Why?

I usually kept power up until pretty close to the airport and/or I needed to slow for some other reason (redline, traffic, etc).

The 1”/minute thing doesn’t do anything to help the engine.

Robert

Over these past 30+ years of flying these air-cooled piston jobs (airplanes & helicopters), and nothing else, I’ve adhered to what I was taught by instructors with regard to engine power/temperature management. If it made sense to me, I would remember it. Progressing from the 90hp C-150 to the 375hp (ea) 421, the larger the piston engine the more susceptible they are to temperature changes. Thus, requiring a smoother, gentler touch vs a ham fisted one. Staying ahead of the plane with regard to descents, I’m a proponent of the 1-2” at a time to prevent any big temp changes/shock cooling. At $100k per engine, I’m interested in longevity and even though I understand the LOP crowd, I’m in the ROP camp. Mostly because after speaking with 135 operators who run these large geared engines to TBO, they do so by keeping the temps cooler, (I know, I know - there’s another side to the curve). Fuel & oil are the cheapest part of ownership and provide the best insurance for longevity imo. So, if burning a few more gallons per hour gives me my best chance of making it to TBO, then it’ll be worth it. Of course I won’t know until I get there (or don’t). But, it makes sense to me so, that’s what I do.

You know, I agree here. This is exactly how I operate my 414A.

I have ran two sets of engines out to TBO, my neighbor owns 3 421’s on charter and has more than 10,000’hours operating these engines. We “do not “use the one inch per minute technique. Smooth power applications and common sense is all that is required.

Running the engines at 900 to a 1000’rpm for a couple of minutes before shutting down is doing more harm than good. Gammi proved it with a temp probe inside the turbo.
The engines are at the coldest when you leave the runway.

I’m still amazed 23 gph keeps that engine cool ROP, and that you get 228 KTAS - that’s a big airplane. I’m impressed.

I use the 1"/minute not due to any fear about shock cooling, but as a convenient way to do a gradual transition from cruise speed to approach speeds. There's no need to show up in the pattern screaming along at 180 IAS, well above flaps speed and gear speed.

If there is a need to change to power faster, I'll go ahead and make the faster power reduction.

A 421C engine PROPERLY baffled runs cool with no cowl flaps. The 414 and 340 engines run hotter and can require more gradual cooling than 421C engines.

On 421C engines be kind to the prop and quill shaft with smooth power adjustments.
Do not put the prop controls up for landing. Keep positive torque on the gear train.

For the 1” per minute crowd, how long is your takeoff roll? Sure seems like it would take a lot of runway to add power at 1” a minute…

Robert

The MVP-50's in 421EE have a 'shock cooling' display. When we first bought it I watched those numbers quite a bit.
Pulling 1"/minute in the descent vs cruise power all the way down and reducing to 25" a few miles out made very little difference in shock cooling.

I can't find any pics of a descent, here are the numbers in cruise (LOP this time) and climb.

When the GTSIO's are dialed in and maintained well they're hard to beat.

Regarding the 1" per minute crowd on takeoff power, I try to operate out of Edwards Air Force Base as much as I can for this reason.