Aviatorvette,
Spinners don't crack from ground handling. That is, if you pulled the airplane by the propeller, it wouldn't crack the spinner. It's possible to bend the back plate by pushing on the spinner, but even if that occurred, you wouldn't likely have seen cracks on your flight.
Without seeing the spinner and knowing where the crack originated or what exactly the owner of the flying club is talking about, it's very hard to discuss in detail the cracked spinner. However, most commonly they crack because they're improperly installed.
A thousand bucks is steep. You can get an STC fiberglass spinner for the same airplane, which will outlast the metal one, for about seven or eight hundred bucks. If it's just the spinner dome, it's about three hundred bucks
http://www.aircraftspruce.com/pdf/20...l/Cat08180.pdf
COMPOSITE SPINNERS<br> FOR PIPERS & CESSNA'S from Aircraft Spruce
HOWEVER, don't ever fly with that operation again. The owner of the flying club has no business at all trying to throw that cost at you. I'd tell everyone you know to stay away from that place. Things break in airplanes, and airplanes are expensive. If the owner doesn't understand this, then he has no business being...in business.
You'll note the commentary in the Aircraft Spruce catalog cited above that it's not uncommon to see a spinner failure within a few hundred hours on something like a Cherokee. While that may be a bit of a stretch, as I've often seen spinners go the life of the engine, it's also true to an extent...a cracked spinner or back plate (bulkhead) isn't at all uncommon, either.
WagAero has the spinner for about three hundred fifty in aluminum...and that's the whole assembly, back plate and all.
Wag-Aero Online Store - September 2009
It would seem the owner of the aircraft or flying club doesn't have a clue, and is making an effort to rip you off. don't let him do that.
Cracks originate in one of three places on spinners. The back plate itself, an attach screw hole, or in the smallest radius of the propeller cut-out. Often it can be something as simple as a scratch that caused it, or a little nick. It's called a stress riser, or a point at which the stresses on the part become concentrated, and eventually the part fails. It may be that someone overtorqued the attach screws, or failed to use plastic washers under them and instead used metal washers on an aluminum spinner. I've even seen people do boneheaded things such as use lock washers under the screws...guarantees a failure.
People frequently slip with a screwdriver while attaching or removing the spinner. They gouge or scratch the spinner, and there's a stress riser, waiting to crack.
When spinners crack, it's not uncommon for them to come apart under the stresses of operation, and leave the aircraft entirely or in part (the latter usually causing a lot of vibration).
I certainly wouldn't cough up a thousand dollars to pay the individual who's demanded it. I don't think he has a right to do so, but then you'll have to look at the policies at the place you fly. Unless he can show that you damaged it, then he should pay for it as an operational expense. You need to be able to look at the spinner and see what crack he's talking about, the size, nature of the crack, where it originated, etc.
You asked about "getting out of this situation." That's easy. The school is making an unreasonable demand. Don't pay it. Refuse. Fly elsewhere. If a school pulled something like that on me, I'd be out of there so fast the wake turbulence would rock the airplanes behind me.
You indicated that you didn't see a crack in the spinner after the flight. Did you post-flight the airplane? Most pilots, especially renters, don't. A post flight should be every bit as thorough as the preflight (and the preflight should always be very, very thorough...treat it like your life depends on it, because it does).
Whether you squawked the item or not is really irrelevant. Had you squawked the item, how would that be any different than not squawking it? If the school believes you damage the airplane, squawking the damage doesn't make it less damaged...therefore the argument by the school that you're responsible because you didn't write it up is meaningless and irrelevant.
The argument that it showed up after your flight is also largely without merit. If it happened during the flight and the spinner didn't come off...of course it's going to be seen after the flight. If not you, then the next guy. Chances are that if it did break on your watch,then it could just as easily have broken during the previous flight with the last guy, or it could have waited until a week later and failed on someone else. It's an airplane. Parts do break, cracks do develop, and that's life.
To be quite honest, if you're sure you did nothing to that spinner (and save for pushing really hard on the spinner, repeatedly, over time, it's very, very unlikely that you did anything to cause cracking...the owner is an idiot and should be blown off.
Does your school have a damage waiver or language in the rental agreement/contract which specifies who pays for what, and how much? The school owner is trying to grossly overcharge you, but even if you do end up agreeing to pay a portion of the cost (at this stage, there's no way I'd consider paying for it), check the documents to find out just how much in dollars and percentage of cost is applicable to you. Don't let this guy walk all over you. See if you can get some photos of the spinner.