Mooney M20M Bravo engine parameters

[Filippo]

Finally , I went to pick up my airplane and now she is in her new home in Carlsbad.

I have few questions for the experts:

1. Takeoff power MP is generally set at 34.5 and RPM around 2570... I spoke with the mooney shop to check if MP needs to be adjusted and I was told 34.5 is ok and the engine self adjust itself to maintain the max power allowable based on pressure altitude and temperature and that 34.5 is ok.... any thoughts?

2. oil pressure is normal on the ground and increase properly with MP increase generally around 77-80 PSI, but it decrease during the climb and reaches 53-56 PSI at 14000 ft, i didn't climb above that altitude because I was concern about damaging the engine. No oil consumption ( added 1 QT after 10 hrs of flying) oil temp at altitude around 199-200 degrees. No oil leak anywhere and steady engine parameters. Is it normal for this type of engine? 

At altitude (14000 ft ) If I have MP above 34 , boost pump comes on, is it normal ?

Photo attached of engine page at 14000 ft . Airplane run smooth no vibrations no abnormal indication ( except for low oil pressure) with no other indications of anomalies.

any tips for me?

thanks

filippo

 

[carusoam]

MS has a pretty good CFII that flies a Bravo.  

It may make some sense to get some time with him to answer the bazillion questions that are going to come up in the next week or two...

Check in with Don Kaye, if that makes sense?

How is it going so far?

Best regards,

-a-

[Filippo]

7 hours ago, carusoam said:

MS has a pretty good CFII that flies a Bravo.  

It may make some sense to get some time with him to answer the bazillion questions that are going to come up in the next week or two...

Check in with Don Kaye, if that makes sense?

How is it going so far?

Best regards,

-a-

So far great, it was great being able to bring it home . We did it very comfortably in 3 days with my wife flying no more than 4 hours on average per day. Enjoyed the scenery, the thunderstorms around the country , ranged from low to high density altitude airports.... just checking now with other mooney owners their experience on engine parameters to find out if an adjustment need to be made or not. 

Thanks again and happy to be a proud owner of a bravo, it was nice to be able to fly on average westbound at 178-189 TAS.... 

[LANCECASPER]

6 hours ago, Filippo said:

So far great, it was great being able to bring it home . We did it very comfortably in 3 days with my wife flying no more than 4 hours on average per day. Enjoyed the scenery, the thunderstorms around the country , ranged from low to high density altitude airports.... just checking now with other mooney owners their experience on engine parameters to find out if an adjustment need to be made or not. 

Thanks again and happy to be a proud owner of a bravo, it was nice to be able to fly on average westbound at 178-189 TAS.... 

Your airplane doesn't care whether your are east or westbound. It still produces the same true airspeed if it is run at the same numbers. Hopefully at 31" of Manifold Pressure and 2400 rpm at 14000 you were doing better than 179-189 KTAS in a Bravo where your TIT is 1528 and your Fuel Flow was 20.7. You should have been over 200 knots true Airspeed. Ground speed though it looks like was 181 which is great at 14000 ft going westbound, meaning that still with a 20 knot headwind you were covering the ground at 3 nautical miles per minute.

i would lean it back to 1600 TIT and try to keep your manifold pressure and your rpms to a combined 53 or less. Example: 29 MP 24 RPM = 53

[DVA]

13 hours ago, Filippo said:

Finally , I went to pick up my airplane and now she is in her new home in Carlsbad.

I have few questions for the experts:

1. Takeoff power MP is generally set at 34.5 and RPM around 2570... I spoke with the mooney shop to check if MP needs to be adjusted and I was told 34.5 is ok and the engine self adjust itself to maintain the max power allowable based on pressure altitude and temperature and that 34.5 is ok.... any thoughts?

2. oil pressure is normal on the ground and increase properly with MP increase generally around 77-80 PSI, but it decrease during the climb and reaches 53-56 PSI at 14000 ft, i didn't climb above that altitude because I was concern about damaging the engine. No oil consumption ( added 1 QT after 10 hrs of flying) oil temp at altitude around 199-200 degrees. No oil leak anywhere and steady engine parameters. Is it normal for this type of engine? 

At altitude (14000 ft ) If I have MP above 34 , boost pump comes on, is it normal ?

Hi Filippo,

I’ll take a stab at this from my Bravo experience, I have also written a bit about that engine and myths and truths about its power setting in my BLOG that you might find helpful as a new owner. And, without further adieu - congratulations on your new aircraft.

1) MP at full throttle during takeoff is a function of the turbo controller system and is critical as far as adjustment is concerned; 34.5” is likely a bit low unless its super cold where you are. The density controller must be adjusted to produce a maximum MP based on inlet air temperature (IAT which is after the intercooler) with a heat soaked engine at full throttle on a static run-up. Too many people think that since the POH says MP max is 38” that they should have that on the roll - nothing could be further from the truth. Even on a hot day, an AF1B at 38” is way over max power. While this won’t necessarily instantly destroy your engine, you are over boosting and causing unnecessary stress, wear and tear.  Most owners do not have a way to measure the compressor discharge or inlet air temp, so you don’t know for sure if your max static MP is correct. Most AF1B run an IAT of ~120dF  so the setup chart from lycoming puts MP at static runup in the range of 35.5 - 36.0. That said, being an inch low is not a reason to run out inconveniently and have it adjusted, but have it looked at at the next maintenance or annual. (see LYC Service Instruction 1187J, I included the chart below)

2) Oil pressure varies for a bunch of reasons, most notably temperate vs viscosity. What you are seeing is not alarming, but does beg a few questions: How old is the engine (older engines showing wear will often have a drop in OP as they heat up for myriad reasons, 2) What type of oil are you running? (multi weight vs straight weight - I like AeroShell w100 in the summer in my bravo and WC20-50 in the winter) 3) Do you keep the oil 10 QTs or do you run the engine below that.  In the end, as long as the oil temp is remaining within range you should not have any problems with oil pressures as low as 40’s from the engines point of view. I would however have the oil pressure relief valve looked at next maintenance to make sure nothing is sticking or gummed up.

3) The boost pump comes on based on throttle position - it has nothing to do with MP. Yes, the pump will come on as you advance the throttle to chase MP in the climb in your going high, it’s fine - that electric FP is designed for continuous operation if need be. (some aren’t). That said, I will refer back to #1 - proper adjustment of the density controller will affect the ability for the absolute pressure controller to regulate MP during ascents and descents so make sure that is adjusted correctly, and also make sure the roller switch on the throttle arm is adjusted correctly. Its intended purpose is to make sure the boost pump come on during “full throttle” position operations, like take off and go arounds.

Hope this helped a bit!

Dave

 

[KLRDMD]

1 hour ago, LANCECASPER said:

Fuel Flow was 20.7.

And that is why I no longer own and fly a Bravo. If I'm going to burn 20+ GPH in cruise, I'm going to have a second engine.

[Filippo]

3 hours ago, LANCECASPER said:

Your airplane doesn't care whether your are east or westbound. It still produces the same true airspeed if it is run at the same numbers. Hopefully at 31" of Manifold Pressure and 2400 rpm at 14000 you were doing better than 179-189 KTAS in a Bravo where your TIT is 1528 and your Fuel Flow was 20.7. You should have been over 200 knots true Airspeed. Ground speed though it looks like was 181 which is great at 14000 ft going westbound, meaning that still with a 20 knot headwind you were covering the ground at 3 nautical miles per minute.

i would lean it back to 1600 TIT and try to keep your manifold pressure and your rpms to a combined 53 or less. Example: 29 MP 24 RPM = 53

Thanks Lancecasper, I didn't lean up to 1600 because if I lean up to there my CHT on cylinder 1 and 6 goes at 420 and prefer not to exceed 400. Has you can see 1 and 6 run slightly hotter then the others 4 and I believe is pretty common considering where they are located.

filippo

[carusoam]

Many people around here use 380°F for CHT limits, when possible...

Better for Cylinder longevity...

There may be a split amongst Bravo owners of maint. cost vs. speed available....

Best regards,

-a-

[Filippo]

3 hours ago, DVA said:

Hi Filippo,

I’ll take a stab at this from my Bravo experience, I have also written a bit about that engine and myths and truths about its power setting in my BLOG that you might find helpful as a new owner. And, without further adieu - congratulations on your new aircraft.

1) MP at full throttle during takeoff is a function of the turbo controller system and is critical as far as adjustment is concerned; 34.5” is likely a bit low unless its super cold where you are. The density controller must be adjusted to produce a maximum MP based on inlet air temperature (IAT which is after the intercooler) with a heat soaked engine at full throttle on a static run-up. Too many people think that since the POH says MP max is 38” that they should have that on the roll - nothing could be further from the truth. Even on a hot day, an AF1B at 38” is way over max power. While this won’t necessarily instantly destroy your engine, you are over boosting and causing unnecessary stress, wear and tear.  Most owners do not have a way to measure the compressor discharge or inlet air temp, so you don’t know for sure if your max static MP is correct. Most AF1B run an IAT of ~120dF  so the setup chart from lycoming puts MP at static runup in the range of 35.5 - 36.0. That said, being an inch low is not a reason to run out inconveniently and have it adjusted, but have it looked at at the next maintenance or annual. (see LYC Service Instruction 1187J, I included the chart below)

2) Oil pressure varies for a bunch of reasons, most notably temperate vs viscosity. What you are seeing is not alarming, but does beg a few questions: How old is the engine (older engines showing wear will often have a drop in OP as they heat up for myriad reasons, 2) What type of oil are you running? (multi weight vs straight weight - I like AeroShell w100 in the summer in my bravo and WC20-50 in the winter) 3) Do you keep the oil 10 QTs or do you run the engine below that.  In the end, as long as the oil temp is remaining within range you should not have any problems with oil pressures as low as 40’s from the engines point of view. I would however have the oil pressure relief valve looked at next maintenance to make sure nothing is sticking or gummed up.

3) The boost pump comes on based on throttle position - it has nothing to do with MP. Yes, the pump will come on as you advance the throttle to chase MP in the climb in your going high, it’s fine - that electric FP is designed for continuous operation if need be. (some aren’t). That said, I will refer back to #1 - proper adjustment of the density controller will affect the ability for the absolute pressure controller to regulate MP during ascents and descents so make sure that is adjusted correctly, and also make sure the roller switch on the throttle arm is adjusted correctly. Its intended purpose is to make sure the boost pump come on during “full throttle” position operations, like take off and go arounds.

Hope this helped a bit!

Dave

 

Thanks Dave,

very clear explanation,  engine has been teared down in 2010 for a gear up replacing both magnetos,  cylinder 1 replaced, 2,3,4,5,6 honed , idler gear, vacuum pump gear, camshaft, all piston pins , tappers,rings,bearings hardware and perishable items,

in 2014 for a sudden stop opened up again and installed new camshaft, exhaust guides, new bolts and repaired in accordance with factory overhaul manual.

since then airplane has flown 100 hrs in 3 years. At last annual, done when I bought it in June compression where1/78 2/76 3/78 4/78 5/77 6/78. Oil used is Aeroshell 15W-50 and I had 9 quarters in when the indications where as per pictures.

thanks

filippo 

[LANCECASPER]

27 minutes ago, Filippo said:

Thanks Lancecasper, I didn't lean up to 1600 because if I lean up to there my CHT on cylinder 1 and 6 goes at 420 and prefer not to exceed 400. Has you can see 1 and 6 run slightly hotter then the others 4 and I believe is pretty common considering where they are located.

filippo

If you are going over 400CHT at 1600TIT the engine baffles need work. They are letting air go over the top of the engine rather than air pressure forcing air down through the cylinder fins. Even a small air leak on the baffles will raise the temps considerably. Right now you are cooling it with fuel flow. If you get the baffles to do their job air will keep the cylinders cool and you can easily run at 1600TIT and keep the CHT 400 or under with cowl flaps completely closed on most days. On the hottest days of the year you might need to crack the cowl flaps open.

 

[DVA]

Thanks Dave,
very clear explanation,  engine has been teared down in 2010 for a gear up replacing both magnetos,  cylinder 1 replaced, 2,3,4,5,6 honed , idler gear, vacuum pump gear, camshaft, all piston pins , tappers,rings,bearings hardware and perishable items,
in 2014 for a sudden stop opened up again and installed new camshaft, exhaust guides, new bolts and repaired in accordance with factory overhaul manual.
since then airplane has flown 100 hrs in 3 years. At last annual, done when I bought it in June compression where1/78 2/76 3/78 4/78 5/77 6/78. Oil used is Aeroshell 15W-50 and I had 9 quarters in when the indications where as per pictures.
thanks
filippo 

I'm not a fan of the aeroshell multiweight, others may argue that. It seems to burn more oil for some reason. It's like the W100plus that a lot of shops sent their stock back and won't sell it. Again because of high oil burn. The plus has an additive similar to the lycoming LW-16702 and the theory (uncorroborated) was that the additive they used was chemically incomparable with the oil) Most have found that running the straight W100 and adding the 16702 cures that excessive burn problem.

Compressions tell little about an engine that's not already coughing up blood, (don't start kids!). If you haven't already done so, get a good borescope done, have them record the video for each cylinder and save to compare as a baseline for the future. With only 30 hours a year on after a top end I'd be curious if it all broke in well.

[mike_elliott]

18 hours ago, Filippo said:

Finally , I went to pick up my airplane and now she is in her new home in Carlsbad.

I have few questions for the experts:

1. Takeoff power MP is generally set at 34.5 and RPM around 2570... I spoke with the mooney shop to check if MP needs to be adjusted and I was told 34.5 is ok and the engine self adjust itself to maintain the max power allowable based on pressure altitude and temperature and that 34.5 is ok.... any thoughts?

2. oil pressure is normal on the ground and increase properly with MP increase generally around 77-80 PSI, but it decrease during the climb and reaches 53-56 PSI at 14000 ft, i didn't climb above that altitude because I was concern about damaging the engine. No oil consumption ( added 1 QT after 10 hrs of flying) oil temp at altitude around 199-200 degrees. No oil leak anywhere and steady engine parameters. Is it normal for this type of engine? 

At altitude (14000 ft ) If I have MP above 34 , boost pump comes on, is it normal ?

Photo attached of engine page at 14000 ft . Airplane run smooth no vibrations no abnormal indication ( except for low oil pressure) with no other indications of anomalies.

any tips for me?

thanks

filippo

 

Hi Fillipo

 

18 hours ago, Filippo said:

Finally , I went to pick up my airplane and now she is in her new home in Carlsbad.

I have few questions for the experts:

1. Takeoff power MP is generally set at 34.5 and RPM around 2570... I spoke with the mooney shop to check if MP needs to be adjusted and I was told 34.5 is ok and the engine self adjust itself to maintain the max power allowable based on pressure altitude and temperature and that 34.5 is ok.... any thoughts?

2. oil pressure is normal on the ground and increase properly with MP increase generally around 77-80 PSI, but it decrease during the climb and reaches 53-56 PSI at 14000 ft, i didn't climb above that altitude because I was concern about damaging the engine. No oil consumption ( added 1 QT after 10 hrs of flying) oil temp at altitude around 199-200 degrees. No oil leak anywhere and steady engine parameters. Is it normal for this type of engine? 

At altitude (14000 ft ) If I have MP above 34 , boost pump comes on, is it normal ?

Photo attached of engine page at 14000 ft . Airplane run smooth no vibrations no abnormal indication ( except for low oil pressure) with no other indications of anomalies.

any tips for me?

thanks

filippo

 

Congrats on your purchase! While I am fortunate and can fly a lot of different Mooney's, the Bravo is one of my favorites. Truly a personal airliner with a lot of capabilities and a very stout dependable engine. I wouldnt fret too much about 34.5" on TO until you know the density controller isnt set up correctly with the IAT  IAW the Lycoming SB. Looking at your engine monitor, I personally would run it a bit leaner <1600 TIT and with a bit less MP in cruise, but thats just me and what Bob Kromer suggested to me to maximize the engine life and what to pass on to my Bravo students. Its your engine now and you can fly it how hard you like. Your low oil pressure at cruise might indicate having the filter bypass spring pressure checked, and is also a function of your oil type. Your boost pump will come on relative to your MP (throttle) physical position. 

Mike Elliott

Master CFII, N49FM, a 1999 Bravo

EDIT - just read DVA's posts....What he said...Spot on Dave! 

[Filippo]

27 minutes ago, mike_elliott said:

Hi Fillipo

 

Congrats on your purchase! While I am fortunate and can fly a lot of different Mooney's, the Bravo is one of my favorites. Truly a personal airliner with a lot of capabilities and a very stout dependable engine. I wouldnt fret too much about 34.5" on TO until you know the density controller isnt set up correctly with the IAT  IAW the Lycoming SB. Looking at your engine monitor, I personally would run it a bit leaner <1600 TIT and with a bit less MP in cruise, but thats just me and what Bob Kromer suggested to me to maximize the engine life and what to pass on to my Bravo students. Its your engine now and you can fly it how hard you like. Your low oil pressure at cruise might indicate having the filter bypass spring pressure checked, and is also a function of your oil type. Your boost pump will come on relative to your MP (throttle) physical position. 

Mike Elliott

Master CFII, N49FM, a 1999 Bravo

EDIT - just read DVA's posts....What he said...Spot on Dave! 

Hi Mike,

i was running it at about 1530-1550 is it ok? I guess map slightly lower so around 29-30?

thanks

[mike_elliott]

Hi Fillipo,

I personally like to set the cruise at 29" 1590-1600 TIT, about 18 GPH ROP. LOP gets you about 4 GPH less, but your plugs, mags, leads, injectors, induction etc all have to be spot on and you give up about 7-8 KTS TAS. Hopefully, your transition training covered all of this with you, or at least it should have. Where are you located if not?

[Filippo]

56 minutes ago, mike_elliott said:

Hi Fillipo,

I personally like to set the cruise at 29" 1590-1600 TIT, about 18 GPH ROP. LOP gets you about 4 GPH less, but your plugs, mags, leads, injectors, induction etc all have to be spot on and you give up about 7-8 KTS TAS. Hopefully, your transition training covered all of this with you, or at least it should have. Where are you located if not?

I was at 1530-1570 ROP never even tried LOP as you can see from temperature and fuel flow. So I was actually running reacher than you do, but noted the 29" at cruise instead of 31.

i have noticed that if I go around 1600 my cht on 1 and 6 cylinders are going over 400 at around 410 all the others are at 385 ish.

thanks

Filippo

[thinwing]

On 7/22/2017 at 11:32 AM, KLRDMD said:

And that is why I no longer own and fly a Bravo. If I'm going to burn 20+ GPH in cruise, I'm going to have a second engine.

My Baron running at Bravo airspeed burned 30 gal /hr and was much more maintance intensive...at over haul 45 k a side was spent or pushing 100 k ...of course the Baron would carry a ton...the Bravo not so much

[Tony Armour]

Yes, look at your baffles and seal around the oil cooler. Silicone every hole and seam you can find open from the rear sheet baffles to the baffles around the alternators. At your TIT and rpm/MP settings  I think mine would be burning more fuel. I'm usually around 27/2400- 1600 TiT and 19.5 to 20Gph. 

Congrats on your purchase ! After 12 years I still love my TLS EVERY flight !

[Tony Armour]

On August 28, 2017 at 1:41 PM, thinwing said:

My Baron running at Bravo airspeed burned 30 gal /hr and was much more maintance intensive...at over haul 45 k a side was spent or pushing 100 k ...of course the Baron would carry a ton...the Bravo not so much

Doesn't a Baron only run Bravo speeds in a descent ? Sorry, I can't help myself !

[Danb]

Tony the descent needs to be over 500 fpm.

[thinwing]

22 hours ago, Tony Armour said:

Doesn't a Baron only run Bravo speeds in a descent ? Sorry, I can't help myself !

Big engine D model ,3200 empty weight ,5200 gross ,300 hp per side running 25 squared at 8 k  ,level flight 

[tls pilot]

F

The oil pressure issue is a concern. A few years ago Lycoming and OH shops started using parabolic shaped lifters.

In my case, normal oil pressure at or near sea level, then a loss of oil pressure every 1000 feet. Above FL 150, oil pressure was near the yellow line. The oil temp (Boyles Law is a factor). But in the case of these lifters being used, that is the issue. Shops will tell you it is a oil pressure indicator issue, but I have a direct reading line and the ships transducer. Even with the one gauge you have it sounds like a lifter issue.

You need to find out from the shop what lifters were used. Lycoming has stopped using these on our engines.

A TLS Bravo is not being useful and a bad choice of planes if not able to be flown above FL150 up to 240!

Also see Beech Talk with same issue https://www.beechtalk.com/forums/viewtopic.php?f=37&t=90490&start=15

The MP issue seems low and is easily adjusted depening on ambient temp.

I would look at fuel flow on takeoff and see what the burn rate is, it should be 29-32gph