A properly maintained and sorted out Aerostar is very reliable.

I fly 150-200 hours a year, the only time I've been stuck is if something pops up on a one day maintenance visit.

I put 350 hours on mine in two years. I only had two unscheduled events that I recall. A starter failed, and an alternator failed. The alternator was a little more involved and took a few days.

Tim

Forgive me for asking Forrest a question hereon, but it may add to the "interest" of the thread.

Forrest, you have "insinuated" that you can keep your TIT's reasonable running LOP.

As you know, I don't run LOP for reasons I'm simply NOT going to discuss AGAIN.

But! , Saturday, I flew over to Guntersville to meet a couple of friends at the Starman auction of some interesting aircraft. I was tooling along at low power, as usual, at 7.5 truing 190 and decided to see if I could lean and power down to get 10 mpg . At 22/22, about 50% power, I started leaning from TIT's of 1575. The TIT's jumped then started down but not before roughness settled in. I never got the TIT's back below 1600 without roughness.

Yes, I have GAMI's.

What are the numbers you see?

Jgreen

John, it may seem like taking a walk on the wild side, but after you've spent a few hours there, what seems unnatural (at first) will seem normal, or even preferable.


I generally run 26-28" and 2200 rpm

Up high (FL230-250) highest TIT is 1645 FF is 12.3-12.7GPH/side.

Down low (5-15K'), %#$@ are 1590-1610, I run a bit higher FF, around 13-13.5GPH.

I do not notice any significant roughness LOP.

IF you are feeling some, your GAMIs may either not have been correctly matched to your motors or they may have been swapped around at some point.

Quickest way to see is to lean slowly (at a lower power setting to keep %#$@ within limits) and see at what FF each cylinder reaches peak EGT. Do the check by moving the mixture in one direction and use the actual temps not any kind of 'lean find' feature.

IF you have a largish Delta (FF) between cylinders, especially between first and last, running ROP (leaned) you may have a cylinder running in the red box.

Once you have your numbers you can verify the letter code on the injectors and either swap cylinder to cylinder or with GAMI to get a tight(er) GAMI spread which should eliminate the roughness you are feeling LOP.

You ought to be able to get the Delta down to less than 1/2 gallon difference between first to peak and last to peak.

This may be review....

APS 101:
The roughness you may feel as you lean past peak EGT is caused by different power output from different cylinders due to different amounts of fuel entering the cylinder.
ROP the power curve is pretty shallow, variations in the amount of fuel don't produce much difference in power produced, LOP the curve is steep, small variations produce noticeable differences, which you feel as vibration.

GAMI 101:
If a cylinder is peaking at a lower FF than the others go to an injector with a letter code closer to A, if a cylinder is peaking at a higher FF, swap to an injector with a letter code closer to Z. The folks at GAMI can assist on how much of a change is needed to tighten up your GAMI spread.

Took this this AM:

http://www.youtube.com/watch?v=xw_6YBZWEwQ


5,000' LOP

28"x2200 14GPH/Side (approx)

180KTAS

CHTs less than 300.

I think highest TIT was 1570.

Smooth

Come over to the Dark Side (we have cookies)!

Forrest,

I had the GAMI's installed so there was no "switch a roo". Best I could tell when I checked soon after installation, I 'm down to a on gph delta.

The big problem is that my mixtures are super, SUPER, sensitive. Leaning to any fine limit is a hassle that I won't tackle.

To me, it's just more trouble than it is worth, though your numbers are pretty impressive.

Thank you for the response though.

In reference to the comments on the cost of A* maintenance, after four years, my total maintenance bills amount to less than the first four years of maintenance on my Mooney Bravo. If there is something I'm not doing, my mechanic, the Aerostar manuals, and the Aerostar gurus Ken Bacon and Jimmy Mullen can't tell me what it is.

Jgreen

Going LOP in a twin is an amazingly quick and imprecise procedure (less than 60 seconds, total).

Level, set 25", pull props to 2200 (MAP comes up to 27-28), manually sync the props, pull one mixture until the props momentarily unsync, then pull the other prop until the props momentarily unsync again.
Maybe add a couple inches of MAP if %#$@ allow.
That's it.

Getting to peak EGT for each cylinder takes a bit of time, set a moderate power setting, and watching each individual EGT slowly lean until the cylinder you are watching peaks, you'll need to do it for each cylinder.

Then you'll know what's going on.

GAMI has a recommendation as to what injector sizes should go on each cylinder on an IO-540, but that recommendation is really just a starting point for figuring out what is the correct injector for each of your cylinders.

If you didn't go through that process when you put in the GAMIs you aren't getting their full benefit.

Got an HD version of that video?

Here you go:

https://youtu.be/3dF5NsaBLz4

I'm working on one with some electronic stabilization

Here it is:

https://youtu.be/yWlYuvLG1oY

Nice. Sounds almost turbine smooth.

Forrest,

When I finish this new house , you and the Mrs. come down for a weekend and we will wrestle that goat together, my A* I mean.

As for the house, it won't be much longer, I don't think.

Jgreen

Here is a quick LOP Demo (HD)

http://www.youtube.com/watch?v=gSKbL46ZHBs

Here is a video in cruise at FL200 between Norfolk and Lexington, KY this morning.

Generally in the Area of Lewisburg, WV.

http://www.youtube.com/watch?v=ZaZzDfoSvfM

LOP

About 26.5-27GPH
Speed between 207-210KTAS
About 120 gallons of fuel
Two occupants