Turn Coordinator Gyro
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There will be a turn and slip somewhere on any IFR certified panel.
Moderator
turn and slip is certifiable where located I dont see what difference there is if you put an AI in the same hole instead of the T and S? It essentailly does the same job - just better
You will get varying opinons as to which is the preferred instrument to fly with, if you only have the one gyro. I certainly don't discount the turn and bank for getting you where you planned to go, in the absense of all other gyro instruments.
I flew an MD500 helicopter 1900 miles across Alaska and British Columbia. It had no gyro instruments. It was the T&B I felt I missed the most.
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I'd take the AI, I mean a rate one turn can be worked out with a relatively simple calculation if one didn't have the turn co-ordinator but an AI tells you everything you need to know really about what the aircraft is doing.
That said, I wouldn't do away with the turn co-ordinator/turn and slip in favour of a back-up AI, it would make more sense to keep it and add an AI somewhere else in the panel.
G1000 system of course if one loses the AHRS or the screen you are left with the back-up AI and no turn co-ordinator, which I'd much rather have than just a turn co-ordinator.
That said, I wouldn't do away with the turn co-ordinator/turn and slip in favour of a back-up AI, it would make more sense to keep it and add an AI somewhere else in the panel.
G1000 system of course if one loses the AHRS or the screen you are left with the back-up AI and no turn co-ordinator, which I'd much rather have than just a turn co-ordinator.
Ajstoner 21
All the red flag on the typical GA turn cordinator tells you is the instrument is recieving power. Since most failures are caused by a failure of the instrument gyro motor the flag will still disappear because while the instrument is recieving power but the instrument will not be functioning because the gyro is not spinning up.
As was pointed out (before the thread diversion into the legalities of back up instruments for IFR flight operations ) a functioning turn Coordinator is not required in the USA for day VFR flight, but if it is installed it must be working.
The likelyhood a failed turn coordinator would actually cause a problem is extremely low, but not zero. The best way to handle this is to have an A & P
have a quick look at the instrument, as the problem could be as simple as a loose connection, and if he/she finds nothing obviously wrong pull and collar the circuit breaker and placard the instrument as U/S.
From your intial post I assume you do not own the aircraft. If that is the case your only duty is to inform the owner of the problem. If you do own the aircraft and assuming you are not flying it IFR than I would shop around for the cheapest exchange overhaul from one of the big instrument repair outfits.
You can send in your unit for repair but usually it is cheaper and faster to just get an exchange instrument.
All the red flag on the typical GA turn cordinator tells you is the instrument is recieving power. Since most failures are caused by a failure of the instrument gyro motor the flag will still disappear because while the instrument is recieving power but the instrument will not be functioning because the gyro is not spinning up.
As was pointed out (before the thread diversion into the legalities of back up instruments for IFR flight operations ) a functioning turn Coordinator is not required in the USA for day VFR flight, but if it is installed it must be working.
The likelyhood a failed turn coordinator would actually cause a problem is extremely low, but not zero. The best way to handle this is to have an A & P
have a quick look at the instrument, as the problem could be as simple as a loose connection, and if he/she finds nothing obviously wrong pull and collar the circuit breaker and placard the instrument as U/S.
From your intial post I assume you do not own the aircraft. If that is the case your only duty is to inform the owner of the problem. If you do own the aircraft and assuming you are not flying it IFR than I would shop around for the cheapest exchange overhaul from one of the big instrument repair outfits.
You can send in your unit for repair but usually it is cheaper and faster to just get an exchange instrument.
A lot of people install a 2nd horizon in place of the T&S/TC because it is much more useful, and flying a precise rate 1 turn is anyway trivial with a horizon (usually 20-22 degrees at a typical IFR tourer cruise speed), and the only time one might be flying precise rate 1 turns is when doing timed turns which is an archaic procedure beloved in partial panel flying (I did most of my FAA IR on timed turns) which one would almost never do in reality, with a battery powered GPS available.
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Richard Collins did NOT advocate removing the turn and slip, what he did advocate was replacing the traditional instrument with a second AI AND installing a 2 inch turn and bank somewhere else in the panel. Without a turn and slip the aircraft would NOT be IMC legal (IFR in IMC), but might be legal under VFR (see posts above).
The designers obviously believed the location of the turn and slip was adequate for partial panel.
At the risk of some having a fit because I invoke an example from a more complex aircraft, it's worth noting that in more complex aircraft we seldom if ever teach, train, or use timed turns. Instead, we handle instrument failures with backup instruments. In a light airplane, this becomes the partial panel world, and it makes sense to resort to timed turns if one has no heading information and is down to the TC or TBI. Fair enough. Having a backup reference powered by a different source, however, is an even better idea.
The problem with the attitude indicator is that while it does provide better overall awareness of one's attitude (try flying partial panel off a turn coordinator in turbulence, while IMC), it does't give actual turn information or turn rate information to enhance one's ability to stay on a heading.
One can still do a very credible job with an attitude indicator, however. For timed turns, using a specific bank angle is closer to the way it's done in complex or advanced aircraft, anyway.
A really handy technique that works in a light airplane is to use the attitude indicator to make corrections. I used to do a job that had an observer requiring slight corrections to heading, and the observer might say "give me 20 left." Snap to a 20 degree left bank, hold for three seconds, and go wings level. It's very close. Same for a 30 degree course correction, or a 10 degree course correction.
I'm sure there are those out there that can fly a 1 degree course of the magnetic compass in turbulence at night in a cloud...but I'm definitely not one of them. I'm not one who has found the magic of being able to fly an accurate heading on the TBI alone in turbulent, IMC, partial panel conditions. I find that use of the attitude indicator enhances awareness substantially.
This may all be a mute point (and I mean mute, as in silent, rather than moot) in a Cessna 172, where one tends to do not a lot of hard IMC work (or shouldn't, really). It's a worthy discussion of instrument flying in general, however, which is a good byproduct of thread drift.
I understand that the proposal was to replace the t&B/TC with a second AI, in that position, but doing so would not conform to the design requirement stated.
So which would you prefer IF you could only have an AI or a T&S?
The second AI would not meet the intent of the design requirement 23.1321:
The instrument that most effectively indicates the attitude must be on the panel in the top centre position; [/font]
in the position of the TC.
The instrument that most effectively indicates the attitude must be on the panel in the top centre position; [/font]
in the position of the TC.
I have, on a number of occasions, taken off with an U/S instrument that was not required for that type of flight (day VFR), and simply taped a piece of paper over said instrument - more to prevent confusion than anything else. Was I legal?
And as an aside, if you disconnect a pitot/static instrument from the pitot/static tubes, do these connectors auto-seal or do you have to put some kind of plug in them, to prevent false readings on other pitot/static instruments?
To open these systems up requires mechanic certification (or "engineer" certification, if you will), and should be left only to those trained to work on the airframe. Improper handling of the components can introduce all kinds of problems. I've experienced a complete instrument loss on two occasions in airplanes in which someone had opened the pitot-static system and not capped the lines while work was being done. Insects entered the system, and died. In IMC, the insects apparently swelled and plugged the system off, causing all kinds of havoc. They were in various parts of the system, too, causing unusual failures that didn't conform to what one might normally expect from a blocked pitot tube, or blocked static source.
The information you get from an AI doesnt change. The purpose of having a second is to take over from the first, when the first fails. The only extra useful information is the ability to check one against the other BUT you still need to be sure you know which one to believe so there is an additional inherent danger in having two of which you need be aware.
Moderator
My modest few hundred hours of actual IFR, and several instrument failures during that time, entitle me to an opinion, but certainly not the last word on the subject. I will leave that to those with much more experience on instruments.
If I were being asked to issue STC approval of an instrument panel layout which did not conform to the design standard, I would be referring the proposed design back to Transport Canada engineering department for review. I agree that a backup AI is great, but if the trade off is loosing the only instrument which actually indicates a turn, the cost seems too big to me.
If the subject aircraft is going to fly enough actual IFR that the affect of instrument failure is really a concern, it should be equipped with redundent systems anyway, then there would already be a back up AI and T&B and the problem has gone away!
If I were being asked to issue STC approval of an instrument panel layout which did not conform to the design standard, I would be referring the proposed design back to Transport Canada engineering department for review. I agree that a backup AI is great, but if the trade off is loosing the only instrument which actually indicates a turn, the cost seems too big to me.
If the subject aircraft is going to fly enough actual IFR that the affect of instrument failure is really a concern, it should be equipped with redundent systems anyway, then there would already be a back up AI and T&B and the problem has gone away!
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I agree that a backup AI is great, but if the trade off is loosing the only instrument which actually indicates a turn, the cost seems too big to me.
A turn and bank indicator won't keep you right side up in a turbulence and a rough flight. By the time you react to a turn in one direction and correct the other, without any other means of keeping wings level, you can be upside down in some airplanes. A 300 or 400 series Cessna with full tip tanks and no additional instrumentation can turn ugly when a pilot gets into a roll oriented pilot induced oscillation on partial panel.
There was a time when a turn and bank was state of the art. That time was a very long time ago. It's a useful instrument, but far less useful than an an attitude indicator when one has to go partial panel.
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And as an aside, if you disconnect a pitot/static instrument from the pitot/static tubes, do these connectors auto-seal or do you have to put some kind of plug in them, to prevent false readings on other pitot/static instruments?
To open these systems up requires mechanic certification (or "engineer" certification, if you will), and should be left only to those trained to work on the airframe. Improper handling of the components can introduce all kinds of problems. I've experienced a complete instrument loss on two occasions in airplanes in which someone had opened the pitot-static system and not capped the lines while work was being done. Insects entered the system, and died. In IMC, the insects apparently swelled and plugged the system off, causing all kinds of havoc. They were in various parts of the system, too, causing unusual failures that didn't conform to what one might normally expect from a blocked pitot tube, or blocked static source.
So even though a VSI is not required for VFR flight, if it shows a defect it has to be disconnected, not just placarded U/S. And I'm not allowed to disconnect it myself so in effect it has just turned into a no-go item, right?
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Backpacker
I dont think that is quite correct. It is not uncommon to see a VSI or tac placarded to indicate over reads / under reads by x, whereas an altimeter must be within tolerance (for obvious reasons). Someone more knowledge that I will need to clarrify where matters stand on these issues so far as the FAA are concerned.
I dont think that is quite correct. It is not uncommon to see a VSI or tac placarded to indicate over reads / under reads by x, whereas an altimeter must be within tolerance (for obvious reasons). Someone more knowledge that I will need to clarrify where matters stand on these issues so far as the FAA are concerned.
Moderator
The inaccurate VSI situation has several possible outcomes:
Pilot decides he cannot safly fly the aircraft in that condition, and writes it up for repair before further flight = Outcome; did not go flying that day.
Pilot flies the aircraft as is, and so do the next pilots = Outcome; it never gets fixed.
Pilot goes flying that day, then tapes across the instrument "U/S", and snags it upon landing = Outcome; the next pilot decides he can still fly his next flight safely, and it probably gets fixed, or at least a error card, at the end of the day's flying.
Pilot (who is not a mechainic) decides to perform "do it yourself" maintenance under the panel = Outcome, he gets caught, and gets a bill for a complete inspection of everything under there which he could have affected, and the authorities discuss enforcement action for unauthorized maintenance, or; his faulty work goes initally un-noticed, then at the time of the accident investigation later, the unauthorized maintentance is discoverd to be a contributing factor. Very not good.
As a pilot, you have some latitude to decide to fly with a known defect, which will not affect the safety of the flight. You my just have to defend it later if challenged. If you have any latitude to go fixing the plane, you are formally qualified for maintenance, and you know exactly what privilages you have.
If you want the standards of servicability for an aircraft in black and white, you'll need to fly an aircraft with a published minimum equipment list, then there's no doubt.
Pilot decides he cannot safly fly the aircraft in that condition, and writes it up for repair before further flight = Outcome; did not go flying that day.
Pilot flies the aircraft as is, and so do the next pilots = Outcome; it never gets fixed.
Pilot goes flying that day, then tapes across the instrument "U/S", and snags it upon landing = Outcome; the next pilot decides he can still fly his next flight safely, and it probably gets fixed, or at least a error card, at the end of the day's flying.
Pilot (who is not a mechainic) decides to perform "do it yourself" maintenance under the panel = Outcome, he gets caught, and gets a bill for a complete inspection of everything under there which he could have affected, and the authorities discuss enforcement action for unauthorized maintenance, or; his faulty work goes initally un-noticed, then at the time of the accident investigation later, the unauthorized maintentance is discoverd to be a contributing factor. Very not good.
As a pilot, you have some latitude to decide to fly with a known defect, which will not affect the safety of the flight. You my just have to defend it later if challenged. If you have any latitude to go fixing the plane, you are formally qualified for maintenance, and you know exactly what privilages you have.
If you want the standards of servicability for an aircraft in black and white, you'll need to fly an aircraft with a published minimum equipment list, then there's no doubt.
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Okay, I've been re-reading post #7 and did some parsing to determine the hierarchy in § 91.213. I thought I had to conform to this bit:
So.. I thought I had to deactivate the VSI, which would require maintenance privileges to disconnect the static tube.
But upon reading the article a bit closer, the following works as well:
Sorted.
(d) Except for operations conducted in accordance with paragraph (a) or (c) of this section, a person may takeoff an aircraft in operations conducted under this part with inoperative instruments and equipment without an approved Minimum Equipment List provided—
[yada]
(3) The inoperative instruments and equipment are—
[yada]
(ii) Deactivated and placarded “Inoperative.” If deactivation of the inoperative instrument or equipment involves maintenance, it must be accomplished and recorded in accordance with part 43 of this chapter; and
[yada]
(3) The inoperative instruments and equipment are—
[yada]
(ii) Deactivated and placarded “Inoperative.” If deactivation of the inoperative instrument or equipment involves maintenance, it must be accomplished and recorded in accordance with part 43 of this chapter; and
But upon reading the article a bit closer, the following works as well:
(d) Except for operations conducted in accordance with paragraph (a) or (c) of this section, a person may takeoff an aircraft in operations conducted under this part with inoperative instruments and equipment without an approved Minimum Equipment List provided—
[yada]
(4) A determination is made by a pilot, who is certificated and appropriately rated under part 61 of this chapter, or by a person, who is certificated and appropriately rated to perform maintenance on the aircraft, that the inoperative instrument or equipment does not constitute a hazard to the aircraft.
[yada]
(4) A determination is made by a pilot, who is certificated and appropriately rated under part 61 of this chapter, or by a person, who is certificated and appropriately rated to perform maintenance on the aircraft, that the inoperative instrument or equipment does not constitute a hazard to the aircraft.
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I was looking for an answer to my question in context of a failed VSI or maybe a backup altimeter. Suppose my VSI is showing a defect, say, reading +100 ft/sec while on the ground. I would normally note this, maybe tape a piece of paper over it to avoid confusion, and that's it. But now you're telling me that I should deactivate this instrument, which would require me to dive behind the panel and start messing about with the pitot/static system (actually the static only, but you get the point) - which I'm not allowed to do (and rightfully so, I'm not arguing that).
So even though a VSI is not required for VFR flight, if it shows a defect it has to be disconnected, not just placarded U/S. And I'm not allowed to disconnect it myself so in effect it has just turned into a no-go item, right?
So even though a VSI is not required for VFR flight, if it shows a defect it has to be disconnected, not just placarded U/S. And I'm not allowed to disconnect it myself so in effect it has just turned into a no-go item, right?
You need to determine if indeed you have a problem. It's very common for the VSI in light airplanes to be indicating a slight climb or descent on the ground. This doesn't necessarily indicate a "defect." In fact, any instrument training handbook I've ever seen states that one should note the difference between the reading on the ground and zero, and apply it in flight. Thus, if the VSI is indicating -100 fpm, then in flight if one intends to establish a 500 fpm descent, one uses the -600 fpm marking on the gauge. Simple enough.
If indeed you do have a static problem, then you need to determine if it's affecting the rest of your system. You're quite correct that you can't fly with inoperative instruments or equipment unless it's in a condition that makes the aircraft "properly altered." You can accomplish this in four ways: a "ferry permit" (special flight permit); applying a Minimum Equipment List (MEL); Deactivating or placarding as required per 91.213; the use of an STC or other supporting paperwork which changes the certification and airworthiness documentation for the aircraft. In each of these conditions, a legal means is made to alter the airplane and it's type certification.
If your VSI has a problem, your altimeter may have a problem. As I said before, you need to look carefully at what's going on and determine if it presents a hazard to flight. You may not be qualified to make that determination; you may need the help of a mechanic to make the determination. Ultimately it's up to you to take the responsibility for the airworthiness every time you get in an aircraft and put it in service, but part of your responsibility is also to defer to qualified individuals in determining the status of a problem or condition.
A day VFR flight, you may be able to go fly without instruments that aren't required for day VFR flight...so long as they're in a condition which meets the requirements of the regulation.
I need to again include the caveat that I don't work with the CAA for certification or maintenance, and can't speak to regulation in the UK, or to JAA maintenance regulation, specifically. Therefore, you may see some difference with local regulation and policy. That part, you'll have to ferret out for yourself. We've discussed 91.213 of the US Federal Code of Regulations, however, and that part I can address.
When you placard a part of a system, you may be unwittingly placarding the entire system. The static system is interconnected; a problem with the system affects multiple instruments. In some aircraft, it can affect dozens of other components and systems. In the airplane I'm flying at the moment, for example, a pitot blockage can affect nearly 30 other items. Static problems affect fewer items, but still have big impacts on what I can and can't do with the airplane, legally (and safely). Even big airplanes with redundant systems have crashed as a result of pitot and static blockages. Clearly it can be serious.
Back to day, VFR: if indeed there is a static system problem (how do you tell it's just the VSI, or that the VSI is actually failed?), then if you're making a determination about something being inoperative, it's actually the static system which is inoperative. This affects more than the VSI, and now you're having to consider instruments that are required for day, VFR flight. Now the airplane can't fly day VFR. You see the point?
All me an example, if you will. As a new pilot in the PB4Y-2 (a version of the B-24), a WWII bomber with dirt-simple instrumentation, very much like a 172, I was sent on a fire dispatch in Florida. The airplane had been sitting in the rain. Heavy rain, in fact. As we taxied out, during execution of the checklist, we noted a discrepancy in the altimeters. Not a big deal, we thought, as we'll not be climbing above 500' anyway, during the entire flight. In fact, the entire flight would be conducted as much by "feel" as by instrument work, due to the low altitude, contact nature of the flying.
Bear in mind that these kind of flights were very quick; five minutes from notification to airborne, in many cases. Often quick enough that one didn't always have the coordinates of the destination when departing; the dispatch might be simply "takeoff and fly south." We might get the destination once in the air; it was firefighting, and time was often a very important consideration. This isn't something that one has to worry about with a weekend rental or pleasure flight, or a condition one shouldn't impose on one's self during a typical private flight, anyway.
On the takeoff roll, I was head down making adjustments to the propellers through a series of switches on the center pedestle. The nose of the airplane was too long to see over, especially once it had been raised, so to see out one had to sit up, stick one's head in a bubble window to the side, and look forward, with a very limited view. Being very new, I was trying to get everything done, perhaps a little behind the curve, so to speak, and was surprised to hear the captain yell "Rotate!" I thought I'd missed my call, and glanced at my airspeed indicator.
Rotation speed was 95 knots, but when I glanced at my airspeed indicator, I saw barely 70 knots. I felt the wheels skipping slightly, just the same as one might in a light airplane when it's ready to fly. The 4Y was flown very much like an oversize light airplane. I felt the captain rotate, and again felt the airplane skip slightly like it was trying to fly, and shortly thereafter the nose slammed back down. That got my attention.
I looked up, put my head in the bubble and saw nothing but trees. We were nearing the end of the runway. I broke the safety wire on the emergency jettison switches, and prepared to blow the tank doors. The captain rotated hard and we were airborne, but went through the trees at the end. We found ourselves in a real fight; a struggle to stay airborne. The captain called for flaps up; this was normally accomplished at 130 knots, but when I checked my airspeed, it was just coming through 95...we were just at rotation speed. I yelled "unable!" Raising the flaps on that airplane made a 50 knot difference in stall speed, and we were still at rooftop level. You can imagine, if you've ever retracted flaps just after takeoff and started sinking, the possible outcome. We were also heavy, at 80,000 lbs.
At that point we were both heads outside, in the bubbles, calling out powerlines, structures, obstacles, because we were going around them, not over. Very, very gradually we climbed. The captain yelled "I don't understand it. I'm over 130 knots; we should be flying!" I yelled back (it was a very loud airplane inside; most communication was done with hand signals) that I was showing 95. We looked at each other and the lightbulb finally went on. "Alternate Static!" The captain opened his, I opened mine, and his sytems quickly dropped back to match mine. He had followed errant indications, had attempted to rotate early, and the nose-high, early rotation delayed our lift off, as well as killed climb performance as we ended up airborne behind the power curve, low, and slow.
There's more to the story, but the point is, drawn out though it may be, one shouldn't make assumptions about instrument error,and what else may be affected by the instrument error. It may not be a simple busted VSI; you may have a static problem, or additional problems. I've seen a number of cases of static blockage that included pitot blockage, too. In fact, I flew in one location where leaf-cutter bees could plug up or block any port in the airplane, including fuel drains, in an amazingly short period of time; where there's smoke, there's often also fire...you may find more than one blockage, or blockage at more than one point in the system.
In the case of the Turn and Bank mentioned earlier, it's well to remember that the problem may be a short in the wiring, not just the instrument. One could placard the instrument, and then still end up with a fire. One needs to make sure the problem is fixed. I saw a Cessna 150 catch fire once because the cigarette-lighter adapter (DC adapter receptacle) in the airplane that was placarded inoperative was a little more than simply inoperatve.
Point is, there's more to the picture. Or could be.
Sorted.
As with most regulation, looking in one place usually won't cut it. There's nearly always more to the big picture.
Let's say you elect to fly with the inoperative VSI. You summon a mechanic, but without opening the static system and blowing out the lines, and putting the VSI on a test bench, the mechanic can't do too much. We've already noted some potential implications of a static or pitot (or both) failure; I'm sure you can think of more. The mechanic glances over the system, and says he doesn't see anything wrong (In the scenario involving the PB4Y, both pilots were A&P mechanics, as well). You put an inoperative sticker on the instrument and go fly. Sounds simple enough. If the aircraft has a squawk sheet or flight maintenance record it should reflect the change.
The mechanic can't do too much with the system, and it isn't self-sealing from one static instrument to the other, because the one instrument can affect another (remember that the alternate static relief in some aircraft is to break the glass on the VSI). You may be operating an unairworthy airplane, and to take the US regulation a bit farther...if the paperwork isn't complete and the aircraft isn't in a properly altered condition, then the airworthiness certificate is invalidated; you're now flying an airplane without a legal airworthiness certificate.
The regulation states that either the pilot, or "a person appropriately rated to perform maintenance" must determine that the aircraft is airworthy. Remember that you're held accountable for the determination. "It looks good," isn't really a determination, nor is "I think it's okay." How, as PIC, will you know the extent of the problem, or whether you have a VSI issue or a static system issue? If you have a static system issue, you'll definitely be flying an unairworthy airplane.
This also applies to the original scenario. The TC or TBI is placarded inoperative. A mechanic is summoned, and he gets behind the panel to disconnect the cannon plug on the instrument. This done, you apply the placard, and off you go. To be legal, reference needs to be made to Part 43, covering maintenance, which will address, among other things, maintenance records. Again, if the maintenance records aren't ammended to show these changes, then the airworthiness certificate is invalidated, the airplane is made unairworthy, and one can be violated (the subject of enforcement action) for flying both an unairworthy aircraft, and one without a valid airworthiness certificate. Simply slapping a piece of tape on there with an "INOP" sticker is often not enough.
Not to belabor a long post any more, but the standard for airworthiness should be briefly addressed. Airworthiness is a two-part concept; the aircraft must be legal, and it must be safe. We mostly understand the safe part; it's what we're looking for on a preflight, and inflight. The safe part may involve things we can't see, however, and we need to be careful to consider that what we think is the problem, may simply be the tip of the iceberg; it may be something else entirely. That slight engine roughness might simply be carburetor ice, but may be more; it may be oil fouling a spark plug, it may be a valve problem, it may be a timing problem. When determining what's safe, it's important not to overlook something and allow an unsafe condition to exist.
I once dealt with a Piper Seneca which pilots reported made a popping noise with the second "notch" of flaps in the traffic pattern. It didn't do this on the ground, but in flight, and most who flew it guessed that it had a bad pulley in the cable system for the flaps. It turned out to be a spar that was cracked in three places, grinding and popping against itself as it shifted position along the break, when the flaps were applied under a load. Given more time, I've little doubt that it would have failed in flight and shed a wing. Be careful not to make the wrong determination.
The other part, or second part of airworthiness is the legality. Unless the airplane is in full compliance with it's type certification, then it's not airworthy. An airplane can be properly altered to conform with additional documentation and be legal, such as conformance with a supplemental type certificate. This supplements the original type certificate, modifying it. Likewise, compliance with 91.213 meets the requirement to be "properly altered in a manner acceptable to the administrator" (FAA considerations here, again)...but one has to be careful that one is actually performing according to 91.213...which by default also includes Part 43, and in some cases additional regulation.
Suppose my VSI is showing a defect, say, reading +100 ft/sec while on the ground.
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Doesn't anyone just whip out their Swiss Army Knife and adjust the zeroing screw?
Absolutely, but then if my T & S fails I get my tool kit out and try to fix that as well.
Rod1
Absolutely, but then if my T & S fails I get my tool kit out and try to fix that as well.
Rod1
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Doesn't anyone just whip out their Swiss Army Knife and adjust the zeroing screw? Or is that not allowed unless you are an AME?
Then again, if you do have a problem other than an instrument requiring a slight adjustment, you may have just disguised, or hidden the problem.
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Guppy did you work out what had caused the problem other than the obvious that it was some sort of static fault? How did the altimeters and VSI behave during the flight?
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Do you mean for the 4Y flight with the erratic instruments on takeoff?
We did find the problem. Externally, nothing appeared amiss. On the ground on return, everything was matched up and working.
The takeoff involved an overrotation in an effort to get airborne before striking the trees, and in so doing, the captain struck the tail. Not the tail itself, but a tailskid that had once been retractable, but that was permanently welded down, in the airplane. It had a thick magnesium skid plate on the bottom. When that struck, the skid was thrust up into the belly of the airplane, and the magnesium ignited. It produced a fireball that enveloped the tail of the airplane, and ended up burning off the last 25' or so of the underside of the airplane...skin, stringers, etc.
The problem was caused by rain. The 4Y had fairly large static ports. Plugs were placed in the ports, but the plugs still allowed water, due to the design of the ports themselves. Because of the nature of the flying, pitot covers and static plugs, and other security devices were removed during the morning preflight. When heavy rains came, with strong winds, the rain was nearly horizontal, and entered both the pitot tubes and the static ports quite handily, as we later determined.
The cockpit indications were fairly nill, but weren't symmetrical or uniform throughout the system. In other words, what appeared to be an altimeter mismatch was part of a bigger problem.
We broke the static system in multiple places and blew the lines out through filters. Water was the culprit in some points, and low areas in the line, and in others we found a dead insect which swelled in the presence of water.
We also instituted a policy of keeping everything covered until the dispatch itself...at which time one person would remove and stow all the covers.
We did find the problem. Externally, nothing appeared amiss. On the ground on return, everything was matched up and working.
The takeoff involved an overrotation in an effort to get airborne before striking the trees, and in so doing, the captain struck the tail. Not the tail itself, but a tailskid that had once been retractable, but that was permanently welded down, in the airplane. It had a thick magnesium skid plate on the bottom. When that struck, the skid was thrust up into the belly of the airplane, and the magnesium ignited. It produced a fireball that enveloped the tail of the airplane, and ended up burning off the last 25' or so of the underside of the airplane...skin, stringers, etc.
The problem was caused by rain. The 4Y had fairly large static ports. Plugs were placed in the ports, but the plugs still allowed water, due to the design of the ports themselves. Because of the nature of the flying, pitot covers and static plugs, and other security devices were removed during the morning preflight. When heavy rains came, with strong winds, the rain was nearly horizontal, and entered both the pitot tubes and the static ports quite handily, as we later determined.
The cockpit indications were fairly nill, but weren't symmetrical or uniform throughout the system. In other words, what appeared to be an altimeter mismatch was part of a bigger problem.
We broke the static system in multiple places and blew the lines out through filters. Water was the culprit in some points, and low areas in the line, and in others we found a dead insect which swelled in the presence of water.
We also instituted a policy of keeping everything covered until the dispatch itself...at which time one person would remove and stow all the covers.
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When that struck, the skid was thrust up into the belly of the airplane, and the magnesium ignited. It produced a fireball that enveloped the tail of the airplane, and ended up burning off the last 25' or so of the underside of the airplane...skin, stringers, etc.
I routinely machine magnesium components in my workshop... made various things for my TB20 out of it. Lightweight conrods really do up the power... Anyway, lots of "experts" told me that the stuff catches fire really easily when being machined.
Well, being really a big kid who loves setting things on fire, I tried to set fire to some magnesium.
It's amazingly hard to do, especially with a thick section. You have to get a blowlamp (an oxy-acetylene welding torch works better but I don't like wasting the gas) and you have to get at least a corner of the component bright red hot. With a hi-temp blowlamp (the one which uses a propane-acetylene mixture; yellow bottles rather than blue bottles) it takes about a minute to set fire to a piece of magnesium.
It's quite impressive after that, though...