Anyone here ever have gyro failure?
St Stephen Ames
failure since this is the topic of the week...
Blue skies,
St Stephen Ames
PP-ASEL
N16402
PA-28-180
My flying site: http://www.stephenames.com/flying/flying.html
---------------------------------------------------------------
- Another part of my pre-flight passenger briefing -
'Smoking is not permitted inside the cabin; however smoking outside
the cabin should be reported to the captain immediately!'
Bob Noel
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
I assume you mean a gyro failure in IMC. (fortunately, mine failed
while VFR).
--
Bob
(I think people can figure out how to email me...)
(replace ihatessppaamm with my name (rnoel) and hw1 with mediaone)
Effie Andree Wiltens
the ADI became very sluggish, and I was trying to do an NDB hold and
teardrop NDB approach when this happened. I was so concentrated on doing
things right that I was trying to compensate for the sluggish behaviour of
the gyro and please the examiner, and didn't realize that the instrument was
faulty until the examiner told me he'd seen enough and it was pointless to
continue the approach with an unreliable gyro. We then did some actual
partial panel work.
It was a good lesson. He passed me, but I became more aware of the insiduous
nature of a DI failure. It turned out that the bearings were worn.
The next day, I flew the instrument to the workshop for repair. The flight
was about 45 minutes each way in VMC, all that time with the big empty hole
staring at me and driving home that of all the instruments we rely on in
flight, the DI is one of the most critical ones.
Of course my aircraft didn't have a backup. Not enough panel space! It had
an extra altimeter (mandatory for IFR flight in the UK) but no extra gyros.
The whole incident really drove home how important partial panel training
is. Fortunately, I also fly historic aircraft (with very partial panels).
Does the slow failure sound familiar to anyone? When is it exactly that you
started to suspect the instrument?
FE.
The examiner caught on, though. He told me that it was pointless to continue
since the instrument was unreliable,
St Stephen Ames <ste...@stephenames.com> wrote in message
news:384916...@stephenames.com...
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
Rich Hare
confusing and ambiguous. I could see the AH and horizon didn't agree
(slow coast-down) but I couldn't quite figure out why for at least a
minute. I think this is consistent with the general concensus of this
thread; it is sneaky, unlike, let's say, an engine failure which is
immediately apparent.
I continued VMC to next place I could get the pump replaced.
notchu
and it has'nt been a big deal (though the potential was there.) what most
of us get in partial panel training duplicates a total vacuum loss, and is
pretty much worst case. lucky me, that's the one failure i hav'nt had. most
of my cohorts are considered to be very sharp on instruments (lots of high
perf. ac without lots of automation), and i don't think to many of them
would want a loss of all the vacuum gyros. i think they would get through
it, but it would be a no kidding around emergency. there's a reason that
we've got peanut gyros in the jets, and its kind of funny that the pistons
don't, since they're the less reliable aircraft.
Roy Smith
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
I had a DG fail in IMC. It was not a vacuum pump failure -- the AI was
still working perfectly. It was during my instrument training, with my
CFII in the other seat.
The gyro just started to precess at a substantial rate. Fast enough to
cause me to get significantly off course, but not fast enough to be
obvious. Our first hint that anything was going on was when ATC querried
our heading.
If I remember the sequence of events correctly, the controller said
something like "say current heading" (which as we all know, really means,
"where the **** are you going!?"). I replied with my indicated heading,
which was what we had been assigned, and the controller said "you appear
to be ...". I then looked at the wet compass, noted that the DG had
precessed a bunch, reset the DG and apologised.
A few moments later, we got the same question. I again checked the DG
against the compass, noticed that it was again off by a substantial
amount, and just about that time, the DG started spinning wildly. I
started flying the wet compass for heading, we explained the problem to
ATC, and completed the flight. In retrospect, that was probably a dumb
decision. We should have diverted to the nearest airport, but things
seemed under control, I was a bit stupider then than I am now, and my
instructor was a bit of a maniac.
I practice a lot of partial panel (and demand the same of my students).
However, I've also seen how these things sneak up on you. We got an
"early warning" from ATC who was watching us on radar and observed our
course deviation. It was also zero turbulence. But, imagine if that was
not the case. I can easily see the following scenario playing out..
We would have kept turning slowly, tracking the ever-precessing DG. The
rate of turn would have been so slow as to be unobservable on the TC and
AI. Pretty soon, the CDI would have started to uncenter and go
full-scale. If I didn't yet suspect anything wrong with the DG, I would
have been scratching my head trying to figure out why the CDI was acting
wierd. I might have pulled out a chart to double-check the frequency and
radial, which would have further distracted me from noticing the onrushing
instrument failure. I would have looked up from my chart to notice that
I'd managed to let my heading drift 30 degrees. Damn, I should know
better than to spend so much time head-down in the chart. Too much time
navigating and not enough aviating. OK, standard rate turn to get back on
heading. Odd, isn't it, that I don't seem to be changing heading at the
usual rate. The wet compass, of course, is useless in a turn, so I don't
even bother double-checking that. By this time, I've figured out that
*something* is wrong, but which instrument, not to mention I've still got
this nagging suspicion I've just set the radio wrong. At this point, the
DG starts spinning wildly, and it's suddenly become obvious which gyro is
at fault, but maybe it's the vacuum pump, so I'm not sure if I can trust
the AI either. Holy shit, how did the airspeed get halfway up the yellow
arc!?
That's a very different scenario than having your instructor slap a sticky
over the gyros and say, "OK, let's try this approach partial panel".
Matthew Whiting
>
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
I had a failure during climb on an IFR flight, but I detected it about
200' before entering IMC (I have a habit of scanning the vacuum gauge
right before I enter a cloud). I broke off the climb, notified ATC and
returned to the departure field. Not a big deal in my case, but I'm
really glad I checked the gauge when I did.
The ironic part is that the "failure" was due to a fitting coming loose
on my Precise Flight standby vacuum system!
Matt
William W. Plummer
believe that. The DG must have failed." And sure enough it spun down. I
wanted to return home, but he said to finish the flight with out the DG.
It was fun and while I preparing to land he said, "Hey. Can you believe
that. The DG must have fixed itself." I guess he was pulling the circuit
breaker. --Bill
"Roy Smith" <r...@popmail.med.nyu.edu> wrote in message
news:roy-041299...@mc-as01-p36.med.nyu.edu...
> ste...@stephenames.com wrote:
> > I would like to hear any stories of folks that have survived a gyro
> > failure since this is the topic of the week...
>
Larry Fransson
Actually, it was an introductory IFR flight - part of an "introduction to IFR"
that the company does every year to promote interest in instrument training.
(Morris, you can ask Paula about this one.)
I was the instructor, with a student in the left seat and another observing in
the back. We were headed into Salem, Oregon for lunch. We were in IMC
(student flying) and starting our descent when I heard a horrendous noise
accompanied by wild gyrations of all of the pitot-static instruments. Given
the noise and the indications we were getting, I figured there must be
something loose on the outside and beating against the static port. I got
some indication of the real problem when we leveled off and the attitude
indicator still showed us in a descent while all other indications (wild
gyrations notwithstanding) indicated we were level. At some point, I
discovered that the crazy pitot-static indications were caused by the
vibrations coming from the dying attitude indicator. It was shaking the whole
instrument panel. I had the student in the back seat retrieve one of my
instrument covers so that I could cover the attitude indicator (I checked
later after the vibration stopped - it was inverted) and I flew the approach.
It would have been one thing to talk a student through a LOC BC circle to land
with all the instruments. I didn't really want to try to talk a student
through it partial panel in IMC! It turned out that the heading indicator was
working, but given that I didn't really know for sure what was going on, I
didn't really trust it. In an effort to ensure that the students were getting
their money's worth, I continued instructing, explaining how we could use
other instrument indications to make up for the loss of the attitude
indicator, etc.
We all flew back to Seattle in other empty seats, and a mechanic flew down to
Salem later when it became VFR to retrieve the plane. It turned out that a
bearing in the attitude indicator had eaten itself, causing the vibrations and
the screwy indications. At least one of the two students has since completed
instrument training.
----
Larry Fransson (lfra...@aol.com)
Pilots are just plane people with a different air about them.
Robin Remde
Effie Andree Wiltens <ea...@hotmail.com> wrote in message
news:82b6rl$n9q$1...@news1.xs4all.nl...
> I had a gyro failure in IMC during an IFR check ride. The failure was that
> Does the slow failure sound familiar to anyone? When is it exactly that
you
> started to suspect the instrument?
>
Sounds very familiar! I've had slow failures on both the AI and the DG
(different flights), and both failed slowly. As luck would have it, both
failures were in IMC. When the DG went, it started precessing like crazy -
never gave out completely, but it was clearly useless. When the AI failed,
the first symptom was that it was overly sluggish righting itself during
turns. After about 15 minutes, it failed completely. Fortunately, my
instrument instructor was big on partial panel work - I would get to do
something once or twice full panel, then he'd start covering stuff up. It
really got me in the habit of cross checking my secondary instruments, which
allowed me to suspect the failures pretty early. It's kinda like that
Sesame Street game - one of these things is not like the other - ;-) If
you're showing wings level, your heading is changing, and your mag compass
is fairly steady, it's time to keep a close eye on the DG (which, by the
way, I think is harder to spot - you expect it to precess a bit).
The funny thing was that both failures happened in two different aircraft
within about a week. It made me realize that no matter how well an aircraft
is maintained, you'll eventually need to deal with a gyro failure.
Robin
HLAviation
>an extra altimeter (mandatory for IFR flight in the UK)
Thats interesting. Do you have one extra for 2 total or 2 spares for 3 total.
If you have only 2 and they dissagree, how do you chose.
Capt.Doug
first was in a C-402b. I was in the right seat trying to rest my eyes when
the PIC shouted that I had the controls. After apprehending reality and
assuming command, I noticed that his AH was spinning wildly. Later, he told
me that the gyro had been doing that lately and the owner wouldn't get it
fixed until after the weekend. I still wonder what the pilot would have done
if he didn't have another pilot next to him.
Two other times happened when the AH froze up. The Navajo's heater wasn't
plumbed because of an AD and the Cessna's heater didn't put out enough BTUs.
Both times, the AH worked after take-off and during climb, but slowly rolled
over dead in cruise. It takes a while to sort out which instrument is
unreliable when it happens in the real world. In both cases, the AH came to
life and functioned normally after descending into warmer air.
The next AH failure I remember involves a dual vaccuum pump failure. It was
in a C-402c on a 3 hour leg. The flight was in VFR but made me realize what
could happen. The C-402 uses big vaccuum pumps, that in addition to
providing vaccuum, also provide suction which sucks the de-ice boots flat
against the leading edge. The inner surfaces of the boots chafe against each
other and, over time, produce rubber dust. This rubber dust will wipe out a
pump in no time.
There are two things about gyro failures that I pass on to others. Try to
cover up the failed gyro so it won't distract you and practice no-gyro
approaches under the hood or in a sim every chance you get. It's one of the
IFR skills that demands practice to remain proficient.
D.
Dan Larsen
> The rate of turn would have been so slow as to be unobservable on the
> TC and AI. Pretty soon, the CDI would have started to uncenter and go
> full-scale. If I didn't yet suspect anything wrong with the DG, I
> would have been scratching my head trying to figure out why the CDI
> was acting wierd. I might have pulled out a chart to double-check the
> frequency and radial, which would have further distracted me from
> noticing the onrushing instrument failure. I would have looked up
> from my chart to notice that I'd managed to let my heading drift 30
> degrees. Damn, I should know better than to spend so much time
> head-down in the chart. Too much time navigating and not enough
> aviating. OK, standard rate turn to get back on heading. Odd, isn't
> it, that I don't seem to be changing heading at the usual rate. The
My question -- why wouldn't you have pulled out your AFD and
double-checked the usable frequency for the VOR? I was tracking a radial
outbound on my solo x-c and then it started missed behaving. I had
planned my route to take me through GAI-ESN-ILG-LNS-MRB-GAI. I was late
getting off the ground, and consequently, by the time I arrived at LNS it
was getting late. I thought about pushing it and going to MRB, but opted
to be safer than sorry (seems to be a running theme with a lot of people)
as I wasn't signed off for night flight and headed direct GAI. I didn't
plan for the LNS-GAI leg, and decided to just track VOR's. I wasn't any
mood to work on my pilotage at that point. I wasn't concerned about
taking a trip "cold" as my instructor and I have done that trip a couple
of times. However, we've always tracked direct Westminster VOR and then
out bound to GAI. I didn't pay much thought and picked a radial and
tracked it outbound from LNS VOR. There was no published airway between
the two, so I just picked one that looked accurate and went. About 15
miles SW of LNS, my CDI started acting funny. I didn't spend much time
messing with that and just tracked Westminster inbound. Back in my mind,
I was wondering what the heck was going on. Thankfully I decided to head
straight back, as it was dusk when I was landing. Back on the ground, it
then occured to me that I should check my AFD, just in case. Sure enough,
there it says: "... LNS VOR unusable on the section that you were
flying..."
Matthew Whiting
>
> There are 4 artificial horizon failures that I remember right away. The
> first was in a C-402b. I was in the right seat trying to rest my eyes when
> the PIC shouted that I had the controls. After apprehending reality and
> assuming command, I noticed that his AH was spinning wildly. Later, he told
> me that the gyro had been doing that lately and the owner wouldn't get it
> fixed until after the weekend. I still wonder what the pilot would have done
> if he didn't have another pilot next to him.
Cover it and fly the turn coordinator and ASI?
Mike Rapoport
caused the autopilot to disengage repeatedly. The first failure was a
Century HSI which had about a thousand hours on it. It began to precess
faster than the slaving unit could keep up with. The second was a vacuum
driven ADI that failed in IMC. This was pretty bad. How many people can
fly moderate turbulence partial panel? I can tell you that it is a lot
harder than you think! The remote gyro has been overhauled and is still
causing problems so it is now driving the right seat HSI. I believe that if
you don't have two ADI gyros and two directional gyros you should overhaul
them on a schedule and not wait for them to fail. I have two of each (and
two turn coordinators of course) and I overhaul them so that the pilot side
gyros never have over 1000hrs on them. While we all flew partial panel on
the instrument check ride, there have been so many accidents following the
loss of gyros that I don't think it makes sense to economize on them at all.
Mike
MU-2
Matthew Whiting wrote in message <3849A814...@epix.net>...
N55BZ
Capt.Doug <Capt...@theworldnet.att.net> wrote in message
news:82c26j$p1g$1...@bgtnsc01.worldnet.att.net...
> There are 4 artificial horizon failures that I remember right away. The
>
I have only experienced one. It was in a P-3C which has two inertials which
provide attitude and heading information to pilot and co pilot, a stand by
gyro to provide back up attitude information and a 2-1/2 inch attitude gyro
(peanut gyro) which is seperate from all of the other systems. INS1, INS2
and the stand by gyro all failed. We flew a no gyro GCA into NAS JAX. using
needle, ball, wet compass and peanut gyro.
Gyro failure is possible even in well equipped aircraft with numerous back
up systems.
Jerry Kurata
trying to line up for a single engine (one had died earlier) VOR approach.
The HSI showed me on course for a while then I started drifting. I
corrected, but had to keep correcting. By the time I figured out that the
HSi was dying I was 7-8 degrees off course. I had to get it down, since we
where single engine, so I dropped back to the secondary indicator and the
compass. I got it in, but I was a sweatty mess!
The biggest thing was how incidiosly slow the thing was in failing. Until
it spun down far enough the Nav flags did not appear. However, by the time
the flags appeared I was well off course.
Jerry
St Stephen Ames <ste...@stephenames.com> wrote in message
news:384916...@stephenames.com...
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
Aaron Kiley
happens if you have the autopilot on the heading bug and the HI spools
down? Or maybe worse, if it works off the turn coordinator and that fails
when the autopilot is set to wing leveling mode. Do you get a bank past
standard rate into an unusual attitude? ... Aaron
Roy Smith
There are too many different kinds of autopilots, with too many different
kinds of interconnections to the gyro instruments, to give an answer to
this any better than "read the manual that came with your autopilot".
Effie Andree Wiltens
concurently. Like keeping one altimeter on regional QNH and the other on
QNE, or during the approach setting one to QFE and keeping the other on QNH.
FE.
HLAviation <hlavi...@aol.com> wrote in message
news:19991204160336...@ng-fm1.aol.com...
Dennis C. O'Connor
due to failure of the vacuum source... One was a cracked 90 degree
fitting, and the other was the pump...
First time, I noted that I was one wing 'just a hair' low, according to
the gyro, and slightly pitched up (non vacuum flag gyros)- and when I
corrected that with a tad of pressure on the wheel, I began a slight
turn and the seat of my pants told me I was descending... While
inspecting the panel with a puzzled look on my face I noticed the
electric t&b was showing a turn also, and the ivsi was showing about 100
fpm down and the altimeter had just begun to creep downwards... So, I
switched my immediate scan to the t&b, vertical speed/altimeter and
whiskey compass and got back to straight and level, on course, and on
altitude... By this time (maybe 5 or 6 seconds) I had finally caught on
to the vacuum needle being low and I watched the horizon as it sloooowly
rolled over on it's back, and the DG froze up on one heading... Kinda
scary to watch... I did not deviate enough for the controller to catch
it and he was surprised when I told him, "I want my mommy!"
"3 0 victor, say again.", was his response...
So, I adopted my most professional tone and used the appropriate
language out of the far/aim to request to be allowed to shoot the ils
with radar vectors (pretty please with sugar) and call it a night...
Once they understood I was not rattled, they got all excited and asked
to be allowed to run me in as a "for real" par, no gyros approach so
they could log it and get credit... Which we did and we all had a
ball...Other than giving the guys at the center something to chuckle
about, it was a non event...
Second time I caught on a lot quicker...
What I fly in imc now has two vacuum sources... But, I have to say that
if a slow gyro failure happened when I was just climbing out, with an
atc ceiling above me, and being really busy with pitch and power
changes, and trying to fly a sids at the same time, it could get more
exciting... I long ago decided that altitude and airspeed are my best
friends, and if the brown stuff hits the fan, I am going to establish a
straight ahead, standard rate climb, above blue line, and inform atc it
is their mission to keep everyone to hell away from ME, not the other
way around... and we will fight about it later... Hopefully the god of
itinerant aviators will take pity and give me time to implement that
flight plan in the event things become exciting...
Denny
DOW_9er7Tango
Thanks!
--97T--
Dennis C. O'Connor <k8...@midmich.net> wrote in message
news:384AEE11...@midmich.net...
Henry A. Spellman
three. The first was a failure of the AH in good VFR. I rolled out of a
turn, the AH didn't. Ten minutes later, it seemed OK. An hour later it
did the same thing again. I bought a new one.
The second was a DG that went out while IFR. As others have commented,
first it precessed more than usual, then started spinning, and finally
stopped completely. I used my ADF to hold a steady heading with my
handheld GPS to tell me what the heading (actually, track) was. Since I
was only 20 minutes from my destination (home) which was good VFR, I
elected to continue. The DG was also replaced.
The third failure was a T&B which laid over to full right hand turn because
of a broken spring. Fortunately I was number one on the runway for takeoff
into low IFR when it happened, so I just canceled out and went back to the
hanger.
My personal checklist for such failures, especially if the AH and DG both
go out, is as follows:
!. Totally abandon the original mission. The mission now is to get on the
ground in one piece at the first place it can be done safely.
2. Declare an emergency.
3. Tell, not request of, ATC that I want help with the navigation, get me
latest weather, and I want vectors to the nearest ILS (assuming low
weather).
4. Tell ATC I want all turns to be level (no altitude changes during
turns) and all altitude changes to be made while in straight flight
5. Tell ATC I want a block altitude, especially if it is not smooth air.
I don't want to upset things by having to go back to an altitude if it is
not really necessary.
6. Assuming fuel range is not a problem, slow down and put down the gear.
Pitch control is the first thing to go, and this adds considerably to the
margin of safety, especially on the high side.
It worked for me.
Hank
Henry A. Spellman
St Stephen Ames wrote:
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
> Blue skies,
> St Stephen Ames
> PP-ASEL
> N16402
> PA-28-180
> My flying site: http://www.stephenames.com/flying/flying.html
> ---------------------------------------------------------------
> - Another part of my pre-flight passenger briefing -
> 'Smoking is not permitted inside the cabin; however smoking outside
> the cabin should be reported to the captain immediately!'
--
Hank Spellman
ha...@abelink.com
Ron Natalie
Bob Noel wrote:
>
> In article <384916...@stephenames.com>, ste...@stephenames.com wrote:
>
> > I would like to hear any stories of folks that have survived a gyro
> > failure since this is the topic of the week...
>
> I assume you mean a gyro failure in IMC. (fortunately, mine failed
> while VFR).
>
Ditto here. I was beginning to wonder why my DG seemed to be precessing
badly when Margy noted that the vacuum had gone to zero (this was on a
VFR climbout from our home field). I watched it and it didn't take
too long for the AI to roll over after that.
Roy Smith
> 3. Tell, not request of, ATC that I want help with the navigation, get me
> latest weather, and I want vectors to the nearest ILS (assuming low
> weather).
I see two possible scenarios to get on the ground -- one is, as you say, vectors
to the nearest ILS, the other is vectors to a more distant airport with good
weather. Personally, I'd rather cruise in IMC for a couple of hours with AI/DG
if it gets me a VFR descent, than try to fly an approach that way. I'd be
interested to hear how other people feel.
--
Roy Smith <r...@popmail.med.nyu.edu>
CP-ASEL-IA, CFI-ASE-IA
John Harlow
> I was under the hood once and my instructor suddendly said, "Hey. Can you
> believe that. The DG must have failed." And sure enough it spun down. I
> wanted to return home, but he said to finish the flight with out the DG.
> It was fun and while I preparing to land he said, "Hey. Can you believe
> that. The DG must have fixed itself." I guess he was pulling the circuit
> breaker. --Bill
Interesting - I thought they usually were vacuum driven.
John Prickett
my first vacuum failure was in imc in a '50 model bonanza, about 5
months
after i got my instrument rating. although i was 'legally current', i
hadn't
practiced any ifr skills since i got my rating, and was totally unaware
of
how rapidly such skills could deteriorate. i followed a leaning a/i
into a
'graveyard spiral', and nearly killed my whole family. i managed to
right
the aircraft after popping out of the bottom of 500'agl clouds.
5 or 6 years later i again had a vacuum failure in imc, and due to
additional
training it was almost a non-event. i did descend to vmc, and landed at
the nearest airport, picked up the plane later on a vfr day to take it
to
the shop to be fixed.
i have had 2 other vacuum failures in imc, but they didn't count as they
were in a p210 with 'dual vacuum pumps', and only one failed.
it _can_ be a hazard!
john
--
the dark ages were caused by a y1k problem.
john.p...@amd.com
Ron Natalie
John Harlow wrote:
>
> ? I was under the hood once and my instructor suddendly said, "Hey. Can you
> ? believe that. The DG must have failed." And sure enough it spun down. I
> ? wanted to return home, but he said to finish the flight with out the DG.
> ? It was fun and while I preparing to land he said, "Hey. Can you believe
> ? that. The DG must have fixed itself." I guess he was pulling the circuit
> ? breaker. --Bill
>
> Interesting - I thought they usually were vacuum driven.
There are some HSI's (DG with overlaid VOR course indicator) that
require
electricity to work.
Larry Fransson
>
> Personally, I'd rather cruise in IMC for a couple of hours with AI/DG
> if it gets me a VFR descent, than try to fly an approach that way.
I would agree with you. Cruising partial panel is not difficult. Climbing or
desending complicates things a little, but not much. The real difficulty
comes when you start trying to turn to a particular heading and track
something like a localizer course.
I'll take VFR if I can get it.
Brett Rabe
> There are some HSI's (DG with overlaid VOR course indicator) that
> require
> electricity to work.
Some? I thought most HSIs were electric? Is
that incorrect?
Brett
--
Brett Rabe br...@uswest.net / 612.664.3078
Senior Systems Administrator U S WEST - Internet Services
An eye for an eye makes the world blind. -- Gandhi
Paul Tomko
St Stephen Ames <ste...@stephenames.com> wrote:
>I would like to hear any stories of folks that have survived a gyro
>failure since this is the topic of the week...
I had my AI go out in VMC. Obviously the world wasn't spinning and bouncing
as much as the AI, so it wasn't a big deal, but it was a bit unnerving to see
it going nuts anyway.
Fortunately, if it was IMC, this one failed in such a spectacular way that
you would immediately know something was awry. And it's only one instrument,
not the whole vaccuum system.
This question got me to thinking of redundant indicators. Some planes have
a backup vaccuum source, and some have duplicate gauges. Does anyone else
think that it might be nice to have a seperate type of backup altogether?
I'm thinking it would be nice to have a GPS display the basic flight
instruments on a multi function display. The altimeter would be the
easiest to display. The directional gyro could be displayed, but would be
off by the wind factor. Rate of climb, descent should be easily calculated.
Angle of bank could be guessed by using air speed and rate of turn (keep the
ball centered, or this could be way off!). It wouldn't be perfect, but should
be enough to keep you right side up.
I know some people have used a simplified version of this just to keep them
straight and level when the gyros fail.
Paul
--
Paul Tomko pa...@tomkoinc.com http://www.tomkoinc.com
8000+ Humorous Quotes http://www.tomkoinc.com/quotes.html
"Crime does not pay ... as well as politics." - Alfred E. Newman
Bob Noel
(CoLiN) wrote:
> >> There are some HSI's (DG with overlaid VOR course indicator) that
> >> require
> >> electricity to work.
> >
> >Some? I thought most HSIs were electric? Is
> >that incorrect?
> >
>
> i thot it was electricity that supplies power to the vacuum pump
> for the vacuum system to work.
nope. The pump on my plane is driven by a belt.
and, iirc, electric HSIs cost more.
--
Bob
(I think people can figure out how to email me...)
(replace ihatessppaamm with my name (rnoel) and hw1 with mediaone)
James Bieker
vacuum to power the AI and the DG, electrical to power the TC. I would
also venture that if any of the above had an autopilot, it is driven by the
TC?
HSI's aside, I wonder what aircraft do not fit the above criteria?
Roy Smith
> i thot it was electricity that supplies power to the vacuum pump
> for the vacuum system to work.
There are electric-driven vacuum pumps, but they are very much the
exception. A friend of mine owns a Bonanza with one of these, as a source
of backup vacuum (primary is the regular engine-driven pump). He also has
a 2nd AI which is electric powered. Belt and suspenders. It's a pricey
setup, but if you're willing and able to equip your plane like that, it's
a good way to fly.
In a typical "modern" GA engine, the vacuum pump is mounted directly onto
a power take-off pad on the rear of the engine, and is driven by an
accessory shaft from the engine, just like the magnetos are.
> I've heard of a "vacuum scoop" (or whatever it's call). An air inlet
> at the side of the aircraft that drives the vacuum system.
It's called a venturi. It was a very popular system in older airplanes.
They are draggy, are prone to icing, and worst of all (as you said) don't
work when the plane isn't moving, which means your gyros don't spin up
until after you takeoff.
Roy Smith
> Okay, then how come when I turn on the master switch on a C172,
> the AI (AH for some of you. <grin>), and my DG spins up and slowly
> erects?
That sure sounds like either electric gyros, or vacuum gyros with an
electric vacuum pump. Either is possible, but would be very unusual for a
172.
Henry A. Spellman
better weather or VFR within range." I agree that going to VFR is better than a
low approach if VFR is within reasonable range. What is reasonable range? It
depends on so many things I cannot make a general case solution flow chart. For
example, I would take a low ILS in day light over cruising for several hours to get
to VFR after dark, especially in an airplane that was already partially broken.
But I agree with your general thrust.
Hank
Henry A. Spellman
Roy Smith wrote:
> "Henry A. Spellman" <ha...@abelink.com> wrote:
> > 3. Tell, not request of, ATC that I want help with the navigation, get me
> > latest weather, and I want vectors to the nearest ILS (assuming low
> > weather).
>
> I see two possible scenarios to get on the ground -- one is, as you say, vectors
> to the nearest ILS, the other is vectors to a more distant airport with good
> weather. Personally, I'd rather cruise in IMC for a couple of hours with AI/DG
> if it gets me a VFR descent, than try to fly an approach that way. I'd be
> interested to hear how other people feel.
>
> --
> Roy Smith <r...@popmail.med.nyu.edu>
> CP-ASEL-IA, CFI-ASE-IA
--
Hank Spellman
ha...@abelink.com
MikeM
"Aaron Kiley" <aaron...@mediaone.net> wrote:
> Was wondering. With a Cessna 172 or 182 with a Cessna autopilot.
What
> happens if you have the autopilot on the heading bug and the HI
spools
> down? Or maybe worse, if it works off the turn coordinator and that
fails
> when the autopilot is set to wing leveling mode. Do you get a bank
past
> standard rate into an unusual attitude? ... Aaron
The Cessna 300 NavoMatic uses the TC as its primary input. The Servo
controller is set up to keep wings level, first and foremost. If the
Heading mode is enabled, the autopilot still keeps the wings (almost)
level, with a slight bank induced if the DG bug is not centered.
You can easily simulate your scenario. Turn on the autopilot in
wing-leveler mode (means that it is using only the TC for input). Crank
the heading bug to either full left or full right (+-90 deg from the
present heading), and then switch the autopilot to "Heading" mode.
The airplane will bank either right or left. The bank will stop at
either a standard rate turn (or one-half standard rate turn, I cant
remember which). As the airplane gets within about 30 deg of the
selected heading, the bank will gradually diminish, rolling back to
level as the select heading is achieved.
Even in the turn, it is the TC which is providing the autopilot with the
primary feedback. A DG failure at worst, would cause the airplane to
fly standard (or half standard) rate turns right or left until the
"heading" mode is disabled.
A failure of the electric TC gyro could be more serious.
--
MikeM, Skylane '1MM
Sent via Deja.com http://www.deja.com/
Before you buy.
Dennis C. O'Connor
electric and the AH to be vacuum... Vice versa would be ok, but an
electric TC is kind of the standard... I want the autopilot to have it's
own gyro's and not be dependent upon the AH...
Of course, like most things in life I don't always get what I want, but
I try... As soon as I take possession of my newly purchased Apache, I
will be diligently moving forward on making the panel reflect the
criteria outlined above...
Unfortunately, the title search shows a 37 year old lien that never had
the release filed with OK City... I'll bet this one is gonna be fun to
find anyone alive who can release it! Jeez, and I wanna go flying...
Denny
Dennis C. O'Connor
the price of electric so it is more common...
Denny
CoLiN wrote:
>
> On Mon, 06 Dec 1999 20:49:11 -0500, r...@popmail.med.nyu.edu (Roy Smith)
> told the whole world:
>
> >pi...@flight2000.com (CoLiN) wrote:
> >> Okay, then how come when I turn on the master switch on a C172,
> >> the AI (AH for some of you. <grin>), and my DG spins up and slowly
> >> erects?
> >
> >That sure sounds like either electric gyros, or vacuum gyros with an
> >electric vacuum pump. Either is possible, but would be very unusual for a
> >172.
>
> Hmmm.. Yeah, it is strange. I think I'll go pay more attention to the
> spinning sounds the next time I go and turn on that master switch again. I
> might be mistakening it for the TC motor (if it has one?) sound. But I
> remember seeing the AH erecting slowly when the master switch turned on.
>
> I'll go confirm it!
>
> Cheers.
>
> ------------------------------
> Colin Nah
> http://www.colin.net
> http://www.flight2000.com
> email:co...@flight2000.com
> ------------------------------
> "A male pilot is a confused soul who talks about women when he's flying, and
> about flying when he's with a woman."
Roy Smith
> Hmmm.. Yeah, it is strange. I think I'll go pay more attention to the
> spinning sounds the next time I go and turn on that master switch again. I
> might be mistakening it for the TC motor (if it has one?) sound.
You often hear two different noises when you turn the master one. One is the TC
spinning up, the other is the avionics fan (if installed, and depending on how
its wired).
Depending on how the Hobbs meter is wired, you may hear a third sound as well --
the sound of dollar bills being torn out of your wallet :-)
Brett Rabe
Hmm. Well. I was thinking of the aircraft
I flew, which are 300HP and have electric
HSI's. And yes, on both of them the A/P
is driven off the TC.
I was just surprised by Ron's comment: I
thought our HSI's were fairly typical.
Brett
--
Brett Rabe br...@uswest.net / 612.664.3078
Windows Novice (and proud) U S WEST - Internet Services
He who dies with the most access, wins.
Ron Natalie
Brett Rabe wrote:
>
> Ron Natalie wrote:
>
> > There are some HSI's (DG with overlaid VOR course indicator) that
> > require
> > electricity to work.
>
> Some? I thought most HSIs were electric? Is
> that incorrect?
They wander all over the place. Some use a vacuum card I think.
Some are all electric. Of course some don't even have a gyro in
the thing you're looking at (it's remotely mounted).
Ron Natalie
CoLiN wrote:
>
>
> i thot it was electricity that supplies power to the vacuum pump
> for the vacuum system to work. I've heard of a "vacuum scoop"
> (or whatever it's call). An air inlet at the side of the aircraft
> that drives the vacuum system. This system is only good at speeds
> and looses performance/accuracy at low speeds.
>
Most installations drive the vacuum pump off the accessory
case of the engine. The pump turns if the engine does.
Ron Natalie
CoLiN wrote:
>
> Okay, then how come when I turn on the master switch on a C172,
> the AI (AH for some of you. <grin>), and my DG spins up and slowly
> erects? But I do agree that suction is affected by engine rpm.
>
You're plane is highly unusual. Usually the turn coordinator
is the only thing that spins up with the master.
A directional gyro doesn't erect.
Are you really flying an airplane?
Ron Natalie
Roy Smith wrote:
>
> There are electric-driven vacuum pumps, but they are very much the
> exception. A friend of mine owns a Bonanza with one of these, as a source
> of backup vacuum (primary is the regular engine-driven pump).
I have a strange inkling that Dr. Jacoby's standby vacuum is one of
these. It was not a Precise Flight one. I've seen these things.
They look lust like an electric motor connected to a standard dry
pump (as a matter of fact, I found one at the consignment tent at
Oshkosh and would have picked it up but it had the wrong voltage
motor).
>
> It's called a venturi. It was a very popular system in older airplanes.
> They are draggy, are prone to icing, and worst of all (as you said) don't
> work when the plane isn't moving, which means your gyros don't spin up
> until after you takeoff.
And seeing how it takes time for the gyros to stabilize after they
get vacuum, it's problematic (lost a bizjet a few years ago when they
launched immediately into IMC chasing a short void time before they
had good gyros). Of course, the only plane I ever flew with venturis
was a tail dragger, so you really didn't have a good reference on the
ground if it were to spin up there.
Roy Smith
> Of course, the only plane I ever flew with venturis was a tail
> dragger, so you really didn't have a good reference on the
> ground if it were to spin up there.
Why not? The gyro doesn't care that the airframe has its nose in the air while
it spins up; it'll find vertical just fine. As for the reference bar, you know
what pitch angle the plane assumes on the ground; just set the bar to indicate
that and it's fine.
Piper News Reader
> I think most of the aircraft in the under 200hp class use engine driven
> vacuum to power the AI and the DG, electrical to power the TC. I would
> also venture that if any of the above had an autopilot, it is driven by the
> TC?
The Century (at least those aka Piper Autocontrols) use the vacuum inst. for the autopilot.
Loss of vacuum (or the inst.) is loss of the autopilot. STec autpilots use an electric TC.
Failures of a system aside, there are benefits to each method.
Phil T
------------------------------------------
Fly Right, Be Safe
PA24-260C N9312P
>
Ron Natalie
Roy Smith wrote:
> Why not? The gyro doesn't care that the airframe has its nose in the air while
> it spins up; it'll find vertical just fine. As for the reference bar, you know
> what pitch angle the plane assumes on the ground; just set the bar to indicate
> that and it's fine.
I'm not sure the pitch bar has that much adjustment to it.
Mark Mallory
Ron Natalie wrote:
> A directional gyro doesn't erect.
Correct; however a DG does contain a "leveling" mechanism that uses
precession to cause the gyro axis to seek a *horizontal* orientation,
which operates much like the "erection" mechanism of an AI.
MikeM
Ron Natalie <r...@sensor.com> wrote:
>
>
> CoLiN wrote:
> >
> > Okay, then how come when I turn on the master switch on a C172,
> > the AI (AH for some of you. <grin>), and my DG spins up and slowly
> > erects? But I do agree that suction is affected by engine rpm.
> >
> You're plane is highly unusual. Usually the turn coordinator
> is the only thing that spins up with the master.
Not if he an electric powered standby vacuum system. It would come on
with the master, prior to engine start, and spin up the vacuum powered
gyros.
Billy Beck
Roy Smith <r...@popmail.med.nyu.edu> wrote:
>Ron Natalie <r...@sensor.com> wrote:
>> Of course, the only plane I ever flew with venturis was a tail
>> dragger, so you really didn't have a good reference on the
>> ground if it were to spin up there.
>
>Why not? The gyro doesn't care that the airframe has its nose in the air while
>it spins up; it'll find vertical just fine. As for the reference bar, you know
>what pitch angle the plane assumes on the ground; just set the bar to indicate
>that and it's fine.
I thought about installing a venturi on my Fly Baby. (Believe it
or not.) I started thinking about the icing issues, and was soon
plotting all kinds of Rube Goldberg nonsense to waft some kinda engine
heat at it. ("Well, if I put it *here*, then I could...but that
wouldn't work, so I could maybe put it *here*, and feed it with a NACA
scoop, and then...") I figured it would be good to run a DG.
The more I thought about it, the more clearly it dawned on me
that I was only fooling around with the "romance" of archaic
technology, that it was all getting out of hand, and that only a moron
would hang a 4" venturi on a 65 hp. airplane.
That was about the end of that.
Billy
VRWC Fronteer
http://www.mindspring.com/~wjb3/promise.html
DOW_9er7Tango
vacuum pump in a plane that will be used for 'light' IFR? Light meaning run
from icing at the first sign, that is. My plane had one originally, it was
taken off. I can put on back on without a lot of rigamarole with paperwork,
I think. I understand there was an AD just recently on the engine vacuum
backups, I think it was shuttle valves failing.
--97T--
CoLiN <pi...@flight2000.com> wrote in message
news:LuRMOFcDuJvbpo...@4ax.com...
> On Mon, 06 Dec 1999 20:03:30 -0500, r...@popmail.med.nyu.edu (Roy Smith)
> told the whole world:
> >
> >It's called a venturi. It was a very popular system in older airplanes.
> >They are draggy, are prone to icing, and worst of all (as you said) don't
> >work when the plane isn't moving, which means your gyros don't spin up
> >until after you takeoff.
>
> Ahh yeah!..That's the name. Har, it suddenly rang a bell. Thanks!
DOW_9er7Tango
battery. Drags the airframe though. I'm thinking it might not be a bad
backup for the vacuum pump in case there's ever a pump or engine failure in
the soup. My plane's too slow to worry too much about the drag anyway.
Heck, sometimes you have to get out and push it!
--97T--
Ron Natalie <r...@sensor.com> wrote in message
news:384D1E41...@sensor.com...
>
>
> Roy Smith wrote:
> >
> > There are electric-driven vacuum pumps, but they are very much the
> > exception. A friend of mine owns a Bonanza with one of these, as a
source
> > of backup vacuum (primary is the regular engine-driven pump).
>
> I have a strange inkling that Dr. Jacoby's standby vacuum is one of
> these. It was not a Precise Flight one. I've seen these things.
> They look lust like an electric motor connected to a standard dry
> pump (as a matter of fact, I found one at the consignment tent at
> Oshkosh and would have picked it up but it had the wrong voltage
> motor).
>
> >
> > It's called a venturi. It was a very popular system in older airplanes.
> > They are draggy, are prone to icing, and worst of all (as you said)
don't
> > work when the plane isn't moving, which means your gyros don't spin up
> > until after you takeoff.
>
> And seeing how it takes time for the gyros to stabilize after they
> get vacuum, it's problematic (lost a bizjet a few years ago when they
> launched immediately into IMC chasing a short void time before they
> had good gyros). Of course, the only plane I ever flew with venturis
Stephen Waits
St Stephen Ames wrote:
>
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
Student pilot, long X-Country from Prescott, AZ to ABQ, New Mexico.
Vacuum failure about 40 miles west of ABQ. No problem, but when my
center controller eventually attempted cancel my flight following and
advise my early descent, I made them aware of the problem and requested
to stay higher and on with him, "just in case".
Center hands me off to ABQ approach. I get "descend pilot's
discretion".. Pull the throttle back to begin my descent, and NOTHING
HAPPENS. That's right, my throttle does nothing, I'm going full speed
ahead!
I mostly freaked out [this wasn't in my POH!], but not so bad that I
couldn't do a full power approach and landing. ABQ tower actually
shutdown all departurs and arrivals until I was on the ground. I got to
pick my runway, [let's see, 10000' or 12000'?, hehe], and they got a
chief pilot from a local FBO to sorta "relax me" by explaining that I
probably had a broken throttle cable [by now they had given me my own
frequency.]
Came in fast, felt too high, turned around and setup for another
approach. This time at the right altitude. Just about over the
numbers, pulled the mixture, and, performed a decent [though nearly
5000'] no flaps landing [which had been practiced many times, just never
approaching at FULL THROTTLE!]. Landed short of the intersecting
runway, shutdown the master, and got out and watched the waiting line of
a/c take off right in front of me while I waited for a tow back to some
FBO.
That's my student pilot vacuum pump AND throttle cable failure story.
--Steve
[ERAU!]
Ron Natalie
CoLiN wrote:
>
> I think Ron is trying to imply the fact that I'm a fool and an idiot and
> shouldn't be in this newsgroup at all.
>
Sorry that was not my intention. As I have oft been the brunt of
other's
attitudes here, I would not endeavor to malign others. My apologies.
Russell Kent
> The more I thought about it, the more clearly it dawned on me
> that I was only fooling around with the "romance" of archaic
> technology, that it was all getting out of hand, and that only a moron
> would hang a 4" venturi on a 65 hp. airplane.
So where did you mount it? :-)
(Sorry, couldn't resist easy shot.)
Russell Kent
Dylan Smith
news:82e3nm$15d$1...@news1.xs4all.nl...
> Having two altimiters gives tou the option of using two different settings
> concurently. Like keeping one altimeter on regional QNH and the other on
> QNE, or during the approach setting one to QFE and keeping the other on
QNH.
> FE.
Translation:
QNH = what we use in the US as altimeter setting (ie what is read out on
ATIS)
QFE = the altimeter setting which will result in the altimeter reading zero
at the airport
QNE = what we use in the US above FL180 (ie altimeter set to 29.92in. or
1013 mb)
--
Dylan Smith, Houston TX.
http://www.icct.net/~dyls
"Maintain thine airspeed, lest the ground come up and smite thee"
Chuck Forsberg
Dylan Smith <dylan...@hotmail.com> wrote:
>Effie Andree Wiltens <ea...@hotmail.com> wrote in message
>news:82e3nm$15d$1...@news1.xs4all.nl...
>> Having two altimiters gives tou the option of using two different settings
>> concurently. Like keeping one altimeter on regional QNH and the other on
>> QNE, or during the approach setting one to QFE and keeping the other on
>QNH.
>> FE.
>
>Translation:
>
>QNH = what we use in the US as altimeter setting (ie what is read out on
>ATIS)
>QFE = the altimeter setting which will result in the altimeter reading zero
>at the airport
How does one calculate QFE given QNH and airport elevation??
--
Chuck Forsberg WA7KGX PP-ASEL/HP Skylane N2469R c...@omen.COM
Omen Technology Inc The High Reliability Software www.omen.com
Author of YMODEM, ZMODEM, RZ, SZ, Pro-YAM, ZCOMM, GSZ, and DSZ
TeleGodzilla BBS: 503-617-1698 FTP: ftp.cs.pdx.edu pub/zmodem
POB 4681 Portland OR 97208 503-614-0430 FAX:503-629-0665
-----------== Posted via Newsfeeds.Com, Uncensored Usenet News ==----------
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------== Over 73,000 Newsgroups - Including Dedicated Binaries Servers ==-----
Effie Andree Wiltens
taking off, just set the altimeter to zero. In the UK, pattern heights are
above field level, not above sea level. Add the field elevation to the
pattern height (in other words, if the circuit must be flown at 1100 feet
and the field is at 350 feet elevation, you fly at 1450 QNH.
QFE helps in orientation: altimeter on the ground reading zero - but it's a
purely local phenomenon.
FE.
Chuck Forsberg <c...@agora.rdrop.com> wrote in message
news:384edb0c$1...@news5.newsfeeds.com...
Billy Beck
Russell Kent <r-k...@ti.com> wrote:
<hah> That's rich.
Actually, it's still mounted on page 314 of the Aircraft Spruce &
Specialty catalog.
Dennis C. O'Connor
that had a single venturi for the single DG...
Denny
Morris Bernstein
>
>Actually, it was an introductory IFR flight - part of an "introduction to IFR"
>that the company does every year to promote interest in instrument training.
>(Morris, you can ask Paula about this one.)
...
>the screwy indications. At least one of the two students has since completed
>instrument training.
Coincidentally, I had lunch with the aviation interest group from my
company on Tuesday. Paula says 'hi', but I'm still not convinced you
exist.
ObAviation: got to see the Navion up close. This is the one for which
Aviation Consumer reports Bonanza drivers who ride one leave saying
"at least my Bonanza is faster". That is one *nice* looking airplane,
just sitting on the ramp. Even the color quickly started to grow on
me. Can't wait for her to complete the insurance checkout. For
people flying out of BFI, it's the day-glo orange one sitting at the
southeast parking. You can't miss it.
Ron&Margie: so this is what you've been flying. Wow.
Morris
--
Malek's Law:
Any simple idea will be worded in the most complicated way.
Billy Beck
"Dennis C. O'Connor" <k8...@midmich.net> wrote:
>> >> The more I thought about it, the more clearly it dawned on me
>> >> that I was only fooling around with the "romance" of archaic
>> >> technology, that it was all getting out of hand, and that only a moron
>> >> would hang a 4" venturi on a 65 hp. airplane.
>I must be a moron... I owned and learned to fly in 65hp taildraggers
>that had a single venturi for the single DG...
Now see? I *knew* it was a fine idea.
highflyer
vacuum. The AH and the DG both began to indicate a turn. As luck would
have it they even agreed about the direction of turn. However, the T&B
and the whiskey compass did NOT indicate a turn. I merely included the
suction gauge into my scan for a round or two and quickly realized that
the vacuum had gone away. I completed the flight on needle, ball, and
airspeed! I was wishing for instrument covers though, because I could
not make my instrument scan skip the failed instruments. Habits die
hard! :-)
--
HighFlyer
Highflight Aviation Services
highflyer
>
> I was under the hood once and my instructor suddendly said, "Hey. Can you
> believe that. The DG must have failed." And sure enough it spun down. I
> wanted to return home, but he said to finish the flight with out the DG.
> It was fun and while I preparing to land he said, "Hey. Can you believe
> that. The DG must have fixed itself." I guess he was pulling the circuit
> breaker. --Bill
>
Now that is the best argument I have ever seen for installing electrical
gyros in an instrument trainer! :-) It is harder than heck to cause the
vacuum ones to "fail" on call.
highflyer
>
> On Mon, 06 Dec 1999 15:03:00 -0600, Brett Rabe <br...@uswest.net> told the
> whole world:
>
> >Ron Natalie wrote:
> >
> >> There are some HSI's (DG with overlaid VOR course indicator) that
> >> require
> >> electricity to work.
> >
> >Some? I thought most HSIs were electric? Is
> >that incorrect?
> >
>
> for the vacuum system to work. I've heard of a "vacuum scoop"
> (or whatever it's call). An air inlet at the side of the aircraft
> that drives the vacuum system. This system is only good at speeds
> and looses performance/accuracy at low speeds.
>
> type. I only saw a picture of this on an old aircraft, but none of
> the more common GA planes I know has this.
>
Normally an aircraft vacuum pump bolts onto the accessory case on the
back of the engine, and is driven by the same basic gear train that
drives the camshaft and the magnetos. I have never seen a primary
vacuum pump that was driven by an electric motor. That would eliminate
the desired redundancy. I always make some gyros in the panel vacuum
driven and some electrically driven so that all will not fail if one
system is lost. I have never seen a primary vacuum pump that was
belt driven. I would not trust that arrangement very far.
Many older engines, that were set up for day VFR flight only, were
built with no provision for a vacuum pump to be added to the accessory
section. When vacuum gyros were added to those aircraft the vacuum
was generally supplied by a "venturi tube" that was mounted on the side
of the cowling. A four inch venturi would drive an AH, while you only
needed a two inch venturi for a T&B. Nowadays, vacuum T&B's are rather
like dodo's. All of the current aircraft use an electrical T&B or TC.
By the way, the "venturi" is not an "air inlet." If you were to
describe it in those terms, it would have to be called an "air outlet"
rather than inlet. The lowered pressure in the venturi throat causes
an airflow to be established from the inside of the instrument case to
the throat of the venturi. Filtered air flowing from the cockpit into
the case of the instrument passes by a turbine wheel that spins up the
gyro. Usually the turbine wheel is also the rotating portion of the
gyro.
Roy Smith
> Now that is the best argument I have ever seen for installing electrical
> gyros in an instrument trainer! :-) It is harder than heck to cause the
> vacuum ones to "fail" on call.
I understand the Russians have a trainer where the instructor (sitting in the
back, out of sight of the trainee) has valves to open the vacuum lines to
atmosphere for just this purpose.
highflyer
>
> Okay, then how come when I turn on the master switch on a C172,
> the AI (AH for some of you. <grin>), and my DG spins up and slowly
> erects? But I do agree that suction is affected by engine rpm.
>
>
Colin, clearly you do not have a good understanding of the system in
your airplane. I would suggest that you make an effort to learn more
about them. It is essential to know that in case of a failure or an
emergency.
Most GA aircraft use vacuum for the AH and the DG because these
instruments, which are available powered either electrically or by
vacuum, are much less expensive in the vacuum version. Both cost
about four hundred dollars in the vacuum version and about one thousand
five hundred dollars in the electrical version.
Sometimes you will see an aircraft that has been or is used for an
instrument trainer where they have opted for the more expensive
electrical
gyros to facilitate failing a gyro in training situations. It is much
harder to turn off an engine driven vacuum pump than it is to flick
off a switch or pull a breaker and fail the electrical instruments.
As for autopilots, a GOOD autopilot uses a full freedom gyro for its
sensing input. A cheap autopilot made for general aviation like the
currently popular one whose name I won't mention, uses a TC for the
input to save a few bucks. An electrical TC is about a thousand dollars
cheaper than an electrical AH. Such autopilots have to receive input
from several instruments to get enough information to fly the airplane
correctly and are more prone to failure. By the way, I got that info
straight from the gentleman who designed and built the first successful
GA autopilots, who happens to be a friend of mine.
If your gyros spin up when you hit the master switch, you clearly have
electrical gyros. Your suction should not vary noticeably with engine
rpm with an engine driven vacuum pump. The vacuum is regulated with a
vacuum regulator behind the panel to maintain the correct vacuum for the
instrument. A DG or AH typically requires around four and a half inchs
of vacuum, while a vacuum T&B, if you have one, only requires an inch
and a half or two inchs of vacuum. You vacuum pump is easily putting
out a vacuum of eight or nine inches, and the vacuum regulator adjusts
this to the proper value for your instruments.
Some aircraft, which are equipped with a secondary backup vacuum system
for use when the vacuum pump fails, will have an electrically driven
vacuum pump. If your airplane is running on this system normally, your
primary vacuum source must have already failed. Other backup vacuum
system utilize the manifold vacuum to run the instruments.
My airplane has an engine driven vacuum pump for the instruments, an
electrically driven T&B, and a manifold vacuum system for operating the
vacuum powered flaps. It is NOT a Cessna.
highflyer
>
> Unfortunately, the title search shows a 37 year old lien that never had
> the release filed with OK City... I'll bet this one is gonna be fun to
> find anyone alive who can release it! Jeez, and I wanna go flying...
>
You will like the "peachy apache." I have frequently found old liens on
aircraft. Years ago, the banks were not required to notify the FAA when
a lien was cleared. They just notified the borrower and it was up to
the
borrower to clear the lien with the FAA. Many either didn't know that
or
didn't bother. The trick is to find the bank that held the lien. The
bank should have records, even that far back. They will usually be
happy
to send you a copy of the lien release, which you can then send on to
the
FAA to clear the lien. I go through that excercise with one of my
customers about once a year! :-)
Edward Zager
|> "William W. Plummer" wrote:
|> >
|> > I was under the hood once and my instructor suddendly said, "Hey. Can you
|> > believe that. The DG must have failed." And sure enough it spun down. I
|> > wanted to return home, but he said to finish the flight with out the DG.
|> > It was fun and while I preparing to land he said, "Hey. Can you believe
|> > that. The DG must have fixed itself." I guess he was pulling the circuit
|> > breaker. --Bill
|> >
|> gyros in an instrument trainer! :-) It is harder than heck to cause the
|> vacuum ones to "fail" on call.
|>
I had always wondered why everything, and I mean everything in the Focke Wulf
is electric (I don't have a vaccum pump). (HSI, horizon, T&B, fuel pressure
oil pressure, oil temp, fuel quantity, tach, CHT)
You sure can create a good set of emergencies with a circuit breaker in this
thing!
Edward Zager Focke Wulf 149JZ
DOW_9er7Tango
stay that way until major overhaul time, when everything in there will get
shuffled. It originally had a venturi but was updated with the addition of
the vacuum pump and a vacuum powered 'autopilot' with its own gyro.
I was thinking it might be possible to put the original venturi back on to
use as a backup in the meantime.
What do you think? It seems like it would be nice to have the option of
keeping the gyros spinning if the engine quit above the clouds.
--97T--
highflyer <high...@alt.net> wrote in message
news:38512588...@alt.net...
DOW_9er7Tango
always did. In case he couldn't find those suction cup soap holder things.
:)
--97T--
highflyer <high...@alt.net> wrote in message
news:38512200...@alt.net...
Perry A
"Roy Smith" <r...@popmail.med.nyu.edu> wrote in message news:roy-CF5637.1...@netnews.nyu.edu...
> high...@alt.net wrote:
> > Now that is the best argument I have ever seen for installing electrical
> > gyros in an instrument trainer! :-) It is harder than heck to cause the
> > vacuum ones to "fail" on call.
>
> back, out of sight of the trainee) has valves to open the vacuum lines to
> atmosphere for just this purpose.
30 years ago, my instructor had a shut-off valve on his side of the plane to just restrict the vacuum flow. 1/4 turn, and it was
gone! Less of a turn and it was going, going...
Perry A
Jerome Kaidor
Roy Smith <r...@popmail.med.nyu.edu> wrote:
>
>I understand the Russians have a trainer where the instructor (sitting in the
>back, out of sight of the trainee) has valves to open the vacuum lines to
>atmosphere for just this purpose.
>
counterclockwise? So when the student messes up, the instructor yells
"MORE LEFT RUDDER!"
...and bangs him on the head with a chart :-).
- Jerry Kaidor ( je...@tr2.com )
robert a barker
Jerry: Welcome back!!!!! Good to *hear your voice*.
Bob Barker
Flight.com
> St Stephen Ames wrote:
> >
> > I would like to hear any stories of folks that have survived a gyro
> > failure since this is the topic of the week...
On climb out in Mexico while flying a Boeing 727, I had the "ADI"
(artificial horizon) fail in a very slow fashion. It was the strangest
thing...it failed so slowly that I didn't realize it was failing (a lesson
to all). I was keeping a constant airspeed (300 kts.) in the climb, which
gave me about 1,000 foot per minute climb. I noticed that I had to keep
pitching back more and more to maintain the 300 kts, but it was very
gradual. Finally, as I was pitching back almost 30 degrees, I realized that
something was off--until that point I just thought the airplane was
"performing well", duh.
Well, of course, I wasn't pitching up 30 degrees, I was maintaining a
constant airspeed and climb rate, so the pitch was actually normal. I had
to look over at the other ADI on the other side of the cockpit to realize
that mine had completely failed.
In big jets, you fly off of the artificial horizon a lot more than you do in
small airplanes. I never got into any kind of incorrect attitude, but for
fifteen seconds or so I was thoroughly confused. I can only imagine what it
would be like in a piston plane with a vacuum failure in the clouds. You've
been trained for so long to trust your instruments, it's almost impossible
to readily identify an instrument problem unless it goes really crazy. Mine
happened so slowly that it wasn't until the reading became so out of whack
with the other instruments (if I had been climbing at 30 degrees pitch up, I
would have had 4,000 or more feet per minute climb, instead of the normal
1,000 and the airspeed would have been dropping significantly) that I
realized there was a problem. I simply compensated for the bad instrument.
Soon after, the red flag came on and the whole thing turned upside down and
died. It was a LOT easier to fly with an obviously malfunctioning
instrument than with one that was malfunctioning in a non obvious way.
Richard
http://flight.com The internet's aviation community.
Tim Hegadorn
On Saturday, December 4, 1999 at 3:00:00 AM UTC-5, St Stephen Ames wrote:
> I would like to hear any stories of folks that have survived a gyro
> failure since this is the topic of the week...
> St Stephen Ames
> PP-ASEL
> N16402
> PA-28-180
> My flying site: http://www.stephenames.com/flying/flying.html
> ---------------------------------------------------------------
> - Another part of my pre-flight passenger briefing -
> 'Smoking is not permitted inside the cabin; however smoking outside
> the cabin should be reported to the captain immediately!'