|
Message
One of the absolute
no-no's when flying a DC-3 was to never reduce the power below
"square" ( M.P. x 100 never less than RPM) other
than at the flare upon landing. Doing so would create
an abnormal wear on a main bearing, causing metal to clog a lubricating
hole and subsequent failure within a very short period of
time. When ATC wanted a rapid descent. we would reduce RPM to as low
as 1500 to us 15" MP and would tell them that was the best we could do.
This was a design flaw that was worked out in later large radial engines, but
application and removal of power was always done in an extremely delicate and
judicial manner.
Running a fleet of
TSIO 520 Continental engines on 402 Cessnas, we were taught to never reduce
power below 15" MP at 2300 RPM also being delicate with
power changes. Don't know if that made any difference, but those
engines consistently ran to 2600 hrs between overhauls.
I would think that
the rapid cooling associated with reverse loading a light aircraft engine would
be a more serious issue than forces caused by the prop driving the engine, but
the only analysis I've come across is anecdotal.
Peter Van
Arsdale
Naples
Fl
|