For the newbies: There is a tremendous amount ofpower off landings from 200 feet
folklore surrounding radial engines and power-off
descents with respect to the danger descending with
the power off, and the prop driving the engine.
With a boxer Lyc or TCM (NOT geared), it is perfectly
acceptable for the prop to drive the engine, which
happens with the power off, and is more noticeable
with constant speed props. I do this in the Lyc-powered
Pitts and TCM-powered Maule all the time. Fantastic
source of drag. In the Maule, I never need to use full
flap or even sideslip. In the Pitts, I can approach at
ridiculous speeds on short final, pull the throttle back
and let the 3-blade prop stop me.
With a geared TCM (eg GTSIO-520) if you pull the
throttles all the way back 'way up high and do a power
off descent with the props driving the engines, you
will damage the gear drives. Don't do that.
Now onto radial engines. If you pull the power all
the way back on a radial engine - carefully, it is
supercharged after all - and let the prop drive the
engine, there is a danger that there will be a lack
of lubrication in the main bearing.
Back to .. From 200 feet, you probably won't
do any damage because if the props do drive the
engines, it will be of extremely brief duration.