Why didn't the Cessna 337 make it?

"Roy Smith" wrote in message
...
"Dudley Henriques" wrote:
It could happen and did. Engine loss on a rear engine twin can be very
deceiving, and it doesn't have to be a complete failure either.

I would think it would be easy (at least from the engineering perspective)
to display a big red warning light when the RPMs of the two engines differ
by more than a certain percent. Did the 337 have anything like that?

Ours didn't. Steam gauges only. EGT was the primary monitor on takeoff.
Dudley Henriques

On 2006-02-28, Roy Smith wrote:
I would think it would be easy (at least from the engineering perspective)
to display a big red warning light when the RPMs of the two engines differ
by more than a certain percent. Did the 337 have anything like that?

They might not differ, though. In a partial power loss or perhaps a loss
of an engine at a lower power setting (such as approach), the RPM on the
engine not making proper power might still be the RPM selected by the
prop lever. The only way you can tell for certain in all circumnstances
which engine has failed from instruments is from the EGT (and in a
partial power los on approach, even that might be hard).

The 337 would probably have been much better with a pair of Garrett
turboprops or PT6s with autofeathering props :-)

--
Dylan Smith, Port St Mary, Isle of Man
Flying: http://www.dylansmith.net
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The non-success story is an intriguing question.
The type had some success in its military declinations (0-2A) during the
Vietnam era. It is recognized and often used today as an engineering testbed
for a variety of new designs and improvements, yet in its principal designated
market it quickly developed an "ugly duckling" reputation which even today
leads to depressed prices.

There is not doubt it was noisy, inside and out. The high prop RPM and the fact
that one of them was close to the rear seats contributed to this. Also, several
models were anything but speed demons, giving lower TAS than some competing
twins. I have heard (don't know the veracity of this) that cooling on the rear
engine was inadequate, leading to a whole host of significant maintenance and
reliability issues.

We'll see how well Adam does with their new, spruced-up 337 (I know, I know -
this airplane bears no similarity whatsoever to the ugly old mixmaster - yeah,
yeah). For now, I see the 337 as one of the rare "deals" available on the
market, the price/performance ration being favorable,in addition to the
"safety" factor of a twin. Saftey is in quote here because most light twins are
more dangerous than singles in the event of an engine failure, so the safety of
a second engine is only theoretical - whereas in the case of the 337 it is
real and useful.

G Faris

On 2006-02-28, Matt Whiting wrote:
Hard to imagine a pilot so sensory impaired that he or she can't detect
the loss of 50% of their power, which results in lost of far more than
50% of most performance attributes. I'd really not want to fly with a
pilot who was that out of touch with their airplane.

I don't think that was necessarily the problem - imagine being just
airborne on an obstructed and reasonably short airfield, then one of the
engines quit. Although you feel the loss of thrust, it's not obvious
which engine has actually failed from the yaw because there isn't any.
Add to that the typical market segment for a 337 (people who percieve
they won't be safe enough in a normal twin) and you're asking for
trouble.

The only way of figuring out which engine has quit short of pulling a
throttle back and see if you lose even *more* power (which is
ineffective if one engine is only losing partial power) is to look at
the gauges. You might not even notice the loss of an engine if it
happens on approach until you throttle up for a go-around and find up to
50% of your power is missing (if an engine fails on approach, the only
indication may be a decreasing EGT - the windmilling prop may still
make the same RPM and the manifold pressure does not change if an
engine isn't actually combusting fuel). Even if one fails on takeoff,
where the failed engine will almost certainly lose RPM you still have to
look at and interpret the gauges which is a slower process (particularly
if it's a high workload instrument departure) than 'dead foot dead
engine'.

The people who are liable to VMC roll a conventional twin are probably
the same people who will stall a 337 while taking their time over trying
to figure out which engine has quit.

--
Dylan Smith, Port St Mary, Isle of Man
Flying: http://www.dylansmith.net
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de
Frontier Elite Universe: http://www.alioth.net

In article ,
says...

Add to that the typical market segment for a 337 (people who percieve
they won't be safe enough in a normal twin) and you're asking for
trouble.


The people who are liable to VMC roll a conventional twin are probably
the same people who will stall a 337 while taking their time over trying
to figure out which engine has quit.

--

Your point is well taken - the "Cirrus Syndrome" of creating a market
sector specifically for those who are doubtful of their own abilities...

However, in light twins this could be more a question of lucidity than
anything else. If the "conventional twin" you refer to is a KingAir, or
something with ample power and ample VYSE, then fine. But remember, in light
twins, which have "just enough" power to demonstrate SE climb, most pilots
faced with real-world situation do not succeed in performing the type of
recovery they demonstrated on their ME checkride.

It's not just a control issue - many of the small singles that "grew up"
into twins have so little excess horsepower available that the recovery must
be perfectly executed in order to be effective. Most of us would have to
admit that we can not always be counted on to do everything perfectly,
particularly under duress, and this is not to mention the fact that the
incident does not necessarily occur at sea level, at standard atmospheric
conditions. Many of the incidents are probably unrecoverable, or very close
to it from the get go.

Adding extra power to deal with this quickly moves one into the 421 or Duke
category, where the plane may not spiral out of control so much as the
operating costs - for a feature that is essentially there only for emergency
use. Suddenly, the ugly little 337 starts to look a whole lot prettier, and
that 'uncertainty' begins to look a lot like just plain good judgement.

All of the above does not really contradict your argument, as you were
talking about perception - and pilots as well as regulators tend to perceive
themselves as capable, and therefore safer in a standard twin than in a
single - even though the accident record has repeatedly disproven this.

GF

"Dylan Smith" wrote in message
...
[...]
The people who are liable to VMC roll a conventional twin are probably
the same people who will stall a 337 while taking their time over trying
to figure out which engine has quit.

I don't see how this is an issue. With centerline thrust, the pilot
shouldn't NEED to know which engine has quit. The primary reason for
knowing which engine has quit in a convential twin is so you can use the
correct control inputs. With centerline thrust, you just keep flying the
airplane. Why would any pilot spend any time trying to figure out which
engine has quit on a 337? What are they going to do with that information,
at least in the immediate sense?

Pete

"Peter Duniho" wrote in message
...
I don't see how this is an issue. With centerline thrust, the pilot
shouldn't NEED to know which engine has quit.

Perhaps there is a need to feather the prop on the dead engine to cut drag?

"Grumman-581" wrote in message
...
Perhaps there is a need to feather the prop on the dead engine to cut
drag?

Ahh...good point, thanks.

Sorry Duniho, the "dufus" guy was somebody else. My mistake.
Dudley Henriques

"Peter Duniho" wrote in message
...
"Grumman-581" wrote in message
...
Perhaps there is a need to feather the prop on the dead engine to cut
drag?

Ahh...good point, thanks.

You need to know hoe to identify the dead engine and feather
the correct prop, otherwise you're going down. In a
conventional twin identification is holding heading with
rudder, "dead foot dead engine" and the litany is

CONTROL
POWER (up)
DRAG (gear and flaps)
IDENTIFY
VERIFY
FEATHER
FLY

secure it

In the 336/337 it isn't as easy or obvious which engine is
sick or dead.

--
James H. Macklin
ATP,CFI,A&P

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"Peter Duniho" wrote in
message ...
| "Dylan Smith" wrote in message
| ...
| [...]
| The people who are liable to VMC roll a conventional
twin are probably
| the same people who will stall a 337 while taking their
time over trying
| to figure out which engine has quit.
|
| I don't see how this is an issue. With centerline thrust,
the pilot
| shouldn't NEED to know which engine has quit. The primary
reason for
| knowing which engine has quit in a convential twin is so
you can use the
| correct control inputs. With centerline thrust, you just
keep flying the
| airplane. Why would any pilot spend any time trying to
figure out which
| engine has quit on a 337? What are they going to do with
that information,
| at least in the immediate sense?
|
| Pete
|
|