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VK5QX > INFO 03.08.02 21:03l 269 Lines 10975 Bytes #999 (0) @ WW
BID : 040309VK5QX
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Subj: Re: "NASA" quality,VK5QX.
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Sent: 020802/1720Z @:VK5LZ.#ADL.#SA.AUS.OC #:40782 [Elizabeth] $:040309VK5QX
From: VK5QX@VK5LZ.#ADL.#SA.AUS.OC
To : INFO@WW
STANDARDS AND QUALITY ASSURANCE (QA).
In reply to a previous bulletin Ian G0TEZ made comment as follows:-
__________
" I remain a lit(t)le confused about 'NASA quality'. UK engineering is
often done to 'aircraft quality' in the UK which is the best possible.
Sometimes it is done to Rolls Royce' quality, which is even better.
I assume 'NASA quality' is equivalent to 'Aircraft Quality' as NASA
vehicles such as shuttles do break down e.g., the 'O' ring failures.
Things built to RR quality just don't.
N.B. the term used to apply to Rolls Royce cars but now only applies to
aero engines as RR cars was sold to the Germans a few years ago. "
__________
In my previous bulletin I did refer to NASA "Quality Assurance" standards
and included the following comment:-
__________
" I once did a relatively short QA course under NASA auspices and,
although I cannot claim an expert knowledge of this subject, I did learn
quite a lot regarding such aspects. "
__________
I had also described some aspects regarding the stringent approach to such
a simple matter as terminating coaxial cables and suggested that I could
perhaps convey a little more information on such matters.
I trust that some of the following may be of interest.
I also hasten to point out that, in any of the material I have provided on
this subject, I refer only to SOME aspects applicable to maintenance of
electronic equipment, with an emphasis on repair work where soldering is
necessary.
I emphasise that I DO NOT claim to be expert in any of the QA matters
referred to and certainly could not claim to have any specialised
knowledge with regard to manufacture of missiles and spacecraft in
general.
The "course" that I did was conducted by an Australian Federal Government
employee who had spent an extended period being instructed in QA matters
at a location in California, USA. This was back in the 1960's when I was
employed on a "seconded" basis in operations here in Australia on behalf
of NASA.
The particular person conducting the course, whose name was Alan, provided
some instruction for the benefit of personnel within the particular
Department to which we belonged, however, the course ran for only about 1
week and provided what could only be described as basic instruction.
Whilst those on the course probably felt that they already knew something
about soldering we certainly had a few things more to learn.
The instruction made a number of points which I will try to describe in a
concise manner rather than attempt to provide a detailed and more
complicated explanation.
Maybe some of this will serve to give you at least some inkling as to how
seriously the matter of such a simple thing as a soldered joint can be
taken.
Some of the particular aspects included;
(PLEASE NOTE: These items are not necessarily sorted in any particular
order of either priority or sequence.)
Continued strict observance to detail so as to ensure high reliability.
The need for precise temperature control. Selection of suitable "bits" for
the soldering iron.
An understanding of problems connected with oxidation.
Cleaning of soldering bits after each application of the soldering iron.
Reduction of oxidation of the soldering iron tips by ensuring that the tip
was "re-tinned", and loaded with solder, after every application.
Cleaning of the soldering iron "tips" every time, both before and after
any single application.
Use of correct cleaning materials for the purposes just mentioned.
(Sponges and cleaning fluids.)
How to apply heat in the correct manner. Ensuring that the solder flowed
properly.
With every soldered joint the solder must have flowed so as to produce the
right kind of fillet for the type of soldered joint involved. (This refers
to the shape taken up by the solder around the item(s) being connected.)
No pin holes were allowed to exist in any joint. Each must be smooth and
shiny with no bubbling of the solder allowed. All signs of flux had to be
cleaned away.
Prior action as far as cleaning and preparation of all components/surfaces
being soldered had to be attended to apart from that mentioned above
regarding the soldering iron tips.
Use of metal tools for shaping/bending of wire leads, including component
leads was strictly taboo. The reason for this being that touching the
plated surfaces of components etc. using metal tools could damage the
plating thus increasing the risk of deterioration of the plating and
possible failure.
No stress to be placed on leads and components when installed.
Suitable plastic material tools and jigs for bending etc. had to be used.
Close and careful inspection of all joints after soldering. This included
a preliminary eyeball check followed by inspection of each joint, in turn
as they were made, using a microscope.
It certainly took a great deal of time and care to carry out the work in
this manner.
And so it went on, with practice after practice to try and achieve even a
single satisfactory soldered connection.
It may seem that some of this is "overkill", however, I will relate just
two stories told to us by our instructor, Alan.
Story No. 1.
When he was in training at the particular laboratory in Los Angeles he had
spent a good several hours trying to achieve a soldered joint of
satisfactory quality.
He then finally satisfied himself as to the fact that he had a
satisfactory result and then took it to the instructor for his
examination.
The instructor, a very experienced person in this particular field of
endeavour, took a good (eyeball) look at the soldered joint and then
said.
"Well, it's not too bad, but without putting it under the microscope I can
tell you 5 faults on it already."
Alan said that the instructor was quite serious about this and proceeded
to show him just what the faults were.
Story No. 2.
Included in the network of stations with which we were connected were
those referred to as comprising the Deep Space Instrumentation Facility
Network (DSIF).
These were 85 foot diameter dishes which carried out the tracking,
telemetry and command tasks in connection with spacecraft beyond earth
orbits. Such stations were located at places such as Goldstone,
California; Johannesburg, South Africa; Madrid, Spain; and Woomera, South
Australia.
The spacecraft were such as the Mariner, Pioneer and Lunar Orbiter
(Moon-Reconnaisance) types. (These latter were used to orbit and take
photographs of the moon's surface towards determining suitable landing
locations for the Apollo missions to come.)
The location of these 4 stations was such that (hopefully) at any time
there would always be contact available with the spacecraft through at
least two stations. One station would take over from another as the
earth's rotation made it necessary.
There was one particular mission where it was necessary to transmit a
command to a spacecraft which was well out in space and travelling a long
way out through the solar system.
The command, which was a mid-course manouver, was to have been transmitted
from one of the stations, however, it became obvious that the spacecraft
had not responded to the command. I guess that some minor panic no doubt
ensued as they attempted to determine the reason for, and possible
whereabouts of, the problem.
The matter was eventually dealt with by asking the Woomera station to
transmit the necessary command, whereupon the spacecraft responded and all
was in order once more.
What is interesting is the subsequent results of an intensive
investigation into the problem and determination as to what had really
occurred as well as identification and location of the apparent fault
condition.
It was discovered that the problem was not due to any difficulty as far as
the spacecraft itself was concerned.
In fact, it was due to A SINGLE FAULTY SOLDERED JOINT WITHIN A RACK OF
COMPLEX EQUIPMENT WHICH FORMED THE COMMAND CONSOLE AT THE STATION WHICH
HAD BEEN SCHEDULED TO SEND THE INITIAL COMMAND.
At the laboratory in California, and in the room where the instruction was
given with regard to high reliability soldering, a very large (at least
some several feet long and wide) photograph of the offending soldered
joint was displayed. Attached to the sign was a large notice carrying the
words;
" DON'T LET THIS HAPPEN AGAIN ! ! "
I point out that, subsequently, the only people who were allowed to carry
out maintenance work on the electronic equipment at these stations were
those who were fully trained and who continued to pass a monthly check as
to the quality of their soldering techniques and other tests of a like
nature.
On a monthly basis they had to complete the laid down tests, and the test
pieces for each were flown to the USA to be examined and validated to
allow those being checked to retain their status as approved personnel for
the necessary maintenance work.
Even if you may think that NASA was going a bit overboard as regards these
matters, it only takes a little thought to evidence the fact that a
spacecraft which has cost possibly 100's of millions of dollars could be
lost as a result of a single fault as described above.
I have no doubt that these days the more modern techniques used would tend
to obviate some problems, although I am well aware that incredibly great
care is taken, particularly with regard to ANY items taken aboard the
various manned spacecraft in use.
Even the Amateur Radio gear aboard the International Space Station has to
undergo rigorous tests before it is allowed to be flown.
It does seem, however, that many people do not realise the necessity of
ground based equipment to be extremely reliable as evidenced in the above
Story No. 2.
Whilst I was not immediately involved with the actual construction of the
only satellite to be launched from Australian soil back in those halcyon
and exciting days of the 1960's, I did have contact with those who were
involved. Great precautions were taken to ensure that a reliable
spacecraft was built.
Much of the work was and is done inside special clean rooms so as to meet
the necessary criteria.
For those wondering, that particular spacecraft was known as "WRESAT" and
it was launched from the Woomera Missile Range in the far north of South
Australia using a "spare" USA Redstone missile made available from the
"SPARTA" Project conducted by the USA here in Australia.
I have great memories of this event as I personally had control of and
tracked the satellite from the launcher into orbit using the 16 yagi array
(16 x 16 element crossed yagis all on the one tracking mount) that I had
previously used to track many USA satellites when the array was installed
at a "then" closed NASA station.
There are other tales to be told of some of those early days, however, you
may have already fallen asleep reading this missive.
Regards,
Ian
__________
73 de Ian, VK5QX
@ VK5LZ.#ADL.#SA.AUS.OC
03 August 2002
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