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looking to buy 2nd. hand Kitfox III

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Posted (edited)

Hi. I am currently looking at a Kitfox III, built 1992, 1187 hrs on airframe, unsure what on the Rotax 582(oil injected).

Can some one tell me what I should be looking out for?

Are there any 'traps'? due to age or design?

Was this model any good? what were/are it's weak points?

What should I expext to performance when I test fly it (very soon)?

THANKS for any help..........

Edited by The Foz

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Posted

Was this model any good haha It has 1187 hrs on it. I think it proved its self to be a good airplane with no weak points.  you will enjoy it.

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Posted

Model III's are good but not quite as good as later models.  The undercambered airfoil caps the airspeed maximum somewhere around 90 mph and many cruise slower than this (my comfortable cruise is 80 mph).

Is the engine logbook detailed with entries covering the engine's life?  You can tell a lot about how carefully maintained it is just by reading the entries.  When was the last overhaul?  Is it an original engine with 1187 hours?

Grey or Blue head 582?  The original Grey head 582's had a problematic rotary valve shaft seal.  These can be converted to the Blue head ceramic seal with a little machining.  Also, according to Rotax, the cranks are time limited parts which can't be refurbished.  Has the crank ever been replaced?

I'd sure like to look at the condition of the cylinder and piston walls by bore scoping through the spark plug holes as well as the intake and exhaust ports.  Scoring of the walls and lots of carbon buildup on the piston tops are not ideal.  Also, examine the rings as they pass by the ports to see if they're free or stuck and how carboned up they are.

Pay particular attention to the seat truss and longerons where the bungee gear attached.  Most model III's started with the bungee gear even if they were upgraded earlier.  Hard landings with the bungee gear could bend or collapse some of the tubing in these areas.

If I were to fly an unknown plane, I'd sure like to carefully examine all the control linkages.  This requires removing the seat.  You want to make sure everything moves smoothly, none of the threaded rod ends are bent and there's no interference with the seat pan or anything else.  Also, there should be little slop when reversing direction of movement. It is common for control rods to be bent to achieve the proper clearance.

Look for potential issues in the fuel system. Older fiberglass wing tanks subjected to Ethanol gas could leak and might be complete junk.  Sniff for gas fumes when you first poke your head in the cockpit.  If things are done right with proper fittings/ tubing/ hoses you shouldn't smell gas.  If you do get a whiff, these things are fairly easily fixed.

Flying a Model III with 582, you should see at least 5800 RPM static and 6000 to 6500 as you takeoff and gain airspeed.  It should get off the ground quickly, even with two aboard depending a bit on density altitude.  582's with bigger props tend to idle a bit rough.  If it has a GSC wooden prop, you're likely to be replacing it soon.

This is an incomplete list and others will chime in.  In the best scenario you would take someone along experienced with the earlier model Kitfoxes.  Add your location to your profile and maybe you'll find someone nearby.

Good Luck!

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Posted

These airplanes are super simple. There's not much you can't inspect and see fairly easily. I agree that after 1187 hrs they must have done something right. It's easy to tell if one was cobbled together or done right. I saw an older Avid a while back that had nails for hinge pins. Rotax recommends 300 hr overhauls on the 582 but that is fairly conservative, especially if it's flown frequently. The original grey head I had on mine had been zero timed 3 times before I got it. Do you have 2-stroke experience? They are pretty straightforward but have some operating quirks to be aware of. Does it have tanks in both wings? The ones with only one tank of 13 gallons limits you to 2 hrs of flying. Not sure if your mission but I've met several people who wished they had more range. With two 13 gallon tanks you can fly for days. Hope the purchase works out for you. So much fun flying these little birds!!!!

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Posted

Hi Foz,

I think KF model 3's are terrific planes and offer a lot of fun and bang for the buck. You will probably pay a little bit more for a KF3 vs. Avid Flyer, due to better parts availability (but be aware both no longer receive factory support), and definitely pay more for a model 4 (the new wing and factory support is worth it), and generally a lot more yet for 912 powered model 4. Many consider that one of the best 2-seat, folding wing light sport compliant aircraft available. The good news is that many were build since the early 1990's, the bad news is owners won't give them up! If you look hard enough and act immediately, you could get lucky. Of course, all depends on your budget and timeframe.

Sed did a great job summarizing the KF3, get someone familiar with the plane to go on an inspection. I wouldn't let the aircraft hours concern you, absent major damage history, they are really rather simple to maintain and repair. You can also visit www.rotax-owner.com and plug in the engine serial number to get a list of Service Bulletins and Service Letters applicable. The 582 will require overhaul at some point. Parts are readily available to D.I.Y. or, for an idea of third party cost, here is one option: 582 Overhaul Pricing

Best of luck. If you purchase, this site will be your go-to reference. 

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Posted

Thank you all, TJay, Av8r_Sed, C5Engineer & dholly. All good advice & appraisal. I take her for a test fly Sunday 5 June. Looking forward to it.....

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Posted (edited)

Thank you all, TJay, Av8r_Sed, C5Engineer & dholly. All good advice & appraisal. I take her for a test fly Sunday 5 June. Looking forward to it.....

The performance question is a moving target.. how big a boy are ya.  Where are you flying at.  Density altitude plays a pretty good part in a 65 hp plane.  The performance I get at sea level on a 20 degree day is WAY better than at sea level on a 70 degree day.  Throw in some altitude with it and you can have a long take off run and marginal climb out.

I assume you are TD proficient.  Keep your feet alive through the entire flight, lead your turns with rudder to make the adverse yaw from the flaperons go away.  The III had a larger tail to help counteract the adverse yaw, but it was not until the IV that they got the mixer right and got the differential better (more up than down on the roll inputs).

All in all the III is a great fun plane, but if your used to flying a 180 its going to be a big step back on performance, yet a huge step forward on fun.

:BC:

 

Edited by akflyer

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