Hi,
nice to hear the 600h limit on the airframe no longer exists.
For the wing spar. Only the the section crossing the fuselage is nitrogen pressurised and it's part of the 'Before Engine Start'- Checklist to check for pressure. The one that lost a wing in 1992 had a problem outside this section at the fittings, where the wings were bolted. AKAIK it was the only 142 ever loosing a wing.
For the engine. It's a nice design, supercharged with a fuel injection, it starts like the engine in your car. Just push the starter button and it runs. I never met an aircraft engine, thats so easy to start. Mixture is pressure sensing, works automatic. Avia prop is constant speed.
The aircraft is designed als a military trainer for basic and advanced training.
It's easy to fly for a low time pilot and has lots of performance for the advanced pilots. And for the aerobatic experienced pilots, it spins like hell.
It's definetly a lot more fun than flying a C172 or a PA28.
Joe