June 22, 2003 at 11:50 pm #605
Operating the Lycoming G0-435/ GO-480/Go-540 Engines
The Lycoming geared engines have acquired a bad reputation over the years, quite undeserved.
These are very solid, reliable engines, but only if operated correctly!
Operated like the engine on your Cessna, they have a tendency to be quite short lived, and very expensive. Treated with care and flown by someone who knows how to operate the engine, they reliably make TBO time and time again.
Tips to make TBO
This information has been derived from conversations with very knowledgeable people. Freight operators, Lycoming engineers,
Aero Commander old-timers and many Lycoming Shops.
In a nutshell, the secret to long life of your GO-series Engine is to Never Ever let the air turn the prop!
The Lycoming planetary gearbox is pretty stout, things really begin to bang and clatter if you dont have a solid, positive power setting.
Always keep the manifold pressure up.
You will be able to hear the gearbox whining if you come down final at too low a throttle setting.
Dont push the prop levers forward upon arrival at the airport.
This probably goes against everything you were ever told by your instructors, but when running a GO-series engine, youll be doing the gearbox a BIG favor by keeping the RPM back at 2700-2800 rpm until landing.
If you need to go around, it is perfectly safe to advance the throttle fully before bringing the RPM up- unless you are running a supercharged engine, GSO-480, ect.
Keep your idle speed up, below a 1500 RPM idle will chatter the gearbox causing rapid wear of the outer planetary ring gear, a $3500.00 part
Move the throttle VERY SLOWLY!
Lycoming recommends a minimum of 30 sec. from fast idle to takeoff power.
Follow this rule when going the other way, go even slower.
If your GO-series engine has a Bendix pressure carb, follow the operators book: maintain Full throttle during climb. The Bendix carb. has an auto-rich compensation circuit that allows the engine to run rich at full throttle setting, if you pull the throttle back during initial climb, the carb goes auto-lean and you will risk over-temping the engine. Again, follow the book!
This is the single biggest killer of any aircraft engine. Lycoming engines especially, suffer greatly from non use. Corrosion on the cam lobes, cylinder rust, and valve damage occur rapidly on engines that dont run frequently.
How to tell if you need an overhaul,
There is a service bulletin that specifies an allowable play measured on the prop. You are allowed ½ in play 4ft from the center of the prop hub; make a pencil mark at the point on the blade. Place the tape measure on the ground with one blade in the horizontal position and measure how much free play you have in the gearbox (move blade up and down)
If you have a distinctive stop at each end of the range of movement,
chances are that everything in the gearbox is OK. If there is more than one clank or contact when moving the blade around, the plate that holds the stationary gear may have partially sheared the attach bolts. Worn gears are not going to self destruct, but if that stationary gear shears the bolts, then the whole gearbox may come completely unglued!
I have heard that it can be pretty exciting.
A CW turn-clunk, CCW turn-Clunk check is always part of my Preflight.
Follow the above steps, and you will have a happy motor.
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