly leaned, with the throttle wide open and the c/s prop adjusted for 2700 rpm; not 2500. Find a copy of a Lyc owner's manual & study the power charts.

Yeah you are right , I got 75% power at 7500 ft 72? F with 21,6 MAP doing 13,6 gals... but speed is only 155 TAS :(

BUT I GOT SOME NEWS....

The aircraft is on the maintenance shop as now, they found out the fuel pump was damaged... rubber diaphragm was torn, there was gasoline in the oil sump , etc...

Very bad... although I did not notice anomaly on the operation temperatures or pressures... the oil was diluted by gasoline , and there was some internal and possibly (in flight) leakage of gasoline. That explains why my fuel flow when set to cruise (all settings done) were strangely fluctuating a lot ... it looks there were no permanent damages... and after replacing the fuel pump, cleaning the fuel system, filters , nozzles and regulating the fuel injector and divider I will have a totally different plane...can't wait to see.

At least will solve the fuel consumption will problems I hope, but I am wondering if I will get some extra HP's from this adjusts...

Many thanks for any previous and future inputs!
 
Are you running standard 100LL fuel or some type of pump gas or ethanol blend?
 
Are you running standard 100LL fuel or some type of pump gas or ethanol blend?

An important question that needs to be answered.

I know that in large portions of Brazil their auto fuel is spec'ed at 25% ethanol, but in reality it is more like 30-32%. This would have a major impact on HP and performance (and fuel economy).
 
Are you running standard 100LL fuel or some type of pump gas or ethanol blend?

Only AVGAS 100/130 LL ! :( But I do suspect from the dealers somehow adulterating it for profit...

Anyway the thing I cannot understand yet is HOW a failure on the mechanical fuel pump could pour gasoline into the engine oil sump...I thought the lines were very separated... Does anyone can explain me that?
:cool:
 
The mechanical fuel pump is driven by a cam and pushrod inside the engine crankcase. The internal mechanism on the fuel pump separates the fuel side from the crankcase side with a rubber diaphragm, which is what your mechanic found was torn. If that diaphragm tears then the fuel can pass through the diaphragm into the crankcase area and into the oil sump, diluting the oil. It is a common symptom of a torn diaphragm on a fuel pump.
 
The mechanical fuel pump is driven by a cam and pushrod inside the engine crankcase. The internal mechanism on the fuel pump separates the fuel side from the crankcase side with a rubber diaphragm, which is what your mechanic found was torn. If that diaphragm tears then the fuel can pass through the diaphragm into the crankcase area and into the oil sump, diluting the oil. It is a common symptom of a torn diaphragm on a fuel pump.


Nice explanation "Airguy" ! Many thanks almost a lecture!
:eek:

I'm spending a lot here , those fuel pump reach us after tax for $ 830 US$ :eek:

But if I got my fuel burn rate (consumption) right and maybe gain some performance I'll be glad and with peace of mind. And I'm learning at cost but am...
 
Sounds like you've solved the excess fuel issue; now the speed issue:

Parallel valve IO 360 180hp
How to check ignition timing? Mag drop is ok though... 80 rpm drop on each mag...

Yeah you are right , I got 75% power at 7500 ft 72? F with 21,6 MAP doing 13,6 gals... but speed is only 155 TAS :(

Many thanks for any previous and future inputs!

If you haven't set the mag (ignition) timing before, get someone with experience to bring their mag timing 'buzz box' & work with you, or let your mechanic do it. It's not hard, if you know how to do it. If you don't, you could do some real damage.

In your 1st post, you said "Guess that because currently it is doing only 151kts TAS (2400rpm) at 65% power at @ 8000 ft OR... 155 kts at 75% (2500 rpm -same altitude conditions). And it does that consuming a lot of gas... about 12 gals at 65% or 13,5 gals at 75% power! - best power ROP adjust -"

Did you re-fly the test at wide open throttle, leaned for best power (not an EGT number, but actual best power, as observed on the airspeed indicator), and *2700* rpm? Until you do, you're not making 75% power at that altitude (unless you're running a turbo).

Hope that helps,

Charlie
 
Alexandre,
For clarity to the group, please specify how you are determining % power.
Is it from a Lycoming chart or graph showing MP and RPM or from an EFIS display that was programmed by the original builder?
 
...

If you haven't set the mag (ignition) timing before, get someone with experience to bring their mag timing 'buzz box' & work with you, or let your mechanic do it. It's not hard, if you know how to do it. If you don't, you could do some real damage.

Did you re-fly the test at wide open throttle, leaned for best power (not an EGT number, but actual best power, as observed on the airspeed indicator), and *2700* rpm? Until you do, you're not making 75% power at that altitude (unless you're running a turbo).

Hope that helps,

Charlie

I'will ask them to do that (mag timing) and after I will do the open throttle test after also! May take a while cause at the present the fuel injection system is up for recalibrating and cleaning...


Alexandre,
For clarity to the group, please specify how you are determining % power.
Is it from a Lycoming chart or graph showing MP and RPM or from an EFIS display that was programmed by the original builder?

I do read it on my Garmin G3X Touch ...


Well something came up to me now I will ask the mechanic but would like your opinion piece of advice also off course.

Despite the fuel pump leaking into the oil sump I did not notice on pre flight check no alteration at all on oil level , it did not increased (as one would suppose - where all that fuel consumed would be ?)!

I think the presence of oil in the sump due to the fuel pump to justify such great consumption must have been in great quantities what would be noticeable checking oil level in pre check flight but it was not...

So I suspect the real reason for the high consumption was excess fuel being injected on the nozzles or an imperfect burn on the chamber thus great part of the excess not burnt fuel was being expeled throug exhaust valves and just a few getting washed up into the oil sump, not enough to increase noticeably the oil level but enough to dilute oil...

That was progressive and got worse into the last few hours of operation (recent get too bad). That would explain a relatively lower CHT I've been having ...

That is my theory! The mechanic could have thought the pump was the main issue but it does not sound right ... the level of gas consumed was too high to be stored only in the oil sump... for me is excess fuel not all of it burnt...
 
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Only AVGAS 100/130 LL ! :( But I do suspect from the dealers somehow adulterating it for profit...

Anyway the thing I cannot understand yet is HOW a failure on the mechanical fuel pump could pour gasoline into the engine oil sump...I thought the lines were very separated... Does anyone can explain me that?
:cool:

If you suspect the fuel might not be top quality, could that be the cause of the seal failure in the fuel pump?
 
Well something came up to me now I will ask the mechanic but would like your opinion piece of advice also off course.

Despite the fuel pump leaking into the oil sump I did not notice on pre flight check no alteration at all on oil level , it did not increased (as one would suppose - where all that fuel consumed would be ?)!

When you crank up at the start of a flight the fuel starts leaking into the crankcase, and starts to accumulate. As you fly and the oil reaches full temperature the fuel in the oil evaporates as fast as it enters. When you land and shut down, the oil and the engine are still hot and most, if not all, of the fuel that is left in the oil will evaporate as it sits on the ramp and cools down. It's entirely possible you would not notice a change in the oil level - but a laboratory analysis of the oil will show greatly increased levels of lead in the oil from the 100LL contamination.
 
I do read it on my Garmin G3X Touch ...

Until you confirm the readings by checking the power levels predicted by the IO-360-M1B Lycoming performance charts, treat the Garmin data as unreliable. It must be programmed by the user. I suspect that programming is wrong and it is showing power levels above actual.

**** EDIT**** On review of your earlier post about power levels I am positive that you are not at the power level displayed by the Garmin. For one example, it is not possible to go from 65% to 75% with an RPM change of 2400 to 2500. It takes more of a change. Additionally, at 8000 DA you MUST be at 2700 RPM to get 75% power with only 21.6 MP.



You have talked about the fuel pump. If memory serves, there are two flexible diaphagms separated by a gap in the pump. The gap leads to the fuel pump "overflow" or drain. Fuel comes out the drain if the first diaphragm fails. Second diaphagm continues to protect the crankcase. I assume you have seen considerable fuel coming out of the drain????
 
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Is your fuel flow meter calibrated correctly? They can have different readings due to installation differences.

Does the USG used correspond with the amount you have to refill?
 
Summarizing the help and findings so far

Folks, these google photos link show a video and pics of the disassembling of the fuel pump
where they detected the presence of gasoline in the oil by the aspect of the sample during a
routine oil change...

https://goo.gl/photos/bZpgHHfAyQjByk728

Before finding that pump failure we where thinking that thee high consumption was due to a failure of settings
on either the fuel injector system (AVSTAR) or the divider or some difference on the injection nozzles or a combination
of all those.

So the main purpose of the maintenance where to sack the fuel injection, divider and nozzles for re-calibrating,
cleaning and check. The oil change where just to seize the opportunity of this maintenance and doing also oil check...
in the end it seems to have led us to one or the sole real reason of the problem

I consider myself a bit of a layman on matters of engine (if compared with most of you) and so this thread is to me
a great lecture and I am learning a lot.. but I have still some doubts lets adress them:

If you suspect the fuel might not be top quality, could that be the cause of the seal failure in the fuel pump?

Ron, yes. Our main suspect is that adulterated fuel (some malicious merchant has subtituted gasoline with some solvent for profiting).
Having somehow the solvent attacked the rubber in the pump... But reading this:

You have talked about the fuel pump. If memory serves, there are two flexible diaphagms separated by a gap in the pump.
The gap leads to the fuel pump "overflow" or drain. Fuel comes out the drain if the first diaphragm fails.
Second diaphagm continues to protect the crankcase. I assume you have seen considerable fuel coming out of the drain????

After enlighted by Ron I'm at doubt if some solvent could have gone through 2 layers of diafragm rubber and start to suspect
poor material conditions and not some solvent could have done all that in such a few time.
Remember I stated this is a the 143 hours engine (fuel pump and all parts) bought zero hours with the engine straight form Lycoming itself.
[/QUOTE]

From reading Airguy:

When you crank up at the start of a flight the fuel starts leaking into the crankcase, and starts to accumulate.
As you fly and the oil reaches full temperature the fuel in the oil evaporates as fast as it enters. When you land and shut down, the oil
and the engine are still hot and most, if not all, of the fuel that is left in the oil will evaporate as it sits on the ramp and cools down.
It's entirely possible you would not notice a change in the oil level - but a laboratory analysis of the oil will show greatly increased
levels of lead in the oil from the 100LL contamination.

I still don't understand how the oil lines being a closed system (the way I see it) how could it could after gasoline leaked inside oil sump
have evaporated so much fuel (the consumption where above the standard at least a 1 gal/h) during operations in a closed system. Such evaporation
should be so high for no oil level increase be noted on pre flight checks. To me as layman such evaporation on a closed system as I imagine oil
line is to be is unlikely. I would have to notice some oil level increase for the mixture with gasoline.

That's why I still suspect that most of the loss of gasoline causing the high consumption may have to do with a incomplete burn
in the combustion chambers , the major part of the gasoline being expeled in the exhaust and some being whased out into the
oil by the pistons. That is more easy to me to figure out but I may be wrong.

So I think tha regulating the fuel injector system (AVSTAR), divider and cleaning nozzles I may have a better spread. And I also
start to think that what a key advice to enhance mixture burnt and fuel economy maybe on rv7charlie writings...


Sounds like you've solved the excess fuel issue; now the speed issue:
If you haven't set the mag (ignition) timing before, get someone with experience to bring their mag timing 'buzz box' & work with you, or let your mechanic do it.
It's not hard, if you know how to do it. If you don't, you could do some real damage.


I stil have lot to check... but I understand a lot of fuel economy has to be gained from the adjustments and fixes are being and also some
power gain, to put it in cruise conditions not only more economical in fuel matters but also more close on performance numbers from the standard VANs specs.

I will keep you dully posted but any opinions , advices or critics are very welcome and great help solve the issue. And I am spending but learning a lot so
I don't mind the problem :eek: (as long as it will get fixed, I hope ;)).

Many many thanks!
 
I still don't understand how the oil lines being a closed system (the way I see it) how could it could after gasoline leaked inside oil sump
have evaporated so much fuel (the consumption where above the standard at least a 1 gal/h) during operations in a closed system. Such evaporation
should be so high for no oil level increase be noted on pre flight checks. To me as layman such evaporation on a closed system as I imagine oil
line is to be is unlikely. I would have to notice some oil level increase for the mixture with gasoline.

That's why I still suspect that most of the loss of gasoline causing the high consumption may have to do with a incomplete burn
in the combustion chambers , the major part of the gasoline being expeled in the exhaust and some being whased out into the
oil by the pistons. That is more easy to me to figure out but I may be wrong.

The crankcase is not a closed system, it is ventilated to allow combustion gases that leak past the piston rings to escape the crankcase, otherwise it would build up pressure until you pop out the crankshaft main seals at the front of the engine. There is a crankcase ventilation line near the top rear of the engine that should be routed down to the bottom rear of the cowling near the exhaust pipe, that dumps the "blowby" gases out of the airplane. If there is fuel in the oil, as the oil heats up this fuel will evaporate and be dumped out of the crankcase along with the blowby gasses from the cylinders.

The pressurized oil system is closed, yes - from the pump all the way until dribbles back down out of the bearings back down into the bottom of the sump for the pump to pick up again - but the entire crankcase itself and the unpressurized oil in it is ventilated to the atmosphere.
 
The crankcase is not a closed system, it is ventilated to allow combustion gases that leak past the piston rings to escape the crankcase, otherwise it would build up pressure until you pop out the crankshaft main seals at the front of the engine. There is a crankcase ventilation line near the top rear of the engine that should be routed down to the bottom rear of the cowling near the exhaust pipe, that dumps the "blowby" gases out of the airplane. If there is fuel in the oil, as the oil heats up this fuel will evaporate and be dumped out of the crankcase along with the blowby gasses from the cylinders.

The pressurized oil system is closed, yes - from the pump all the way until dribbles back down out of the bearings back down into the bottom of the sump for the pump to pick up again - but the entire crankcase itself and the unpressurized oil in it is ventilated to the atmosphere.


Greg "Airguy" excellent explanation and arguments I did not know that... I' almost agreeing with you.

But reason with me. See If I don't have a point when I still think that if there was such quantities of gas being drop entirely in the sump, the dilution would be such that the lubrication would be so compromised that the temperatures would show an noticeable increase... We are talking of each hour at least 4 litres of gasoline being leaked into sump.

That was not what I saw. There was no temperature increase. On the contrary the EGTs where very cool, CHTs history looking colder on the last few flights never reaching 399F not even on takeoff full power period (as was before). CHT drop in cruise from a log history of 385F average to 373F in cruise settings!

So I still think based on that the fuel loss where in combustion chamber... this pump leakage is something but not the main cause.

By the way ALMOST ALL LOGS to this plane , since 0 hours to few days ago are here in the link I share with you for your appreciation :

http://cirrusreports.com/flights/PRZTI

* Just an observation , it does lack the last 4 hours of flight in the logs, before entering mantenance. Those las 4 hours the CHTs operated considerable colder than the logs you see there in the link, the leg I flew to maintenance I remember it going at 363F on the CHT at 22 MAP and 2450 rpm. Ok it is winter here now... but the temperature of the day here nowadays is not that cold and it is on the human confort zone when comparing to summer days. I think 66F now versus 95F on summer.

What do you thing in the view of that?

Aiguy and others your knowledge of the engine works I realized is far beyond mine but you did not have yet this data to bias your conclusions. Considering those do you still think it may be the fuel pump leakage the main reason for high fuel consumption?
 
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I'm not saying that all your fuel went into the crankcase instead of being burned as a rich mixture. I'm saying that it's entirely possible that a good portion of it went into the crankcase and evaporated out without you noticing it.

Yes, it will dilute the oil, but not necessarily to the point that you'll notice increased oil temperature during operation. In fact, the opposite may be true to some degree - until you reach a point of dilution where increased friction causes increased heating, you'll actually see a lower temperature on the oil due to the cool fuel diluting it and the evaporation of that fuel carrying away heat.
 
you'll actually see a lower temperature on the oil due to the cool fuel diluting it and the evaporation of that fuel carrying away heat.

I think you nailed it, particularly where you state that evaporation causes cooling.
 
Just a note to Alex: In Alaska and other cold places without heated hangars, it is not uncommon for aircraft to have a system where they deliberately add gas to the oil, at shut down. The next (very cold) morning, they can crank the engine because the diluted oil is so thin. As the oil warms up, the avgas evaporates away. Of course I have no idea where your avgas is actually going, but out the oil breather is possible.
 
So an easy way to determine if the diaphragm is leaking would be to install a vented collector on the fuel pump drain tube and go for a ride or ground run it. Nothing in it, it's not leaking. Right?
Maybe I missed it in an earlier post. Have you tested the fuel for ethanol?
 
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Considering those do you still think it may be the fuel pump leakage the main reason for high fuel consumption?

My guess is yes, leakage was the major loss, then loss to the oil. It is a fact your diaphragms were leaking, so with replacement of the pump, it is a good time to recheck the flight fuel burn, and airspeeds. It is always possible for multiple things to be occurring, so a new baseline with the new pump is in order before taking additional action unless there is direct evidence of an issue.

If a lot of fuel was being lost to oil and evaporating, then an oil change would be warranted too.

Please report the performance at 2700, WOT and altitude conditions, with new pump.
 
Isn't the other option that the fuel is going out the drain tube?
Possibly, but that orifice is super tiny. I am not sure you could push that much fuel out of there but perhaps.
The OP stated there was fuel in the case. For fuel to get into the case, both diaphragms would have to be compromised. It is unlikely that the upper diaphragm would fail first, but I guess it is possible. More than likely it was the lower one and it was simply not noticed in preflight for a very long time before the upper burst.

I had a diaphragm failure and it was very obvious during preflight with the tell tale blue stain coming out of the drain, but it was a very small streak of fuel.

Check your fuel pump drain on every preflight folks.
 
INFO UP TO DATE

My guess is yes, leakage was the major loss, then loss to the oil.
It is a fact your diaphragms were leaking, so with replacement of the pump, it is a good time to recheck the flight fuel burn, and airspeeds.
It is always possible for multiple things to be occurring, so a new baseline with the new pump is in order before taking additional action
unless there is direct evidence of an issue.

If a lot of fuel was being lost to oil and evaporating, then an oil change would be warranted too.

Please report the performance at 2700, WOT and altitude conditions, with new pump.

Yes I also think the main part of the fuel was leaking through the drain into the atmosphere, some
inside the engine but most outside.

I also think there are fuel burn problems associated , because of great fuel flow variation in cruise
indicated in the gauges.

The aircraft engine a ENGINE LYCOMING YIO-360-M1B 180HP SERIAL EL - 36628 - 51E WITH HORIZONTAL INDUCTION
is at the moment at the shop being service, things they will do:

- Replace fuel pump (damaged as in the pics: https://goo.gl/photos/bZpgHHfAyQjByk728).
Installing a new Lycoming 62B26931 fuel pump
- They will change the oil and filter
- Clean and inspect the fuel filters and lines
- Clean nozzles
- Inspect Divider : AVSTAR AVX 3015004-1 and fuel injector system FUEL INJECTION AVSTAR AVX-5VA1.
They ALREADY have some test data on that and told me the AVSTAR fuel injection were way out of max pph in
idle in WOT regimes , they are looking if it is only a question of recalibrating it to standards
- Inspect the mag ignition timing as very well stated/reminded by rv7charlie in this post
- Oil collected for lab analysis for lead , etc. There is a oil analysis history I wil post here
afterwards

I'm confident that all that done I will gain a bit of power to attain the normal performance for a RV
(most likely) and that is sure that will solve fuel consumption issues.

By the way does anyone have tech data on the AVSTAR injections I quoted? Either the tech manual or
AVSTAR manufacture contatc email for me to ask. The shop here in Brazil is used to is having trouble
getting it (technical manual for it, they are only used with BENDIX/ PRECISION RSA 5AD1 and others
mainly certified ones... That would help.

As one more piece of information for your analysis this airplane always operated with temps and
temperatures inside green arc - more to the cool side than to the hot spectrum of the green arc.
Since new it got cooler and cooler with time but always on green arc, oil pressures logging a
drop in its history but always within operation limits. Fuel pressure always very high and steady
about 29 psi. Fuel flow always erratic and fluctuating a lot during any phase of flight.

Drop in both magnets on pre flight checks where always about 90 rpm and equal on each.
Always used 100/130 LL AVGAS from what I believed to be reputed dealers can't affirm it anymore though.

Data log since new (all but the last 4 hours - the coolest ones): http://cirrusreports.com/flights/PRZTI

rv&charlie and rzbill I was a bit mistaken on describing the power settings , the G3X Garmin is calibrated
ok, the numbers was what I described wrong. Poor memory... don't worry with that. WOT best power (TAS adjust
mix) maximum at pressure altitude 6500ft = density altitude 8000 this day about only 155kts TAS with a fuel
flow in 14,6 gal/h range...that's the average history. Sometimes worse some slight better consumption numbers
but never faster than 155kts though. 147kts is a number I could rely on attain any day anything more was
depending on the conditions of the day.

I'm not saying that all your fuel went into the crankcase instead of being burned as a rich mixture.
I'm saying that it's entirely possible that a good portion of it went into the crankcase and evaporated
out without you noticing it.

Yes, it will dilute the oil, but not necessarily to the point that you'll notice increased oil
temperature during operation. In fact, the opposite may be true to some degree - until you reach a point
of dilution where increased friction causes increased heating, you'll actually see a lower temperature
on the oil due to the cool fuel diluting it and the evaporation of that fuel carrying away heat.

I think you nailed it, particularly where you state that evaporation causes cooling.

I DO THING airguy nailed also , great piece of info all of them , about oil system, pump and ventilation. And
the cooling through evaporation. Excellent diagnoses/explanations.

With all that I think the problem performance and fuel consumtion was in order of cause:

1 - leakage throgh pump drain to the atmosfhere (firt diafragm rubber failure with maybe 100h)
2 - injection system pouring to much fuel into the cilinders (service shop bench test data today
confirmed they were out limits rich, but can't precise to what extent it would overall afect the high consumption)
3 - possible bad mag timming (2 and 3 causing a poor burning and excess gas being expelled through exhaust and some washed up into crankcase)
4 - latter in engine operation life from 100h to today 143h (1,8 years time spam) the second diafragm rubber in
the fuel pump failed/rupture leaking also some gas into crankase (can't precise it in time or quantities and its
relative contribution for the consumption problem)

All that summing up to a bad performance (in speed) and gas consumption about 15% - 20% mored than standard in
any regime.

**Bear in mind that up to 100h I was in engine break-in phase so operating almost WOT full rich and so unable
to give normal consumption numbers. After that I started to go 100-50 ROP or even 50 LOP (under 60%) to
see consumption and started to have some doubts about engine health.

It does have a lot of take off power though... strangely it used to take off with less runway than other rv7s I operate.
But cruise was bad and range was limited due to consumption to 389nm with very litte reserve (about 20 min reserves).

So an easy way to determine if the diaphragm is leaking would be to install a vented
collector on the fuel pump drain tube and go for a ride or ground run it. Nothing in it, it's not leaking. Right?
Maybe I missed it in an earlier post. Have you tested the fuel for ethanol?

Too late for that... Pump was replaced. Never noticed outside clues of it... But if you seen the pictures
(link above) of the replaced pump on its inspection you will agree that it sure was leaking (two enormous rips).

Just a note to Alex: In Alaska and other cold places without heated hangars,
it is not uncommon for aircraft to have a system where they deliberately add gas to the oil, at shut down.
The next (very cold) morning, they can crank the engine because the diluted oil is so thin. As the oil warms up,
the avgas evaporates away. Of course I have no idea where your avgas is actually going, but out the oil breather is possible.

Great to know BobTurner it gives me a peace of mind that the leakage into crankase ought not to have
caused permanent damage ( as temps were always so cool)

My guess is yes, leakage was the major loss, then loss to the oil.
It is a fact your diaphragms were leaking, so with replacement of the pump, it is a good time to recheck
the flight fuel burn, and airspeeds. It is always possible for multiple things to be occurring, so a new
baseline with the new pump is in order before taking additional action unless there is direct evidence of an issue.

If a lot of fuel was being lost to oil and evaporating, then an oil change would be warranted too.

Please report the performance at 2700, WOT and altitude conditions, with new pump.

Yes as soon as the repairs finishes and I get to flight testing it I will keep you posted. I really hope
to bring only good news and numbers... Hope the darn AVSTAR can get fixed. Too bad if I have to buy a new
one... This engine from new mind you. Bought zero hours in Lycoming had with 143 hours all kinds of problem!
To bad for their reputation. At least with this pilot that writes you. Forgot to say that I got it with
ZERO compression in one of the cilinders , that were replaced in guarantee with 25 hours because of that.


Possibly, but that orifice is super tiny. I am not sure you could push that much fuel out of there but perhaps.
The OP stated there was fuel in the case. For fuel to get into the case, both diaphragms would have to be compromised.
It is unlikely that the upper diaphragm would fail first, but I guess it is possible. More than likely it was the lower one and it was simply not noticed in preflight for a very long time before the upper burst.

I had a diaphragm failure and it was very obvious during preflight with the tell tale blue stain coming out of the drain, but it was a very small streak of fuel.

Check your fuel pump drain on every preflight folks.

Your theory would spoil mine... but you may be right. :)


Now the compressions are ok 78/80 psi on all cilinders, I hope that I will get it as a NEW LYCOMING ENGINE
should be. :mad:

Its just too bad luck for one man and such a new engine at a time.

Thanks again all help... If anyone has tech info on AVSTAR or their contact (I don't reside in US) please would be of great help also.

Keep you posted :cool:.
 
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Almarton 0 this statement does not make sense.

"WOT best power (TAS adjust mix) maximum at pressure altitude 6500ft = density altitude 8000 this day about only 155kts TAS with a fuel
flow in 14,6 gal/h range...that's the average history. "

You cannot be at best power if you are burning 14.6 gph. My RV-8 with IO-360 fuel injection 180 hp burns about 8.5 gph max power at 8000 ft density altitude. I do not think 6 gph is going into the oil. I would expect about 160 KTAS at that point. My RV-8 is not especially clean aerodynamically but 160 is not bad.

I've not read all the posts to see if EGTs are reacting to leaning the mixture. Have you yourself as pilot leaned the mixture to find peak EGT? If you did and it is burning 14.6 gph something is wrong. Probably the fuel flow transducer is not properly calibrated. Have you verified it by recording total fuel consumption for a flight on a full tank, and comparing total calculated fuel consumed with gallons pumped to refill the tank?
 
Almarton 0 this statement does not make sense.

"WOT best power (TAS adjust mix) maximum at pressure altitude 6500ft = density altitude 8000 this day about only 155kts TAS with a fuel
flow in 14,6 gal/h range...that's the average history. "

You cannot be at best power if you are burning 14.6 gph. My RV-8 with IO-360 fuel injection 180 hp burns about 8.5 gph max power at 8000 ft density altitude. I do not think 6 gph is going into the oil. I would expect about 160 KTAS at that point. My RV-8 is not especially clean aerodynamically but 160 is not bad.

I've not read all the posts to see if EGTs are reacting to leaning the mixture. Have you yourself as pilot leaned the mixture to find peak EGT? If you did and it is burning 14.6 gph something is wrong. Probably the fuel flow transducer is not properly calibrated. Have you verified it by recording total fuel consumption for a flight on a full tank, and comparing total calculated fuel consumed with gallons pumped to refill the tank?

I Know! You did not understand me. Let me explain better.

To my knowledge best power adjust "by the book" should be somewhere at 50 to 100ºF Rich of Peak EGT

But as my airplane engine is not behaving normal... SO my best power adjust was based in results not standards.

What I did was go WOT full rich 2700 rpm and fiddling with the mixture until I got the best TAS speed possible 155kts but it was attained with an enormous consumption... that's it.

Can't see where it was wrong (best power = best performance speed) and the difference in numbers from that to an normal engine settings shows symptoms to how different my engine problems are to
corroborate to a diagnose.
 
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Alexandre,
Your 1st report specified 2500 rpm; your most recent says 2700 rpm. Did you re-fly the test, or mis-state the rpm in the 1st report?

Bubblehead,

Run your numbers. If you're making 75% on a 180 HP Lyc and only burning 8.5 GPH, you just need a couple more events for it to be the 1st Lyc qualified for sainthood. That would be .377 BSFC. Extremely unlikely with a stock Lyc.

Charlie
 
Alexandre,
Your 1st report specified 2500 rpm; your most recent says 2700 rpm. Did you re-fly the test, or mis-state the rpm in the 1st report?

Kinda ignore first report . It has some confusion in the power percentages :confused:.

But trying to assert better it I do think , if I recall right, that WOT full rich with 2500 or 2700 rpm and adjusting mixture to attain the highest TAS possible I'll have only slight different results from 151kts (2500rpm) to 155kts (2700 rpm)

They just called my the injector servo had a broken spring, it being replaced and recalibrated. They will check now flow divider and nozzles. After reassemble in the engine and do mag timming ignition checks. By 24th I expect to go flight test it and fetch the airplane. They will do , off course, some ground tests.

I'll keep posting here the updates and data. Expecting a complete new performance now! Very Optimistic!
 
Hey folks!

There were a bulletin for this fuel pump:

https://www.lycoming.com/sites/default/files/SB621B Diaphragm-Type Fuel Pump Replacement.pdf

Continued operation of a non-conforming fuel pump can cause fuel leakage out of the airframer?s vent line
or into the engine crankcase.

And that what happened!

Got very lucky indeed so.

My plane despite only 143 hours since new was bought from a professional Company in 8/2015

They never told me about that bulletin despite they have a department just for that...:eek:
 
Folks,

Glad to inform that:

1 - After detecting a fuel pump leak and changing it to a new one.
2 - Cleaning injection nozzles
3 - Setting AVSTAR Fuel System to standards

But mainly due to (1) , got the aircraft 30% more economical. 30% reduction on fuel consumption.

Did few tests yet but the numbers point to 153 kts TAS ate 8000ft (density altitude) with 31,5 lts/h (aprox 7,8 gal/h) - 65% power ( 21.5 map / 2450 rpm)

The engine sound changed a lot (due to fiddling in the injection) it is a bit rough in comparison to before, but the temps and pressures are ok with little variation between cylinders.

Keep you posted as new tests go and data is consolidated...

Happy already.


A note.... The fuel pump should have been changed in the 25 hours inspection by (warranty) but the shop that did stated that Service Bulletin No. 621B did not apply , they where mistaken it did and it almost cause a flight incident with problabe costs and injuries. I am claming for a refund on the fuel pump change costs.

Keep you posted!
 
Alex,

Good job finding the problem and fixing it.

On another note, do you have any threads and pics detailing your RV flying experiences in Brazil?
 
Folks,

A note.... The fuel pump should have been changed in the 25 hours inspection by (warranty) but the shop that did stated that Service Bulletin No. 621B did not apply , they where mistaken it did and it almost cause a flight incident with problabe costs and injuries. I am claming for a refund on the fuel pump change costs.

Keep you posted!

Do you know which fuel pump you had and how it was missed by identifying it as "did not apply"? I just checked mine a couple of months ago and also did not apply to mine. There is three or more conditions need to match to apply.
 
Bubblehead,

Run your numbers. If you're making 75% on a 180 HP Lyc and only burning 8.5 GPH, you just need a couple more events for it to be the 1st Lyc qualified for sainthood. That would be .377 BSFC. Extremely unlikely with a stock Lyc.

Charlie

My point is he can't be at best power at 14.6 gph 8000 ft density altitude. Maybe I was at 70% or 65% I don't know and it's not important. I was just going off the top of my head. But at cruise I expect to see about 8.5 gph not 14.6 and this is verified by monitoring what I put back into the tank.
 
Alex,

Good job finding the problem and fixing it.

On another note, do you have any threads and pics detailing your RV flying experiences in Brazil?

Thanks! I'm overall very happy with the results. After some more tests It seems that the results are consolidated. The plane is behaving as it should in respect to speed and fuel consumption now.

The only one oddity (to me) remaining is the fuel flow with the engine warming in idle (1000 rpm) indicates up to 4,5 gal/h (about 16 lts/h) but after warmed up it drops to 3 gal/h (about 9 lts/h) - That phenomena important to say happens now that is winter here (cold days about 59F / 15 C). Cruise consumption at 155 kts (TAS) is about 9 gal/h ! (confirmed) = 34 lts/h

Is that NORMAL? Do you verify that variation (idle warming flow vs idle hot flow) on your operations?

With regarding to my experiences here pics and movies I have this channel:

https://www.youtube.com/channel/UCCvqfbSIm4DgLBUhGuenKIA

Alex,

Do you know which fuel pump you had and how it was missed by identifying it as "did not apply"? I just checked mine a couple of months ago and also did not apply to mine. There is three or more conditions need to match to apply.

Well its pretty easy to tell [IF[ you have visual access to the fuel pump, just print the bulletin and inspect it to answer the 4 questions written there in the SB to see if you pump applies. BUT in my case I asked to the repair shop (another one) to that was servicing my aircraft in 50 hours inspection to verify that. They did not and , even worse, when asked again they told me it was not applied to my pump. They mislead me. :mad:

Doing more testing and will post...

Nice flights! Blue Skies!
 
Alex,

Your numbers jive with mine on a recent long cross-country (GA>TX>PA>GA). I was seeing 155TAS at 2450-2500 RPM, 20" MAP (60%) and 7.5 GPH fuel burn at 8500. At higher altitudes (10.5) I could get down to 7 GPH. I still have a lot of small jobs to further reduce drag and hoping to get the TAS up to 165. I may have to upgrade to the Superior cold air induction to get there (supposed to add 5-8 HP). Also need to perform the nozzle tuning checks as I think my #4 cylinder may be running rich compared to the others.

I took a bunch of screen shots of my Dynon screen while flying but they are on the USB stick in my plane. The one I like the most had a 30 KT tail wind with ground speed of 182 KTS (~210 MPH).
 
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Alex,

Your numbers jive with mine on a recent long cross-country (GA>TX>PA>GA). I was seeing 155TAS at 2450-2500 RPM, 20" MAP (60%) and 7.5 GPH fuel burn at 8500. At higher altitudes (10.5) I could get down to 7 GPH. I still have a lot of small jobs to further reduce drag and hoping to get the TAS up to 165. I may have to upgrade to the Superior cold air induction to get there (supposed to add 5-8 HP). Also need to perform the nozzle tuning checks as I think my #4 cylinder may be running rich compared to the others.

I took a bunch of screen shots of my Dynon screen while flying but they are on the USB stick in my plane. The one I like the most had a 30 KT tail wind with ground speed of 182 KTS (~210 MPH).

Ray, I'm getting happier and happier with my plane now! Its just a question now of adjust (improve) roll rate and fix a aileron buffet when full deflected and I declare it finished.

When you state those altitude numbers in you post it is Density Altitude or indicated (pressure altitude)?

Many thanks
 
fix a aileron buffet when full deflected

Are you talking about the aileron buffeting that occurs during an aileron roll at higher entry speed and full deflection?

If so, there's nothing to fix there...search the forums for threads on this phenomenon.
 
SNIP

The only one oddity (to me) remaining is the fuel flow with the engine warming in idle (1000 rpm) indicates up to 4,5 gal/h (about 16 lts/h) but after warmed up it drops to 3 gal/h (about 9 lts/h) - That phenomena important to say happens now that is winter here (cold days about 59F / 15 C). Cruise consumption at 155 kts (TAS) is about 9 gal/h ! (confirmed) = 34 lts/h

Is that NORMAL? Do you verify that variation (idle warming flow vs idle hot flow) on your operations?

SNIP

This phenomenon has be noted before - no one, to my knowledge, has figured out exactly why. Mine has done this for 16 years. My sensor is between the fuel servo and flow divider. It has been discussed on these forums. I recently re-configured the physical location and orientation of my sensor (for other reasons), and it seems to be much better.

Glad you seem to have found the solution to your larger problem!
 
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