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1. 07:24 AM - Commander Wing Spars (steve2)
2. 08:49 AM - Re: Commander Wing Spars (YOURTCFG@aol.com)
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| Subject: | Commander Wing Spars |
My Dad and I have always been fascinated by the Commander wing spars.
It's an interesting story whose final chapter is perhaps not written. In
the early years it wasn't corrosion, and I'm not so sure about the
cold-bend theory, though it sounds plausible. (The cap was cold-bent?)
The spar caps are radiused and this I thought was a major issue. The
outer station that broke on the bathtubs wasn't in an area that was cold
bent, right? Not being an engineer however, I'm not contributing to
factual information by speculating.
After 41 years and 9000 hours, some of it aerial survey work, we just
went through our 500B wings at annual to give a thorough inspection to
tighten and replace some smoking rivets on the top and bottom caps in
various locations along the spar.
About a year ago my Dad jotted down some notes to send to Barry Collman,
with my dad still trying to learn more about the origins of the spar
problem. I've read the Aussie reports, and heard a lot of speculation. I
suspect there is someone out there that knows a hell of a lot more, but
I thought I would include some edited messages that add another
perspective, not of an engineer but of an old survey pilot. If nothing
else it makes for a little good reading..... I've deleted anything of a
personal nature.
We don't operate or abuse aircraft anything like these guys did...... It
was their job.
What follows are a couple notes my Dad jotted down. Barry, I know my Dad
enjoyed recollecting them after all these years.
Steve
>>>>>>>>
I know the 680E family perhaps as well as anyone, having flown several
of them to just short of eventual destruction, in low altitude (read 100
[that's one hundred] feet in all sorts of mountainous terrain, all over
the world. Most of them had pods, booms and other assorted gadgets stuck
on, and sticking out of them. I made the papers (in the US) from time to
time, as local reporters dubbed the machines as "mystery ships." In fact
we were doing commercial aero-magnetic surveys for multi-national
corporations, and were not at liberty to talk about the work.
The lower spar caps at stations 22 (for sure) and 144 (if I remember
correctly) were deadly, and the planetary gear cases (77:120) on the GSO
480's (model B1A6) would come apart at the most inopportune moments. We
actually launched a starboard propeller into the Red Sea - followed by
having the Shah of Iran - Mohammed Rhezza Palavi - (spelled wrong, I'm
sure) give us a brand new engine, a spare for his own 680-E.
The dynamic counterweights on the crankshafts forced an interesting
convention of pulling the mixtures instead of retarding the throttles,
as to keep the iron wedges from breaking their positioning pins and
tearing the entire engine to pieces - which happened frequently in
survey service until we developed a trick. We used the pressurized air
from the centrifugal blower to maintain compression, so that no
instantaneous reversal of torque would result from the necessary
termination of power. We had to keep the machine within 100 ft. of the
down-slope of a cliff as we went to 'fine-bite', and threw out flaps &
gear to retard the predictable increase in airspeed on the way down. It
was kind of weird, needing to adjust the throttles to manage manifold
pressure as altitude changed - while the engines were not even running.
On the plus side, we never threw another counterweight. When the descent
was done and power was again required, one simply pushed the mixture
controls forward, and the noise came back. That's really about as
exciting as the exercise ever got. It scared the hell out of visiting
pilots, but there was really nothing to it. If there was a down-side, it
was quite disconcerting to hear the creaks and clinks as the dimensions
of the engines changed with the frightening rate of temperature drop
that resulted from an absence of combustion - with no change in manifold
pressure or RPM. Imagine - 48 inches at 3,800 RPM with no airspeed and
the cylinder head temps pegged - while struggling to clear a peak;
followed by a quick pitch down to maybe -30 degrees, pull the mixtures,
all the rest, and then be entertained by the cylinder head temp needles
hanging a quick left, and racing for their pegs.
Interesting times. We were quite pleased to get 600 hours without a
catastrophic failure. Notwithstanding, we usually ran them til they
folded up anyway. Work time was premium - engines were (in terms of
production time) cheap, and we operated (in the States) in the
Restricted category. We always had spares crated and ready to ship. I
ordered one to a job site in Nevada, thinking the port side was about
finished. Two days later, the right one mulched the front gear assembly.
Guess where we hung the spare (using a tow truck in the desert)? I know;
sounds like baloney - but Steven has all the pictures. The port one ran
(poorly) another hundred or so hours til we finally got back to ISP
(home base). We changed that one before it caved in.
I have a ton of this anecdotal and documented junk if you're interested.
Steven has my full collection of slides, enough to bore anyone's spouse
to death.
Steven - Referring to the time I let our neighbor Tom Kanas first try a
takeoff - perhaps you can scan or photocopy for Barry the M&D I sent to
FAA after the starboard control yoke on 41C parted company from the
elevator control rod. Our survival, you'll recall, generated a revision
to several NTSB probable cause findings - changing them from pilot
error, to component failure. You may recall they grounded the whole
fleet while we convinced them that the factory spec for rigging the
eye-end at the forward bell crank was wrong.
Ron
>>>>>>>>
This is CF-ULD (nee N1005S) when I was operating it out of Palu, on
Sulawesi, Indonesia, in around 1969. It started life as a 560, and I
think it was our company that hung the GSO 480's on it to make it into a
"680E". It had gone to our sister Company, Lockwood Survey Corporation
Limited - in Toronto. There were few enough qualified survey pilots in
those days, that we hardly paid attention to which company had what
assignment.
This was a former WWII Japanese fighter base with a bumpy 1,000 meter
dirt strip. We always went out over gross (273 gallons in 17 cells, plus
all the survey stuff - and this one had a big Doppler dish on the
belly).
The lower cap eventually fractured at station 22 on the port side (we
dye checked both sides after every mission). After stripping the thing
to the bones, I ferried it to Singapore, the closest factory authorized
Commander repair station. The company elected to do the civilian (FAA
approved) spar mod as opposed to the heavier - much more expensive
survey mod. My colleague Bill Moriarty, some months later, ferried the
machine to Brazil. My understanding is that the company had sold it to
the Brazilian government. Last I heard, the excited new pilot came
zooming low down the Amazon and did a pull-up to impress his friends -
as the story goes; everything went up (momentarily) except the left
wing. End of story - as I know it.
I flew the other two collectively for probably a couple thousand hours
and could bore a knot off a tree with the stories. I ferried 06S to the
Factory with a cracked lower cap, and worked with engineer Jerry Germin
(not sure of the spelling) to lend a survey pilot's perspective to the
crafting of what became known as the survey mod. I do not know what
became of 06S as I left the Company to form AeroGraphics Corp. (I put my
money where my mouth was), and shortly thereafter LIA went out of
business.
You probably know that John Bratton (with his wife aboard) had the
misfortune of going into the ocean off Anchorage with 41C. That was the
best of our Commanders, and by far my favorite.
Prior to Long Island Airways, I flew N9368R in local airline service for
Stanley Pell (Commander Airlines, Inc.) The business was purchased by an
'enthusiast' named Sheldon Bash, and I was tasked to train Herb Baugh,
who was Sheldon's primary instructor, to be the company's pilot. I
recall that Herbie - at various times - put a bunch of wrinkles in the
tin and shortened the life of a pair of beautiful engines (that Stanley
babied) with his inability to stop pushing the throttles so as not to
overboost on takeoff.
When you spotted 06S at Luton, it was probably being ferried back from
Saudi Arabia by Bill Moriarty, having completed several hundred thousand
line miles of low level aero-magnetic survey.
Finally: The name Doug Jacob does ring a bell, but in all honesty, I
can't say that I remember why. Now that you've resurrected all these
memories, it may come to me. Could it be that he was flying DC-3s for
Bouraq? If so, then I do remember him.
Kind regards,
Ron
>>>>>>>>
I am curious. How much do you know about the flaw in the spar, and is
info on that subject of interest, or available? The fact that it got
into production the way it was made is, in my opinion, quite stupid.
Could the idiotic radii in the lower cap at stations 22 and the lesser
width in between have been the result of an ''oops" when they found they
couldn't get the rear seat back erect (that was the prevailing myth)?
It's always bothered me that the machine got into production with that
obvious and deadly 'soft spot.'
It was said that Bob Hoover's later aerobatic performances in the new
design were a factory sponsored effort to overcome the bad rep that
resulted from all the fractures (and, tragically, failures).
Can you shed any light?
Thanx,
Ron
>>>>>>>>
Having lived with that anomaly daily for a good number of years, I like
many of my contemporaries became quite intimately familiar with the
physical realities of that particular weakness. I guess I'm somewhat
over sensitive compared to many long-time Commander pilots, as we worked
the hell out of the machines, and the two that were not somewhat
'babied' (that one being S/N 789-52) each developed fractures at sta. 22
during the time that I was operating them - one (S/N 605), at my hands.
Having participated (in the role of 'seasoned' pilot and only for ideas,
advice and commentary) at the factory in the crafting of the long strap
'survey-mod' applied to S/N 385-67 after ferrying it there (yet another
almost funny story), I may be able to contribute to your efforts.
How can it be that this major factory reconstruction event appears not
to be recorded in your compilation (not a challenge, but rather a
curiosity about the paper trail)? If you can find out how it came to be,
I'd really like to know about it. Indeed - as I sit here, I'm kind of
surprised that I don't.
Have you seen the lower cap as it enters - passes through - and then
leaves the fuselage? It looks like the afterthought of an imbecile
("Duh, we need more room at the back of the cabin. Let's cut away that
metal bar, back to the flat part."). They did it again, out in the
nacelles. That's part of what the survey mod was about.
The fracture that develops in the radius at station 22 essentially
severs the lower spar cap. That lower cap carries - under tension load -
the weight of the airplane. The upper cap transmits the force of the
tension back toward the longitudinal axis, as an approximately equal
compression load on itself. In the entire wingspan, the spot where the
tension load is at its' peak, is the place where they cut a radius into
the metal that carries that load.
The web (two vertically oriented plates of .060) holds the separation
between upper and lower caps, providing the geometry to make all this
work. Absent an external strap under the cap to bridge the fracture (and
thereby take on the entire tension load) - the wing WILL break away from
the airframe. The web will be simply torn in half like a piece of paper.
Pease note: They were all strapped. That's why most of the fractures
were not catastrophic. Look at any wing root just aft of the upper right
corner of the cabin door. If the laminated .060 straps extend into the
nacelle, then that's the survey mod - and its' ugly.
Of all the many types of airplane I spent a lot of hours flying: Given
its complexity, sophistication and its magnificent performance,
operating and handling characteristics, none was overall as satisfying
to me as the 680E. I dearly loved that breed of machine.
I suspect that I have an experiential anecdote to cover most of the
screwy things that could (indeed - did) go wrong while flying these
machines. My family has given up on my ever writing a book about all
this - with Steven, I think, being the last holdout.
I look forward to your comments.
With kind regards,
Ron
Message 2
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| Subject: | Re: Commander Wing Spars |
I would be interested in a copy, maybe for the newsletter?? Thanks jb
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