Correct way to descend (503)

[XP503]

Hi guys. Does anyone out there know the correct way to descend with a 503 i.e what power setting? Do I go full idle for 500ft then power up to get temps then idle down another 500ft, or do I pull back to about mid range 3800rpm and cruise down. What is best for the engine? Thanks

 

 

[Doug Evans]

I try to fly down with my 503 & 582 maintain about 3800- 4000 steady descent keeping the temp warm That seem too work for me ... Cheers

 

 

[turboplanner]

If you think of the combustion chamber temperature being about 1,000 degrees, it's not good for metal to be rapidly heated and cooled, one minute working with very loose clearances, then with very tight clearances.

 

Little $250.00 stationary engines, governed to a constant speed often exceed 1,000 hours, so that is probably a pointer.

 

When you get into detailed analysis with the right equipment its amazing how much all of the engine is flexing, including the block.

 

Isuzu were testing their truck engines to get longer life, and found the skirt area of the block didn't stay rigid, but flexed so much that the main bearing loads were continually changing from one end to the other. They stiffened the block with a ladded frame about 40 mm thick, sandwiched between the block and the sump - and got a massive jump in engine life - from about 500,000 to about 760,000 km on bench tests.

 

 

[horsefeathers]

If you have time, watch this EAA video, "Is your 2 stoke engine about to fail?" - It has heaps of info about running your 2 storke

 

 

 

[Doug Evans]

Very good video thanks .horsefeathers .,

 

 

[facthunter]

A longish idle descent with a two stroke on premix means it ends up with little oil in it as well as cooling off. Leave as much power on as you can comfortably do and allow your speed to increase a little as long as this is not a safety issue with VNE etc or turbulent conditions. Nev

 

 

[horsefeathers]

A longish idle descent with a two stroke on premix means it ends up with little oil in it as well as cooling off. Leave as much power on as you can comfortably do and allow your speed to increase a little as long as this is not a safety issue with VNE etc or turbulent conditions. Nev

Exactly!!

 

I watch my EGT temps, and they are always tending towards the lower range, until I start descending, with low power, and they can climb very quickly.

 

I try to keep power up above 3500 rpm, with the nose raised a bit, so that the EGTs stay in a comfortable range

 

 

[ausadvance]

Exactly!!I watch my EGT temps, and they are always tending towards the lower range, until I start descending, with low power, and they can climb very quickly.

I try to keep power up above 3500 rpm, with the nose raised a bit, so that the EGTs stay in a comfortable range

This is what both Wayne and Phil Stonebank always taught me. the temp doesn't get that high in the 2 stroke for it to be a problem over oil flow, so just keep your revs up at your cruise range if you can without exceeding VNE, and just enjoy you increased speed and let the engine enjoy its feed of oil.

 

 

[XP503]

Thank you so much for this info guys!!!!