Im not sure if this one counts.  I wasn't flying this bird, I was only a passenger.  Flying from CYVR to CYYC in a 737, climbing up to FL220, the cabin got REAL HOT!  All the passengers got anxious, and were fiddling with the blower valve thingy on the top.  The captain reported that the aircraft has lost one of its air conditioning pacs.  

At that time I wasnt too sure what it was, and im sure most of the passengers didnt either.  Few months after, I was taking an Aircraft Systems course, and found out that on the 737, if you lose both pacs, that plane is decompressing!  At higher flight levels, that could be a scary thing... especially if you don't reach the oxygen mask in time.  Good thing theres two...

The heat was actually from the engine bleed air... which my word, is really quite warm.

The closest thing to a real emergency I ever had was a smoking transponder aboard a C172 while on a PP training flight. Fortunately, we were very close to the home airport (TEB), and it never smoked very much, but it was a little nerve-wracking as we expected the thing to fill the cabin with smoke at any moment, which would've been a very bad deal, as we were pretty low over a congested area. Didn't know until later that it was the transponder (tower radar was actually still getting our squawk!), so we had no idea what device to shut down. It was just a vague trickle of smoke coming from under the panel, smelled like an electrical device overheating.  So we just made a normal approach and landing.
Only other thing was an alternator failure in a different Cessna... stopped somewhere for a few hours and didn't know anything was wrong until the plane wouldn't start. I'd had just enough juice in the battery to use flaps on approach earlier, I guess. I'd seen the warning light on takeoff that morning, but this particular plane had a reputation for false readings on that circuit, so I just reset it (stupid? Yes!), and didn't see it again for the remainder of the flight. Good thing the battery was too low for me to start the plane later, or  I would've probably found myself suddenly approaching TEB w/no transponder or radio ("let's see, what are those light-gun signals again?")

Auto-rotation in a Puma due to some rather nasty engine related problems (read bits everywhere they shouldn't be from the gearbox). That was scary, only because I was the loadie not the pilot so I had no control of the situation

Back in the good 'ol days of working on my license, we were doing my first night XC.  About 3/4 of the way through the first half of the trip we started losing electrical power, the battery was on a constant discharge and we weren't getting enough power from the alternator.  So, since we had to get gas, just shut down everything we didn't need.  Which, was pretty much everything except the radio.  It was a clear night and the moon was out, so I could make out large hills, lakes, and all that.  Once we got gas, the engine wouldn't start!  It'd only turn over once... so my instructor told me what to do, and he  hand proped it...  on the way back it was a bit more dark as the moon was almost gone but it was still pretty cool. 
We still had enough power to get the landing lights, nav lights, and flaps down... so that was good.

I've also had the engine choke up several different times due to carb ice.  I first noticed it in the rudder pedals actually... they had a funny vibration to them, then about 5 seconds lader the engine started to sputter... put on the carb ice, RPM dropped, then slowly rose another 60 or so RPM... man it's good to k now the things you read about actually work!  So, every other time I felt that odd vibration in the pedals, I just added carb heat, and the problem was gone.  Oh, and each time, the OAT was aroun 60*. 

Nastiest thing ever happened to me was a go-around...

Go-arounds are fun though...

Cheers,
Ashar

Quote:


They better have diverted to the nearest alternate!

i want shore if i where  there but.
about 5-10years ago, My dad was about to jump in a cessna.
He heard a load grinding sound. He then turned around and ran to a T-28 trojan.  I arnt shore what happened next.
But the last pilot on it had bumped the landing gear switch
when the engine was off. When the next piot got in and started the engine, all of the hydrolic pressure came back.
Raised the landing gear and then the propeller grinded a hole
1metre deep into the ground!.

cya