Oil on the windshield. What would you do?

"Duncan (NZ)" wrote in message
. nz...
In article . com,
says...
A "frost plug" in an aircooled motor????? Geez I can see a oil line
plug but most of those are the screw in type, not press fit ...

heh - I'll see if I can find the write up - I think one was done in a
newsletter. But yer right, it obviously wasn't a frost plug.

--
Duncan

I think maybe he means the crankcase breather. If that freezes, it'll blow
the oil overboard pretty quickly.
Having flown several thousand hours towing banners, a leaky prop seal is
quite common, and pretty much a non- issue in the airplanes I fly (PA-18/
J-3 with lyc o-360 and fixed pitch propeller). Depending on the condition of
the seal, usually they leak about 1-2 qts. over a 5-6 hour day. It's more of
a hazard to visibility than to the engine. It may be different for an
airplane with a constant speed prop. I haven't nor would I ground an
airplane for it, then again, your results may vary.

Frank

"Robert M. Gary" wrote in message
oups.com...

... I'd probably avoid touching anything and head towards the airport.
Could a prop seal really leak enough oil to make drops appear on the
windscreen? Usually prop seal leaks show up as moisture under the
prop.

-Robert, CFII


A blown seal (just about anywhere) can result in oil on the windscreen. My
brother blew an oil pressure sending unit that is under the cowl and ended
up with the greasy windshield syndrome (T-18).
If there is an airport within gliding range, sure, pull back the power - it
might save you an overhaul. I wouldn't shut down the engine unless you have
a glider rating and are skilled at real life dead stick landings. Otherwise,
just point towards the nearest airport - no need to panic. Depending on what
kind of seal blew out, it can take a few minutes to actually pump all the
oil overboard. And, even without any measurable oil pressure an engine will
keep running for five to fifteen minutes. Easing off a bit on the power can
help it last longer. The big problem is going to be making the approach and
landing with an oil covered windshield. If you are accumulating a lot of oil
on the windscreen you won't be able to see out - this is a real problem for
an off field landing where you won't be able to see obstructions like wires.


--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Prop seals leak because people use the blades as tow-bars on
the ground. Front crankcase seals leak because of blocked
case vents.

In-flight, centrifugal forces make the pressure on the seals
at right angles, does not cause leaks.


"Ash Wyllie" wrote in message
...
| BT opined
|
| the oil will "streak" in the slip stream
| changing power prop settings "even to fine" will cause
the seals in the prop
| hub to flex, why move them more than you have too.
|
| Because the governor is constantly changing the blade
angle, and thus
| aggravating the leak. Going to fine pitch means that the
blades will move
| only once more for the rest of the flight.
|
|
|
| -ash
| Cthulhu in 2007!
| Why wait for nature?
|
|

One thing to consider. You may have a choice of airports. The closest
one has no mechanic and the further one has a mechanic.

I would pick up flight following. I might file a flight plan if I
wasnt on one, if there was time.

I've heard the same thing Barry.. don't know where the stats are found
BT

"B A R R Y" wrote in message
...
On Sat, 27 Jan 2007 18:25:05 -0800, "BT" wrote:

touch nothing, divert to the nearest airfield,

I've heard a statistic tossed around at Wings seminars stating that
most engine failures occur during a change or adjustment. Guest
engine experts seem to always agree not to touch anything if it's
still running and high confidence of the exact problem isn't
available.

I wish I could find the detailed information. Has anyone else heard
this?

"What to do about it" depends entirely on how much oil. In addition to
the prop seals, it could also be the front crankshaft seal or the oil
filler gasket. I have had both - and neither was casuse for panic. The
former I had my mechanic attend to, and the latter I fixed myself.
I've never had leaky prop seals in 29 years of flying behind a CS prop
- but my former mechanic had a prop that leaked a bit on his own
plane. He chose to live with it for awhile - apparently a little was
not much cause for concern.

The incident that got my attention happened many years ago when I was
in a partnership that owned a Cessna 150. One fine day I went for a
flight, and soon streaks of oil started working their way up the
windshield. I of course headed for the nearest
airport. An inspection revealed nothing apparently amiss. I had a
mechanic wash down the engine compartment with solvent, then look into
the access door while I ran it up to
a pretty high RPM. Nothing. Took off again and all was well - but I
went home anyway.

The truth came out later when I related the incident to my partner. It
seems that he had committed the sin of leaving the dipstick unsecured
- and, of course, got oil all over the place when He took off. Even
worse, he wiped up all the oil he could see - and failed to tell
anyone or leave a note. So my day had been spoiled for nothing.

David Johnson

You do realize that the govenor changes blade angle when you change
power settings don't you?

On Jan 28, 7:02 am, "Ash Wyllie" wrote:
BT opined

the oil will "streak" in the slip stream
changing power prop settings "even to fine" will cause the seals in the prop
hub to flex, why move them more than you have too.Because the governor is constantly changing the blade angle, and thus
aggravating the leak. Going to fine pitch means that the blades will move
only once more for the rest of the flight.

-ash
Cthulhu in 2007!
Why wait for nature?

Jim Macklin wrote:
Prop seals leak because people use the blades as tow-bars on
the ground. Front crankcase seals leak because of blocked
case vents.

That's a gross oversimplification. As I said, the old
Hartzell prop seals go because they are life limitted to
a few years. They aren't even anywhere near the blades.
While there's grease up there in the blade hubs, there
ain't any engine oil.

Had a crankcase seal blow out because the case was misassembled.
Had nothing to do witht he vents.

In-flight, centrifugal forces make the pressure on the seals
at right angles, does not cause leaks.

What?

BT wrote:
I've heard the same thing Barry.. don't know where the stats are found
BT

No supporting stats. Lycoming has researched it and it's a myth.
You can find the info in their tech briefs on their website.

Doug opined

You do realize that the govenor changes blade angle when you change
power settings don't you?

Yes, but if the prop is in in fine pitch, it can't get any finer.

On Jan 28, 7:02 am, "Ash Wyllie" wrote:
BT opined

the oil will "streak" in the slip stream
changing power prop settings "even to fine" will cause the seals in the
prop hub to flex, why move them more than you have too.Because the
governor is constantly changing the blade angle, and thus
aggravating the leak. Going to fine pitch means that the blades will move
only once more for the rest of the flight.

-ash
Cthulhu in 2007!
Why wait for nature?



-ash
Cthulhu in 2007!
Why wait for nature?