BeechTalk - BT

Username Protected · **Posted:** 20 Jan 2025, 20:29

This seems rather bizarre in an airplane designed to operate at night altitudes where ISA is way below -16C. Is this issue a regular occurrence?

Username Protected · **Posted:** 21 Jan 2025, 13:07

Mike,

I defer to more experienced 421 drivers out there, but in nearly 500 hours, what I described roughly a year ago is the only time I've seen it happen. Granted, it was an unusually cold day with an unusually "tight" temperature inversion (it was much warmer at 15,000 than it was from 11,000 - 5,000 that day).

On advice from some people I trust and respect here at BT, as well as some others, I switched from 100W Aeroshell to a multi-viscosity oil after this flight a year ago. While I haven't encountered any conditions similar to that day a year ago, it does "seem" like the engines prefer the multi-viscosity oil on the whole...but I have no hard data to back up my claim.

Username Protected · **Posted:** 21 Jan 2025, 22:37

Username Protected wrote:

I am curious about the same subject. Just flew from Bloomington to Warsaw +/- 45 min flight, OAT was -26 at 15,000 feet. Oil temp on right engine slowly climbed to 208 degrees and of course oil pressure was dropping. I was running at 1800 RPM w/ 32" manifold pressure, I pulled power back to 1600 rpm and slowly reduced manifold pressure (1" every minute) to 27" manifold pressure. When I did this right engine plateaued 208 and then slowly cooled and my left engine oil temp started climbing. Fortunately, I was in my descent into Warsaw and landed with no issues.

Is there a part on the market that is approved as an oil cooler restrictor plate?

Call Peter, he has plates for the cooler.

https://premiere-aviation.net

Username Protected · **Posted:** 22 Jan 2025, 19:00

Today I flew a 1974 Cessna 421B back from Louisiana to 76N in PA at FL 230. No tape on coolers or any mods.

Aeroshell 100W and camguard. Oil temps were middle of the green. CHT about 340F OAT was -32C. Running 27" and 1800 RPM most of the trip. 75 Rich of peak TIT on single point ALCOR. Oil pressure top of the green. 4 hr flight.

Descent I just pushed the nose over. 600ft a min Kept the same power setting all the way down to 9000. Airplane automatically adjusted waste gates and mixtures all the way down. Oil temp and pressure never changed. 1/2 green arc on both during cruise and descent. Airspeed was always well in the green arc.

CHT did come down to bottom of the green in descent. I have original 3:1 gauges only no engine monitors.

On the trip down to Louisiana yesterday I was lower at 10,000 most of the way into the wind. Running 31" and 1725 RPM. Descent I did notice the right engine oil temp creep up a bit but still well in the green. No temp markings but maybe 1/2 green on left and 2/3 on right but matched in cruise for 3 hrs. OAT was warmer yesterday down low but below freezing. -14C I believe in cruise first leg 76N to Lexington. I was a lower power setting on descent maybe eased down to 25" over time to slow down in the bumps.

https://www.flightaware.com/live/flight/N1946G

I really like the 421

Cessna 421 Oil Pressure Episode