I haven't flown one, but do know, (from many who have flown), that they are very under powered. The joke is, they can't get out of their own way
I have been looking at purchasing one as well. What I have been taking into consideration are the conversions. The Apache, (I think), has 150 hp a side. This doesn't provide for a very great useful load or performance if you loose an engine. As a matter of fact, I don't believe you will even maintain alt if you loose an engine, (depending on load). Even if loaded with one pilot and no baggage and light fuel, you will not be impressed with performance on one engine. Back to conversions: In my Apache searching, I found many Geronimo's. A Geronimo was the 180 hp conversion. I noticed you could find an Apache without any conversion for around 40k. Geronimo's around 60k+ with an average of 80k.
There is nothing wrong with an Apache. They are good planes, and in fact can make good trainers. They are one of the best assymetrical planes (meaning it has a critical engine). There are some things you should know about them though.
They have a lot of AD's, so study them good when look at them. One of them can cost you a lot of money. Depending on the hub system on the props, there is an AD that comes every 250 or 500 hours. Try to find one with the 500 hour hubs. Otherwise you'll be pulling props off every 250 hours and having the hubs checked and overhauled. With the 500 hour ones, at least you can enjoy your plane for a while longer. You could opt for the prop conversion, but it will run you roughly $ 6,000 per prop and that will do away with that AD. Most can't afford that. Just make sure that you have a savvy mechanic ready to tackle those AD's and any problems that will arise. Remember these planes are getting close to 50 years old, and some out there have been neglected. Find the right one and you'll have virtually a trouble free economical twin to fly around.
The one that I teach in is one of my student's planes and it has had a few minor problems, but it is very reliable. Engine out procedures at 5,000 or 6,000 MSL aren't too bad at all. You more than likely won't maintain altitude, but maneuvering around on one engine is easy. It handles very gently. At lower altitudes it can hold altitude and though it is one of the best handling critical engine aircraft, be careful. The lower your altitude, the higher your Vmc speed will be due to more dense air for your engine to breath, and your prop to bite. Single-engine go arounds are not even an option. Don't even try one. I watched one of the other Apache's on my airport try one and he lost at least 50 feet flying over the 5,000ft runway on a standard temp day. Better to put it in the grass somewhere than to attempt that go around. Chances of a engine failure in an apache are slim to none. The 0-320 engines are some of the best engines ever made. Keep your guard up in there anyway.
One thing to ask yourself is where are you going to fly the apache? Are you near sea level, or at higher altitude airport? Apaches make great valley airplanes, but lousy mountain planes due to being underpowered somewhat. You don't want to be crossing a mountain range somewhere and risk losing an engine, or factor in single engine service ceiling. The airport density altitude may be higher than your Single engine service ceiling. So if you plan to fly the apache near sea level airports, I would recommend buying one. Just shop around and you'll find a nice one out there.
I owned a 1/5th share in an Apache from 1991 to 1997. It was a 1956 model with the 150hp O-320's. There was plenty of power in those engines. It is true that if you load up the Apache to max gross, or even something a little less that you won't be able to hold altitude, but with 80 gallons of fuel and two people it will maintain at least 3,000 feet.
My take on the engine out performance is this...If you lose an engine, you need to get down and land. Having the other engine operating will increase your glide and decrease your rate of descent as compared to a single-engine airplane. Do you currently fly any singles at all? What is the engine out performance in those? What altitude are you able to hold in a single with an engine failure?
As far as the weight capacity...I have taken off with 4 adults in the plane on a 70 degree day from South Lake Tahoe airport (elevation about 6300'). Not the greatest performer, but it sure did the job.
After I sold my share in the plane, I figured out how much it actually cost me to operate over the years I owned it. It came out to just over $55/hr (this was when gas was, at most, $2.15/gal). Doing pattern work I had the burn at 5.7gph/side. On longer flights it was more like 7.1gph/side.
The interior is roomy. The backseat took about 1 minute to remove if more cargo room was needed. If need be you could even sleep in the plane with the backseat removed.
I was very happy with the airplane overall. I had a good group of partners who all helped out to work on the plane to keep the maintenance costs down. If you've never owned an airplane before, consider what your time is worth. Would it be better to save a little money and have an airplane that could be down for weeks, or to pay the extra money to rent an airplane?
For me, it was better to own. Not only did I learn a lot about the mechanics and systems of the aircraft, but I built up those ever-important multi-engine hours that helped me gain meaningful employment as a pilot.
I am gonna have to agree with my good firend GP. I have about 70 hours in one with the 160-hp engines.
The payload on that one was 795 with the tanks full so you can carry 4 FAA people plus over a hundred pounds of bags. Never had the chance to load it up that much but I wouldn't have had any problems with doing it. Yeah, you would probably drift down after an engine failure at max gross but like GP stated, if you lost your engine in a single you would have the same problem. That extra engine will buy you some more time if you know what you are doing.
As far as training, I am glad I did my initial multi training in the Apache instead of a counter-rotating prop trainer like a Seminole or Duchess. I learned from the start what a critical engine was (especially because the only aircraft had its only hydrualic pump on the left side). The thing felt like a truck but it flew great. Landings were easy as long as you kept your speed on target.
One of the best things about the aircraft is the low fuel burn. I was getting less than 12pgh total for cruise which, with 108 gallons usable allows you to fly longer than my bladder will allow. I think I was getting like 140mph TAS during cruise if I remember.
Anyway, if you are getting one I would look out for the prop AD as the other stated. Additionally, try to get one with an STC for the alternators and a hydrualic pump on the right engine.
Coming out of an Aztec I used in training, I was half scared to death by all the various "experts" around the airport about the "underpowered" Apache.
When I got checked out in it, I found a delightful little brother the the Aztec. Just as soft and easy on the controls. Plenty of power in one of those engines. Just a hoot to fly. Talk about cheap twin flying with a critical engine and hydraulic systems to worry about - it is a great trainer and timebuilder.
Hard to find one with something near a standard "six-pack" instrument cluster (i.e. arranged in the modern standard configuration), but just a wonderful airplane. Generators can play havoc with modern avionics when added to the stack (read voltage fluctuations may affect performance).