Had a discussion about my 2500 hour engine with my IA

[ryoder]

So it went like this. I asked about the engine which just turned 2500 snew with no major overhaul. There is mention of a top overhaul in the logs but the original engine log is missing so I take it with a grain of salt.

Since I put new fine wire plugs in it it has been running very smooth and power is great. He said to just play it by ear and when a cylinder gives us a problem we will replace it. He said that with a 180hp O360 the bottom end should go 4000 hours or so. This engine had a new cylinder back in the 80s and every cylinder is pumping in the 70s. I think for now I'll invest in a full tank strip and seal and new interior because the paint and engine are solid. We just changed the oil and the screen is clear. I fly as safe as I can maintaining a close proximity to airports and fields and I baby the engine as I learn and build time.

[Andy95W]

Sounds like you have found yourself a good mechanic with common sense. It sounds like your mechanic has found an airplane owner who understands the pros and cons of his machine, the possible risks involved, and wants to take care of his airplane without being unsafe OR wasting money.

It has been my experience with engines, both my own and customers, that they will start talking to you and dropping hints when they are nearing overhaul time. Good owners listen and start noticing as new oil leaks pop up, as more accessories like fuel pumps or carburetors need attention or rebuilt, top speed or climb rate starts dropping, or more and more small flecks of metal show up in the filter.

It doesn't sound like you're there yet. Good luck and happy flying!

[garytex]

what he said

[ryoder]

He is a good guy and I trust him. But I will try to stay safe and listen to the engine.

[Parker_Woodruff]

What do you mean by babying the engine? Some things do more harm than good (such as pulling the power back immediately after takeoff).

[Mooneymite]

I'm a big believer in "on condition" and "if it aint broke, don't fix it", but as you move beyond TBO, you move into an area where the engine, not you, may decide when "it's time".

 

Yes, the engine will probably give you hints, but nothing lasts forever.  My idea of a nightmare would be some small, out of the way location and my airplane needing a new engine.

 

When I was beyond 2400 hours on my engine, a Lycoming rep reminded me that TBO is based on flight hours....tach time includes non-flight hours.  He opined that 10% over tach time would be a conservative estimate.

[nels]

I would be more worried about doing a long cross country in a fresh overhaul than with an engine like the one in your plane. I do sometimes wonder about just jumping into an overhaul at 2000 hrs when nothing is showing up with the engines performance or oil check.

[DAVIDWH]

As a politician would say, "It all depends".

 

I had much the same experience with a big bore continental at 2450 hours and still running smooth and delivering good power.

 

At annual time, compression had dipped on one cylinder to basically worthless. So, mechanic pulled cylinder to re-work or replace, both of us thinking all would be well soon.

 

Then I got the call to "Come to the airport and look at this".  Upon arrival, the mechanic put his hand on the connecting rod and begin to flex it back and forth. It wasn't much, but I could see the angular movement of the rod as he flexed it on the

 

worn bearing. Oh my, that was an expensive click. Just thinking if this one is so worn, the others cannot be far behind.

 

Long story short, my rod throwing through the cylinder paranoia set in and engine was shipped to Western Skyways the following week for overhaul.

 

As the politician would say "It all depends".

[jetdriven]

I'm a big believer in "on condition" and "if it aint broke, don't fix it", but as you move beyond TBO, you move into an area where the engine, not you, may decide when "it's time".

 

Yes, the engine will probably give you hints, but nothing lasts forever.  My idea of a nightmare would be some small, out of the way location and my airplane needing a new engine.

 

When I was beyond 2400 hours on my engine, a Lycoming rep reminded me that TBO is based on flight hours....tach time includes non-flight hours.  He opined that 10% over tach time would be a conservative estimate.

 

Tach time on the ground is only about 30% of clock time.  Tach time approximates flight time, but the only way to truly measure flight time is with a squat switch wired to a hobbs meter.

 

I have heard from people I know is on a Lycoming engine with the 7/16" exhaust valves, that as the engine gets over 1200 hours, a valve will break off. Its happened to two people I know. If you have the 1/2" exhaust valves, soldier on. But I'd want to know what I had if it were my engine.

[aviatoreb]

Tach time on the ground is only about 30% of clock time.  Tach time approximates flight time, but the only way to truly measure flight time is with a squat switch wired to a hobbs meter.

 

I have heard from people I know is on a Lycoming engine with the 7/16" exhaust valves, that as the engine gets over 1200 hours, a valve will break off. Its happened to two people I know. If you have the 1/2" exhaust valves, soldier on. But I'd want to know what I had if it were my engine.

 

Hi Byron, I think you are saying something important that I want to understand but I am not understanding.  Can you restate please?

 

First thing is regarding how to count tbo hours - is it tach hours or hobbs hours that are used when counting tbo?

 

The second is regarding Lycoming specifically, which I don't have, but still curious.  

[jetdriven]

"Time in service" is what TBO is based on, which someone said earlier was "flight time". However, a tach only approximates flight time.  On the ground the tach adds up hours much slower. IE you taxi 15 minutes per flight but it only adds 5 mins to tach time. Then you fly two hours. Anyways, the tach time, assuming you have the right hour recording ratio, is pretty close to actual time in service.

 

Ours has a 2300 RPM tach installed in 1982. It then ran some 4,000 hours, counting 10% too much time, and it was reading a further 10% too high. I discovered this after a few long flights where the tach time recorded more than the hobbs meter. The correct tach recording speed is 2566 RPM.  After I discovered this, I installed a new 2566 RPM tach, I made a log entry, and poof, subtracted 600 hours from the AFTT.

 

In short, tach time approximates "time in service" IF the tach reads accurately, and IF it is the correct part number with the right recording speed.

 

The other part was that 7/16" exhaust valves dont like extended service, according to Lycoming their TBO is 1200 hours.

[ryoder]

What do you mean by babying the engine? Some things do more harm than good (such as pulling the power back immediately after takeoff).

 

Whatever I need to do I guess.  Starting it up and leaving the idle low until I get good circulation, smoothly applying power, keeping the engine warm but not overheating it, flying it often, not shock cooling it, keeping the right amount of oil in it, not operating it at full power etc.

 

I do pull power back to 25 squared once I retract the gear and clean up the flaps.  Is that a problem?

[WardHolbrook]

There is a huge difference between first run engines and engines that have been overhauled at least once. You've got to listen to your engine, but don't forget that once you go beyond TBO, that engine honestly doesn't owe you anything. It can be false economy to fly hours beyond the recommended TBO if those hours cause some very expensive components to wear beyond limits. I'm assuming that you're doing oil analysis and have an engine analyser. 

[WardHolbrook]

What do you mean by babying the engine? Some things do more harm than good (such as pulling the power back immediately after takeoff).

 

"Babying" engines has shown to be bad for a lot of aircraft engines.

[aviatoreb]

"Time in service" is what TBO is based on, which someone said earlier was "flight time". However, a tach only approximates flight time.  On the ground the tach adds up hours much slower. IE you taxi 15 minutes per flight but it only adds 5 mins to tach time. Then you fly two hours. Anyways, the tach time, assuming you have the right hour recording ratio, is pretty close to actual time in service.

 

Ours has a 2300 RPM tach installed in 1982. It then ran some 4,000 hours, counting 10% too much time, and it was reading a further 10% too high. I discovered this after a few long flights where the tach time recorded more than the hobbs meter. The correct tach recording speed is 2566 RPM.  After I discovered this, I installed a new 2566 RPM tach, I made a log entry, and poof, subtracted 600 hours from the AFTT.

 

 

I have been aware for some time that the tach is set a bit slow to cruise - and also considering taxi considerations.  In fact, since I don't have a hobbs, and I am not too worried about flight time as I am not a pro, I always just wrote in my tach time as my flight time in my pilots record book.  I bet I am 10% low...

 

I was looking after I wrote my question to you, where in the regs it says TBO means hours in the air according to a (quartz) clock rather than cycles of the engine as in rpm - hours.  I could see arguments as to why to define it either way, but in any case, I am sure the FAA wrote a rule somewhere if I could only find it.  Since I fly part 91 it is just for curiosity but I am sure the part 135 operators and on up need to know this rule and live by it.

[aviatoreb]

"Babying" engines has shown to be bad for a lot of aircraft engines.

 

For children too.  They don't grow up as strong, self willed and confident adults.

[aaronk25]

Whatever I need to do I guess. Starting it up and leaving the idle low until I get good circulation, smoothly applying power, keeping the engine warm but not overheating it, flying it often, not shock cooling it, keeping the right amount of oil in it, not operating it at full power etc.

I do pull power back to 25 squared once I retract the gear and clean up the flaps. Is that a problem?

I think your gonna hear some responses from others that pulling the power back doesn't do any favors for the engine because of a few reasons:

Indicated airspeed will be less, so less airflow for cooling.

Your not going to be climbing as fast and in the first few mins of flight altitude is important as in the event of a failure your choices are less.....

In my 201 backing of to 25" raises cht

[ArtVandelay]

.

In my 201 backing of to 25" raises cht

Does it go above 380? If not I wouldn't worry about it

[ryoder]

Thanks for the tips.  No I don't have an analyzer.

 

I guess I should reconsider the 25 squared.  That is how my instructor taught me to fly the airplane and he is an A&P IA and CFII.  I like the thought of maintaining takeoff power in order to get some altitude.

It seems that the POH would have me use 3 power settings: takeoff, just after retracting the gear, enroute climb.  I go directly to 25 squared from takeoff power after the gear is retracted.

 

This is from the POH. 

 

As soon as the Mooney is airborne and under good control perform the following:

1. Apply brakes to stop wheel rotation.

2. Retract the gear.

3. Reduce propeller rpm to 2550-2600.

4. Retract the flaps.

5. Establish climb-out attitude.

6. Turn electric fuel pump off (note fuel pressure indication)

 

An enroute climb speed of 115-120 mph IAS is recommended for improved cooling and good visibility.  The speed for best rate of climb is approximately 105 IAS.  The speed for best angle of climb (obstacle clearance) is about 80 mph IAS.  Recommended power setting for climbing is 2500 rpm and 25 inches of manifold pressure.

[aaronk25]

Does it go above 380? If not I wouldn't worry about it

Chts go up about 15. Degrees but, it's not really easy to pinpoint because OAT and angle of attack ect changes it all.

I never let CHTs go north of 380. Everyone can fly there plane the way they choose, but it's not doing the engine any extra good backing off the power on climb. I also don't see how it could do any harm.

I just like to get to 2000ft agl without delay as there is more options available in the event of a power failure...

[aaronk25]

Thanks for the tips. No I don't have an analyzer.

I guess I should reconsider the 25 squared. That is how my instructor taught me to fly the airplane and he is an A&P IA and CFII. I like the thought of maintaining takeoff power in order to get some altitude.

It seems that the POH would have me use 3 power settings: takeoff, just after retracting the gear, enroute climb. I go directly to 25 squared from takeoff power after the gear is retracted.

This is from the POH.

As soon as the Mooney is airborne and under good control perform the following:

1. Apply brakes to stop wheel rotation.

2. Retract the gear.

3. Reduce propeller rpm to 2550-2600.

4. Retract the flaps.

5. Establish climb-out attitude.

6. Turn electric fuel pump off (note fuel pressure indication)

An enroute climb speed of 115-120 mph IAS is recommended for improved cooling and good visibility. The speed for best rate of climb is approximately 105 IAS. The speed for best angle of climb (obstacle clearance) is about 80 mph IAS. Recommended power setting for climbing is 2500 rpm and 25 inches of manifold pressure.

Some of these POHs were written back in the old days and still contain some great info but some info is due for a update.

If you do a little reading you will find our 360 engines carb or IO are rated for continuous max rpm.

Also as you know as you go higher (without a turbo) the mp pressure comes down.

Have fun and fly it how you like, it's not that big of a deal.

[jetdriven]

In 4 minutes your engine is below 25" anyways, and the lower RPM is higher cylinder pressure than 2700 RPM for a given manifold pressure.

And it cools less because of less air through the cowling. It also spends more time in the way ROP climb mode. You have more total time of climb than you would had you let the engine run at rated power, which means more carbon in the engine.

[Hank]

Ryder, I don't pull back my C until at cruise altitude. Yes, the Book says to reduce ~100 RPM, but you're pulling back 200 RPM & 4" MP.

I push everything forward for takeoff, rotate, positive rate, gear up, and climb at or near Vy all the way to my desired cruising altitude. Then level off, accelerate and set power.

When approaching my destination, I push forward to establish 500 FPM descent, trim force to neutral, and as MP climbs will occasionally pull it back to my cruise setting and enriched mixture to the cruise EGT. This often puts me ~170 MPH, but I will reduce throttle only if it gets too bouncy.

This gives me pretty much 9 gph from turning the key to shutdown, and 135-140 knots depending on altitude and power settings. Last weekend, I was at 22"/2400 at 6000 msl, indicating 135 MPH = 152 true, into a stiff headwind that rarely let me reach 95 knots groundspeed. Until I turned inbound on the GPS approach at 3000 msl when ~17"/2300 gave me 130+ knots!

[philipneeper]

So it went like this. I asked about the engine which just turned 2500 snew with no major overhaul. There is mention of a top overhaul in the logs but the original engine log is missing so I take it with a grain of salt.

Since I put new fine wire plugs in it it has been running very smooth and power is great. He said to just play it by ear and when a cylinder gives us a problem we will replace it. He said that with a 180hp O360 the bottom end should go 4000 hours or so. This engine had a new cylinder back in the 80s and every cylinder is pumping in the 70s. I think for now I'll invest in a full tank strip and seal and new interior because the paint and engine are solid. We just changed the oil and the screen is clear. I fly as safe as I can maintaining a close proximity to airports and fields and I baby the engine as I learn and build time.

Mine had about the same hours and ran fine. Im doing a field overhaul for piece of mind.

[BigTex]

Ryder, I don't remember if you have an engine monitor but if not, don't walk but run and get one installed. It's absolutely critical that you monitor your engine temps.

In regards to takeoff power setting, this has been discussed and debated to death in other threads so I would you use the search feature to find them. But I will say that I've found that I can't climb out my C like its a J. I'd like nothing more than to firewall everything and not touch anything until I reach my cruise altitude but that's not reality for a mid1960's C with a doghouse cowled Mooney. In order to keep CHTs in line, I generally have to climb out 25 squared. You'll also want to get your plane to 120mph as soon as possible to maintain engine cooling.