Unintended RCS Jet firing

[Craig Fink]

An RCS jet has failed ON, not during a flight, but during a simulation. A
simulation that if it had occurred during a flight, would have resulted in
an uncontrolled RCS jet firing. It happened four of five years ago during
training for a flight. They were flying a TAL. At a point just after MECO,
an RCS jet came on just as the flight software began an OPS transition.
During the transition, some of the memory gets overwritten with the new
code for the next OPS, and some of the the memory doesn't. There was a
status word for the RCS jets that didn't get overwritten or reset, so the
RCS jet that was ON before the transition remained ON after the transition.
Essentially, the flight control didn't know that it was still commanding a
jet ON.

As you can imagine, the vehicle began to tumble out of control during a
critical phase of a TAL. Critical because there isn't much time between
MECO and Entry, and a lot of things have to happen in this short time span.

As to what happened during the sim? I believe they stopped the sim to dump
the computers to try to figure out what happened.

If it had happened on the actual flight? I can imagine that the Commander
would have figured out on her own how to fix the problem. It was similar to
what happened during Gemini, where if something wasn't done very quickly,
the vehicle would have continued to spin up.

Craig Fink

[James Oberg]

V-E-R-Y interesting, thanks for the report! I'm looking forward to hearing
more details on this pretty amazing event. Frankly, I'm surprised, because
the 'saw-tooth' command form was adopted in the early 1980s to preclude
exactly this kind of failure. Can you estimate the year of the event a
little more closely so I know who to ask for corroboration?



"Craig Fink" > wrote in message
hlink.net...
> An RCS jet has failed ON, not during a flight, but during a simulation. A
> simulation that if it had occurred during a flight, would have resulted in
> an uncontrolled RCS jet firing. It happened four of five years ago during
> training for a flight. They were flying a TAL. At a point just after MECO,
> an RCS jet came on just as the flight software began an OPS transition.
> During the transition, some of the memory gets overwritten with the new
> code for the next OPS, and some of the the memory doesn't. There was a
> status word for the RCS jets that didn't get overwritten or reset, so the
> RCS jet that was ON before the transition remained ON after the
transition.
> Essentially, the flight control didn't know that it was still commanding a
> jet ON.
>
> As you can imagine, the vehicle began to tumble out of control during a
> critical phase of a TAL. Critical because there isn't much time between
> MECO and Entry, and a lot of things have to happen in this short time
span.
>
> As to what happened during the sim? I believe they stopped the sim to dump
> the computers to try to figure out what happened.
>
> If it had happened on the actual flight? I can imagine that the Commander
> would have figured out on her own how to fix the problem. It was similar
to
> what happened during Gemini, where if something wasn't done very quickly,
> the vehicle would have continued to spin up.
>
> Craig Fink

[Craig Fink]

Hi James,

I could be wrong, but I'm pretty sure it was just prior to Eileen Collins'
first flight as Commander (STS-93) and she was the one who found the bug.
It had been there many many years. It just took the right set of
circumstances for it to be found.

Just goes to show that all the simulations that NASA performs on the flight
software is really worth it.

It also show, that no matter how much testing and verification is done,
there can always be some unique path through the software that can cause a
problem. A problem that may require some human intervention.

If the computer is still commanding a 'saw-tooth' the RCS jet will think
it's a valid command, it would just protect more of a wiring failure. A
short "ON", not a bad command coming from the computer.

Craig Fink





James Oberg wrote:

>
> V-E-R-Y interesting, thanks for the report! I'm looking forward to hearing
> more details on this pretty amazing event. Frankly, I'm surprised, because
> the 'saw-tooth' command form was adopted in the early 1980s to preclude
> exactly this kind of failure. Can you estimate the year of the event a
> little more closely so I know who to ask for corroboration?
>
>
>
> "Craig Fink" > wrote in message
> hlink.net...
>> An RCS jet has failed ON, not during a flight, but during a simulation. A
>> simulation that if it had occurred during a flight, would have resulted
>> in an uncontrolled RCS jet firing. It happened four of five years ago
>> during training for a flight. They were flying a TAL. At a point just
>> after MECO, an RCS jet came on just as the flight software began an OPS
>> transition. During the transition, some of the memory gets overwritten
>> with the new code for the next OPS, and some of the the memory doesn't.
>> There was a status word for the RCS jets that didn't get overwritten or
>> reset, so the RCS jet that was ON before the transition remained ON after
>> the
> transition.
>> Essentially, the flight control didn't know that it was still commanding
>> a jet ON.
>>
>> As you can imagine, the vehicle began to tumble out of control during a
>> critical phase of a TAL. Critical because there isn't much time between
>> MECO and Entry, and a lot of things have to happen in this short time
> span.
>>
>> As to what happened during the sim? I believe they stopped the sim to
>> dump the computers to try to figure out what happened.
>>
>> If it had happened on the actual flight? I can imagine that the Commander
>> would have figured out on her own how to fix the problem. It was similar
> to
>> what happened during Gemini, where if something wasn't done very quickly,
>> the vehicle would have continued to spin up.
>>
>> Craig Fink

[Craig Fink]

Jon Berndt wrote:

>> "Craig Fink" > wrote in message
>
>> > An RCS jet has failed ON, not during a flight, but during a simulation.
> A
>
> Which simulator?

I'm pretty sure it was the SMS. I wasn't involve with the simulation, just
verifing the fix.

Craig Fink

[[email protected]]

Craig Fink > wrote in message .net>...
> Hi James,
>
> I could be wrong, but I'm pretty sure it was just prior to Eileen Collins'
> first flight as Commander (STS-93) and she was the one who found the bug.
> It had been there many many years. It just took the right set of
> circumstances for it to be found.
>
> Just goes to show that all the simulations that NASA performs on the flight
> software is really worth it.
>
> It also show, that no matter how much testing and verification is done,
> there can always be some unique path through the software that can cause a
> problem. A problem that may require some human intervention.
>
> If the computer is still commanding a 'saw-tooth' the RCS jet will think
> it's a valid command, it would just protect more of a wiring failure. A
> short "ON", not a bad command coming from the computer.
>
> Craig Fink
>
>
>
>
>
> James Oberg wrote:
>
> >
> > V-E-R-Y interesting, thanks for the report! I'm looking forward to hearing
> > more details on this pretty amazing event. Frankly, I'm surprised, because
> > the 'saw-tooth' command form was adopted in the early 1980s to preclude
> > exactly this kind of failure. Can you estimate the year of the event a
> > little more closely so I know who to ask for corroboration?
> >
> >
> >
> > "Craig Fink" > wrote in message
> > hlink.net...
> >> An RCS jet has failed ON, not during a flight, but during a simulation. A
> >> simulation that if it had occurred during a flight, would have resulted
> >> in an uncontrolled RCS jet firing. It happened four of five years ago
> >> during training for a flight. They were flying a TAL. At a point just
> >> after MECO, an RCS jet came on just as the flight software began an OPS
> >> transition. During the transition, some of the memory gets overwritten
> >> with the new code for the next OPS, and some of the the memory doesn't.
> >> There was a status word for the RCS jets that didn't get overwritten or
> >> reset, so the RCS jet that was ON before the transition remained ON after
> >> the
> transition.
> >> Essentially, the flight control didn't know that it was still commanding
> >> a jet ON.
> >>
> >> As you can imagine, the vehicle began to tumble out of control during a
> >> critical phase of a TAL. Critical because there isn't much time between
> >> MECO and Entry, and a lot of things have to happen in this short time
> span.
> >>
> >> As to what happened during the sim? I believe they stopped the sim to
> >> dump the computers to try to figure out what happened.
> >>
> >> If it had happened on the actual flight? I can imagine that the Commander
> >> would have figured out on her own how to fix the problem. It was similar
> to
> >> what happened during Gemini, where if something wasn't done very quickly,
> >> the vehicle would have continued to spin up.
> >>
> >> Craig Fink

it can be done with hardware, too. www.gusgrissom.com

[John Maxson]

> wrote in message
om...
>
> it can be done with hardware, too. www.gusgrissom.com

In the case of Mission 51-L, the firings observed from lift-off
through t+58 seconds were discrete (on-off, bang-bang).

Even the continuous, right-aft, yaw firings (beginning at about
t+59 seconds) stopped briefly prior to the terminal firings.

--
John Thomas Maxson, Retired Engineer (Aerospace)
Author, The Betrayal of Mission 51-L (www.mission51l.com)

[James Oberg]

"John Maxson" > wrote in message
...
> > wrote in message
> om...
> >
> > it can be done with hardware, too. www.gusgrissom.com
>
> In the case of Mission 51-L, the firings observed from lift-off
> through t+58 seconds were discrete (on-off, bang-bang).
>
> Even the continuous, right-aft, yaw firings (beginning at about
> t+59 seconds) stopped briefly prior to the terminal firings.
>
> --
> John Thomas Maxson, Retired Engineer (Aerospace)
> Author, The Betrayal of Mission 51-L (www.mission51l.com)
>
>

[Roger Balettie]

"John Maxson" > wrote:
> In the case of Mission 51-L, the firings observed from lift-off
> through t+58 seconds were discrete (on-off, bang-bang).

Please provide telemetric evidence of these "observed firings".

> Even the continuous, right-aft, yaw firings (beginning at about
> t+59 seconds) stopped briefly prior to the terminal firings.

Please provide telemetric evidence of these "right-aft, yaw firings".

Please define "terminal firings".

Evidence and definitions will provide a common ground on which we can
discuss your claims.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/

[[email protected]]

"Roger Balettie" > wrote in message >...
> "John Maxson" > wrote:
> > In the case of Mission 51-L, the firings observed from lift-off
> > through t+58 seconds were discrete (on-off, bang-bang).
>
> Please provide telemetric evidence of these "observed firings".
>
> > Even the continuous, right-aft, yaw firings (beginning at about
> > t+59 seconds) stopped briefly prior to the terminal firings.
>
> Please provide telemetric evidence of these "right-aft, yaw firings".
>
> Please define "terminal firings".
>
> Evidence and definitions will provide a common ground on which we can
> discuss your claims.
>
> Roger

Roger, please comment on the S-11 rcs A&C roll switch. show
us that you know something about flight dynamics.

[Jay Windley]

"James Oberg" > wrote in message
...
|
| What's "S-11"? At least, give us a clue which decade -- maybe, which space
| program -- you're referring to?

Jim, he's talking about Switch 11 on Panel 8 of the Block I command module
in which his father unfortunately perished. Scott claims that switch was
intentionally sabotaged with a small piece of metal, creating a short
circuit which caused equipment to intentionally overheat and start the
Apollo 1 fire.

Needless to say, none of his claims stands up to much scrutiny.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

[Derek Lyons]

"Roger Balettie" > wrote:

>"John Maxson" > wrote:
>> In the case of Mission 51-L, the firings observed from lift-off
>> through t+58 seconds were discrete (on-off, bang-bang).
>
>Please provide telemetric evidence of these "observed firings".
>

Please trim sci.space.history from your replies and keep your spam in
sci.space.shuttle.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

Enhanced HTML Version:
http://www.io.com/~o_m/columbia_loss_faq_x.html

Corrections, comments, and additions should be
e-mailed to , as well as posted to
sci.space.history and sci.space.shuttle for
discussion.

[OM]

On Sat, 16 Aug 2003 18:03:53 GMT, "James Oberg"
> wrote:

>"Jay Windley" > wrote i
>> Jim, he's talking about Switch 11 on Panel 8 of the Block I command module
>> in which his father unfortunately perished. ,,,,
>> Needless to say, none of his claims stands up to much scrutiny.
>
>I cut him a lot of slack, and he hasn't reached the end of it yet, in my
>account book.

....Jim, I'd love to talk to your accountant, then. Because somewhere
he's juggling the books in a way that the ISS - Internal Slack Service
- would put you away for life over.



OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

[Kent Betts]

"OM" > ...Jim, I'd love to talk to your accountant, then.

Not me. I am building a lunar rover out of Legos.

[[email protected]]

"James Oberg" > wrote in message >...
> > wrote in message
> > Roger, please comment on the S-11 rcs A&C roll switch. show
> > us that you know something about flight dynamics.
>
> Scott, preserve the sympathy you have left by avoiding silly pointless
> games.
>
> What's "S-11"? At least, give us a clue which decade -- maybe, which space
> program -- you're referring to?
>
> Questioning Roger's knowledge of flight dynamics is a pointless and
> unwinnable tantrum.

jim, this ain't no game. it's well documented where you get the
bucks from. this ain't no tantrum. he can answer the question. we
know where he gets the bucks from, too.

[[email protected]]

Bruce Palmer > wrote in message >...
> Roger Balettie spewed out:
> > "John Maxson" > wrote:
> >
> >>In the case of Mission 51-L, the firings observed from lift-off
> >>through t+58 seconds were discrete (on-off, bang-bang).
> >
> >
> > Please provide telemetric evidence of these "observed firings".
> >
> >
> >>Even the continuous, right-aft, yaw firings (beginning at about
> >>t+59 seconds) stopped briefly prior to the terminal firings.
> >
> >
> > Please provide telemetric evidence of these "right-aft, yaw firings".
> >
> > Please define "terminal firings".
> >
> > Evidence and definitions will provide a common ground on which we can
> > discuss your claims.
> >
> > Roger
>
> And another thread goes down the ****ter.

a whole roll of northern followed you. at least the maid is happy.....

[[email protected]]

"Jay Windley" > wrote in message >...
> "James Oberg" > wrote in message
> ...
> |
> | What's "S-11"? At least, give us a clue which decade -- maybe, which space
> | program -- you're referring to?
>
> Jim, he's talking about Switch 11 on Panel 8 of the Block I command module
> in which his father unfortunately perished. Scott claims that switch was
> intentionally sabotaged with a small piece of metal, creating a short
> circuit which caused equipment to intentionally overheat and start the
> Apollo 1 fire.
>
> Needless to say, none of his claims stands up to much scrutiny.

needless to say, you haven't shot any holes it it yet.

[[email protected]]

OM <om@our_blessed_lady_mary_of_the_holy_NASA_research _facility.org> wrote in message >...
> On Sat, 16 Aug 2003 18:03:53 GMT, "James Oberg"
> > wrote:
>
> >"Jay Windley" > wrote i
> >> Jim, he's talking about Switch 11 on Panel 8 of the Block I command module
> >> in which his father unfortunately perished. ,,,,
> >> Needless to say, none of his claims stands up to much scrutiny.
> >
> >I cut him a lot of slack, and he hasn't reached the end of it yet, in my
> >account book.
>
> ...Jim, I'd love to talk to your accountant, then. Because somewhere
> he's juggling the books in a way that the ISS - Internal Slack Service
> - would put you away for life over.
>
>
>
> OM

mosley, i was in austin a couple of weeks ago and i found out
that the city jailers call you "peach". you shouldn't drop the soap in
the shower, son.

[James Oberg]

> wrote in message
> jim, this ain't no game. it's well documented where you get the
> bucks from.

What do you think these documents show?

And what is the implication you invite people to draw?

[Jay Windley]

> wrote in message
om...
|
| needless to say, you haven't shot any holes it it yet.

Not any holes you feel like acknowledging. Every hole I pointed out, you
sidestepped and told me to tell you instead "what a hard short could do."
Never once did you consider whether a "hard short" had actually occurred.
Your argument, from a failure analysis point of view, falls into one huge
gaping hole that you refuse to talk about.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

[[email protected]]

"Roger Balettie" > wrote in message >...
> > wrote:
> > Roger, please comment on the S-11 rcs A&C roll switch. show
> > us that you know something about flight dynamics.
>
> Scott -- the question that you seem to be asking regarding a hardware
> switch have nothing to do with flight dynamics, when you're referring to
> your questions regarding the Apollo 1 on-the-pad fire.
>
> Am I correct or incorrect in your questioning?
>
> Roger

??? it's not a hardware switch. it's a hardware problem in a
flight control system. from my way of thinking, a flight dynamics
officer would/should be well versed in stability/control, flight sys.
control, operation and testing. i know there's a great deal more to
the job, but the title implies knowledge of flight control systems.

[Roger Balettie]

> wrote:
> "Roger Balettie" > wrote in message
>...
> > > wrote:
> > > Roger, please comment on the S-11 rcs A&C roll switch. show
> > > us that you know something about flight dynamics.
> >
> > Scott -- the question that you seem to be asking regarding a hardware
> > switch have nothing to do with flight dynamics, when you're referring to
> > your questions regarding the Apollo 1 on-the-pad fire.
> >
> > Am I correct or incorrect in your questioning?
> >
> > Roger
>
> ??? it's not a hardware switch.

When you ask me to comment on the "S-11 rcs A&C roll switch", it's a
hardware switch.

> from my way of thinking, a flight dynamics
> officer would/should be well versed in stability/control, flight sys.
> control, operation and testing. i know there's a great deal more to
> the job, but the title implies knowledge of flight control systems.

It does.

However, the Apollo 1 fire was a "static" incident and not a flight dynamics
situation.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/