From: bunda@cs.utexas.edu (John Bunda)
Newsgroups: rec.aviation
Subject: Re: More propping large engines
Date: 3 Sep 92 05:23:42 GMT
Article-I.D.: peaches.lacbfuINN832
Organization: U Texas Dept of Computer Sciences, Austin TX
NNTP-Posting-Host: peaches.cs.utexas.edu

In article <184eekINNohr@darkstar.UCSC.EDU> rob@cats.ucsc.edu (99708000) writes:
>Well, what I wanted to hear was how, or should, do you prop this particular
>type of engine (an IO-520, low time--lots 'o compression resistance)
>on a 210?
>
>Have any of you >actually done this<?  If so, what techniques/precautions
>were necessary?  (Doesn't have to be that particular engine/ac combo--
>any LOW TIME (lots of compression) (TS)IO520-540).

Well, the best I can do is a mid-time O-470, but at my weight (135)
I'm probably at as much of a disadvantage...

Anyhow, here is the procedure I was taught.  Facing the prop head on,
(mags cold of course), position a prop blade at about 10 o'clock.
With a tight engine, not being right up against a compression stroke
helps a lot.  (When turning the prop, make sure the mags are cold,
treat it as if they were hot, and so forth.  Depending on the engine,
turning backwards may be easier and certainly safer, but I've heard
this is bad for some engines ??).  Some say turning it through a few
pulls cold to "loosen her up" is a good idea - 	I've no idea whether there
is any technical basis for this.

With a blade at about 10 o'clock (9-11 depending on your reach) tell
the qualified, experienced at prop-starting pilot at the controls to
make it "Hot!", wait for confirmation.  Grab the blade, with hands as
flat as possible, 6-12" from the tip.  They say don't hook your finger
tips around the blade, keep your fingers flat on it, but with these
big monsters, I can't get the prop to move that way.  Heavy leather
gloves, if you've got 'em, would surely help, expecially if the
trailing edge is sharp.

With both hands on the prop blade, lift one knee, then as you
throw that leg back behind you, throw the prop blade down and
through.  The leg action will give you some momentum, and
have you already backing away from the prop as you release it.
If it catches, great.  If not, have the pilot confirm it "Cold!",
reposition the prop and repeat until (1) it starts or (2) you
are completely exhausted.  

If the problem is a slightly flat battery that just can't get the
thing past a compression stroke, have the pilot engage the starter
as you pull it; sometimes just getting things moving is good enough to
get it going, and the starter will keep it cranking for a few turns.
On the other hand, if the battery is truly defunct and the plane has
an alternator (instead of a generator), even with the engine running
there may not be enough juice to drive the field windings, and you
still won't have an electrical system.

Sometimes, there is just no point in hand-propping.  If it's flooded,
(e.g. from a flubbed hot start with an injected engine), give it
a rest, you'll have a heart attack before you get it going.
It's good to have experience hand-propping a particular plane so you 
know about how it "should" start.  If you find yourself saying,
gee, it usually starts by now, there may be a more serious problem
to consider.

Being able to hand-prop has a few times been the difference between
getting home and a minor ordeal.  I had a solenoid fail on me last
summer in the 182, of course, on a Sunday evenings as the sun was
going down with three days of rain forecast to begin early Monday
morning.  I hand-propped it and flew home.  At the last 100hr,
I had an APU plug installed and now carry a set of cables (12v
electrics, I can jump from a car).  This spring, when I tossed a
generator belt and ended up with a flat battery, I jump-started it
instead.

Because I am experienced with hand-propping my plane, I'm less afraid
of it than other nose-dragger city-slicker pilots like me.  But don't
get me wrong, I still avoid it assiduously.  It's just something else
in my bag of tricks.  I've never had one kick back at me, and I've
never seen it, but I've heard it can happen.  I'd consider
hand-propping a valuable skill if I was going to fly to any remote
areas where services like an APU truck or battery charger might be
tough to find.  Or if the starter drive failed ;-)

It may be that a tight, high-compression TSIO-520 would be too much of
a handful compared to the O-470.  Before I got someone to demonstrate
hand-propping on that engine, I'd want to know if they had actual
hand-propping experience on that engine, and maybe even that
particular aircraft.  As Ron said, it's different enough from what I
know that I wouldn't do it without knowledgable help.  On the other
hand, if someone whose abilities I respect says it can be done, it's
something I'd like to know about a plane I was flying a lot, and
trying it out before you're stranded in the back-country is, for sure,
the way to go.
-- 
John Bunda * bunda@cs.utexas.edu * {uunet,harvard}!cs.utexas.edu!bunda