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Do 160f pdf

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RTCA DOF, "ENVIRONMENTAL CONDITIONS AND TEST. PROCEDURES FOR AIRBORNE EQUIPMENT". RTCA Inc. Issued December 6, DO, Environmental Conditions and Test Procedures for Airborne Equipment is a standard . RTCA, INC., December 9, ; RTCA/DO F, RTCA, INC., December 6, ; RTCA/DO G, RTCA, INC. of Available Documents, RTCA Inc., (March ). 5 List of Test Equipment. RTCA DOF Tests for DC Operated Devices. The equipment indicated below was used for testing according to RTCA DOG.

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Uploaded by: KANDICE - Ebook download as PDF File .pdf), Text File .txt) or read book online. The FAA strongly encourages the use of RTCA/DOG for new . RTCA/DO- F, Section 26, Fire, Flammability, is not sufficient for 14 CFR. and revisions of, DO, Section 22, within the past few years. Many of these { Comment} This means that the requirements in RTCA DO F are Advisory.

The V is to have less than 1. Step 1: Refer to the paragraph Potassium dihydrogen orthophosphate The cleaning methods shall not include the use of corrosive or protective films.

Steps 3. Step 3: Over a two-hour period. Step 4: The test chamber shall be vented to the atmosphere to prevent buildup of pressure. Allow 15 minutes maximum following the application of primary power for the equipment to warm up.

Moisture shall be provided by steam or by evaporation of water having a percent Hydroxide pH value between 6. Step 7: At the end of the exposure period. Immediately following the warm-up period. The procedure shall be in accordance with the following steps: Step 1: Install the test item in the test chamber.

During this period. Within one hour after the two cycles are completed. Step 5: During the next hour period. For equipment that does not require electrical power for operation. Step 2: The velocity of air throughout the exposure area shall be between 0. Repeat these steps until a total of 10 cycles hours of exposure have been completed.

Within one hour after the 10 cycles are completed. If the equipment is removed from the test chamber to conduct a spot check. Within one hour after the six cycles are completed. Repeat these steps until a total of six cycles hours of exposure have been completed.

Step 7. Two operational shock test curves are provided. This test applies to all equipment installed on fixed-wing aircraft and helicopters. Using a dummy load on the shock test apparatus may be necessary to ensure that the recorded shock pulse will be within the specified tolerances of Figure The crash safety test verifies that certain equipment will not detach from its mountings or separate in a manner that presents a hazard during an emergency landing.

Category B Equipment tested for standard operational shock and crash safety. For such equipment. These tests do not satisfy FAR requirements for all equipment. The 20 ms pulse may not be adequate to test against the effect of longer duration shocks on equipment that have its lowest resonance frequency as per section 8 below Hz.

These shocks may occur during taxiing. Category D Equipment tested for low-frequency operational shock. For fixed-wing aircraft: It applies to equipment installed in compartments and other areas of the aircraft where equipment detached during emergency landing could present a hazard to occupants. Normal upright. After application of the shocks.

Suspended upside down. The accelerometer used to measure or control the input shock pulse shall be placed as close as practicable to an equipment attachment point. The mounting of the equipment should include those non-structural connections that are a normal part of the installation. An equivalent shock response spectrum may replace the terminal saw-tooth wave shape.

With the equipment operating and with its temperature stabilized. The characteristics of instrumentation used to demonstrate compliance and the shock pulse tolerance limits are shown in Figures and When using a conventional drop shock machine.

If equipment requires monitoring during the application of the shock pulses. The nominal pulse duration shall be 11 ms for standard shock testing and 20 ms for low frequency shock testing.

During the impulse tests of paragraphs 7. The equivalent weight shall not contribute to the strength of the equipment case or its mounting fastenings to a greater extent than the components it replaces. In each of the six equipment orientations listed in paragraph 7.

Such equivalent weight shall approximate the weight of the components that it replaces and shall be so located that the center of gravity of the equipment is essentially unchanged.

In certain cases. There shall be no failure of the mounting attachment and the equipment or dummy load shall remain in place. After application of the six shocks. If a static test were used to demonstrate compliance. Where the orientation of the equipment to the aircraft axes is known. That would simulate the inertia loads the equipment would see for the Forward 9g condition.

If a centrifuge is used. The crash safety load requirements represent inertia load requirements. Apply the appropriate test loads for a minimum of three seconds in each direction of load.

Fixed-Wing Transport 2 F 3. For instance. Fixed-Wing Non. In order to simulate the inertia loads doing a centrifuge test. Helicopters 1 F 4. If the orientation of the equipment under test is unknown or not fixed in relation to the aircraft axes. These test levels may not satisfy the installation requirement in the FARs. The airplane directions together with the definitions regarding a centrifuge test are provided on Figure 7- 3.

All Fixed-Wing F 3. Helicopter and All Fixed. After application of the six loads. The oscillogram shall include a time duration T1 or T2 with a pulse located approximately in the center. The integration to determine velocity change shall extend from 0. The acceleration amplitude of the terminal saw-tooth pulse is A and its duration is D. Short Duration Vibration Test Procedure Instrument Panel This test should be performed on all equipment where resistance to effects of long duration exposure to vibration must be demonstrated.

For equipment on helicopters. The need to do the high level short duration test is dependent upon the equipment performance requirements. Categories U and U2 are for equipment to be installed in helicopters with unknown rotor related frequencies.

This test should be applied to equipment in which a functional loss of performance can hazardously affect the aircraft's performance. If the vibration environment is known. The specific vibration tests to be performed to show compliance with the performance standards are defined in this paragraph and are dependent upon three identifiers: A service life test depends on the vibration environment the equipment is subjected to relative to the test levels.

U2 The robust vibration test demonstrates that equipment will operate satisfactorily while being subjected to vibration and that it will continue to operate satisfactorily after being subjected to endurance vibration levels.

It combines a demonstration of the equipment functional performance and structural integrity. The necessity for conducting this test in lieu of the standard vibration test shall be determined by the relevant equipment specification.

Z High-level short duration transient vibration levels are encountered during abnormal fixed wing aircraft vibration conditions that occur during an engine fan blade loss. The robust test may or may not represent a service life test.

For equipment on fixed wing aircraft. See the procedures for a more detailed description. Therefore this test alone may not be sufficient for some applications without additional test or analysis. A full analysis of vibration levels related to some specific engine imbalance conditions has not been evaluated against these limits. These tests do not replace the standard or robust tests.

The Category Z test covers restricted low fan frequency applications. Test repeated 3 times for Category U.

The "fuselage" zone applies to all equipment not installed in multiple slot equipment racks but that is attached to frames. Any test fixture used shall be as rigid and symmetrical as practicable. The control accelerometer s shall be attached to the test fixture as near as practicable to the equipment mounting location for each axis of test. Where applicable. The random vibration signal should have a Gaussian distribution.

Install the equipment under test so the input vibratory motion is parallel to one of its three major orthogonal axes. Locations selected may include principal structure. Note that the zone for "instrument panel. The specified test time shall be applied to each frequency band. For all vibration input types.

When more than one accelerometer is employed for test level control. The random and sinusoidal standard and robust test levels may be reduced by 0. Note that a 6. If the random vibration test requirements exceed the power capability of the vibration test system. Weight Allowance — For equipment items weighing greater than The equipment shall be attached to the fixture or vibration table by the means specified in the equipment specification.

On-line contiguous filter. Swept frequency analysis systems characterized as follows: Specific analyzer characteristics or their equivalent shall be as specified below. At the completion of the test. For Aircraft Type 6 Zone 7. Any difficulty in reading any display feature of the test item.

The procedures for both sinusoidal and random tests are defined below. The bandwidth-time product is equal to the number of records used to obtain one APSD i.. Critical frequencies are defined as those frequencies where: During the initial up-sweeps.

Any changes in the critical frequencies that occur during the test shall be noted on the Environmental Qualification Form see Appendix A. For restricted Category Z applications. For general Category H applications. For this application. Repeat the sinusoidal scan of subparagraph 8. For Category Z. During this vibration period. Resonant frequencies are defined as response peaks that are greater than twice the input acceleration amplitude.

Any changes in vibration resonant frequencies shall be noted on the environmental Qualification form see Appendix A. Operational performance requirements during and after the test shall be defined by the equipment specification. With the equipment not operating. Record plots of response accelerometers at selected position on the equipment to determine resonant frequencies and amplification factors. Near the beginning and again near the end of the vibration period.

During the initial up- sweeps.

If no critical frequencies are identified. During each resonance dwell. Select the four most severe frequencies from the critical frequencies identified in 8. At the completion of the tests. The time spent performing these sweeps may be included in the total sweep time of subparagraph 8. If no change occurs. Following the vibration dwell test. If fewer than four critical frequencies are identified.

Dwell at each of these selected frequencies for 30 minutes. Unless otherwise defined in the equipment specification. The time spent at frequency cycling will be three hours minus any time spent at testing resonances in 8. For helicopters where data have been measured. If the test item is not operating during the endurance level vibration test. For the unknown helicopter frequency case. Hz The blade passage frequencies of the rotor blades are defined using the number of blades for the main and tail rotors: Hz The test frequencies to be used for each helicopter zone can be determined using the formulae provided in Table a.

The test procedures cover both known and unknown helicopter frequency cases. The maximum required test time at the endurance levels is 3 hours. The dwell tests may include multiple frequencies. A performance and endurance vibration test shall be performed in each of the equipment's three orthogonal axes using the test procedure defined below. The combined sinusoidal and random curves appear generically as a total test curve in Figure Perform sinusoidal dwells at each of these frequencies for 30 minutes.

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The random levels are also given in Table b. If more than two resonances are found. If one or several of the equipment resonant frequencies determined in 8. After completion of 8. Any changes in vibration resonant frequencies shall be noted on the Environmental Qualification Form see Appendix A. During this time period.

Test 1: The following test sequence may be applied to Table a Zone 1a and Zone 2 equipment only. After the three hour test. It may also be used for Zone 1b tail boom equipment. Perform three tests per 8. This includes the fuselage. Single Eng Less than 5. Curves B to E are random. Curves B and B1 contain higher levels and reflect the expected environment for all cases. Fixed Wing S C 3 B. Multi Eng Less than 5. Curves B3 and B4 are representative of large aircraft.

Does not include equipment mounted on structure directly affected by jet efflux. U applies to zones 1a and 2 only: Fixed Wing S Y 3 B. U2 is an alternate to U and applies to 1a. They are representative of levels expected on many fixed wing aircraft but are not sufficient for many others. NM and NT are defined in Paragraph 8. The sine on random test curve is shown in Figure For equipment located externally on the airframe and exposed to the external airflow.

In this figure the use of English units was retained because the graphs were derived from these units originally. The vibration frequencies are determined using the equations in Table a.

Use these frequencies together with the equations in Table b to determine the vibration levels. A4 are Sinusoidal Curves. W0 is a random PSD curve.

Instrument Panel. Appendix A is applicable for identifying the environmental tests performed. Suite Washington. Installed equipment shall meet the standards and test procedures for any one of the explosive atmosphere categories paragraphs 9. The flammable test fluids. It also refers to normal and fault conditions that could occur in areas that are or may be subjected to flammable fluids and vapors during flight operations. Installed equipment shall meet the explosion containment and fault condition requirement for Category A.

These standards do not relate to potentially dangerous environments occurring as a result of leakage from goods carried on the aircraft as baggage or cargo. The explosive atmosphere tests shall be conducted after the article being tested has been subjected to other environmental tests of this document see subsection 3. During normal operation. The equipment test requirements are the same as for Environment II except that fault conditions in Category A equipment need not be considered.

Category E equipment is not intended for installation in Environment I. In normal operation the temperature of any surface will not rise to a level capable of causing ignition. Hermetically sealed equipment meeting subparagraph 9. Such equipment shall be designed so that in normal operation the temperature of any external surfaces will not rise to a level capable of causing ignition.

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Ignition of an explosive mixture is contained within the equipment without igniting an explosive atmosphere surrounding it and so that it meets the Category A tests specified in paragraph 9. Such equipment shall be designed so that in normal operation the temperature of any external surface will not rise to a level capable of causing ignition.

When the test facility is designed for fuel vaporization inside the explosion chamber. For hexane. For an example of test apparatus see Figure 9- 1. For propane. The equipment used to vaporize the fuel for use in the explosive atmosphere test should be so designed that a small quantity of air and fuel vapor will be heated together to a temperature such that the fuel vapor will not condense as it is drawn from the vaporizer into the chamber. A spark gap device for igniting the explosive mixture within the case or enclosure shall be provided.

In designing the air supply system for forced air ventilated equipment. The specification for Category A equipment. Hose Installation. Equipment that may come into contact with flammable fluids or vapors and that in normal operations may produce arcs. When inserting a hose from a blower.

The case or enclosure with either the test item or a model of the test item of the same volume and configuration in position within the case or enclosure shall be connected and oriented in the explosion chamber mechanically and electrically.

Such design constraints should include the following as appropriate: The case or enclosure may be drilled and tapped for the spark gap device. Case Installation.

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This information is contained in national documents. Preparation of Test Case or Enclosure — The purpose of this procedure is to intentionally fill the case or enclosure under test with a volatile gas mixture then ignite it. If the equipment and its ducting. Equipment that may come into contact with flammable fluids or vapors. Spark Gap Device. Test Facility — The required apparatus consists of a chamber or cabinet together with auxiliary instrumentation capable of establishing.

An explosive mixture within the chamber shall be obtained by using the mixture defined in paragraphs 9. Use a chamber with a means of igniting the fuel-air mixture such as a spark-gap device. At least five internal case explosions shall be performed.

If ignition of the mixture does not occur immediately. The occurrence of an explosion within the case may be detected by use of a thermocouple inserted in the case and connected to an appropriate temperature recorder outside the test chamber.

An alternative method of determining the explosive characteristics of the vapor is by using a calibrated explosive gas meter which verifies the degree of explosiveness and the concentration of the fuel-air mixture.

The internal case ignition source shall be energized in order to cause an explosion within the case. If the air-vapor mixture in the main chamber is found not to be explosive.

Ample time shall be allowed between internal case explosions for replacement of burnt gases with fresh explosive mixture within the case. The chamber shall be sealed and the internal pressure maintained at site level pressure.


If the internal case explosions produced did not cause a main chamber explosion. If no explosion has occurred as a result of the test item operation. The test chamber shall be sealed and the ambient temperature within shall be raised to the Operating High Temperature. Large test items may be tested one or more units at a time by extending electrical connections through the cable port to the balance of the associated equipment located externally.

At this time all electrical contacts of the test item shall be actuated. The test item shall be operated to determine that it is functioning properly.

The test item shall be connected and oriented mechanically and electrically as recommended by the manufacturer for normal service installation. This shall include any cooling provisions as necessary to perform the tests described herein so that normal electrical operation is possible and mechanical controls may be operated through the pressure seals from outside the chamber.

External covers of the test item shall be removed or loosened to facilitate the penetration of the explosive mixture. If the air-vapor mixture is not found to be explosive. The required quantity of fuel paragraph 9. Mechanical loads on drive assemblies and servomechanical and electrical loads on switches and relays may be simulated if proper precaution is given to duplicating the normal load in respect to torque.

Circulate the test atmosphere for at least three minutes to allow for complete vaporization of fuel and the development of a homogenous mixture. In all instances. The operation of the test item shall be continuous throughout this period and all making and breaking of electrical contacts shall be conducted as frequently as deemed practicable. The maximum temperatures attained at the suspected components or surfaces shall be recorded.

Paragraph 9. The equipment shall be turned on and operated in its normal mode until thermal stabilization of the equipment has been attained. For equipment intended for installation in such locations. These tests are not intended to verify performance of hermetically sealed equipment. Category R Equipment installed in locations where it may be subjected to a driving rain or where water may be sprayed on it from any angle is identified as Category R.

Equipment that has passed the Category S requirements may be considered to meet the Category W requirements without further testing. For equipment intended for installation in such locations the continuous stream proof procedure applies. Equipment that has passed the Category R requirements may be considered to meet the Category W requirement without further testing. Equipment shall be considered hermetically sealed when the seal is permanent and airtight.

Water is used in this test to simulate the actual fluid forces. Category W Equipment that is installed in locations where it is subjected to falling water generally the result of condensation in the course of normal aircraft operations is identified as Category W. Category S Equipment installed in locations where it may be subjected to the forces of a heavy stream of fluid such as would be encountered in aircraft de-icing. After the three-hour stabilization. The drip hole pattern shall be sufficiently large to meet or exceed the horizontal cross sectional area of the equipment under test when installed in its normal position.

With the equipment not operating let the equipment stabilize for a minimum of three hours. The water shall be directed perpendicular to the most vulnerable area s of the equipment as stated in the applicable equipment performance standards.

The showerhead shall be located not more than 2. Each of the areas under test shall be subjected to the spray for a minimum of 15 minutes. Prior to the start of the Drip Proof test. If desired. Connectors or other fittings shall be connected as in normal operation. This test shall be performed with water at a temperature of 50 degrees C. The equipment shall be subjected to this stream of water from a distance of one to two meters. The stream of water shall be of sufficient pressure to produce.

Susceptible materials such as gaskets shall be subjected to the appropriate tests of Section The equipment need not be operated during this test. Subject the equipment. Fluids not listed herein and for which susceptibility tests are indicated shall be included in the relevant equipment specification.

Due consideration should be given to this possibility before commencing the tests. The equipment is not required to operate during this test and shall be at room ambient. Sections Section Details of the test fluids involved and the methods used shall be provided in the Environmental Qualification Form See Appendix A.

Spray the equipment with the appropriate fluid one or more times per day as necessary to maintain a wetted condition for a minimum of 24 hours. In addition there are 23 specific fluids that are used to test these classes. Fluids susceptibility tests should only be performed when the equipment will be installed in areas where fluid contamination could be commonly encountered.

The fluids are representative of those commonly used fluids encountered in airborne and ground operations. Table contains the class of fluids. Some contaminants may themselves or in combination with other contaminants or with the test sample be toxic.

At the end of this period. The precautions noted elsewhere in this section should be observed. Unless otherwise noted in the equipment specification. Following the two-hour period. Fluids should not be pre-mixed prior to spraying. The spray shall be a fine mist maintained at the temperatures in Table and shall be directed toward every major surface. At the end of 24 hours.

If the equipment is to be tested with more than one class of contaminating fluid. The equipment is not required to operate during this test and shall be at ambient temperature. Immerse the equipment in the appropriate fluid for a minimum of 24 hours. Do not pre-mix any solution. The fluid temperature shall be maintained at the temperature shown in Table and shall cover the test specimen completely.

Following this period. Material specimen tests are not permitted if the equipment is to be subsequently subjected to the continuous stream proof test paragraph The results of these tests shall assure that the material will protect the equipment from deleterious effects after being exposed to the relevant fluid in the manner defined in the equipment test procedures Subsection Black fluids. Suitable precautions should be taken after exposure to the fluids before operating the equipment.

Testing should always be performed in a suitable pressure vessel. Category S Equipment tested as recommended in the following paragraphs for both Dust test and Sand test is identified as Category S. Pollution of fluids. Such equipment can be installed in locations where the equipment is subjected to blowing dust in the course of normal aircraft operations. Penetration into cracks. Such equipment can be installed in locations where the equipment is subjected to blowing sand and dust in the course of normal aircraft operations.

National documentation may contain other more specific distributions. Such location includes cockpit or any other location not intentionally protected against sand and dust exposure. Sand abrasion may also influence the results of the salt spray.

Consideration must be given in determining where in the sequence of environmental tests to apply this test procedure. Action as nucleus for the collection of water vapor. Formation of electrically conductive bridges.

The recommended particle size distribution for the sand particles is: Note 1: Unless otherwise required in the relevant specification. This large tolerance is due to the difficulties of measuring concentrations at low levels.

Note 2: Health and safety regulations regarding the use of dust should be observed. The air velocity shall be maintained between 0. Externally accumulated dust only on surfaces of the equipment required to verify proper operation e. Under no circumstances shall dust be removed by either air blast or vacuum cleaning.

After removing the excess dust. After removing the excess sand. A vertical chamber may be utilized to preserve the uniformity of sand distribution. Under no circumstances shall sand be removed by either air blast or vacuum cleaning. At the end of this exposure period. If the test item will not directly see wind velocities of this magnitude during normal service life cockpit screen displays then the test item shall be submitted to air velocities of 0.

Externally accumulated sand only on surfaces of the equipment required to verify proper operation e. Direct attack on materials. Fungi proximity to other materials. Enzymes and organic acids. The physical presence of fungi can also cause health problems and produce aesthetically unpleasant situations in which users will reject using the equipment.

This test shall not be conducted after Salt Spray or Sand and Dust. A heavy concentration of salt may effect the fungal growth. Products of natural origin carbon based are most susceptible to this attack.

Microorganisms digest organic materials as a normal metabolic process. Examples of nonresistant materials are: The detrimental effects of fungal growth are summarized as follows: The physical presence of microorganisms produces living bridges across components that may result in electrical failures.

This results in deterioration affecting the physical properties of the material. Nonresistant materials are susceptible to direct attack as fungus breaks these materials down and uses them as nutrients. If non-nutrient material certification is u tilized for this verification. Provisions shall be made to prevent condensation from dripping on the test item. There shall be free circulation of air around the test item and the contact area of fixtures supporting the test item shall be kept to a minimum.

If all materials used in the construction of the equipment can be shown to be non- nutrients for the growth of fungi. When forced air is employed. Damage to fungus-resistant materials results from indirect attack when: Indirect attack on materials. Prepare sufficient salt solutions for the required tests Potassium dihydrogen orthophosphate Unless otherwise specified Adjust the pH of the solution by the addition of Subcultures used for preparing new stock cultures or the spore suspension shall be incubated at 30 degrees C for seven to ten days.

Repeat this operation for each organism used in the test and blend equal volumes of the resultant spore suspension. Dilute the final washed residue with sterile mineral-salts solution in such a manner that the resultant spore suspension shall contain 1. Mineral salts agar is identical to the mineral salts solution described in paragraph Use a sterile platinum or nichrome inoculating wire to scrape gently the surface growth from the culture of the test organism.

Wash the spores obtained from each of the fungi in this manner three times. Resuspend the residue in 50 ml of sterile water and centrifuge. This process should remove large mycelial fragments and clumps of agar that could interfere with the spraying process. Filter the dispersed fungal spore suspension through a six millimeter layer of glass wool. Prepare a spore suspension of each of the five fungi by pouring into one subculture of each fungus a 10 ml portion of a sterile solution containing 0.

Pour the spore charge into a sterile l25 ml glass-stoppered Erlenmeyer flask containing 45 ml of sterile water and 10 to 15 solid glass beads. If genetic or physiological changes occur. Shake the flask vigorously to liberate the spores from the fruiting bodies and to break the spore clumps. Centrifuge the filtered spore suspension aseptically and discard the supernatant.

If the control items show satisfactory fungus growth. Incubate these at 30 degrees C at a relative humidity not less than 85 percent.

The strips should be hung to air dry before being inoculated and placed into the chamber. After seven days. The control items shall consist of unbleached cotton duck g strips that are 3. If the surfaces are non-wetting. Inoculate the test and control items with the mixed fungus spore suspension paragraph Absence of such growth requires repetition of the test.

Keep the test chamber closed during the incubation period. In spraying the test and control items. Inoculate these with the spore suspension by spraying the suspension from a sterilized atomizer1 until initiation of droplet coalescence. Mount the test and control items on suitable fixtures or suspend from hangers. If inspection reveals that the environmental conditions are unsuitable for growth.

There shall be copious growth on all three of the filter paper control specimens. Incubation is to be started immediately following the inoculation. The greatest danger. The following information is provided to assist in the evaluation of the test results. This is only likely to happen after the specimen has dried out.

Surgical gloves may be worn to protect the hands. If the inspection is not completed in eight hours. For this reason there is a possibility that the specimen after exposure may be a hazard. Any fungal growth on the test item must be analyzed to determine the species. If possible. It is also possible. Any growth must be completely described. If the specimen is carried quickly from the test chamber to a normal chemical fume hood before it has time to dry.

Any fungal growth on the test item material s. It is possible for an individual to be allergic to one of them. Except for hermetically sealed equipment.

Evaluate human factors effects including health risks. Where the test location may contain such a harmful fungus. High temperature steam. The use of a fume hood as suggested above. Detached portions of growth may be so small that no protection is offered by wearing a gauze mask and only a special respirator for sub-micron particles is effective.

The salt fog test shall not be conducted prior to the fungus resistance test see Subsection 3. Clogging or binding of moving parts as a result of salt deposits. Corrosion of metals. A means for humidifying the air at temperatures above the chamber temperature. A means for atomizing the salt solution. A salt solution reservoir with means for maintaining an adequate level of solution. Insulation fault. A means of heating and controlling chamber temperature. Category T When the equipment is installed in locations where it is subjected to a severe salt atmosphere.

Exposure chamber with racks for supporting test items. Damage to contacts and uncoated wiring. The discharge end of the vent shall be protected from strong drafts to prevent strong air currents in the test chamber.

A satisfactory method is to pass the air in very fine bubbles through a tower containing heated water that is automatically maintained at a constant level. Means shall be provided to humidify and warm the compressed air as required to meet the operating conditions.

The chamber and accessories shall be constructed and arranged so that there is no direct impingement of the fog or dripping of the condensate on the test items. In addition. Unless otherwise specified. To avoid clogging the atomizers with salt deposition. The temperature of the water should be at least 35 degrees C. The chamber shall be properly vented to prevent pressure build-up and allow uniform distribution of the salt fog. Atomizing nozzles shall be made of materials that are non-reactive to the salt solution.

The air pressure shall be suitable to produce a finely divided dense fog with the atomizer or atomizers used. The solution shall be adjusted to and maintained at a relative density between the limits shown on Figure by utilizing the measured temperature and density of the salt solution. Nozzle pressure shall be as low as practical to produce fog at the required rate.

When using large size chambers having a volume considerably in excess of 0. The pH measurement shall be made electrometrically. Satisfactory methods for controlling the temperature accurately are by housing the apparatus in a properly controlled constant temperature room. The use of immersion heaters within the chamber for the purpose of maintaining the temperature within the exposure zone is prohibited.

Orifices shall be between 0. Only diluted chemically pure hydrochloric acid or chemically pure sodium hydroxide shall be used to adjust the pH. The pH shall be measured when preparing each new batch of solution and as specified in subparagraph Atomization of approximately three liters of salt solution per 0. | Calibration | Atmosphere Of Earth

The salt solution from all collection receptacles used can be combined to provide the quantity required for the measurements specified. A small laboratory type hydrometer will be required for measurement within this volume. The test item shall not be exposed to this test run.

For salt fog chambers that are used infrequently. Test items having an organic coating shall not be cleaned with a solvent. Those portions of test items which come in contact with the support and. The cleaning methods shall not include the use of corrosive or protective films. A minimum of two receptacles shall be used. For salt fog chambers in continuous use.. Receptacles shall be placed so that they are not shielded by test items and so that drops of solution from test items or other sources will not be collected.

The test item shall then be inspected for corrosion. Before any dismounting or washing operation. Repeat the interval if fallout quantity requirements are not met. At the end of the drying period and unless otherwise specified. Any corrosion must be analyzed for its immediate or potential effect on proper functioning of the test item.

If necessary. Continuously atomize a salt solution of a composition as given in 4. Within an hour of removing the equipment from the chamber. At the end of the drying period. Do not disturb the test item or adjust any mechanical features during the drying period.

Moisture remaining after the hour drying period could cause electrical malfunctions. Salt deposits can cause clogging or binding of mechanical components and assemblies. Analyze any corrosion for its immediate and potential long-term effects on the proper functioning and structural integrity of the test item.

The extent of any deposits resulting from this test may be representative of those induced by anticipated environments. This test ensures that equipment can operate properly without interference which may affect the nearby equipment. This measurement may be performed with either an uncompensated compass or an equivalent magnetic sensor.

This category should be used for equipment whose installation is placed between 0. If the horizontal component of the magnetic field produced by the earth at the location of the test lab is within the tolerance stated above.

This bundle is to be routed along the east to west axis of the compass. NOTE 2. Dc is the equivalent deflection angle to be used in determining equipment category. All cables and extended power leads for the EUT are to be placed in one bundle for the test.


NOTE 1. If the horizontal component of the magnetic field produced by the earth at the location of the test lab exceeds the tolerance stated above.

This test is performed as follows: With the EUT removed from the test area. Category B Equipment Only Category D Equipment Only Designation H Designation R Designation L. Designation I Designation P Category reference: D or Z All ac equipment categories are to be followed by additional letters to indicate if the equipment has to be submitted to: Equipment categories and frequency classes. It covers the following electrical power supplies: AC only equipment test designations such as the letter H are not to be marked after dc equipment categories such as A.

DC only equipment test designations such as the letter R are not to be marked after ac equipment categories such as A CF.

Should the unit accept both ac and dc power. The control or protective equipment may disconnect the battery from the dc bus. A WF and A Equipment intended for use on aircraft electrical systems where the primary power is from a constant or variable frequency ac system and where the dc system is supplied from transformer-rectifier units.

Category D V dc equipment intended for use on aircraft electrical systems where the dc is generated from primary power supplied from either a constant or variable frequency ac system.

A WF designates ac equipment intended for use on aircraft electrical systems where the primary power is from wide variable frequency to Hz ac system. Category A CF. A NF designates ac equipment intended for use on aircraft electrical systems where the primary power is from narrow variable frequency to Hz ac system.

The dc supply does not have a battery floating on the dc bus. Retrieved from " https: Namespaces Article Talk. Views Read Edit View history. This page was last edited on 17 October , at By using this site, you agree to the Terms of Use and Privacy Policy. Cover of original issue. Standard conditions.

This checks the effects of temperature on the system. Condensation also can be a factor coming from cold temperatures. Factors tested include dielectric strength , cooling under low pressure, and resilience to rapid change in air pressure.

The norm defines the different temperature profiles under which the equipment must be tested. Due to the variety of aircraft, the equipment are classified in categories. These tests exercise the assemblies capability of surviving extreme temperature changes and the effects of differing coefficients of thermal expansion.

These tests under humidity check the effects of high concentrations of humidity and the articles ability to withstand moisture effects. Typically moisture sensitive devices have issues with this test and require conformal coat or other types of protection.

This aircraft type dependent test checks the effects of mechanical shock. Crash safety test insures the item does not become a projectile in a crash. The norm describes the test procedure for airborne equipment. Aircraft type dependent test checks the effects of vibration and the equipment's ability to operate during all vibration scenarios.

Explosion proofness. These tests subject the test article to an environment under vacuum, with a gaseous mixture of combustibles. The unit must operate and be subjected to any actuation including knob turns and button pushes and not ignite the environment.

These tests subject the test article to various scenarios of dripping water or pooled water to verify the unit will fully operate in the given condition.