Very interesting , 6 years flying chieftains and Navajos and company transitioned from ROP exactly as stated above to LOP towards the end of my time there . We had engines running well over their normal OH times by going on condition inspections . LOP was not popular at the beginning by us but after reading posts here it became a acceptable operating technique. I finished up with the aircraft just prior to the vortex generators arriving , just a happy coincidence in my mind . Good memories of helping in hanger and trying to get those 2 red lights to buzz and light up at same time .

I distinctly remember how there was a direct correlation between a persons thirstiness for getting out of GA and their resistance to entertaining the thought of operating LOP.

Im laughing , it was one reason on a very long list of reasons by then but looking back it was some of the best times of my life , like most I’d say . Navajo still a favourite.

Leaning in the old days, Constellation, LOP.


https://cimg3.ibsrv.net/gimg/pprune....6f2dbac5d8.png

megan,
Thank you so much for posting that.
I have done the APS class in Brisbane run by Andrew Denyer and David Brown. Using dyno data and literature from the days of Super Connie and so on, it became clear that all the methods that we were taught were in fact based on old wives tales. They even explained how that came about. It made some of my CPL theory rather confronting in its lack of truth in engine operations.

I sure hope they run a class again next year once all the covid restrictions ease. I was looking forward to booking in for the one this year but it was cancelled.

Torukmacto,
Your story sounds like yourself or a colleague was on the class a couple of years ago with me. An operator in Melbourne had made huge gains from following the APS instructors advice, especially magneto timing and spark plug maintenance. Too much of a coincidence for sure.

I vaguely remember hearing that the Japanese may have used LOP technique to get the extreme range they achieved with zeros in the war. I've read a few books where they talk about some specific leaning procedure but don't expand on it much past that. Definitely have read the notes on big radials in DC-6/7 and Connies dramatically increasing reliability and life using LOP technique. They were getting some impressive TBOs on those big radials by the time the jets took over.

Interesting, have not found any such reference in the newer manual where LOP is prescribed but maybe they were too busy at Piper back then for these little details. Like deleting the climb power leaning chart and replacing it with CLIMB FULL RICH!

We have many more hours on our PA31 nearly all LOP now. Zero issue except if anyone can share their CHT data would much appreciate it. Not sure if it's just ours but both sides CHTs are spread ridiculously - looks like most off the effective cooling air goes past No.6 and leaves Nos.3&4 warmer than they should be. I suspect the cowls were designed for looks back then, scant attention paid to where the air actually goes.

If I owned a PA-31 these days I'd be at least strapping inter-coolers on them, if you are seriously wanting performance and economy. Especially for Australian conditions.