Did your Engine reach TBO?

[Guest brentc]

JYet I spoke at length to several 230 owners at Natfly who are still quoting cruise fuel consumptions of 19 - 20 LPH. Such a fuel burn would worry the heck out of me.

It used to worry the 'heck' out of me too burning 20 litres an hour. It was a while after that that I had to rebuild my engine

 

I remember when the 'economy' kit was released that I specifically asked Jabiru if would burn out my valves and I was assured by Jabiru that it wouldn't.

 

I was right. It used to burn 27 an hour so there had to be a side-effect of some kind.

 

Nowdays with the new jet it's probably back up near 27 again but I won't be complaining.

 

 

[Yenn]

My figures were from the Jab handbook but you are probably correct that they come from the dyno. Every Jab engine is run on the dyno, I am not sure how long for but I watched one once for about 30 mins, so it possibly an hours run. Speeds and loads are varied but they would have no way of knowing what load the prop puts on the engine.

 

If anyone gets the chance a trip to the factory is worth while. The engine factory that is, but it would have to be teed up at the factory at the aerodrome.

 

I did training as a metal machinist but the machinery at the factory works a night shift practically unattended. The day shift fixes up the needed tools and loads the materials to be worked on.

 

 

[Captain]

It used to worry the 'heck' out of me too burning 20 litres an hour. It was a while after that that I had to rebuild my engine

B

 

 

 

What EGT's were you seeing at cruise at 20 LPH?

 

 

 

And what do you have now (I assume the same as I stated here)?

 

 

 

Regards G

 

 

[Guest J430]

Guys

 

When the economy kits came out they were a 285 needle jet.......I had the first trial 278 Jet. We ran that for about 450 hours.

 

Valves were perfect!

 

We did not chase super lean steps....in the cruise even then (we now have the 285....orig econ kit) and now we have always gone for 22LPH plus. the RPM is definately more than 2800.....more like 2900RPM.

 

Who knows???????

 

J

 

 

[Guest brentc]

Captain I used to get (@20lph) around 730 in the cruise and 670 at full power. Figures now are less but with the cooler weather it's hard to tell how much. Probably maximum of 700 in the cruise but I'll have to have a closer observation for you.

 

Changed my plugs for the first time after the rebuild and they were quite dark in colour so I'm happy enough with that even if I waste a litre or two.

 

 

[Thruster87]

Predicted Performance Points:

 

 

 

 

 

 

 

 

• 120 hp @ 3300 rpm
   
   
  
• 110 hp @ 3000 rpm
   
   
  
• 100 hp @ 2750 rpm
   
   
  
• 93 hp @ 2551 rpm
   
   
  
• 90 hp @ 2475 rpm
   
   
  
• 80 hp @ 2200 rpm
   
  

 

 

 

 

 

 

 

 

 

[jetjr]

J200 economy ?

 

Guys,

 

Ive got an J200 which is still running the original carb I think. Ive bought the economy kit but havent fitted it

 

Engine runs sweetly at 2800, EGT all 635-689, CHT 107-160. Uses 25 lph.

 

Not sure what im going to achieve but putting kit in carb?

 

Leakdown shows one cyl leaking close to limits past rings. Do I bother fitting kit?

 

JR

 

 

[Guest brentc]

I wouldn't fit the economy kit if you have the old one, you would need to get the new and updated one. It's not just a decreased fuel burn, there are changes to mixture throughout the rev range.

 

I would think that it would be a good idea to fix your dodgey cylinder unless you are really close to TBO.

 

 

[jetjr]

Change kit?

 

The kit I have is just from last year - is this the latest?

 

The engines done 525hrs so TBO is a long way off but I doubt It will get even close

 

At this stage Im doing Leakdown every 50hrs and watching changes, Jab reckon if its leaking past rings its not that serious so long as it doesnt change.

 

JR

 

 

[Guest BaronVonEvil]

Hmmm... time till TBO

 

Hi All,

 

My Friend has a J170 with a 2200 and it has a total of about 201 hrs on the engine. He purchased the plane new. The two rearward cylinders (nearest the firewall) had 40 of 80psi and 55 of 80psi for a leak down test. The two forward cylinders were 70 of 80psi and 71 of 80psi. He is using the plane for a flight training school and has been changing the engine oil every 25 hrs.

 

He pulled the heads and cylinders of both low reading cylinders. There was some minor vertical scratches in both cylinders and evidence of oil blow-by past the piston rings. There was also stains between the cylinder head and cylinder barrel indicating leakage at this joint. The two forward cylinder also show signs of head leakage.

 

The exhaust valve in the worst cylinder shows signs of galling at the stem. The valve seats faces appeared to be wider than one would expect, almost full width. One exhaust valve appeared to not be fully sealing around its edge. A build up of carbon deposits were found in the intake valve passage in both of the heads.

 

It would appear that the engine was running hotter than what was indicated by the EFIS.

 

I believe my friend will end up 'Topping" all the cylinders because of this problem. Since he is using it for USA Sport pilot training, he needs to avoid down time due to engine problems. By refurbishing all cylinders, he feels this will keep things moving along and avoid the possibility of having to have the plane down again for work on the forward cylinders.

 

The BaronVonEvil

 

 

[Yenn]

BaronVonEvil. What oil is your friend using?

 

 

[Guest BaronVonEvil]

TBO

 

Hi Yenn,

 

He is using AeroShell 15w50 as recommended by Jabiru. I came onto the forums to see if there was an alternative oil that would work in his application.

 

BaronVonEvil

 

 

[DKM1]

HI to all

 

Just read all the threads on TBO and cruise percentage, to find the power percentage of an engine you have to base it on the power curve not rpm because the bulk of the power would be produced in the upper rpm say 2200-3300 or there abouts hope this helps a bit.

 

Cheers Daniel:thumb_up:

 

 

[jetboy]

The published engine power curves are based on full throttle setting. If you reduce throttle for an easy cruise the prop load is not the same.

 

fuel flow or prop load is the only way to know where % power is at.

 

of course fuel flow might be higher due to other factors.

 

Graph fron continental O-200 engine manual: 100 hp full power

 

propellor load, rpm, % power, fuel gals/hr @ 5.8lbs/gal (US gallons!)

 

2040 40% 4.8g

 

2180 50% 5.4g

 

2320 60% 6.2g

 

2450 70% 6.7g

 

2570 80% 7.5g

 

2670 90% 8.25g

 

2800 100% 9.3g

 

Ralph

 

 

[DKM1]

Hi Ralph

 

As yet I haven't been in the hot seat of an aircraft with mixture control hope to soon. I was just trying to shed some light on how the boys at Jabiru, would have set the given rpm vs power settings with fixed pitch prop and no mixture control. Mixture control would be an advantage and fuel injection would be better and where is Omaha flats in this great country of ours.

 

Regards Daniel

 

 

[jetboy]

Daniel,

 

Omaha Flats is on the charts, Northeast of Warkworth & Matakana, being non-certificated it does not have a VFG entry, nowadays used by prior arrangement due to the amount of livestock around - horses mainly - that require consideration and training by the resident 701 and gyro operating there.

 

Scroll down here for more

 

http://homepages.paradise.net.nz/skypilot/airfields.html

 

I missed the 75% point from the graph and the 100hp rpm so have added these. Another factor is these figures are static load, I have a table of flight load rpm vs. % power load for a C150M but wont bore U with these. However I added the equivalent rpms for jabiru engines to the table, for the various engine power settings

 

propellor load, rpm, % power, fuel gals/hr @ 5.8lbs/gal (US gallons!)

 

Using these characteristics of propellor load vs rpm, scaling for Jabiru engines

 

If you achieve 3300 rpm @ full throttle, then setting throttle to lower loads results in the following rpm and hp;

 

rpm %pwr g/hr % scale rpm 2.2/hp 3.3/hp

 

2040 40% 4.8g 74% 2448 34 48

 

2180 50% 5.4g 79% 2616 43 60

 

2320 60% 6.2g 84% 2784 51 72

 

2450 70% 6.7g 89% 2940 60 84

 

2520 75% 7.25g 92% 3024 64 90

 

2570 80% 7.5g 93% 3084 68 96

 

2670 90% 8.25g 97% 3204 77 108

 

2750 100% 9.3g 100% 3300 85 120

 

Ralph

 

 

[DKM1]

Hi Ralph

 

:thumb_up:Just looked at the home page looks like a nice place, no wonder I have never heard of the place different country. Good info

 

Regards Daniel

 

 

[zodiac3813]

Jab TBO

 

Hi there,

 

I've recently purchased a jab LSA55 with a 40-hour (jabiru factory) reco engine around 2 1/2 years old. After receiving advice from an experience level2 who maintained 2 jabs for a local flying school, and much research, these will be my maintenance/running criteria:

 

• Oil change every 25 hours
   
   
  
• Oil filter change every 50 hours (I use Puralator "pure one" filter)
   
   
  
• Using BP Ultimate 98 octane mogas with fuel pump ON at all times
   
   
  
• Check tappets & head torque every 50 hours
   
   
  
• Leak-down compression test at 300 hours (or sooner if warranted)
   
   
  
• NEVER let the engine overheat! Monitor the gauges, ensure good ducting/air flow (a) around cylinders and (b) through the oil cooler
   
   
  

 

 

I found it a bit perplexing to read through the list of engine parts that Jabiru didn't replace with new, but I guess I'll have to live with that. A lot of Jabiru engine problems seem to stem from overheating at some point.

 

BTW, I calibrated the oil temperature sender by dipping it in boiling water and checking the gauge reads 100 deg. c.

 

Cheers, Jim.

 

 

[BigPete]

If you leave the electric fuel pump on i_dunno - how will you know that the mechanical one is still working

 

and,

 

If I read your post right - the motor has only done 40 hours in the last 2.5 years. :yuk:

 

I'd be ripping the heads off and having a good look at the internals.

 

regards

 

:big_grin::big_grin:

 

 

[Guest brentc]

My comments regarding your proposal.

 

Oil change every 25 hours

 

- Great. Shell W100+ or 15w/50

 

Oil filter change every 50 hours (I use Puralator "pure one" filter)

 

- Every 25 is even better and a Ryco only costs around $11 from an auto shop. Why try filtering new oil with an old filter for around 50 cents an hour?

 

Using BP Ultimate 98 octane mogas with fuel pump ON at all times

 

- Great you'll save money on Avgas, however you won't know if the mechanical pump is working as stated and fuel pump normally goes off at the top of climb as per the flight manual. Agreed that vapour lock is less likely with pump on though.

 

Check tappets & head torque every 50 hours

 

- Too long. If the engine has been operated at the warm end of the scale or even normally, then 50 hours may be too late and the tappets may all be closed by 50 hours and performance will be degraded significantly.

 

Leak-down compression test at 300 hours (or sooner if warranted)

 

- Good idea. My engine was beyond repair at 400'ish hours, so try less if practical!

 

NEVER let the engine overheat! Monitor the gauges, ensure good ducting/air flow (a) around cylinders and (b) through the oil cooler

 

- Of course

 

 

[jetjr]

As Brent said

 

Do oils and filter every 25 hrs, Ive taken a liking to 15W50.

 

Elect Fuel pump should make no difference to TBO and as Brent said how do you know mech pump is OK?

 

Tappets are quick and easy i check them every 50hrs

 

Same for a leakdown test, maybe 100hrs if Im busy - this will tell you alot about engine condition and potential problems

 

Also new plugs at 100hr

 

Maintenemce items really arent very expensive, especially on a 4 cyl, why skimp

 

JR

 

 

[zodiac3813]

Thanks for the input and advice guys, I will take it on board for sure. A couple of points:

 

Yes, will change filter as well as oil at 25 hours.

 

Purolator filter is actually a superior product to Rycu one.... costs more but made from better materials.

 

I'll know the mech pump is working because I'll turn the electric one off to check. It is advised to leave on to prevent vapour lock in hot weather by pushing fuel up rather than sucking it up. I know it makes no difference to TBO: just a point of interest.

 

There will be less carbon build-up in heads and around rings when using 98 octane mogas.

 

Brent, I agree with you, on reflection, regarding the frequency of tappet adjustments.

 

BigPete, the motor was turned over or started frequently (owned by a mechanic ) to keep it lubricated.

 

Once again, thanks.

 

 

[Ross]

On the question of fuel pump working or not.

 

You might be able to monitor your fuel pressure and hence the condition of your fuel pumps depending on where you mounted the take-off for the fuel pressure.

 

As the pressure is likely to be oscillating depending on what types of pumps you have it would necessitate having a restriction in the pressure line and possibly an air reservoir to smooth out the varying pressures unless you wanted to go digital and display the pressures on an oscilloscope type screen.

 

I am guessing that the pressure each pump could produce are likely to be quite low - again I guess something like 3 to 8 psi.

 

Also a pressure sensor or sensor line line is another possible place for the fuel system to have a fault. An air leak or a fuel leak.

 

Pressures produced by in line pumps (like the electric pump + the mechanical pump) are cumulative so a measurement point just before the carburettor can pick up total pressures from both pumps.

 

Also running both pumps could raise fuel levels in the carburettor compared to one pump at a time possibly making the engine run richer than with one pump.

 

This condition is not likely to be objected to on take off and initial climb or on final for landing but it might not be desirable for cruising.

 

The construction manual (early J160 manual) locates the electric fuel pump a little above the header tank and between it and the mechanical fuel pump on the engine. It would be more desirable to have that electric pump in the lowest point in the system especially if using fuels with vapour pressures higher than normal.

 

Someone that knows something about the subject might like to comment.

 

Regards

 

 

 

[Yenn]

At 40 hours the engine would not be run in. The normal tappet checking is several times in the first 50 hours ( I forget the exact requirement) Keep checking until they settle down. Mine have hardly changed in the last 75 hours.

 

Taking off the heads for a look is good advice and if the correct run in procedure was not used it may also be prudent to put in new rings, but seek the advice of a LAME or experienced mechanic who can look at the wear patterns in the bores, before going that far.

 

 

[zodiac3813]

Thanks Ian, yes the proper running in procedures were adhered to, all documented in well-kept maintenance logs. The only thing I'm now cursing is that my dear wife and fellow adventurer, while tidying the hanger/workshop, has thrown out the old oil filter which I had intended to dissect/inspect. Spilt milk. Irretrievable from landfill!

 

Cheers, Jim.