Postby Petrodactyl » Thu Aug 13, 2009 5:16 pm
Hi ZU-no plane yet
I trust my 800 hour 503 to do the job I ask of it. The motor is about as simple as it gets mechanically, and that means less to go wrong. Many have flown to well over 1000 hours without a problem.
However, you have to understand that reliability is not just a factor of the make or type of the engine. Many factors affect how reliable an engine will be. Among the major ones on the 503 are:
1)How often the engine is used - more often is better, because a 2 stroke engine is lubricated by the oil mixed into the fuel, and a regular dose of oil reduces corrosion in critical components like the crank bearings. Also, fuel degradation (from standing) can cause detonation engine damage.
2)Prop balance, and the type of gearbox fitted. - The old B-boxes are less forgiving with prop weight and pitch imbalance, that can lead to more stress on the crank and premature failure. The C and E boxes have a rubber 'donut' drive coupling, which transmits less of the prop forces to the crank. This is also more forgiving on the crank in the event of a prop strike.
3)Maintenance and inspection (Perhaps I should have put this first). Not cleaning air filters or checking them for damage, not changing plugs at recommended intervals, not checking and tightening the cooling fan v-belt, not setting up and maintaining your carbs correctly, not checking fuel for dirt or water, not decoking the engine at the prescibed intervals and so on - all can lead to major engine wear or damage, which is not obvious from an external inspection.
When buying second hand, it is very difficult to determine whether the previous owner(s) have been consciencious in their upkeep of the motor or whether the aircraft has stood unused for long periods. Hopefully the log-book will be an honest reflection of the engines life. But you can get a feeling for what kind of treatment the engine has received by carefully checking (or having someone else who you trust check) the rest of the airframe. Owners who care about the airframe will in all probability also care for the engine.
I, for one, appreciate the skill and wisdom of the AP to whom we entrust the repair and maintenance of our aircraft, but it is me who will be flying the thing. So I believe I have a duty to myself, to those that care for me, and to aviation in general to know as much as I can about the aircraft, and especially the engine.
One other consideration with the 503 is where you will be flying with it. Here near the coast they are plenty powerful enough, but if your airfield is anywhere above 4000 ft, consider a 582, because 2-up on a hot day, a 503 becomes marginal.
Hope this helps. I am sure that there are many others out there who can help as well
Christian
Christian Carver
Go Fly a Trike!
ZU-BBU
