PA-31-350 Cylinder Temps

[Skymac]

Just curious for those out there most experienced with Navajo operations. I’ve already heard they tend to run hotter. After all it’s a big ol’ plane those 540’s are carrying around.

What should I treat as a reasonable red line for treating the engines well in a climb? I’m one who likes to keep cylinders below 375 in the Lycoming but that’s not going to happen in this bird. 415 would be easy to hit on this bird. Fuel rich, good fuel flow, and cowl flap open.

 

[Bell206]

What should I treat as a reasonable red line for treating the engines well in a climb?

I knew one operator who adopted a lower max EGT as the limiting factor with CHT a secondary limit. I dont recall the exact figure but it was about 200 degrees less than the book value. They were experiencing valve seat issues attributed to higher EGT vs CHT temps. Once they did that the valve issues went away and they got a better life out the engines even though the aircraft flew 100+ hours per month.

 

[3393RP]

Perhaps @Zeldman and @Kristin can help you. They both have extensive PA-31 experience.

 

[Zeldman]

I knew one operator who adopted a lower max EGT as the limiting factor with CHT a secondary limit.

The companies I flew for did the same thing. I don't remember the EGT readings, but I still have the power settings.

For take off we used 35'' at 2700rpm.

For climbout, 28'' at 2500rpm.

Cruise setting 26'' at 2400rpm.

These power settings kept the EGT's at the levels the Director of Maintenance wanted to see.

Please keep in mind that almost all my Navajo experience was in Alaska, where ambient temperatures were between -40 to 75f.

YMMV

 

[Kristin]

I don't like to see more then 435F in the climb and 400-420F in cruise. I ran a set of TIO-540-A2C engines in the Upper Midwest from installation to TBO (Lyc OH) running between 375-400F in winter and 400-420 in summer, with only occasionally higher in the climb, with no significant cylinder issues. The Chieftain's TIO-540-J2BD are more temperamental and I would no hesitate to use cowl flaps to keep temps below 420F.