Bravo power settings

[FlyDave]

In my Bravo in cruise I keep TIT under 1600 dF and CHT’s under 400 dF. Typical power settings at FL180 are either:

29"/2400 rpm/18.5 gph/200 KTAS
or
26"/2400 rpm/16.5 gph/190KTAS

29”/2400/18.5 gph is what Don Kaye taught me on my checkout. He also taught me the Key number concept and for the Bravo he stated as follows:

Key #    % power
53          75%
50           65%
47           55%

Mike Elliot and DanB use the Bravo key numbers from the PPP Manual: (derive MP/RPM from key #):

Key #    % power     FF
58         75%            18 gph
54         65%            16 gph
50         55%            14 gph

These are significantly different than the numbers Don teaches, both in key number/% power and increment between each 10% power difference.
The POH for the Bravo doesn’t list % power (that I have found) but does list power settings with associated fuel burns. But if I flew by these POH numbers my temps would be so high I’m sure I’d have to top the engine and rebuild the turbocharger and exhaust system every 400 hours. I’m wondering if the reason people were topping the TLS engine every 300-400 hours was they were flying the POH power settings.
So, all this is leading up to a conversation around how people are flying their Bravo’s and performance they’re seeing. Anyone willing to share the following:

•    CHT and TIT temp limits
•    Climb power setting & FF
•    Cruise power settings and FF
•    Any engine work you’ve done SMOH

• Top
• Turbo rebuild/replaced
• Exhaust work/replaced

I got my plane in December, 2013 at just under 1,500 hours TTAF&E (wet head done at 1,000 hours). The only engine work I've done was replace the front crossover tube on my exhaust system. Prior work was Cyl 1 & 3 exhaust stack segment replaced. My Tach time is just under 1,800 hours and all compressions have consistently been in the mid to high 70's.

I think both current and potential Bravo owners will benefit from this thread.

Dave

[carqwik]

Simply put, max cruise in the Bravo should be at 30/2400 (according to Mooney's flight test engineer on the Bravo program - spoke to him directly way back when)...leaned about 125+ ROP...and every power setting less is ok.  Typically I cruise at 27/2400 leaned about 100 ROP and 16.5+ gph.

The only real engine-related work done on mine with 1200 hours is a rebuild of the exhaust collection tubing.  Of course, Lycoming did an effective "overhaul" when I had the crank AD addressed...basically got a bunch of new discounted parts (new crank, rings, etc.) and some full price parts...new rockers, push rods, etc...

[rocketman]

Good Topic Dave because I have been studying these numbers for a while. I have been using the magic number of 58 (MP + MPH) for break in at 75% power for the past few weeks on my Factory Rebuilt engine and after 8 hours there is negligible oil burn (1/4 quart from "topping" the oil sump at the10 quart limit) and CHT's are now around 375 at the 58 setting. I did look at your post before I first flew the engine and I guess since Mike Elliott and the PPP both agreed on 58, I used it, taking nothing away from Don Kaye.

I bought the factory rebuild after putting 2100 TT on the Bravo even though the engine was strong, smooth, good compressions (except one cylinder), and very little oil burn, clean filter and oil analysis. I did it because I do fly my family and friends over mountainous terrain. I asked Don Maxwell at Oshkosh last year if Bravo owners ever go over TBO and he said yes, all the time. But only over it by a few hundred hours. So that sealed the deal and started talking to Lycoming at the booth there in Oshkosh.

So I am going to fly another 8 - 10 hours at my calculated 75% power than come down to 65% power or lower, 29/2400 seems good.

So if and when you do change out your engine, These are the things I have learned:

1. Fly for at least two hours

2. Stay around the airport - don't go wondering just yet. Things can happen and the weakest chain will probably break during this time

3. Do full power take-off but power back as soon as it is safe to minimize engine heat

4. Do very very shallow climbs. Your engine will love you for this. In the Bravo, I used around 130 knot climb speed (normally after break in I always climb at 120 knots)

5. Keep cowl flaps open. You won't hurt the flaps by keeping them open

6. CHT's will creep up over 400 quickly - Don't let your engine stay there. Check your baffling before you depart on your first flight

7. Read Lycoming's and Continental's recommendations on first flight power settings and use it.

8. Don't even try to go LOP (in fair disclosure, I never go LOP. It's like half choking a marathon runner to use less oxygen to burn less energy to keep      their temp's down during a 26.2 mile race)

9. Use speed brakes while descending (as you should always) to keep the power settings up as long as possible

10. Read your engine instruments very carefully during the entire flight. Pretend like their your attitude indicator during an IFR flight. Bring a co-pilot with you if necessary to help share in the work load

11. Stay at lower altitudes to increase airflow and engine cooling

12. Change your oil, filter, and check screen and filter after the two hour flight. It's a pain to do and who wants to go throw out perfectly good oil but "just do it"

13. During this flight, use all your 5 senses to help monitor your engine - sight, hearing, smell, touch, and taste (well maybe not the latter)

Ron Dubin

 

 

 

 

[Awful_Charlie]

Good thread, and looking forward to some more answers coming along.

Normal SOP for me is TIT limit 1650 and CHT limit 400, but would take a higher CHT (say 420) if I had to climb for an ATC restriction or terrain cleananceas long it it was only a few minutes. I also try to manage cooling (myth or not, I'd rather not be cracking heads if it is avoidable).

TT 1900 hours, new turbos with previous owner, then I got 1000 hours out of the last one, two new cylinders, one early in its life and one from me at about 1700 hours, the other 4 are original with good compressions. Oil consumption is about 5.5hours per litre/quart. I bought the aircraft with about 1400 hours on it

I normally run LOP, about 10-15degress if I set it right. Standard cruise is 30"/2200 at 13-14GPH for 180KTAS ish at FL180, and might back off for a tailwind (just a few days ago I was running 24"/2200 at just under 11GPH for about 155-160KTAS at FL170 as we were 600lbs of people & baggage, and I was trying to get enough fuel on board for a return trip - as it turned out I was a few gallons short after the outbound leg, so had to do a fuel hop on the return).

I can't hit a TIT of over 1650 at 30" and below, but going up to 32" and 2400 and above I can, I normally run 34"/2400 at 22-23GPH and 120KIAS for the climb and keep CHTs under 400 without a problem. The rate of climbs deteriorates above FL200 (critical turbo alt should be FL210, but I'm keeping the IAS up)

The Lycoming operators manual has some interesting figures: it graphs 91Lbs/hr for 75% which is 15.2-15.7GPH depending on the density you use for fuel, yet for the "normal cruise(75")" it quotes 17.1 GPH which is 102lbs/hr. For 65% from the graph is is 78lbs/hr (12.7-13.1GPH) yet quotes 12.5GPH. From the graph, the best BSFC is 0.45 which you get in the 65-80% band. All remarkably inconsistent!

I put the POH figures into a spreadsheet in a previous post - it is still available there

if someone can make sense of the Lycoming figures that would be great!

Ben

Edited April 1, 2016 by Awful_Charlie

[carusoam]

Just realized who Dr. D. is...

-a-

[Bravoman]

11 hours ago, rocketman said:

Good Topic Dave because I have been studying these numbers for a while. I have been using the magic number of 58 (MP + MPH) for break in at 75% power for the past few weeks on my Factory Rebuilt engine and after 8 hours there is negligible oil burn (1/4 quart from "topping" the oil sump at the10 quart limit) and CHT's are now around 375 at the 58 setting. I did look at your post before I first flew the engine and I guess since Mike Elliott and the PPP both agreed on 58, I used it, taking nothing away from Don Kaye.

I bought the factory rebuild after putting 2100 TT on the Bravo even though the engine was strong, smooth, good compressions (except one cylinder), and very little oil burn, clean filter and oil analysis. I did it because I do fly my family and friends over mountainous terrain. I asked Don Maxwell at Oshkosh last year if Bravo owners ever go over TBO and he said yes, all the time. But only over it by a few hundred hours. So that sealed the deal and started talking to Lycoming at the booth there in Oshkosh.

So I am going to fly another 8 - 10 hours at my calculated 75% power than come down to 65% power or lower, 29/2400 seems good.

So if and when you do change out your engine, These are the things I have learned:

1. Fly for at least two hours

2. Stay around the airport - don't go wondering just yet. Things can happen and the weakest chain will probably break during this time

3. Do full power take-off but power back as soon as it is safe to minimize engine heat

4. Do very very shallow climbs. Your engine will love you for this. In the Bravo, I used around 130 knot climb speed (normally after break in I always climb at 120 knots)

5. Keep cowl flaps open. You won't hurt the flaps by keeping them open

6. CHT's will creep up over 400 quickly - Don't let your engine stay there. Check your baffling before you depart on your first flight

7. Read Lycoming's and Continental's recommendations on first flight power settings and use it.

8. Don't even try to go LOP (in fair disclosure, I never go LOP. It's like half choking a marathon runner to use less oxygen to burn less energy to keep      their temp's down during a 26.2 mile race)

9. Use speed brakes while descending (as you should always) to keep the power settings up as long as possible

10. Read your engine instruments very carefully during the entire flight. Pretend like their your attitude indicator during an IFR flight. Bring a co-pilot with you if necessary to help share in the work load

11. Stay at lower altitudes to increase airflow and engine cooling

12. Change your oil, filter, and check screen and filter after the two hour flight. It's a pain to do and who wants to go throw out perfectly good oil but "just do it"

13. During this flight, use all your 5 senses to help monitor your engine - sight, hearing, smell, touch, and taste (well maybe not the latter)

Ron Dubin

 

 

 

 

Ron, as you may recall I am about to follow in your foot steps when my reman gets delivered and hung. I don't think I understand your power setting formula, i.e. What "mph" stands for. What mp and rpm setting are you using  to yield 75% power? For me it has been around 29/24, (53) as described by Dave above. 

 

Thanks, Frank

[donkaye]

 

13 hours ago, rocketman said:

Good Topic Dave because I have been studying these numbers for a while. I have been using the magic number of 58 (MP + MPH) for break in at 75% power for the past few weeks on my Factory Rebuilt engine and after 8 hours there is negligible oil burn (1/4 quart from "topping" the oil sump at the10 quart limit) and CHT's are now around 375 at the 58 setting. I did look at your post before I first flew the engine and I guess since Mike Elliott and the PPP both agreed on 58, I used it, taking nothing away from Don Kaye.

You are SO wrong!!!   75% power is 29"/2400 rpm per the Lycoming Manual.  There is a specific break-in procedure which should be followed to the tee. Running at 34"/2400 rpm is basically running the engine at 100% power.  Go look at the Red Lycoming Manual for confirmation of what I am saying.

[mike_elliott]

To clarify my position, I stated in a previous thread that I believed the magic number of 58 was 75% power based on the MAPA PPP manual

"I have always used 58 as a key number for 75%, perhaps because I read it in the MAPA manual some time ago."

My JPI tells me that 29/2400 at 1600 TT is 90% power, which is wrong. On Take off, I run 36/2500 until reaching 800' AGL, then I reduce to 34/2400 and climb at 120KIAS

All that said, I don't use magic numbers to derive power. Ill cruise at 29/2400 and <1600 TIT about 18 GPH. The Engine isn't in a happy place LOP, Unlike AwfulCharlie's

When Ron called me, I did tell Rocketman I would run the first couple hours hard, like at 34/2400 then vary the rpm, but defer what I say to what the Lyc break in manual and Don Maxwell says to do. These engines are rated to be run at 100% power to TBO. Don M also said for Ron to run it at 34/2400 for the first few hours, if I am not mistaken.

[rocketman]

Don - I am looking at the little red Lycoming book on page 3-48 which plots out percent rated horse power to fuel flow on the TIO-540 A series engines. This graph shows a 75% rated hp to a fuel flow of 105 pounds per hour or 17.5 gph. That fuel flow seems way to low for that power setting. Likewise the graph shows a 100% rated hp at a fuel flow of 175 lbs per hour or 29.1 gph. My 100% power on TO is higher than that setting. Something does not seem right about this graph. You know way more than I do Don so your expert opinion is again appreciated.

However, running the engine at 34"/2400 is certainly not redline or 100% rated HP

[carqwik]

IIRC, 34/2400 is 88% power.  29/2400 is 75% power and 17.5 gph would be about right for the fuel flow.  And at T/O power, you should be at 29 gph or so...

[donkaye]

8 hours ago, rocketman said:

Don - I am looking at the little red Lycoming book on page 3-48 which plots out percent rated horse power to fuel flow on the TIO-540 A series engines. This graph shows a 75% rated hp to a fuel flow of 105 pounds per hour or 17.5 gph. That fuel flow seems way to low for that power setting. Likewise the graph shows a 100% rated hp at a fuel flow of 175 lbs per hour or 29.1 gph. My 100% power on TO is higher than that setting. Something does not seem right about this graph. You know way more than I do Don so your expert opinion is again appreciated.

However, running the engine at 34"/2400 is certainly not redline or 100% rated HP

I'm not at home right now, but am out doing 2 initial Ovation 3 transition trainings right now.  But one thing I can tell you until I get home on Friday and pull out the correct chart is that this is NOT the correct Chart for the TIO540AF1B engine.  It was an insert into the book.

---And believe me when I say 34/2400 IS 100% rated power depending on temperature.  If you are pulling 38/2400 get your checkbook out because I venture that you will not reach TBO.

[Awful_Charlie]

Here is the AF1A/AF1B fuel flow vs. BHP chart. Pencil additions are mine - use at your own risk!

Agree with Don - 100% does not necessarily need 38", and at 2400 RPM anything over 34" makes you engine tester

[PaulM]

Those fuel flow charts are at the lean limit..  Peak TIT or just lean of peak.   If you are running best power or full takeoff power the flows are much higher. 

Image 1 doesn't give us a MP but the fuel flow doesn't match the max lean 200HP setting, so it would need imply max power.  Image 2 has about 28.5" for 200HP @ 2400 (best power mixture)   There are similar charts for 2575 and 2200 rpm. 

I usually run a power setting that gets me 17-18G/hr at peak TIT. which is 80% power. 

[carqwik]

How does 34/2400 equal 100% power when the engine's max power setting is 38/2575 is also 100%? 

[manoflamancha]

Is it possible to fly at low power settings safely without damaging the engine? Like for example 30% power to save on gas and still get 150-170 knots in econ cruise.

 

[carusoam]

At low power settings you may even get it to run LOP.

John (the MS lawyer that went on to buy an Aerostar) had found some success with LOP, but it was too slow where it was running smoothly.

Best regards,

-a-

[rocketman]

11 hours ago, carqwik said:

How does 34/2400 equal 100% power when the engine's max power setting is 38/2575 is also 100%? 

I am just trying to figure this out as I break in my new engine. If I go to low on power settings, oil burn will increase throughout the life of the engine and the rings will not properly seat against the cylinder wall. If I go too high while maintaining comfortable CHT below 375 with the cowl flaps open and a richer mixture, whats the problem? After all the engine is rated to 2000 TBO at full power. I wish Lycoming would have published real figures instead of leaving us to figure out the "politics" of HP settings and engine break in. 

[carusoam]

RM, 

See if you can find a copy of what Continental says for comparison.

I was looking for my notes, but was unable to find what pile I filed them on.

They gave some guidance that was pretty specific to the first two flights.  The next flights were changing power settings every fifteen minutes varying RPM and MP.  Using the MAPA guidance for 75% and 65% hp. Summing the Rpm/100 and mp numbers.

The oil was so clean for tens of hours...

Then, flying LOP, the oil got exhaust stained lightly and the excess oil blew overboard via the case breather tube.

Filling the oil to the top level is good for keeping oil cool.  Flying near to the ground is good for keeping cylinders cool and for NA engines high MP is best down low to help seat the rings properly...

good things....

- high power for ring seating.

- low altitude and cool day for cylinder cooling.

- max mp and rpm for some portion of the flight to move the Pistons to the top and bottom of their travel.

- full rich mixture for improved cooling

Objective....

- good even break in.

- no steps left in the cylinder walls.

- no glassed over cylinder surfaces.

I rented the skills of some MAPA CFIIs to specifically help with the break-in of my factory reman engine. Low flights over the ocean along the Jersey shore.  I would have to look closely at the JPI data to even tell there was a break-in going on.  The actual break-in was probably done on the Dyno at the Continental factory, or maybe the first few hours that the mechanic flew it...

Hope that sparks some ideas.

i am only a PP, not a mechanic.

Best regards,

-a-

 

[Awful_Charlie]

On 31/03/2016 at 5:19 AM, rocketman said:

... I wish Lycoming would have published real figures instead of leaving us to figure out the "politics" of HP settings and engine break in. 

OK, let's all work together on this to see if we can produce something more useful than Lycoming

I was thinking that together we can take a few steps to get to a sane usable set of limitations, flows and power with limits: I suggest we start with MP and RPM, then add fuel flows, and then from that we can overlay resultant power.

To this end, here is an alternative 'graph' of MP and RPM, which is so far solely my understanding and interpretation of Mooney PoH 3502 Rev H (28 Apr 2005) and Lycoming 60297-23P-2 4th Edition (Oct 2006). It's not overly pretty or neat (it can be tidied up when we have agreed the numbers/bands) but is hopefully a starting point. Parts I am particularly unhappy with are the areas for notes 4, 6 and 9, but I'm looking for constructive suggestions for the whole lot

Ben

MP vs RPM.pdf

[Awful_Charlie]

On 30/03/2016 at 5:34 PM, carqwik said:

How does 34/2400 equal 100% power when the engine's max power setting is 38/2575 is also 100%? 

Curve 13491 Sheet 1 of 3 - "Normal Rated Power 270HP 35" HG"
Curve 13495-A - "Density Control Full Throttle setting Limits" between 34" and 37.5" for an IAT of 70dF to 170dF
Curve 13492 "Max Cumulative Manifold Pressure" - 38" MP is maximum for "standard hot day" (I can't find a definition of what "hot" is though) at 19,000 ft AMSL. Standard day at 6000'AMSL max is about 34.5"
So 38" is not something you should normally see, and is a hard limit that must not be exceeded in a similar way to the 500dF CHT limit 

[FlyDave]

Charlie,

Good chart.
You are the only Bravo driver I know of that can run LOP. I have tried but the engine just isn't happy doing it (and either am I!).
I stated my limitations and power setting in my original post but here they are again:

In my Bravo in cruise I keep TIT under 1600 dF and CHT’s under 400 dF. Typical power settings at FL180 are either:

29"/2400 rpm/18.5 gph/200 KTAS
or
26"/2400 rpm/16.5 gph/190KTAS

Cruise climb for me is from 29"-32" and 2400 RPM. If I lean in cruise I lean to keep CHT's under 400 dF with resultant FF from 20-24 gph.
I don't usually get close to 35" MP except when OAT is very low and have never seen over 35.5". On takeoff I typically get 34.5" and 2575 RPM. Once 1,000' AGL I reduce to cruise climb as stated above unless I need maximum climb rate.
I'm not sure either of the stated key numbers are valid and I think we should just state temperature limits and MP/RPM/FF settings with variations in FF to adjust temperatures.
I just got my latest oil analysis back from Blackstone and they think my engine is in great shape (see attached). So I think my power settings work well for this engine.

Dave

[Awful_Charlie]

You're looking very similar to me Dave

The high alu back after 1700 odd hours was due to a new (second hand!) #3 cylinder being installed at 1727.7 and flushing out all the disturbance that created

I'm not very good at recording FF/KTAS in a spreadsheet (I make the odd note on my kneeboard, but then frequently omit transferring them to something more permanent!)

So far together we've got:

I run LOP with GAMIs (#5 last to peak by about 0.5GPH)  as fuel is the lowest it's been for a long time with a best price around €1.60 a liter - which is about 7USD a gallon

Here's a Savvy upload with a few FF sweeps at different MPs: https://www.savvyanalysis.com/flight/1302605/a40ba126-3dd6-461f-ac4d-f18e0b2165d5

 

Edited April 1, 2016 by Awful_Charlie

[FlyDave]

Charlie,

So it looks like you're flying at 2200 RPM at all power settings. My engine is smoother at 2400 than 2200 and smoother at 2500 than 2400.

Is there a difference in smoothness between 2200 and 2400 with your engine?

Dave

[Awful_Charlie]

It's probably marginally smoother at 2400 than 2200, but not significantly. I think I need to have a prop balance, as the vibration is a bit high for my liking, but I need a prop reseal anyway as one of the de-ice boots is starting to perish, and I'll get that all done together when I go over to Straubing for the avionics work later in the year (MT prop HQ is at the same field, and they service the standard McCauleys)

[rocketman]

I discussed performance figures with Mooney at Sun-n-Fun recently and they reminded me that the engine is actually rated much higher than 270 hp so the actual performance figures should be adjusted accordingly. Just because it was derated to 270 does not mean that the 270 is 100% hp, especially during break-in procedures. Interesting thought. The truth of the matter is that there is no absolute truth to this matter!