/D [1 0 R /XYZ null 575 null] << ), After aircraft has been parked on one heading for over a year, The magnetic compass remains a time tested reliable instrument, although as avionics evolve, the magnetic compass is being seen increasingly as a standby or back-up instrument, Although NOT approved for use by the FAA, products such as the, Deviation errors are unavoidable but is a moving target as any modification may require a compass swing. 27 0 obj Found inside – Page 4( 4 ) All magnetic compasses shall be kept as closely adjusted as practicable , and when any excessive deviation is observed , every effort should be made to swing ship for adjustment . If the magnetic compass is installed properly ... /D [1 0 R /XYZ null 262 null] /D [1 0 R /XYZ null 346 null]
106 0 obj << | Privacy Policy | Terms of Service | Sitemap | Patreon | Contact, Advisory Circular (43.13-1B CHG 1) Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair, SUUNTO Core All Black Military Men's Outdoor Sports Watch [Amazon], Federal Aviation Administration - Pilot/Controller Glossary, Federal Aviation Regulation (91.205) Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements, Instrument Flying Handbook (3-10) Magnetism, The magnetic compass is the most primal and basic instruments used by the pilot to determine or verify aircraft heading, The instrument operations on the principles of, Some of these errors include the various display methods to include the, The Earth is a huge magnet with lines of flux which make its magnetic field, These lines extend from the poles around the Earth [, Any magnet that is free to rotate (such as an aircraft's magnetic compass) will align with the poles, A magnet, typically made of iron, attracts and holds lines of flux, Opposite poles attract, while similar poles repel, A compass is a simple magnetic bar suspended in fluid, The float and card assembly has a hardened steel pivot in its center that rides inside a special, spring-loaded, hard-glass jewel cup, The magnets align with the Earth's magnetic field, and the pilot reads the direction on the scale opposite the lubber line, When the pilot is flying North as the compass shows, East is to the pilot's right, but on the card "33", which represents 330° (West of North), is to the right of North, The reason for this apparent backward graduation is that the card remains stationary, and the compass housing and the pilot turn around it, always viewing the card from its backside, A compensator assembly mounted on the top or bottom of the compass allows an aviation maintenance technician (AMT) to create a magnetic field inside the compass housing that cancels the influence of local outside magnetic fields, The compensator corrects for deviation error, The compensator assembly has two shafts whose ends have screwdriver slots accessible from the front of the compass, Each shaft rotates one or two small compensating magnets, The end of one shaft is marked E-W, and its magnets affect the compass when the aircraft points East or West, The other shaft is marked N-S, and its magnets affect the compass when the aircraft points North or South, An aircraft magnetic compass has two small magnets attached to a metal float sealed inside a bowl of clear compass fluid, The compass housing is full of compass fluid, similar to kerosene, to avoid freezing at lower temperatures/higher altitudes, The buoyancy of the float takes weight off the pivot, and the fluid damps the oscillation of the float and card, This jewel-and-pivot type mounting allows the float the freedom to rotate and tilt up to approximately 18° angle of bank 45° pitch up/down, At steeper bank angles, the compass indications are erratic and unpredictable, The rear of the compass case is sealed with a flexible diaphragm or with a metal bellow in some compasses to prevent damage or leakage when the fluid expands and contracts with temperature changes, The magnetic compass is a reliable, self-contained unit requiring no external power source, It is extremely useful as a standby or emergency instrument, A graduated scale, called a card, is wrapped around the float and viewed through a glass window with a lubber line across it, The card is marked with letters representing the cardinal directions, North, East, South, and West, and a number for each 30° between these letters, The final "0" is omitted from these directions; for example, 3 = 30°, 6 = 60°, and 33 = 330°, There are long and short graduation marks between the letters and numbers, with each long mark representing 10° and each short mark representing 5°, The magnetic compass is the simplest instrument in the panel, but it is subject to several errors to consider. That diaphragm allows the liquid to vary in volume due to the daily temperature changes without upsetting the working of the compass. /Subtype /Link << Although with greater problems it may take three turns.” Among the magnetic anomalies are weird disturbing fields from direct hits of lightning to the vessel, which ultimately decay with time and normal vessel vibrations. 205 0 obj /Type /Annot /D [1 0 R /XYZ null 298 null]
Found inside – Page 22Deviation is found by consulting the magnetic compass table ( fig . ... RED UP 11 HEELING MAGNET : Le 307 , SWINGING SHIP The navigator computes deviation and prepares the magnetic compass table by an operation called swinging ship . To find the true course when the compass course is known: Compass course ± deviation = magnetic course ± variation = true course, Compass tends to dip toward the magnetic pole, most dominant as latitude increases, The lines of magnetic flux leave the Earth at the magnetic North Pole and enter at the magnetic South Pole, pronouncing magnetic dip near the poles, At both locations, the lines are perpendicular to the Earth's surface, At the magnetic equator, which is roughly halfway between the poles, the lines are parallel with the surface, Within 300 miles of the poles, the instrument is unreliable due to extreme errors, The south end of the compass is therefore weighted to minimize this error, The magnets in a compass align with this field; near the poles, they dip or tilt the float and card, A small dip-compensating weight balances the float, so it stays relatively level when operating in the middle latitudes of the northern hemisphere, To counter this, the pivot point on which the bar magnet swings is deliberately placed at a position other than the magnet's, The pull of the vertical component of the Earth's magnetic field causes northerly turning error, which is apparent on a heading of north or south, When an aircraft flying on a heading of North makes a turn toward East, the aircraft banks to the right and the compass card tilts to the right, The vertical component of the Earth's magnetic field pulls the north-seeking end of the magnet to the right, and the float rotates, causing the card to rotate toward West, the direction opposite the direction the turn is made, When turning from a northerly heading, the compass will initially turn the opposite direction and catch up by due East/West [, When turning from a southerly heading, the compass will indicate a turn in the proper direction but will lead the actual heading, slowing down by due East/West [, The rule for this error is: when starting a turn from a northerly heading, the compass indication lags behind the turn, The rule for this error is: When starting a turn from a southerly heading, the compass indication leads the turn, If the turn is made from north to West, the aircraft banks to the left, and the compass card will tilt down on the left side, The magnetic field pulls on the end of the magnet that causes the card to rotate toward East, This indication is again opposite to the direction the turn is made, When an aircraft is flying on a heading of south and begins a turn toward East, the Earth's magnetic field pulls on the end of the magnet that rotates the card toward East, the same direction the turn is made, If the turn is made from south toward West, the magnetic pull starts the card rotating toward West-again, in the same direction the turn is being made, New heading: roll-out heading ± latitude - half the bank angle, The dip-correction weight causes the end of the float and card marked N (the south-seeking end) to be heavier than the opposite end, When the aircraft is flying at a constant speed on a heading of East or West, the float and card is level, When the aircraft accelerates on a heading of East/West, inertia causes the weight to lag, and the card rotates toward North [, When the aircraft decelerates on a heading of East/West, inertia causes the weight to move ahead, and the card rotates toward South [, The airspeed changes that are needed to make this noticeable are infrequent, As soon as the speed of the aircraft stabilizes, the card swings back to its East indication, Fluid fills the compass body, which provides damping, thereby decreasing unwanted oscillations due to turbulence of the magnet and float, Fluid should therefore fill the compass, and no air bubbles or compass fluid discoloration should be present, The clear compass face (window) has on it a vertical line called a "LUBBER LINE" so that the pilot can use it as a datum to set the required heading, Oscillation is a combination of all of the other errors, and it results in the compass card swinging back and forth around the heading flown, Turbulence causes the compass to "bounce" or move in the container, When setting the gyroscopic heading indicator to agree with the magnetic compass, use the average indication between the swings, The floating magnet type of compass not only has all the errors just described but also lends itself to confused reading, It is easy to begin a turn in the wrong direction because its card appears backward, East is on what the pilot would expect to be the West side, The vertical card magnetic compass eliminates some of the errors and confusion, The dial of this compass is graduated with letters representing the cardinal directions, numbers every 30° and marks every 5°, A set of gears rotates the dial from the shaft-mounted magnet, and the nose of the symbolic airplane on the instrument glass represents the lubber line for reading the heading of the aircraft from the dial, Eddy currents induced into an aluminum-damping cup damp oscillation of the magnet, As mentioned earlier, the lines of flux in the Earth's magnetic field have two basic characteristics: a magnet aligns with these lines of flux, and an electrical current is induced or generated in any wire crossed by them, The flux-gate compass that drives slaved gyros uses the characteristic of current induction, The flux valve is a small, segmented ring made of soft iron that readily accepts lines of magnetic flux, An electrical coil is wound around each of the three legs to accept the current induced in this ring by the Earth's magnetic field, A coil wound around the iron spacer in the center of the frame has 400-Hz alternating current (A.C.) flowing through it, During the times when this current reaches its peak, twice during each cycle, so much magnetism is produced by this coil that the frame cannot accept the lines of flux from the Earth's field, But as the current reverses between the peaks, it demagnetizes the frame so it can accept the flux from the Earth's field, As this flux cuts across the windings in the three coils, it causes current to flow in them, These three coils connect in such a way that the current flowing in them changes as the aircraft heading changes, The three coils connect to three similar but smaller coils in a synchro inside the instrument case, The synchro rotates the dial of a Radio Magnetic Indicator (RMI) or a horizontal situation indicator (HSI), Made of soft iron that readily accepts a line of flux, A coil wound around the iron spacer has 400-Hz AC flowing through it, As current peaks, twice during each cycle, there is so much magnetism that the frame cannot accept the lines of flux, but as the current reverses, it demagnetizes to accept more, The three coils connect to three similar but smaller coils in a synchro inside case, The synchro rotated the dial of a Radio Magnetic Indicator (RMI or an HSI), Magnetic direction indicators (of which a magnetic compass satisfies) are required by, Full of fluid; card in place and indicating a correct heading, Compass card installed (does not need to be filled out), A compass swing must be performed whenever any ferrous component of the system (i.e. /D [1 0 R /XYZ null 298 null] 200 0 obj /D [1 0 R /XYZ null 599 null] endobj << 15 0 obj >> /D [1 0 R /XYZ null 599 null] “For a compass to demonstrate absolute freedom from pivot-and-jewel friction, it must return consistently and completely from each two-degree rotational deflection.
Still looking for something? /Subtype /Link Captains of the Nether Skies /Dest [61 0 R /XYZ null 829 null] endobj /D [1 0 R /XYZ null 743 null]
All the RAF bases I worked at had a dedicated area as I described. and electrical equipment can deflect the compass from magnetic north. >>
<< >> The magnetic compass itself is not an accurate instrument for navigation because of . << Precautions. The compass calibration requirements for large aircraft (more than 12,500 lbs maximum take-off weight) can be found in FAR's 25.1327 and 25.1547. << >>
endobj endobj /Dest [1 0 R /XYZ null 575 null] /D [1 0 R /XYZ null 443 null] /Rect [194 360 209 371] /Border [0 0 0] << COMPASS SWING must be per-formed whenever any ferrous component of the system (i.e. 183 0 obj 14 0 obj 73 0 obj endobj 102 0 obj /D [1 0 R /XYZ null 731 null] << endobj endobj /D [1 0 R /XYZ null 335 null] %���� Home > Directional Meter Maintenance and Training Manuals > > Compass Swing Procedure - TM-11-4920-292-150186. >> >> Peter transfers from the classroom onboard to talk about the subject of compasses 28 0 obj 149 0 obj /D [1 0 R /XYZ null 683 null] endobj endobj << /Dest [59 0 R /XYZ null 490 null] 173 0 obj endobj >> “With time you can see a deviation as slight as half a degree,” Barber said, “so I can usually correct any deviation with two complete rotations of the vessel. /Subtype /Link << 198 0 obj endobj /D [1 0 R /XYZ null 647 null] endobj endobj 100 0 obj 5.1 A Compass Swinging Site is a prepared area, with minimum magnetic abnormalities, on which an aircraft may be oriented (or swung) to various headings, for the purpose of checking the aircraft on-board compass system(s), including the standby compass. /D [1 0 R /XYZ null 296 null] 123 0 obj 94 0 obj electronic parts mount on the test panel. Found inside – Page 60A basic compass check swing consists of positioning the aircraft on four cardinal headings, each 90 degrees apart, and comparing the actual ... Following any modification, repair or component replacement involving magnetic materials 3. << Found inside – Page 212SWINGING or swinging , n . 1. Oscillating ; turning ; rotating . 2. A momentary variation of the frequency of received radio waves . 3. The process of placing a craft on various headings and comparing magnetic compass readings with the ...
<< >> Found inside – Page 1The electrical compass system calibration is a two-part procedure: part one consists of an area magnetic survey, and part two consists of an electrical compass swing. An area magnetic survey is the selection of a proper area to be used ... /Subtype /Link >>
/Dest [76 0 R /XYZ null 419 null] endobj << endobj transit that has been modified to operate as a part. Corrective magnets, colored red and silver to indicate north and south poles, are placed inside non-magnetic copper tubes. endobj endobj 40 0 obj << 188 0 obj Federal Register - Volume 57, Issues 29-34 - Page 5099 Ship Magnetism and the Magnetic Compass: The Commonwealth ... 51 0 obj endobj Vessel owners and masters each have responsibilities for ensuring that magnetic compasses are maintained in good working order, adjusted and a table or curve of residual deviations is available. /Border [0 0 0] >> Circular concrete platform marked out in degree divisions accurately aligned with local magnetic north. >> /Subtype /Link >> 144 0 obj The needle in the magnetic compass is a small magnet. Then after all is said and done, SWING the compass and update your Deviation Card. >> /D [1 0 R /XYZ null 503 null] >> >> >> In the past 23 years, the natural deviation for Vancouver Harbour, currently “less than 20 degrees East,” has decreased. /Rect [650 276 653 287] /D [1 0 R /XYZ null 647 null] /Border [0 0 0] /Border [0 0 0] >> Found inside – Page 21-29The direction and uniformity of the earth's field shall be determined prior to use of the area for compass swinging . Magnetic interference shall be checked annually thereafter . Any changes in physical features of the site that might ... PDF ) Calibration of Compass Thus, one ball can be removed and the fine-tuning of Coefficient D deviations engineered with the remaining ball, most often ever-so-slightly adjusted toward center,” Barber said. >> << 77 0 obj many airfields had a compass-swinging area set aside (away from hangars, etc) with directions accurately surveyed and painted on the concrete. 43 0 obj /D [1 0 R /XYZ null 214 null] After the magnetic deflector tape is removed following each deflection, where the compass settles is carefully observed. /D [1 0 R /XYZ null 392 null] Compass Swing Site: means a prepared area with minimum magnetic abnormalities on which an aircraft may be oriented or swung to various headings for the purpose of checking the aircraft on-board compass systems and the standby compass. 139 0 obj >> >>
The process of swinging and compensating a ship or aircraft compass by determining and reducing the deviation coefficie. This AC describes five acceptable procedures that may be used when compensating a standby compass or preparing a correction card: A surveyed site (often referred to as a compass rose), a master site compass, a simulated rotation system, a portable magnetic standard, or an air swing. >> 48 0 obj /D [1 0 R /XYZ null 743 null] >> >> >> 185 0 obj The performance of the compass should be monitored and, for a vessel more than 100GT, deviations recorded in a compass deviation book . 90 0 obj >> endobj 46 0 obj 84 0 obj 193 0 obj Found insideBesides the magnetic fields generated by the Earth, other magnetic fields are produced by metal and electrical accessories within the airplane. These magnetic fields distort the Earth's magnetic force, and cause the compass to swing ... 92 0 obj << << /Border [0 0 0] endobj >> The Magnetic Compass is the most familiar compass type. << (b) Secure all effective magnetic gear in normal seagoing position before beginning adjustments. /D [1 0 R /XYZ null 443 null] << endobj >> endobj 204 0 obj << 95 0 obj endobj >> 2586257-1) controls. endobj << endobj 190 0 obj endobj Per the FAA (AC 43.13-1B CHG 1) page 620, paragraph 12-37. << >>
141 0 obj << Found inside – Page 5099( 3 ) Accomplish a compass swing of the standby compass in accordance with British Aerospace Service Bulletin ATP - 24-34 ... the effective date if this AD , fabricate and install a temporary Placard near the standby magnetic compass . endobj /D [1 0 R /XYZ null 683 null] endobj endobj /Type /Annot 206 0 obj << 13 0 obj 78 0 obj >> 31 0 obj << >> << >> endobj Compasses built in Europe or Japan have a 50/50 mix of distilled water and alcohol, while those built in the U.S. have a light oil. /Rect [415 396 462 408]
Now, suppose that at North the aircraft compass shows 003 degrees with the external compass showing 001 degrees; at East . >> << endobj /D [1 0 R /XYZ null 344 null] %PDF-1.2 Compass swing bay is a designated location free of local magnetic interference, away from buildings, machinery, powerlines, etc.
>> /D [1 0 R /XYZ null 286 null] endobj /D [1 0 R /XYZ null 575 null] >> /S /GoToR 87 0 obj stream Compass Swing. Compass Swing.
endobj << 136 0 obj >> >> << >> << << Found inside( h ) Installation of major components of electrical equipment in the vicinity of the magnetic compass . ... ( 4 ) When a compass swing is made , the deviations should be recorded both with degaussing off , and with degaussing coils ... >> 111 0 obj << << << The compass card, in the most common configuration, has an inverted cone under the center. 178 0 obj 202 0 obj 186 0 obj /D [1 0 R /XYZ null null null] 162 0 obj /D [1 0 R /XYZ null 464 null] 207 0 obj 55 0 obj It takes about an hour for me to do a swing on a King Air. << 38 0 obj By mounting the main indicating magnets of the compass on a shaft rather than a float, through a series of gears, a compass card can be made to turn about a horizontal axis. <<
<< /Border [0 0 0] endobj It functions as a pointer to "Magnetic North", the local magnetic meridian, because the magnetized needle at its heart aligns itself with the horizontal component of the Earth's magnetic field.The magnetic field exerts a torque on the needle, pulling one end or pole of the needle approximately toward the Earth's North magnetic . Sorry about misspelling Compass Rose . endobj /D [1 0 R /XYZ null 260 null] /Rect [415 264 462 276] /D [1 0 R /XYZ null 250 null] >> Aircraft Instruments - Page 101
endobj /Border [0 0 0] Found inside – Page 12-12COMPASS SWING must be performed whenever any ferrous component of the system (i.e. flux valve compensator, or Standby Compass) is installed, removed, repaired, or a new compass is installed. The magnetic compass can be checked for ... >> >> Therefore, to steer a true course of 180°, the pilot would follow a compass course of 188°. This video explains the deviation of the ship's magnetic compass.The terms of deviation, variation, compass error are explained.The difference between true, . 68 0 obj /D [1 0 R /XYZ null 202 null] endobj /D [1 0 R /XYZ null 551 null] /D [1 0 R /XYZ null 587 null]
endobj endobj He affixes a small plastic mount to the compass glass over the center of the compass rose. The term compass compensation refers to any change in the current slupplied to the compass compen-sating coils to reduce degaussing errors. /Subtype /Link 5 0 obj endobj << /Subtype /Link
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endobj Found inside – Page 277The test is generally made by means of a stop watch and auxiliary magnet or coil to start the compass swinging . The card is set swinging and the time noted either for the half period or the complete period , according to the ... endobj /D [1 0 R /XYZ null 503 null] /Subtype /Link
endobj 167 0 obj The magnetic compass consists essentially of a small magnet in the shape of a needle which is allowed to swing freely on a pivot. Compass Swing Procedure - TM-11-4920-292-150185: Compass Swing Procedure-CONT. 54 0 obj 153 0 obj
The process used to produce a deviation card is called 'swinging the compass'. /Border [0 0 0] >> >> << << Basically you need a qualified compass repair shop to take care of this. >> /D [1 0 R /XYZ null 515 null] /D (E.P9n0017) This advisory circular (AC) describes procedures for calibrating an aircraft magnetic compass to minimize the effect of aircraft-induced magnetic fields. /D [1 0 R /XYZ null 524 null] >> >> A compass is a device that shows the cardinal directions used for navigation and geographic orientation. >> endobj /D [1 0 R /XYZ null 212 null] << >>
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