Loss of manifold pressure as I climb. I can maintain about 75% power at FL200, and less as I go higher. I can maintain 100% power to about 10,000' off the top of my head, and it should maintain it to FL210...

I purchased an Aerostar 702P instead of a 2007ish Meridian. Zero regrets after two years. Useful load on mine is around 2140.
Up to 237 gallons fuel


If by fresh engines you mean fresh U2A engines and you have the aux tank then 702P would be a good choice for your mission.

The potential maintenance issues with an Aerostar vs a TBM is known.
TBM 700C2 should fly 285 knots.

YES, Aerostar will fly 255ish knots at FL250 (702P tends to be a bit heavier) at 75% power.

I fly mine mostly 55-65% power. Occasionally 45% and sometimes 75%.

On a longer trip I generally plan on 240 knots, 65% power
about 50 gph
keep TIT at/under 1580

I still a newbie in Aerostar
my mental cliff notes from the guys I consider experts say keeping TIT below 1600 helps turbos last longer

Are you climbing at 100% power? My training and charts call for a reduction from initial takeoff power, 42"x2500RPM, to 37.5x2400 after takeoff. And I start losing MP above ~20k so I wind up climbing at even less than 37.5 up high. I'm also relatively new to the Aerostar (coming up on 2 years this fall), and I just assumed this was typical. Like you, achieving 42" on takeoff isn't an issue.

It has been a few years (alright five) since I sold my Aerostar.
It took me about a year to get the engines pretty well dialed in. I loved the plane.
I do not recall the altitude, but on the U2A engines I could maintain full power to somewhere in the mid twenties.
I am also fairly sure I read somewhere that you can run the U2A engines 100% continuous; with the aux tank you would only have about a 2.5 hour range but you should be pushing around 300 KTAS in the FLs.
Before trying this, check with someone who knows, like Jim Christy.

Tim

Are you climbing at 100% power? My training and charts call for a reduction from initial takeoff power, 42"x2500RPM, to 37.5x2400 after takeoff. And I start losing MP above ~20k so I wind up climbing at even less than 37.5 up high. I'm also relatively new to the Aerostar (coming up on 2 years this fall), and I just assumed this was typical. Like you, achieving 42" on takeoff isn't an issue.

Might be a dumb question, but how do you have the waste gates set up? When you actuate them, are the rod end holes past the closed position of the waste gate?

Does the actuator have the tiny restrictive fitting still? They the fully open on, easy change out.

Run a new line from the controller straight to the actuator.

How tight is the seal on your alternate air door in the air box?

Have you tried another intercooler? I doubt it has an internal leak, but you’re loosing air somewhere.

Have you taken the intake air tubes off everything and checked that they are okay? You would have known if it was turbos by taking them off, if there was no oil, that wasn’t the issue, sorry for wasting all that money.

I have not tried another intercooler. It is a turbo control issue. It makes almost full power (41.5" vs 42" at 17,500') when the wastegates are tied fully closed and test flown.

You didn't tell me you had "the Shultz STC'd actuator filter." That is a very restrictive porous bronze filter. I will go out on a limb and say that is it. In any event you need to replace it with the Aerostar waste gate actuator filter and clean it every 50 hrs.

I agree with Jim, that’s why I said run a new line that bypasses the filter. I’ve seen some actuators without the kit, and they put in an oversized fitting (same as the return side).

If you’re making full boost at 17500, I’d venture to say it’s not an air leak. With changing out the controllers and not having a change, it can only be the lines that control the controller or the actuator. I think you said you did the manuals leak check of it, you could always throw another one on to rule it out.

I’d personally bypass that filter with another hose, and make sure there are no T fittings that could be bleeding pressure from the actuator system. I’d also replace the line that goes from #2 cylinder to the controller. Maybe Jim can chime in but consider pulling that air from another cylinder?

There is the Marsh Brothers Aerostar Seat roller mod kit that is now available and makes the renewal of the rollers easy.

Sandy

I thought I mentioned that, but maybe it was to John that we talked about it. I've been cleaning it in an ultrasonic cleaner every 35 hours.

I took the element out of the canister last week and we'll see on Tuesday's flight if it makes a difference. I verified the restrictor fitting was clean again last week after we talked.

After our last discussion I swapped controllers with a used one (your 8130 guy was on vacation last week and John had none), and it didn't make a difference. It also wasn't the cause of oil leak, which I found and fixed.

Thanks!

So you have isolated it to a controlling system problem. I think it is safe to assume that the oil pressure building up in the actuator is not high enough to close the waste gates completely. It takes about 45 psi. to do that. The oil flows in through the .049" orifice. which is why you need a filter in that line, and then flows out an unrestricted fitting to a #4 or 6 line to the controller which restricts the flow of oil back to the sump, allowing oil pressure to build in the actuator. When the oil is cold the #4 line is more restrictive than the controller which is why the hose was changed to a #6. The bottom line on the actuator returns any oil that gets by the actuator piston seals to the crankcase, so that needs to be checked for oil bypassing the piston seals preferably with a pressure pot filled with 10wt. oil (that is going to be as thin as 50 wt. when 90 degrees C) because any leakage will also reduce pressure build up. A flapper in an oil supply hose could also cause your problem or any combination of the above. A leak in the hose from the front cylinder will cause the engine to not turbocharge. I suppose a tiny leak in that hose could cause the problem but I have never heard of that. I have seen the cylinder fitting carbon up and that caused surging. Putting in a larger orifice of say a .070 could be a work around for something else not being in spec. but it will cause a mismatch in throttle sensitivity and I don't recommend it. I think you are on the right track.

I have verified the restrictor fitting is in the proper port in the actuator. Thursday we had an ah-ha moment and I checked the actuator with pressure to verify that the there was no leak through the actuator, which there wasn't. The #2 cylinder did not have the restrictor fitting installed when I bought the airplane, but I ordered them (#5 for MAP also missing) from Aerostar and installed them, so I've had the same result with no restrictor fitting, and a new one. John (parts) figured that one out. Thinking back on it, I believe I have the #6 hose between the actuator and controller as both oil lines took a 11/16" wrench and both air lines a 9/16" wrench.

All of this leaves me with it being either the filter, or a hose restriction. I'll know after Tuesdays flight without the filter element installed. If that's the case, I'll have a huge smile on my face Wednesday when I call John and order the Aerostar filters!

Right now, I clean the Shultz elements every 35 hours (at oil changes) by flushing them in a dunk tank with mineral spirits, then they each spend about half an hour in an ultrasonic cleaner. That was last winters ah-ha when I found one that I couldn't blow through after cleaning. John in parts mentioned the restrictions then, but I never got around to, or remembered to just plain removing them for a flight.

The one good thing about this airplane is I've found and corrected issues with every part of the turbo control system that I've looked at. Unfortunately, I haven't had time to just rip into the system and replace everything until the problem goes away, so it's been find an ah-ha item, put it all back together, fly it, and go on to the next item after my next two weeks at work...

Between Jim, John in parts, and Ken Bacon, everyone is probably sick of hearing from me with this issue! I will say everyone had been great to work with though, much better support that I've had with other manufacturers!

I had a similar issue in my 601p. A hose clamp on one of the turbo inlets was loose. Wish they were all that easy.

Noticed this guy rocketing into an airport near me the other day. 323kts over the ground in the initial descent. That's hauling butt for a piston twin.