Al,
You and I usually share a common perspective, and your obvious
frustration is to
some extent shared in this 1320 lb. STC thread. You have made it clear
you don't
think it serves a purpose worth its cost, but you have thus far failed
to
explain why in terms I am able to understand. I'll try one final time
because others
may also be similarly confused and I don't see genuine confusion as an
acceptable
way to end legitimate discussion on this list.
Our problem may lie in what "over gross" means to each of us. My copy
of ATC 718
dated March 25, 1940, allowing the issuance of "...an airworthiness
certificate upon
showing compliance with the terms of this specification" lists, for "II
- Model 415" a
"Weight - Standard 1125 lbs." and "III - Model 415-C" a "Weight -
Standard 1175 lbs."
At the time, one airframe with a five gallon fuselage tank and one nine
gallon wing
tank, Serial No. 1 had been used for (each) required certification
flight testing.
After the war, Erco adopted the C-75 engine with starter, generator,
voltage regulator
and battery and two wing tanks as standard. The CAA allowed Erco an
increase in
allowable operational weight under the CAR 4 regulations to 1260 lbs.
Apparently
Erco's 415-C design was found to be adequate. Were there flight tests?
Likely so,
but I don't know. Would it matter? Is 1260 lb. operation "over
gross"? Absolutely not.
You seem to accept that the D Model and later Ercoupes, etc., tested to
meet Part 03
"Normal" structural requirements are structurally and operationally
safe for flight as
approved by the FAA at 1400 or 1450 lbs., respectively. I agree with
your supposition
that the FAA likely required no flight testing in the process of review
and approval
of the 1320 lb. STC, but your point here continues to elude me. Flying
an Ercoupe
at 1320 lbs. with said STC is not in any manner flying "over gross",
either as a legal or
practical matter.
Does it affect takeoff and altitude performance? Sure. Everything in
aviation is a
compromise of some sort. It is the pilot's responsibility to make many
choices every
flight, but there is a measure of risk in everything he/she does that
can never be
totally eliminated. The effects of density altitude on the Ercoupe are
considerable,
and those who are too lazy to carefully consider them before each and
every hot and/
or high altitude takeoff have only themselves to blame for unreasonable
expectations.
I believe we agree that compliance with applicable requirements of
current regulations
for a materially greater gross weight increase had been previously
demonstrated by
Erco in the process of gaining FAA approval of their model 415-D. It
would be my
opinion that additional flight testing would have served no meaningful
purpose; and if
that was essentially what the FAA decided, why would anyone object?
Just as Ercoupe flight performance at 1125 or 1175 lb. gross with 65 hp
became
meaningless once installation of a second wing tank and/or 75 hp
engines in later
prewar 415-C Ercoupes was allowed with a higher 1260 lb. gross, what
practical or
structural concerns arise as to the safety of operating a structurally
identical airframe
at 1400 lb. gross? With the weight approved for the 415-D and 85hp
approved in the
415-E, I would be so bold as to suggest none. The physical structure
of the 415-C has
been definitively shown to be more than adequate for such operation
over many years.
If the FAA has in some other instance allowed a "GWI STC" without
appropriate testing
or prior verification that every applicable regulatory requirement is
conclusively met, it
would clearly be irrelevant to the safety and desirability of the1320
lb. Ercoupe LSA STC.
As I understand it (I don't have a copy, but would like one for my
files), this STC does
modify structure, in that it requires every change set forth in ATC 718
Note 3.
The trim tab and main gear oleo orifice modifications required on
certain airframes are
physical changes. The substitution of stainless sheet for original
aluminum fuselage
skin over the nose tank for all 415-C airframes is "structural". I
would agree, however,
that such change has no effect whatsoever on airframe load carrying
capability.
You asked Ed why the CD's gross weight was not increased. The answer
is in the model
chronology. When Erco asked for CAA approval of the 415-C for 1400
lbs. gross, IMHO
unreasonable Ercoupe-specific testing parameters were applied.
The first production model 415-D came off the line 3/25/47. ATC 787
restricted "up"
elevator movement to 9º. The landing characteristics were deemed
unacceptable, but
Erco had already changed over parts and assembly production to the
415-D model.
Erco immediately sought CAA approval (likely without flight testing) of
the D model airframe
with 13º up elevator under ATC 718 as the 415-CD. This allowed
production to continue
until approval for the 1400 lb. gross weight was possible. The CD was
an entirely unplanned
interim model. Ercoupe Information Letter No. 1 of 1/1/56 explained
how to convert a CD to a
D for the increased gross weight, thusly no gross weight increase for
the CD was ever sought.
So long as I can get a third class medical, I believe a 415-C converted
to a D model to be
the "best" Ercoupe for me, as I don't care for the appearance or "feel"
of the panel-mounted
quadrant. It no longer makes economic sense to convert a LSA-compliant
415-C for most
of us, but nice 415-D models come available from time to time for
$8,000-$9,000 less.
At such time as I deem it wise to "lapse" into LSA, I would definitely
look for a 415-C with
the 1320 STC, or buy and install it. That's because, for me, the
Ercoupe is much more
than an "around the patch" or $100 hamburger" airplane. It's my "one
and only" ;<)
It is for each to make an informed choice appropriate to individual
"mission requirements".
And yes, there are 415-C models in the field with split elevators
installed and approved; and I
believe Hartmut or his brother has a CD model with it.
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Feb 15, 2009, at 13:47, Al Demarzo wrote:
Before we further get off on a tangent, I was not speaking about the
flight testing for the D mod, I was speaking about flight testing for
the 1320 gwi STC. The D model was from the manufacturer and a few
years before I was born. Let's keep this in perspective. And the
1320 gwi STC does not modify structure. People who think so are
exactly my reason for not buying into it.
I never said the coupe's structure wasn't safe to fly at 1400 in clear
air. I'll even further say that I don't have a problem over gross in
certain circumstances. And by probably referencing the D weight,
the holder was able to slide the STC through. But, by what reasoning
do people have to assume the structure is safe to fly over gross?
Anyone tell me? It's out there, you know. No, it's not FAA.
I'll say it again, I just don't buy into the paper GWI STC's. Not in
any of the airplanes I own. It's a bullcrap way of getting around
rules and the designs of the manufacturer.
I think we're done. I'm not going to change my opinion on this and
additional participation fortifies the fact that not many people are
getting my reasoning.
