ROP vs LOP

[KSMooniac]

Its true that is the way it was done long before engine monitors existed. I don't see any issue with this method either, but it would be interesting to see if you could see a difference in how many engines made it to TBO (and overall engine health) and beyond 50 years ago versus today, I would bet that there is little to no difference in that data, even with the implantation of engine monitors in a majority of the GA fleet. 

The APS crew shares data in their class about the airlines re-discovering LOP ops with the last of the big piston airliners. TBOs went from 600 hours to 3600 hours. That is fact.

Sent from my LG-LS997 using Tapatalk

[MyNameIsNobody]

17 hours ago, Marauder said:

But you left out the most important attribute -- good taste in women!

AND Men based on photos.

 

[Marcopolo]

  I probably shouldn't open...or re-open this can of worms, but I feel compelled to correct a statement that was made against Mr. Busch.  It was stated that he (Mr. Busch) suggests that owners push rebuilds beyond TBO which is simply not true.  His entire philosophy on maintenence is based on the "On Condition" theory of doing maintenence.  I have read all the articles of his that I can find and I have watched and listened to all of his webinars, along with many other so called aviation maintenence experts.  Not once has he suggested that an owner, without supporting diagnostic data, push a rebuild beyond TBO.  He has only tried to get us as owners to treat TBO as an arbitrary number, which in my OPINION, it is .  He has a pretty good legal department supporting his maintenence programs and I highly doubt that they would allow him to push owners to make uneducated or unsupported decision around anything having safety of flight ramifications.

 

Sorry, rant end!!

Ron

[MyNameIsNobody]

10 hours ago, Shadrach said:

I don't have FF displayed (though I did plan for it by adding a transducer when I replaced the fuel hoses).  I run LOP mostly at high power down low into the wind or on short hops to visit family around the state. I am perfectly happy running firewalled with the ram air open at 2500 rpm at 2500ft... in February!  I have spent a great deal of time in the vicinity of 80% power LOP (can't confirm exactly without FF displayed). My engine is very happy there, but it can be challengine to keep CHTs above 300df in the coldest months.  If winds are favorable, I am flying as high as I can and choosing my power setting based on what I need to do.  

'Git 'r done...

[Marauder]

1 hour ago, Marcopolo said:

  I probably shouldn't open...or re-open this can of worms, but I feel compelled to correct a statement that was made against Mr. Busch.  It was stated that he (Mr. Busch) suggests that owners push rebuilds beyond TBO which is simply not true.  His entire philosophy on maintenence is based on the "On Condition" theory of doing maintenence.  I have read all the articles of his that I can find and I have watched and listened to all of his webinars, along with many other so called aviation maintenence experts.  Not once has he suggested that an owner, without supporting diagnostic data, push a rebuild beyond TBO.  He has only tried to get us as owners to treat TBO as an arbitrary number, which in my OPINION, it is .  He has a pretty good legal department supporting his maintenence programs and I highly doubt that they would allow him to push owners to make uneducated or unsupported decision around anything having safety of flight ramifications.

 

Sorry, rant end!!

Ron

Has anyone had any dealings with their insurance on what their views are with respect to TBO? I have no concern going past TBO and would do it again provided the engine appears to be operating within its' performance specs.

[mccdeuce]

14 hours ago, Shadrach said:

You wouldn't be running anything other than 100LL through it would you?

If not, I find the fuel smell puzzeling. At .5 spread, you should be able to run smooth to well leaner than you'd ever need to.

Only 100LL for this aircraft. 

12 hours ago, carusoam said:

McD,

check your Fuel injector vent holes.  They are known to vent fuel.  If it is venting fuel there is probably a small blue trace around it.  It is supposed to be oriented in one direction or another.  The FI doesn't know it is running LOP.  It doesn't talk to anything.

I agree there is no talk - but I only get this smell when lean LOP.  Will check them out see what direction they are pointing. 

-Mark

[Cyril Gibb]

17 hours ago, mccdeuce said:

Out of curiosity - I generally am running ROP right now. I want to fly her LOP but am seeing some roughness and a fuel smell whenever I attempt it. 

Have GAMIs and electronic ignition. (Had same rough/fuel with 2 mags too). 

Last spread test was within .5gph will try another test soon. The fuel smell makes me more nervous than the roughness. 

For an 0360 all bets are off without careful work on baffling and leaning technique.  However, for your IO360 a .5 GAMI spread is very poor.  If you're getting a .5 spread even with GAMI injectors then something is very very wrong. 

You have justification to be nervous.  Combine the big spread with a fuel smell depending on the mixture setting and it's time to have a close look at your fuel system.

A fuel smell in flight from an unknown source would be extremely troubling for me... but I'm a nervous Nellie. 

[mccdeuce]

Just now, Cyril Gibb said:

A fuel smell in flight from an unknown source would be extremely troubling for me... but I'm a nervous Nellie. 

Fuel smells are always troubling - I guess I didn't consider it unknown because it's always when I try and operate LOP and if I go back ROP it's completely gone. 

I just don't realistically have the piston experience to understand what's going on. 

My primary background is turbines and rotary engines. 

[Shadrach]

27 minutes ago, Marauder said:

Has anyone had any dealings with their insurance on what their views are with respect to TBO? I have no concern going past TBO and would do it again provided the engine appears to be operating within its' performance specs.

I don't think your Insurance Co cares how many hours you got past TBO. However if the plane ends up on its belly with an geriatric engine, I'd not expect much of a claim for it. They'd likely start at core value and you'd have to negotiate from there.

[Cyril Gibb]

1 minute ago, mccdeuce said:

Fuel smells are always troubling - I guess I didn't consider it unknown because it's always when I try and operate LOP and if I go back ROP it's completely gone. 

I just don't realistically have the piston experience to understand what's going on. 

My primary background is turbines and rotary engines. 

I have a slight fuel smell in Gladys when I get in initially.  It's a tiny amount from her fuel selector which will get new o-rings soon.  Yours is different.  If it varies with your mixture setting it's almost certainly coming from your engine compartment, not a tank, fuel sender, fuel selector, etc which you'd smell regardless of mixture position.

To be strong enough to smell in the cabin in flight, there's raw fuel somewhere around a hot engine.  I'd get pressure into the system on the ground by the boost pump with the cowls off and play with the mixture to see if anything is obvious. 

Clarence et al may provide some ideas.

[Shadrach]

13 minutes ago, Cyril Gibb said:

For an 0360 all bets are off without careful work on baffling and leaning technique.  However, for your IO360 a .5 GAMI spread is very poor.  If you're getting a .5 spread even with GAMI injectors then something is very very wrong. 

You have justification to be nervous.  Combine the big spread with a fuel smell depending on the mixture setting and it's time to have a close look at your fuel system.

A fuel smell in flight from an unknown source would be extremely troubling for me... but I'm a nervous Nellie. 

0.5 on the gami spread is not "very poor". It could be better, but it is acceptable should run fine beyond peak with that spread. 

 

[kortopates]

2 minutes ago, Shadrach said:

I don't think your Insurance Co cares how many hours you got past TBO. However if the plane ends up on its belly with an geriatric engine, I'd not expect much of a claim for it. They'd likely start at core value and you'd have to negotiate from there.

If the plane is totaled you'll get the insured hull value; that has nothing to do with time or hours on the engine or any other component.

If its repairable and the plane came down from reasons nothing to do with the engine, like fuel starvation, then I wouldn't expect any help on OH'ing engine and to expect that to be considered all betterment; similar for the prop. At most you might get a tear down inspection covered.

[Shadrach]

10 hours ago, KSMooniac said:

The APS crew shares data in their class about the airlines re-discovering LOP ops with the last of the big piston airliners. TBOs went from 600 hours to 3600 hours. That is fact.

Sent from my LG-LS997 using Tapatalk
 

Indeed this is true, but I don't think that carries through to modern flat engines.  As I said in an earlier post, years ago Mr. Atkinson suggested they had no data to support a statistical difference in engine life between ROP and LOP operated engines. Maybe that has changed, if it has, I've not heard.

If there was a way to track engine temps in the fleet, I am betting there's a strong correlation between high temps and early mortality regardless of where the mixture knob is set...

[kortopates]

Much of this discussion on LOP ops leaves out that the ignition system is just as important as a descent GAMI spread of 0.5 GPH or less. Without both you're engine won't run LOP smoothly.

[Shadrach]

2 minutes ago, kortopates said:

If the plane is totaled you'll get the insured hull value; that has nothing to do with time or hours on the engine or any other component.

If its repairable and the plane came down from reasons nothing to do with the engine, like fuel starvation, then I wouldn't expect any help on OH'ing engine and to expect that to be considered all betterment; similar for the prop. At most you might get a tear down inspection covered.

I think we're saying the same thing excepting that I believe if the engine is damaged due to the prop strike, it should be worth its core value. 

[Cyril Gibb]

30 minutes ago, Shadrach said:

0.5 on the gami spread is not "very poor". It could be better, but it is acceptable should run fine beyond peak with that spread.

I absolutely agree about being able to run LOP successfully with a .5 spread.  I was remarking on the Lycoming IO360 which usually has a reasonably even spread out of the box.

If the injectors are clean, the spider is providing even volumes (baby food bottle test), there are no induction leaks, there are no individual weak cylinders and the ignition system is set up accurately the spread can and should be much less.based on my limited experience and a quick perusal of MooneySpace threads.

I have a spread of 0.2 - 0.3 at 8 GPH and 0.0 - 0.2 at 9 GPH.  My goal was 0.0 at my normal cruise of 9 GHP, so set it up that way.

eg. Coming back from West Virginia yesterday:  note coarse leaning when leveling off at 20 mins and fine tuning at 1 hour

https://www.savvyanalysis.com/flight/1858762/4d97c7b9-f6e5-419e-aacb-fc69914c6062

 

[Brian Scranton]

1 hour ago, Cyril Gibb said:

eg. Coming back from West Virginia yesterday:  note coarse leaning when leveling off at 20 mins and fine tuning at 1 hour

https://www.savvyanalysis.com/flight/1858762/4d97c7b9-f6e5-419e-aacb-fc69914c6062

 

Wow. I didn't realize that the IO-360 is sucking 19gph on climb out...I always thought it was around 16. I really need to add FF to my panel. 

[carusoam]

FF for T/O is generally near 2X cruise FF for our engines.  Lowering the FF during T/O and climb usually results in some higher CHTs...

So... if your four cylinder engine cruises with 9gph, expect a number closer to 18gph at FT, mixture in, at SL....

The recommended settings for max FF are documented in the important documents for your airframe and engine.  Your mechanic  can look this up before setting up your fuel system.  I have no idea how he does it without a FF(?) indicator.

The 310hp IO550 uses around 15gph in cruise ROP.  On T/O it supposed to be 27.2 gph. Some people prefer a slightly higher setting for improved cylinder cooling....

PP thoughts only. Not a mechanic.

Best regards,

-a-

[Shadrach]

53 minutes ago, Brian Scranton said:

Wow. I didn't realize that the IO-360 is sucking 19gph on climb out...I always thought it was around 16. I really need to add FF to my panel. 

His is obviously functioning well. I'm always amazed when folks complain about the CHTs of their O/IO 360s during climb out and then you see they are burning 16.5-17gph.  It's just not rich enough at sea level. The carb or the servo should be serviced under those circumstances.  On a dense winter day a a Lyc 360 can gulp more than 20gph at take-off power.

[Shadrach]

15 minutes ago, carusoam said:

FF for T/O is generally near 2X cruise FF for our engines.  Lowering the FF during T/O and climb usually results in some higher CHTs...

So... if your four cylinder engine cruises with 9gph, expect a number closer to 18gph at FT, mixture in, at SL....

The recommended settings for max FF are documented in the important documents for your airframe and engine.  Your mechanic  can look this up before setting up your fuel system.  I have no idea how he does it without a FF(?) indicator.

The 310hp IO550 uses around 15gph in cruise ROP.  On T/O it supposed to be 27.2 gph. Some people prefer a slightly higher setting for improved cylinder cooling....

PP thoughts only. Not a mechanic.

Best regards,

-a-

Fuel flow is only really adjustable on the Continental engine. The Bendix RSA on the Lyc engines uses the differential of mass airflow (impact tubes) and venturi suction to determine FF. It's an elegant and simple set up.

[Shadrach]

2 hours ago, Cyril Gibb said:

I absolutely agree about being able to run LOP successfully with a .5 spread.  I was remarking on the Lycoming IO360 which usually has a reasonably even spread out of the box.

If the injectors are clean, the spider is providing even volumes (baby food bottle test), there are no induction leaks, there are no individual weak cylinders and the ignition system is set up accurately the spread can and should be much less.based on my limited experience and a quick perusal of MooneySpace threads.

I have a spread of 0.2 - 0.3 at 8 GPH and 0.0 - 0.2 at 9 GPH.  My goal was 0.0 at my normal cruise of 9 GHP, so set it up that way.

eg. Coming back from West Virginia yesterday:  note coarse leaning when leveling off at 20 mins and fine tuning at 1 hour

https://www.savvyanalysis.com/flight/1858762/4d97c7b9-f6e5-419e-aacb-fc69914c6062

 

Yeah my late 60s era IO360 will run way further LOP then I care to under most circumstances in box stock configuration. However, I don't have the same confidence in the later engines. I know of several that were delivered with atrocious spreads.

[Cyril Gibb]

7 minutes ago, Shadrach said:

Yeah my late 60s era IO360 will run way further LOP then I care to under most circumstances in box stock configuration. However, I don't have the same confidence in the later engines. I know of several that were delivered with atrocious spreads.

I didn't realise that.  I thought that the engines were more or less identical forever. I learn something every day... sometimes more than one thing

 

[Shadrach]

38 minutes ago, Cyril Gibb said:

I didn't realise that.  I thought that the engines were more or less identical forever. I learn something every day... sometimes more than one thing

 

 These are QC issues not design flaws. The intake and fuel delivery system is a balanced design.

[cnoe]

On 5/4/2017 at 0:26 PM, Brian Scranton said:

Wow. I didn't realize that the IO-360 is sucking 19gph on climb out...I always thought it was around 16. I really need to add FF to my panel.

Shadrach nailed it above. I fly out of an airport with a field elevation of 25 msl and generally see 19.1-19.3 gph at takeoff (IO360-A3B6). I think it may be just a TAD rich but I'd rather be rich than lean during takeoff.

Here's a blurb from a really good AVWeb article:

• For a normally aspirated fuel injected engine designed to run on 100-octane fuel (8.5-to-1 compression ratio), takeoff power fuel flow in GPH should be roughly 9% of the engine's maximum rated horsepower.

The entire article can be viewed here:

https://www.avweb.com/news/savvyaviator/SavvyAviator_65_WhatsYourFuelFlowAtTakeoff-199805-1.html

[Brian Scranton]

I was helping my A&P with a 231 today--he installed a new fuel pump and was adjusting the aneroid to get the right flow (25.5 gph at max)--trial and error is the name of the game on that one. Also, made me realize that I really need to invest in a FF gauge. I tried to run LOP again today. I get to that 4th cylinder (the richest one) and the engine feels like she's about to die--I guess I have to get some GAMIs too!