Maximum Manifold Pressure - Acclaim

[Bentonck]

Howdy to everyone...

I am looking for a little guidance on maximum manifold pressure in the Acclaim.  I have read through the POH which states Maximum Manifold Pressure at 33,5" ... 

In normal takeoff procedures it states: Power advance slowly to full RPM (Watch manifold pressure, adjust throttle as required to avoid overboost)

and in the go-around procedure it states:

POWER....FULL FORWARD/2500RPM (no mention here of overboost...)

The last owner has flown about 7 hours in the plane with me to help me transition and told me he just never used a throttle setting over 30.5" ... (On a side note, I don't think he ever used one under that as well but it's a different issue).... so while the POH says you can go up to 33.5" and the previous owner says you can get all the performance you need at 30.5", and the G1000 illuminates in flashing red the pressure if it get`s over 31.5", what does everyone use for take-off and go-around normally for MP?

Thanks in advance...

Edited April 20, 2020 by Bentonck
Correction of spelling error

[exM20K]

G1000 flashes red over 33.5"

I use full throttle, which is around 33" as my wastegate controller is set now.  it will vary with oil temp.

-de

Edited April 20, 2020 by exM20K

[Aspen2013]

I use max power. Sometimes it reaches 33.5 at which time the G1000 does flash red. Just give a slight twist on the throttle to reduce slightly so you won't have that red flashing.

Some things to remember about this engine: It is a 350 HP engine (on Malibu) that has been down graded by Mooney to 280HP. So it will take this MAP no problem. I believe on the Malibu they set it at 34 MAP. Talked with a person who worked at TCM engines and helped develop this engine.  He gave me this advice. The engine has tuned air induction that was tuned at 2500RPM.  80% of 350HP is 280 HP!!  WOW, That is where this engine is limited at 2500 RPM. So Mooney made it easy for you to fly. Just push everything forward for take off!!  30.5 MAP will be about 80%. Maybe that's why the other pilot used it.  Notice you never reduce RPM because there is no 2700 RPM ability on this Mooney like its earlier models.

75% of 350HP is 262HP which is the cruise power setting. This occurs at about 29-29.5 MAP.  He states no TCM engine was designed to operate below 2300 RPM and 15 MAP except during landing. Therefore the most efficient and easiest on the engine is to stay at 2500 RPM.

Flying TIPS:

Take off - 2500 RPM at 33.5 or MAX power whichever is LESS. I reduce mixture such that TIT is 1400 + or - 25 degrees. Usually for me 1425 degrees. Usually throughout the climb but you can pull it back to whatever you feel comfortable with. Sometimes if longer climb then I do 30.5 MAP and 120 Kt climb using FLC mode on AP on all climbs

Cruise - 2500 RPM at 29-29.5 MAP. Push lean button on G1000 and lean to -50 degrees LOP and it should be about 16.5 GPH (Rich is 20.5 GPH)

Descents - I usually reduce power and try to start farther from destination and use 300 fpm if ATC allows. Faster descents throw up speed brakes and less power.  

IAP - if you want to start the approach at 120 -130 kts you need to slow a lot before IAF. Use 2300 RPM and around 18-20 MAP. I just do that until FAF and drop gear and T/O flaps and now 16 MAP or a little lower for 90kt final. Full flaps when I am sure I am going to land. Short final VFR, runway environment IFR.

 

It is all very easy with Acclaim. Have FUN

 

 

[carusoam]

All that being taken care...

On a go-around...

Get practice...

Full throttle probably won’t be necessary...

Full throttle with flaps down on a GA... is a surprise for some... the nose will point to the sky if not held under control...

Remember, a GA is probably not an emergency requiring full deflection of controls... including the throttle...

It takes some amount of force to hold the nose level while re-trimming...

PP thoughts only, not a CFI...

Best regards,

-a-

[Aspen2013]

Good point. That is one of the reasons for full flaps once you are sure of landing or you are going for a wild nose pitch up ride!! Not good in actual IMC.  You are right not an emergency! You don't need to shove it full throttle.  Train in VMC conditions for sure. G1000 is an awesome system. Paired with GFC700 and there is a lot to learn and know what happens on GA and especially if you push GA button. Understand FD. 

[Bentonck]

Aspen thanks a lot for your insight.  I have thoroughly enjoyed flying the plane to date, it certainly is fun to fly!

I went out this afternoon to update the databases and the jeppensen charts in the G1000...everyone at the hangar wants to know all about the plane.  You are right about the airspeed control, that part is all new to me as my time is in high wing planes that slowed down pretty much at will....the Mooney takes some doing.  You have to keep reducing the MP well out to get the plane down.  It is fast... 

Thanks again for your thoughts and insight!

Benton

 

[Bentonck]

And you are right, Caruso, regarding the GA not needing full throttle.  I was more asking as a general "How much MP can I use" ... 

I have read a lot on this forum about trimming in the flare and that is one of the things I was worried about.  I was practicing (with a Mooney pilot friend on the right and my wife in the back) an aborted landing and I found I had a lot more trim in there than I thought when I hit the throttle.  The nose was pointed a lot higher than it should have and I had to fight the yoke until I could get the trim down.... with flaps full and trimmed for a flare you are not set up to go around...

I will practice that a bit more, probably without the wife in the back next time... (she didn't get sick but she looked like she was going to)

 

[LANCECASPER]

1 hour ago, Aspen2013 said:

Some things to remember about this engine: It is a 350 HP engine (on Malibu) that has been down graded by Mooney to 280HP. 

Not true.

The Malibu (PA-46) from 1984-1988 came with a Continental TSIO-520BE engine and was 310hp. In 1994 an STC to replace the Continental TSIO-520BE engine with a Continental TSIO-550-C was approved, however the 550-C was still rated at the same 310hp. (The Acclaim does not use the -C engine, but the -G engine)

From 1989 on, Piper went with the Lycoming TIO-540-AE2A, which was the only PA-46 ever with 350hp, this PA-46 was called a Malibu Mirage and later the M350, which is still in production.

[Aspen2013]

Remember you now have speed brakes!  That’s why a lot of Mooneys have them. You need them. I find ATC, or equivalent in Brazil, likes to keep you high and then descend you like the jets do. Maybe the ground speed you are flying throws them off. But I have to use them every flight. I know some pilots are popping them up just right before touchdown to help reduce floating. 
 

GA - after you now experienced that ride you know why you are putting Down full flaps when you know you are landing. Otherwise it’s Red knob forward, Blue knob forward, Black knob forward just enough to stop descent and flaps one click up to T/O position and then gear up. About as quick as you can read it. 
 

IMC - once on short final I usually already have red and blue knob in position, ALT preselect SHOULD be set to MA altitude and so it’s hit GA button, that suspends, maybe hand fly according to FD , throttle in and gear up. Then activate A/P and  NAV and VS to say 500-600 rpm nose up and you are sitting pretty. Flaps probably going up after 400 feet of climb. 
 

Brave man taking wife! 

[Aspen2013]

Lancecasper,
Thanks for the history of mirage. I heard the story of this TSIO 550 whether G or not I don’t know but a plane out there uses it at 350 or 355 HP version. Do you know which one it might be?

[carusoam]

When you talk to the author of the 310hp STC for Mooney’s IO550(n or g)...

You find out how much HP can actually be handled by that engine... in the range of 500+ (?)

Keeping the cylinders cooled... without extremely high FF rates has got to be a challenge...

PP thoughts only, not a mechanic...

Best regards,

-a-

[LANCECASPER]

40 minutes ago, Aspen2013 said:

Lancecasper,
Thanks for the history of mirage. I heard the story of this TSIO 550 whether G or not I don’t know but a plane out there uses it at 350 or 355 HP version. Do you know which one it might be?

The Columbia 400 (later named Cessna 400, Corvalis and TTX) used the TSIO-550-C at 310 hp, and seems to never get more than 600 hours out of the cylinders. The Cirrus G3 Turbo uses a 315hp version with similar cylinder life. At least at 280hp and flown conservatively the TSIO-550 version in the Acclaim sometimes makes it to half TBO or more before the cylinders need to be replaced.

The experimental Lancair IV, IV-P uses a 350hp version of the TSIO-550 (https://en.wikipedia.org/wiki/Lancair_IV)

There were some versions that were rated to 350hp, but I don't see in which other airplanes they were installed. https://en.wikipedia.org/wiki/Continental_IO-550

 

[Aspen2013]

This engine is strange to figure out exactly what they were thinking. As Benton mentioned the POH states max MP is 33.5 and

max recommended cruise is 262HP

max continuous power is 280HP.

We know in the ovation that it has 310 HP. 

 

Most POH’s recommend cruise at 75% power.  262/.75=350

other wise 75% of 310 is 210. 

33.5 MP SHOULD BE WAY OVER 280hp probably close to 310hp  

 

 

[Aspen2013]

Benton,

 

I am sure you have your techniques for IFR but one last note on the missed approach- The other piece to the landing phase that I evaluate is the runway length. I like to have as little to do after FAF so once configured its stable approach to landing, hopefully,  without having to change much. So real world scenario is that most of these runways are longer ones with RNAV's and ILS approaches. More than 6000 ft. So full flaps is not necessary. If it takes a little longer to touch down and you go a little longer on the runway who cares. Bottom line is I don't use the full lap configuration in hard IMC, too much change at the last part of flight. The plane lands just great with T/O flap setting. Practice that one.

 

Fly high, fly fast and fly safe

[carusoam]

Keep in mind...

HP numbers for the O1 maxed out at 280hp... max rpm was 2500.   Max FF was around 25gph...

Bumping things up... the O3 maxes out at 310hp... max rpm is 2700. Max FF is over 27gph...

The 310hp is at best nominal (a fun name, not based on an accurate measurement). However, It is a seat of the pants difference. And a measurable performance difference...

 

For examples of an Acclaim flying with 310hp... find the writings of Joe Z. around here... he wrote about his ship’s performance a whole bunch...

800’ T/O and 2000fpm climbs... not bad for a nine liter flat six...  

The compression ratio of the TN is also different than the O3’s NA engine...  

So... it’s more than TN’d... it is actually TC’d...   or the limits of MP would be around 29.92”

Maintaining CHTs at high power settings is probably going to take a lot of FF...

PP thoughts from old memories...

Best regards,

-a-

[Bentonck]

Thanks again Aspen, I will keep that in mind and work on TO flap approaches in IFR, that's good advice. 

Heading out to warm up the engine this morning.  We are still in quarentine here but having a new plane sitting in the hangar certainly does put ants in ones pants!

B