I have an OT-90 here in the UK. Compared to it's nearest UK equivalent of that era, the FV432, it is fast, fun and easy to maintain. No sure how it compares to an M113 though - never had a chance to play with one of those.
At the time it was a toss-up between the OT or a CVR(T) - no contest as at 6' tall and of ample build I do not fit CVR(T)'s that easily!!
The advantages of the OT over the BMP are additional shock absorbers on the second set of road wheels (does make a difference off-road) and the smaller turret cuts the weight a bit whilst the lack of autoloader means you can easily enter the turret from the left hand rear door. Downside is there is no turret hatch so the gunner has to exit via the troop compartment!
The turret is not powered but the gearing is light enough to operate easily. It's quite spacious in there without the weaponry installed, the main gun does take up a lot of room though - I "borrowed" one from a dealer in 2008 and was amazed at how much turret space it took up. Mind you - the KVPT is nigh on 6' long and nearly half of that is inside the turret....
If you can drive a car you can drive an OT - they are more or less idiot (conscript?) proof. 5 speed manual box, power steering via a tiller bar and either electric or air start. They can be steered using a single finger - the steering is that light!
The clutch can be sharp - so be warned, never have a person stood less than 6' from the front when moving off - unless you want them having the leading edge of the hull embedded in their teeth! First time in a show arena I almost decapitated the arena marshal who stood up close when signalling the move off.....
Performance-wise the top speed is approx 40 mph, on or off road and the economy is around 4 mpg (Imperial). they are
VERY manoeuvrable and it is possible to drift/power slide them......
If you want to use them on-road and all-steel tracks are a problem you can retrofit BMP-2 track pads. A lot of work as the track has to be broken down to individual links and two holes plasma cut to take the mounting bolts. pads are around £16 each here in the UK and there are around 90 required (I forget the exact figure now). Here in the UK that raises the on- road speed to the limit of 20 mph as opposed to the 5 mph for steel tracks.
As B3.3T points out - they are over-width so need to moved on low-loaders here in the UK. Bit of a sore point with me as I contacted the Gov't agency responsible for such things (VOSA) when I bought mine and asked what I needed to do to make it UK road legal - they forget to mention that at 2.9m wide it was too wide for road use as they had changed the rules 9 months earlier! Moral - never trust Gov't agencies!!
To answer the questions then:
How are they as far as maintenance?
Like I said - easy. Provided you have access to either a willing accomplice or a hoist to get the top deck off everything is accessible. 90% of routine maintenance cane done with just the front deck lifted - this is hinged ahead of the swim vane and has a sprung prop to keep it open. This gives you access to the drive-train, brakes, and rear of the I/P for electrical's etc.
This pic should give an idea:
Best thing to do is wander over to eBay and keep an eye on the seller "magnety222" as he sometimes has all the servicing and repair manuals for the BMP-1, 90% are common to the OT-90
Are spare parts available in the U.S. or do the Europeans have the market cornered?
Can't help you there I'm afraid. In the UK there are about 4 main dealers who can source spares. Things like filters etc. are, funnily enough, standard commercial items so no problem there. I would think, apart from weaponry any of the 4 dealers would be more than happy to sell stuff to the US.
On the subject of weapons - the main gun for the OT-90 is the 14.5mm KVPT - I've been trying to source on of these for 3 years now. Not helped by our stupid gun control laws.
Co-axial mount is the PKT - I have this fitted (deac of course). The hull mounts - first one on either side is for the PKM squad M/G whilst the remaining three each side and one on the rear door are for the AK-47/Vz-58. All easily available.
What kind of heavy equipment do you need to work on these?/QUOTE]
Not a lot really - a hoist to lift the armoured top deck off occasionally and some very large spanners/sockets is about it. If you can get hold of the track tools for the BMP-1 series then they are an advantage if you need to split the tracks at any time. Track tensioners are inside each rear door thus easy to access, lift out the left hand (viewed from the rear) troop seat and you have full access to the fuel pump and filters.
In summary - the ones sold here are complete internally - all radios and intercom systems work (radios cover the 27 Mhz spectrum so we can use them with CB radios). Crew helmets come up regularly on eBay but the fly leads that link the helmet to the vehicle and which have the radio switches in do not. you may have search for them. The driver and anyone in the turret seat should be wearing one of these. If running with a commander in the #2 seat they will need one to to talk to you - the engine/exhaust noise is loud to say the least!!
This is my old girl being put though her paces together with a Soviet re-enactment group at the annual War & Peace show here in the UK:
YouTube - Arena display at War & Peace show 2010
YouTube - W&P 2010 - Arena
If you want to know anything else - feel free to ask !