What is the top cruising power setting that will not damage the engine running rich of peak?

[Beau]

I HAVE A TLS BRAVO M20M WITH AN IO540 ENGINE. IT DOES NOT HAVE GAMMI INJECTORS SO IT HAS TO BE FLOWN RICH OF PEAK. I FIND THAT IF I RUN THE ENGINE FOR AND EXTENDED PERIOD OF TIME RICH OF PEAK. THE HIGHEST POWER SETTING I CAN RUN IT AT IS 65% WITH THE COWL FLAPS OPEN. OTHERWISE THE ENGINE BURNS 1 QUART OF OIL AN HOUR. THE COWL FLAPS HAVE TO STAY OPEN IN THE SUMMER OR THE OIL PRESSURE FLUCTUATES. THE BRAVO IS SLOW AT THIS POWER SETTING WITH THE COWL FLAPS OPEN. IT WILL ONLY GO 145-150 KNOTS. IS THERE ANOTHER WAY TO FLY THIS PLANE WITHOUT HAVING AN UNPEGGED OIL PRESSURE AND WITHOUT BURINING OIL?

 

[Danb]

Lance or Don K will chime in, get your baffling checked. Bravos are tough to run LOP mine did ok even without GAMIs My typical long range flight were 30”/ 2300RPMs..Oil Temp 175-178 CHTs 370 TITs 1575 & 19GPH at 12,000 I trued in low 190’s at those numbers, no TKS no Air conditioning but great baffles.

Check your baffling there most important seriously sounds like you have issues I’d get checked out. Send data to Savvy get borescoping done to see what’s going on inside.

D

.

 

[LANCECASPER]

1 hour ago, Beau said:

I HAVE A TLS BRAVO M20M WITH AN IO540 ENGINE. IT DOES NOT HAVE GAMMI INJECTORS SO IT HAS TO BE FLOWN RICH OF PEAK. I FIND THAT IF I RUN THE ENGINE FOR AND EXTENDED PERIOD OF TIME RICH OF PEAK. THE HIGHEST POWER SETTING I CAN RUN IT AT IS 65% WITH THE COWL FLAPS OPEN. OTHERWISE THE ENGINE BURNS 1 QUART OF OIL AN HOUR. THE COWL FLAPS HAVE TO STAY OPEN IN THE SUMMER OR THE OIL PRESSURE FLUCTUATES. THE BRAVO IS SLOW AT THIS POWER SETTING WITH THE COWL FLAPS OPEN. IT WILL ONLY GO 145-150 KNOTS. IS THERE ANOTHER WAY TO FLY THIS PLANE WITHOUT HAVING AN UNPEGGED OIL PRESSURE AND WITHOUT BURINING OIL?

 

Everything @Danb says regarding baffle seals. If you can, post a picture of your engine with the top cowling off.

Plus if your engine is burning a quart an hour under any circumstances it's time to start digging for answers. Get your cylinders borescoped. Your engine is taking to you . . .  listen. If this was flown hard (hot) before you owned it, your exhaust valves might be suspect. Not to scare you but if it was flown hard, you need to carefully look over the exhaust system.

When you say 65% power what MP and RPM are you using to get there?  What instruments (factory gauges or engine monitor) do you have to tell you that? What year is your M20M (what factory gauges)? (Your profile still says you fly an M20R) What are your CHTs at this power setting?

When you say that your oil pressure is pegged, what number are you seeing? If I remember correctly the green range for oil pressure on an M20M is around 47-87. That could be a bad transducer, but unlikely if it's reading high. You say that your pressure fluctuates unless you leave the cowl flaps open. Bad vernatherm maybe?

I would get it to someone that's very familiar with the Bravo. The only airplane in the world that uses a Lycoming TIO-540-AF1B engine is a Mooney TLS Bravo and it has it's own personality. Someone that has a lot of experience with it will be a lot less expensive that someone who you are paying to experiment and educate.

 

Edit: Beau, I think I met you once. Did you used to keep your Ovation at LaGrange TX?

[Shadrach]

1 hour ago, Beau said:

I HAVE A TLS BRAVO M20M WITH AN IO540 ENGINE. IT DOES NOT HAVE GAMMI INJECTORS SO IT HAS TO BE FLOWN RICH OF PEAK. I FIND THAT IF I RUN THE ENGINE FOR AND EXTENDED PERIOD OF TIME RICH OF PEAK. THE HIGHEST POWER SETTING I CAN RUN IT AT IS 65% WITH THE COWL FLAPS OPEN. OTHERWISE THE ENGINE BURNS 1 QUART OF OIL AN HOUR. THE COWL FLAPS HAVE TO STAY OPEN IN THE SUMMER OR THE OIL PRESSURE FLUCTUATES. THE BRAVO IS SLOW AT THIS POWER SETTING WITH THE COWL FLAPS OPEN. IT WILL ONLY GO 145-150 KNOTS. IS THERE ANOTHER WAY TO FLY THIS PLANE WITHOUT HAVING AN UNPEGGED OIL PRESSURE AND WITHOUT BURINING OIL?

 

Something odd is going on for sure.  From your post it appears to be more than just the power setting.  Poor performance and excessive oil consumption suggest that there is more to the story than mixture/power setting. 

[Fritz1]

I run my Bravo 30" 2300 RPM 100 dF rich, which is about 78% power I think and the maximum that most people use for cruise, typically that makes 18-18.5 GPH, at 19,000 ft I typically see 185 kt TAS with TKS, max CHT 400 dF, max TIT 1600, if my CHT reaches 400 in cruise I reduce power to 29" or 28" which rarely happens, climb 24/34 at about 120 KT and 23-24 GPH, oil burn is about 1 qt every 6h on a 700h factory reman, at 1 qt/h something is not right, have engine checked out asap, Bravo is very sensitive to leaking baffles, it pays to seal every nook and cranny

[Beau]

Thanks for the info. I have had this plane 16 years and flown it about 1600 hours. During that time I have replaced the engine once.  I did this because the oil pressure dropped to 37 lbs over the Rockies and was making metal by the time I got to Grand Junction from Texas.  I flew the plane at peak as the manuel states. After the new engine I. flew rich of peak so that the fuel burn was 19 GPH and 75% power.  The speed below 8000 MSL was 160 KTS. The engine burned oil at about 1 quart an hour. I replaced all 6 cylinders 300 hours ago.  When it is run at 65% it burns no oil.

[LANCECASPER]

On 8/16/2023 at 5:33 PM, Beau said:

Thanks for the info. I have had this plane 16 years and flown it about 1600 hours. During that time I have replaced the engine once.  I did this because the oil pressure dropped to 37 lbs over the Rockies and was making metal by the time I got to Grand Junction from Texas.  I flew the plane at peak as the manuel states. After the new engine I. flew rich of peak so that the fuel burn was 19 GPH and 75% power.  The speed below 8000 MSL was 160 KTS. The engine burned oil at about 1 quart an hour. I replaced all 6 cylinders 300 hours ago.  When it is run at 65% it burns no oil.

There's your answer, running it conservatively is the way to go. This is going to sound crazy, but you can't fly the M20M by the POH and come close to getting the engine to go to TBO.

Even after Lycoming recognized that the TIT allowed in the POH (1750), was way too hot and that they were going through cylinders every few hundred hours, Mooney CEO back then under the French ownership, Jacque Esculier, wouldn't agree to revise the POH. 

Legend has it that Lycoming told Mooney that owners had to keep the TIT under 1650 to stand any chance of making TBO. This would bring the top speed and range down below where Jacque thought they needed to be from a marketing standpoint ("Personal Airliner") and vowed they would never use another Lycoming engine in any of their new airplane designs. (So far that promise has held true.)

Finally what came out of all of it was the Bravo wet-head conversion released in early 1996. A couple years later Lycoming came out with a small booklet on Engine Management  and tried to get it in the hands of owners of Mooney M20M and Piper Mirage (PA-46) airplanes. It mentioned that for the sake of engine life, TIT should not exceed 1650, even though to this day the M20M POH still has the TIT redlined at 1750. The TIO-540-AF1B engine is one of the few engines that Lycoming says must have 25 hour oil changes, as specified in a Lycoming Mandatory Service Bulletin 480F. In a Lycoming seminar at a Mooney Homecoming probably 20+ years ago the Lycoming rep said that with the heat this engine produces, that they saw rapid degradation in the oil's viscosity past that mark. The oil that runs through those extra oil cooling lines past the exhaust valve area sees a greater temperature than in most other engines and apparently breaks down faster. 

In practice, M20M owners who want their engines to make TBO disregard the high numbers printed on the sunvisor and in the POH. They keep TIT below 1600 and CHTs below 400, preferably below 380. They use "53" as the number not to exceed (meaning, as an example, that 29" MP + 2400 RPM = that "53" number). Even at that number, or other power settings below that, it's still an amazing airplane which stands a good chance of reaching TBO.

[Beau]

GREAT ANSWERS: IT IS A 1991 TLS BRAVO M20M. I HAVE FLOWN THIS PLANE IN MANY POWER SETTINGS. TYPICALLY 2440 RPM AND FROM 75% MP TO 65% MP.

THE 2430 RPM AND THE 65% MP BURNS NO OIL AT ALL. HOWEVER THE PLANE IS TOO SLOW AT THAT SPEED, ESPECIALLY WITH THE COWL FLAPS OPEN.  I NEED TO FIND AWAY TO FLY AT 75% MP 2400 RPM WITH 160 KTS BELOW 8000 FEET WITH NO OR LITTLE OIL BURN OR GET A GOD FORBIDE MERIDIAN OR TBM (BOTH BEING REDICULOUSLY OVERPRICED).  

[McMooney]

buy an ovation ?

[LANCECASPER]

1 hour ago, Beau said:

GREAT ANSWERS: IT IS A 1991 TLS BRAVO M20M. I HAVE FLOWN THIS PLANE IN MANY POWER SETTINGS. TYPICALLY 2440 RPM AND FROM 75% MP TO 65% MP.

THE 2430 RPM AND THE 65% MP BURNS NO OIL AT ALL. HOWEVER THE PLANE IS TOO SLOW AT THAT SPEED, ESPECIALLY WITH THE COWL FLAPS OPEN.  I NEED TO FIND AWAY TO FLY AT 75% MP 2400 RPM WITH 160 KTS BELOW 8000 FEET WITH NO OR LITTLE OIL BURN OR GET A GOD FORBIDE MERIDIAN OR TBM (BOTH BEING REDICULOUSLY OVERPRICED).  

No reason the cowl flaps should have to be open in cruise if the engine baffle seals are good. If they are the original seals they are 32 years old and have gotten "lazy" and let the air escape the back of the cowling instead of forcing the air down over the cooling fins.The best seal kit is from GeeBee (800-556-3160).

If the Bravo is unable to give you 160 knots something else may be wrong - your fuel set-up, rigging, landing gear doors, etc. You're in Texas, take it to Don Maxwell in Longview or David over at Dugosh in Kerrville or JD & Laura at SW Texas Aviation in Smithville or the Mooney Factory Service Center in Kerrville.

@donkaye is also the resident expert at flying Bravos and has transition-trained many people on how to fly them efficiently and knows the numbers you need to be at by heart.

[donkaye]

I've had my Bravo for 31 years as of next week.  During that time I have flown it 4,105 hours.  I'm on my 3rd engine.  The 1st one went 2,295 hours after the Bravo upgrade at 1,300.  That engine never had an engine monitor.  The 2nd one went 1,600 hours before an incident that occurred as the airplane was being Annualed presented me with the choice of an engine teardown or sacrificing the remaining 400 hours before TBO and buying a reman.  I took the reman route, since I got a $50,000 discount on the engine replacement.  All this is to say I know the Bravo engine well.

The sweet spot for this engine using the key number of 53 is 75% power at 2400 rpm and 29 inches mp with cowl flaps closed.  At that setting you should be using a quart of oil about every 10-12 hours.  In 25 hours between oil changes I usually add 2 quarts.  Using the MVP-50 as a guide, I run the engine at a maximum of 1595 TIT. At this setting I get 18 gph for the 1st hour and 17.5 gph thereafter.  CHTs by the MVP-50 are all below 375°F.  IAS at 4,500 feet at that setting is about 165 kts.  At 17,000 TAS is between 195 and 205 knots.  I do have GAMIs, but run my engine ROP only.

Summary:  you have a major engine problem and need to get it looked at immediately.  No way you should be burning 1 quart an hour.  Personally, I wouldn't fly the plane until this issue was resolved.

 

[Beau]

GREAT REPLIES ESPECIALLY FROM DONKAYE! IF THE BRAVO CAN BE FLOWN AT 2400 RPM, 75% POWER AND 29 INCHES THE PLANE BECOMES USEFUL AGAIN!

JD CASTILLE WITH SW AVIATION IN SMITHVILLE,TX. IS VERY KNOWLEDGEABLE ABOUT ALL THINGS MOONEY. I WILL TRY THE BORE SCOPE, BAFFELING, VALVE EXHAUST. MAYBE IT IS TIME FOR A NEW ENGINE? THIS ONE IS 13 YEARS OLD AND HAS ABOUT 1300 TT. NEW ENGINE TIME??

[donkaye]

If it is the Bravo engine and not the -A, then except for a Turbo and Wastegate overhaul at about 1,300 hours, it should have made it to TBO from my experience.

[donkaye]

I'm confused.  The airplane listed under your name, N444HK, is an Ovation.  Do you have a Bravo, too?

[midlifeflyer]

Beau, why are you yelling? caps lock stuck?

[Shadrach]

On 8/17/2023 at 3:43 PM, Beau said:

GREAT ANSWERS: IT IS A 1991 TLS BRAVO M20M. I HAVE FLOWN THIS PLANE IN MANY POWER SETTINGS. TYPICALLY 2440 RPM AND FROM 75% MP TO 65% MP.

THE 2430 RPM AND THE 65% MP BURNS NO OIL AT ALL. HOWEVER THE PLANE IS TOO SLOW AT THAT SPEED, ESPECIALLY WITH THE COWL FLAPS OPEN.  I NEED TO FIND AWAY TO FLY AT 75% MP 2400 RPM WITH 160 KTS BELOW 8000 FEET WITH NO OR LITTLE OIL BURN OR GET A GOD FORBIDE MERIDIAN OR TBM (BOTH BEING REDICULOUSLY OVERPRICED).  

Burning no oil is a red flag. Burning 1qt an hour is a red flag. Doing both but at different power settings does not make one cancel out the other. If indeed this is how your engine is performing, there is something wrong beyond where you set the knobs. 

[Fly Boomer]

On 8/17/2023 at 2:43 PM, Beau said:

GREAT ANSWERS: IT IS A 1991 TLS BRAVO M20M. I HAVE FLOWN THIS PLANE IN MANY POWER SETTINGS. TYPICALLY 2440 RPM AND FROM 75% MP TO 65% MP.

THE 2430 RPM AND THE 65% MP BURNS NO OIL AT ALL. HOWEVER THE PLANE IS TOO SLOW AT THAT SPEED, ESPECIALLY WITH THE COWL FLAPS OPEN.  I NEED TO FIND AWAY TO FLY AT 75% MP 2400 RPM WITH 160 KTS BELOW 8000 FEET WITH NO OR LITTLE OIL BURN OR GET A GOD FORBIDE MERIDIAN OR TBM (BOTH BEING REDICULOUSLY OVERPRICED).  

mooney is certainly not known as a heavy hauler but the meridian is reputed to be both weight and range limited payload in the 500 pound range with full fuel also 43 foot wingspan 30 feet long and over 11 feet high big hangar

[LANCECASPER]

On 8/21/2023 at 7:59 AM, Fly Boomer said:

mooney is certainly not known as a heavy hauler but the meridian is reputed to be both weight and range limited payload in the 500 pound range with full fuel also 43 foot wingspan 30 feet long and over 11 feet high big hangar

I was a partner in a Meridian from 2003-2005 and for trips 900nm or less the speed and comfort was amazing. (I had been a partner in a Mirage with the long range STC from 2000-2002 and the range was considerably better in the Mirage)

I did a 5 hr 30 min trip each way last month in the Acclaim of about 1050nm nonstop with over 40 gallons of fuel remaining when I landed (LOP 27"/2400 15.1 per hour in cruise). The Meridian would have burned a lot more fuel and, by the time you factor in the fuel stop, wouldn't have been much, if any, faster. The pressurization was nice though on both the Mirage and the Meridian.

[Fly Boomer]

12 minutes ago, LANCECASPER said:

I was a partner in a Meridian from 2003-2005 and for trips 900nm or less the speed and comfort was amazing. (I had been a partner in a Mirage with the long range STC from 2000-2002 and the range was considerably better in the Mirage)

I certainly agree that the Meridian is an amazing and delightful airplane but, despite it's size, weight, comfort, and speed, it too has limitations.  I talked to a pilot who flew one for an attorney who traveled quite a lot.  He said that the dirty little secret with the Meridian is that every flight is over gross.  His attorney's airplane may have been an extreme example because it just had a new all-leather interior -- including the floor.

[Shadrach]

10 minutes ago, Fly Boomer said:

I certainly agree that the Meridian is an amazing and delightful airplane but, despite it's size, weight, comfort, and speed, it too has limitations.  I talked to a pilot who flew one for an attorney who traveled quite a lot.  He said that the dirty little secret with the Meridian is that every flight is over gross.  His attorney's airplane may have been an extreme example because it just had a new all-leather interior -- including the floor.

One of the recurring attitudes I’ve observed from pilots that regularly fly over gross is that they’re confident that “everyone is doing it” so it’s normal and completely ok.  Seems to work out most of the time…

[Fly Boomer]

1 minute ago, Shadrach said:

One of the recurring attitudes I’ve observed from pilots that regularly fly over gross is that they’re confident that “everyone is doing it” so it’s normal and completely ok.  Seems to work out most of the time…

That works for so many things in life -- everything is okay until it isn't.  We can't mitigate every risk, but I like to work on the things I have some control over.

[LANCECASPER]

On 8/21/2023 at 8:49 AM, Fly Boomer said:

I certainly agree that the Meridian is an amazing and delightful airplane but, despite it's size, weight, comfort, and speed, it too has limitations.  I talked to a pilot who flew one for an attorney who traveled quite a lot.  He said that the dirty little secret with the Meridian is that every flight is over gross.  His attorney's airplane may have been an extreme example because it just had a new all-leather interior -- including the floor.

Maybe on his flights that was true, and more likely if it was one of the first Meridians without the Gross Weight Increase. But I never took off over gross. Ours had the Gross Weight Increase. But with any airplane it's a balance between people fuel and cargo. With most airplanes it has to do with what the weight that the landing gear was able to withstand on the drop test. They may take off over gross, which is still not a good idea, but they may justify it by landing well under gross once they've burned up a lot of fuel.

[JackM20M]

On 8/16/2023 at 4:56 PM, LANCECASPER said:

The TIO-540-AF1B engine is one of the few engines that Lycoming says must have 25 hour oil changes, as specified in a Lycoming Service Bulletin.

Anyone have a reference to this service bulletin?  Been searching but so far have yet to find it.  Thanks!

[LANCECASPER]

30 minutes ago, JackM20M said:

Anyone have a reference to this service bulletin?  Been searching but so far have yet to find it.  Thanks!

https://www.lycoming.com/sites/default/files/attachments/SB480F%20Oil%20ServicingMetallic%20Solids%20Identification%20After%20Oil%20Servicing%20and%20Associated%20Corrective%20Action.pdf

Page 2 on that SB

 

Also the Mooney Maintenance Manual for the M20M on page 4 of section 12-10-04 specifies 25 hour oil changes on this engine.

[Beau]

Sorry about the capitol letters. I was not intenting to "yell".  The 1991 TLS Bravo has an engine monitor EDM 900. It has been based at Lockhart, Tx. which is an Austin suburb.  The engine has new oil and the baffeling is fine. The engine is not making metal accoring to oil and oil screen test results.  In cruise flight the oil pressure will not peg. It fluctuates 4-5 degrees at 70% power.  The oil pressure is irradick. The greater the % power the more the oil pressure varies.The cylinders never go above 390 degrees, The EGT exhaust is always below 1500 degress. Normally its 1460 degrees. The engine does burn oil at 1 quarts every 2 hours. If the engine is run at 78% power it will burn a quart an hour. JD at the Smithville Mooney Center is going to check it out Tuesday. I appreciate all of your comments and ideas!