Max Gross with an O-320

[CraigS]

I am looking to purchase a Cozy Mk iii that has been upgraded to an O-320 Lycoming. However, the aircraft was never put back into "phase 1" to validate a new max gross weight. The POH, therefore, is still advertising 1500 lbs (1600 max under certain conditions). Currently I'm told the empty weight is 1136 lbs and I'm concerned about that narrow of a useful load. Has anyone gone through this process? If so, what were you reasonably able to achieve? Would the gear be able to handle 1800lbs? Any performance considerations with the increase?

Thank you in advance!

[Marc Zeitlin]

7 hours ago, CraigS said:

However, the aircraft was never put back into "phase 1" to validate a new max gross weight.

Minor nit - there is only ever one Phase I. If a major change is made, there are two possibilities (and the OL's need to be checked to see what they are). Either the AWC is invalidated and a new AWC and OL's must be obtained (fairly old OL's require this, from the 80's and early 90's) or some test test period to re-establish compliance with 14 CFR Part 91.319 must be flown, with or without contact with the FSDO, per the OL's.

Consult the OL's to determine what the rules for THIS plane are.

7 hours ago, CraigS said:

The POH, therefore, is still advertising 1500 lbs (1600 max under certain conditions). Currently I'm told the empty weight is 1136 lbs and I'm concerned about that narrow of a useful load. Has anyone gone through this process? If so, what were you reasonably able to achieve? Would the gear be able to handle 1800lbs? Any performance considerations with the increase?

1136 lb for a COZY III is pretty high. There are certainly IIIs flying at that empty weight, but I'd want a new W&B performed to determine if that's REALLY the empty weight - most planes are heavier than their owner/builder think they are. And a 364 lb payload leaves you with one person and 3/4 fuel, max, which is pretty useless for a COZY III unless you just want to cart styrafoam around with you.

Asking what folks were "able to achieve" is the wrong question - folks have flown Long-EZs and COZYs at 2200 lb. MGW. They fly like pigs, climb like pigs, and a hard landing will beat the crap out of the gear. However, many folks fly LEs and IIIs at or around 1800 lb. MGW, and if you're careful about landings, the plane will last a while. More weight means lower climb rate, longer takeoff and landing rolls due to higher speeds, and lower cruise speeds. You can choose to change the MGW to anything you want, as long as you test to it. But with the very high empty weight, with one 200 lb. person and 1/2 fuel (150 lb) you're basically at 1500 lb., so you're pretty much always flying at or near the original MGW. So you just need to keep that in mind.

[Kent Ashton]

I will just add that the Cozy III was not designed for heavy people. (used to own one).  Nat and Shirley Puffer were little people.  It is just a Long-ez with a side-by-side cockpit so visualize two people in the front seat of a Long-ez.  I was about 215 and I flew with a few people that size or heavier.  However, I didn't want to have to do an off-airport landing at that G.W.   I don't recall the weight but I suppose I flew it in the "takeoff only" zone a number of times.    I did everything I could to reduce the G.W--smaller battery, moved the battery aft, removed the starter (later used a Skytech starter), lightweight alternator, but there is only so much you can do.  Mine used an O-320 also. 

[Marc Zeitlin]

8 hours ago, Kent Ashton said:

I will just add that the Cozy III was not designed for heavy people. (used to own one).

Which version of heavy person did you own? I've been looking into getting one or two...