11-3 PROCEDURES

11-3.1 Procedvire I - Engineering, developmBnt

Step 1. Mount test item in accordance with II-2. Step 2. Confirm that the test item is operational.

Step 3. Start test and test to conditions specified in test plan developed as outlined in 1-3.2.1.

Step 4. Conduct test and ncnitor performance of test item aigainst failure criteria.

Step 5. Continue test until malfunction occxjrs (see 1-4.2) Step 6. Analyze failures and take corrective actions. Step 7. Docvnent malfunctions per II-4 and 1-4.3.

Step 8. Continue test until a suitable nvscber of hours of environmental exposure have been achieved (see I-3.3a).

Step 9. Repeat steps 1 through 8 for each single stress or conbination of atrsssea until all the stresses have been combined.

Step 10. Docvnent entire test per II-4.

II-3.2 Procedure II - Flight/operational sxjpport test.

Step 1. Mount test item in accordance with II-2.

Step 2. Confirm that test item is operational.

Step 3. Start test cycle with a cold-day park simulation and continue the sequence as shovm in table 520.1-IV.

Step 4. Manitor test item performance throughout environmental exposure.

Step 5. Continxje test until a test item malfunction occurs.

Step 6. Analyze and docunent malfunction per II-4 and 1-4.3.

Step 7. Continue test until a suitable nurber of hours of environmental exposure have occurred on at least one specimen (see 1-3.3b).

Step 8. Docvnent entire test per II-4. NETHOD 520.1

II-3.3 Procedups III - Qualification test

Step 1. Mount the test item and instrumentation per II-2. Step 2. Start the test cycle developed from 1-3.2.3.

Step 3. Ftoietion the test item while being exposed tc envir-onmsntal stresses in step 4.

Step 4. Expose the test item to the пглА>ег of test cycles decided on per 1-3.3c.

Step 5. Check the test item for functioning in accordance with General Bequirements 4.5.

Step 6. Repeat steps 1 through 5 for each of the single or combined environment tests specified in 1-3.2.3 unless they were cond\x;ted as one test that combines all the environments.

Step 7. Document test results as given in 11-4.

I1-4 INFORMftTION TO BE RECORDED

a. Test item identification (manufacturer, serial пглЬег, etc.).

b. Pretest, during teat, and post-test performance data according to (Seneral RequiremBnts, and the individual test specification аша/ог test plan.

c. Test cycle, including environmental conditions applied.

d. Teat time history of each failure occxjrrence.

e. Nature ox failure, including environmental effects

f. DC ripple voltage, as applied dicing th© mission simulation portion of each test cycle.

g. AC voltage variation, as conducted during the mission-simulation portion of each test cycle.

h. Type, location, and orientation of stress-neasuring ger.sorg.

1. Description and calibrations status of data recording and analysis equipment.

j. Voltage modulation, as applied dtjring the mission-simulation portion of each test cycle.

k. Frequency modulation, as applied dtring the mission-simulation portion of each test cycle.

1. Electrical stress induced by mission-related transients within the electrical system.

m. Prior test history of test item, n. Corrective action proposed.

520.1-28

hEthOD 521. i IClHQ/FiINQ RAIN

SECTION I

I-l PURPOSE................... 521.1-1

1-2 ENVIK)iB 3frAL EFFECTS............ 521.1-1

1-3 GLIDELINES FOR DETERMINING TEST

ряостшшз -resT CONDITIONS....... 521.1-2

1-4 SPECIAL CONSIDERATIONS............ 521.1-4

1-5 REFERENCES.................. 521.1-S

SECTION II

Il-i APPARATUS .................. 521.1-5

II-2 PREPARATION FOB TEST............. 521.1-6

II-3 PBOCEDUHES.................. 521.1-8

11-4 INFORMATION TO BE RECORDED......... 521.1-8

SECTION I

I-l PLliPOSE. Th© icing/frsszing rain test is conducted to evaluate the effect cf icing produced by a freezing rain, mist, or sea spray on the operational capability of materiel. This method also provides tests for evaluating the effectiveness of deicing equipment and techniques, including field expedients.

1-2 ENvIЮNMEifГAL tLfftajTS. Abuildip of ice occvrs in three principal ways: from rain falling pn an item iC3e temperature is below freezing (CC), from freezing rain fallir.g on an item at cr near freezing, or from sea spray #>.ich coats equipment vhen temperatures are below freezing. MIL-STD-210 identifies two conditions cornnonly encountered: (clear) glaze ice and (granular) rime ice. Glaze ice occurs when rain or drizzle freezes on objects, and it is nearly as dense as pure ice. Rime ice occurs when fog droplets or drizzle falls on surfaces colder than 0°C. It is white and. since it is saturated with air, is raLic-h less dense than glaze ice. Since glaize ice is more difficult to remove and has a density approximately four times greater than rime ice, it is a more significant factor and will be the focus of this test. The Synopsis of Background Material for MIL-STD-210B (reference f. p.l04, p. 149) identifies extremes for ice accumulation. These extremes may be used for calculating design and structural evaluations but are not suitable for establishing test conditions. Ice formation can inpede equipment operation and survival and affect the safety cf operatirig personnel by creatir>g the following problems:

a. Binds moving parts together.

b. Adds weight to radar antennae, helicopter rotors, etc.

c. Increases footing hazard.

d. Interferes with clearances between moving parts.

e. Induces structural failijres. t. Reduces airflow efficiency.

g. Iitpedes visibility through windshields and optical devices.

h. Affects transmission of electromaignetic radiation.

i. Leads to increased probability of damage to equipment from the eiiployment of mechanical, manual, or chemical ice removal neasures.

1-3 GUIDELINES FOR DETERMIMING TEST PROCEDURES АШ> TEST COMDITIOMS

NOTE: The tailoring process as described in Section 4 of this docrjment should be used to determine the appropriate tests and test variables.

a. -Application. This msthod is applicable te rasteriel sshieh may be exposed to icing or freezing rain conditions during normal \jse,

b. Restrictions. This method does not simulate Snow conditions, nor does It simulate ice buildup on aircraft flying through supercooled clouds.

c. Sequence. (See (Seneral Requirements, 5.1.4) The possibility of st-rjctural danage to the test materiel due to the icing test should be ccr.sidered when determining test seq\ience. This test should follow the rain tests (msthod 506.3) ш^d precede the salt fog tests (method 509.3) and mechanical tests (such as 513.4 through 519.4) so that parts will not be loosened before the icing tests.

d. Test variations. The freezing rain test contains one test procedure that Is applicable for most equipment. All test variables should be specified In the test plan before actual tegting is initiated.

1-3.1 (aioice of test procedure

a. Test objectives. This method is designed to determine If the materiel and ancillary equipment (mounted So that it is directly exposed to the environment) can operate after ice accuiulation from rain, drizzle, fog, splash, or other gourceg. iere ice removal is required before operation, the use of the integral deicing equipment or expedients normally available to the operator In the field will be enployed. Deicing equipment and expedients will be evaluated to stssess their effectiveness and the potential for damage that may degrade performance.

b. Test proeedupe. Wien an icing test is deemed necessary, the procedure included in this method is considered suitable for most test items. Since natural icing conditions will be the same for all materiel located out-of-doors on land, the sane test Is applicable for all such equipment. This test involves a Sssr. layer of ice followed hy a 13 nsn layer of ice. For isstrine materiel hich may be exposed to sea spray, a third thickness of 75 im is suggested.

1-3.2 Choice of related test conditions. The test variables are configuration, tenperature, rain rate, rain delivery method, droplet size, and wind velocity. The values chosen for the variables are primarily dependent on the intended ше of the test item, and the level of severity desir-ed.

a. ConflginfatiQn and orientation. The following factors are to be considered:

(1) All equipment will receive icing on all sides and on top.

(2) Equipment nust be in the configuration that it would be in when deployed. If required, duplicate tests may be performed in the shipping or outside storage configuration.

(3) Some equipment covered with ice will be expected to operate inmediately without first undergoing deicing procedures; other equipment would not be expected to operate until some form of deicing has taken place (e.g., clearing windshields).

(4) Ice removal will involve a conbination of the bxiilt-in ice-removal system together with expedient msar.g which could be expected to be enployed by ndlitary personnel in the field.

b. Test temperature. Test tenperatures are reconmended in the test procedure that may be vised to produce the required environmental conditions. If extremes other than those shown are known, they should be used instead of the reconnended values.

c. Rain del iverv rate. The rain delivery rates identified in the test procedine are based on data used for previous testing (I-5a and b). These rates are considered representative of the spectrum enconpasslng both typical and worst-case conditions. Rain delivery rates are furnished as suggestions only. The objective is to produce a clear, uniform coating of glaze ice. Variations in delivery rate that produice UTiiforra coatings of glaze ice ar-e acceptable.

d. Rain-del iverv method. Rain delivery in the form of a uniform spray can be achieved by any of the arrangements described below:

(1) Nozzle arrays directing spray to the top, sides, front, and rear of the

test item.

(2) Nozzle arrays that direct spray straight down onto the test item. Sidespray coverage is achieved by using wind or nanual method.

КЕТЮО 521.1

(3) A Single, hand-held nozsle directing the spray over the surfaces of the

test itera.

e. Droplet size. Droplet size is not considered to be of any particular significance; however, fine spray (1.0 to 1.5 nn nominal droplet size is sijggested) nay be necessary to produce the icing.

1-4 SPECIAL C0NSIDERA7I0KS

1-4.1 Fail\jre analysis. (See General Bequirements, 5.2.7)

a. The test item shall be considered to have failed the test if:

(1) For equipment that must operate without ice removal, the performance of

the test item has been degraded below that specified in the requirements docjnsnt.

(2) For equipment that can await ice removal before operation, the performance of the item has been degraded below the specified requirements after norneil ice-removal efforts have been undertaken or if ice removal damages the

equipment.

(3) A nonapparent hazardous situation has been created.

b. The failure of a test item to satisfy its operational and maintenance requirements nust be analyzed carefully, and related information must be considered, such as:

(1) Degradation allowed in operating characteristics follo elng the fizzing rain conditions.

(2) Necessity for special kits or special operating procedures.

1-4.2 Sunmarv of ..test Information required. The following information must be provided in the test plan for the adeqшtte conduct of the tests of Section II:

a. Test item configuration.

b. Test tenperatiffe conditions.

c. Rain delivery method.

d. Wind velocity (if applicable).

e. Ice thickness.

1-5. REFEREiiCES

a. TOP 2-2-S15i Rain and Freezing Bain. 19 Jxmm 1975= DTIC пшЬет AD-A029-317,

b. Letter from С, Teat & Siport Branch, TERWT, Eglin AFB, FL, subject: Freezing Rain Tests, to: US Arny Test and Evaluation Coimand, ATTN: DRSTE-AD-M, Aberdeen Proving Qround №, 15 Noveirber 1979.

с American National Standards Institute. Test Code for High Voltage,Air Switches. ANSI 037.34A-1975. IEEE 326.

d. AIR 70-38, Research. Development. Test and Evalijation of Materiel for Ebctreme Climatic Conditions. 1 August 1979.

e. №L-sTO-2l0, Climatic Information To Determine Design And Test

Reouireiaentg far Military SvstciiiS and EGuiPffisnt. 9 January 13S7.

f. Synopsis of JBackground Material for MIL-STD-210B. Climatic Extremes

for Military Equipment.. Bedford, MA. Air Force Cambridge Research Laboratorties, 1974.

g. AMD ram 706-116, EnKineering DesiRn Handbook. Environmental Series. Part Two. Natural Environmental Factors. 15 April 1975.

h. Tattleman. P. and I. Qringorten, Estimated Glaze Ice and Wind Loads

at the Earths. Surface for the Contiguous United States, AFCRL-TR-73-0646, October 1973. DTIC nvnber AD-775-068.

i. Doviiden. D. T. et al, Епк1пввг1пк Зшиагу of Air Frajne leina Technical Data. U.S.A.: Federal Aviation AQency. ferch 1964. F.A.A. Technical Report ADS4.

j. DEF STAN 07-55 (Part 2) Section 2/1. Test - BIP.Icing/Frosting London. England: Ministry of Defence. April 1975.

MIL-STD-elOE 14 JVuY 1SS9

METHOD 521.1

ICINQ/FBEEZINQ BAIN SECTION II

II-l УАВАТия

II-l.l Test facilities

a. The required apiaratus consists of a chamber or cabinet with auxiliai?y equipment which has the ability to establish and maintain the test conditions specified. The chanfcer must be equipped so that est conditions within the chasber car. be stabilized vrathin a reasonable time after the test item is loaded. Mb.ter delivery equipment (nozzles and drains) shall be arranged to preclude the collection of puddles in the chamber. The chanber shall be equipped with instrumentation capable of maintaining and continuously monitoring the test conditions. (See Oeneral Requirements, S.1.2)

b. The thickness of the ice and the temperature during equipment operation are the inportant parameters. The precise methods for depositing the ice on the equient are not inportant. (See 1-3.2d)

II-l.2 Controls. Before each test, critical parameters Shall be verified. A spray pattern wide enough to guarantee uniform inplngement for all test wind velocities shall be assured. Suggested есЬ п1ф 8 for spray calibration (if specified or considered essential) can be found in reference I-5J. Unless otherwise specified in the equipment specifications (or other documents), if any action other than test item operation (such as opening the chanber door) results in a significant change in the test item or chanber air tenperature (more than 2C iZ.CPF)), the test item will be restabilized at the r-equired teirature before continuation. If the cperatlorial check is not conpleted within 15 minutes, reestablish the test item tesperatvpe conditions before continuing.

II-1.3 Test interruption. (See General Requirements, 5.2.4)

a. Undertest interruption. Interrtption of a freezing rain test is inlikely to generate any adverse effects and normally the tsst shall be continijed from the point of Interrxptlon once the test conditions have been reestablished.

b. Overtest interruption. Any interr4>tion that results in more extreme exposure of the test item than required by the requirements docшaent or equipment specification should be followed by a conplete operational and physical check. Iz no problems are encountered, the test Item shall be restored to its pretest condition and the test reinitiated.

II-2 PREPARATION FOR TESX

II-2.1 Preliminary Steps. Before initiating any testing: NETHOD 521.1

521.1-е

a. Detepmine fr-oni ths test plan the test item configuration and other test parameters.

b. Determine from the test plan the operational requirements.

c. Clean all traces of oil and grease from all outside surfaces of the test item %ihich are not oily in the normal operating mode. Even thin films of oil or-grease will prevent ice from adhering to the test item and change the test results.

d. To facilitate measurement of ice thickness, copper bars or tubes 2.5 cm in diameter and at least 60 cm in length shall be mounted in a horizontal position in places where they will receive the same general rainfall as the test item, Other thickness measurement techniques may be used if they can be shown to accurately msasurs and indicate the ice thickness.

NOTE: Structures with large height variations, svch as antenna masts, should have test bars placed at the different heights, since artificially produced freezing accretion rates tend to depend т.фОП the distance between the test item and the spray frame.

e. Vfeter used in the spray system should be cooled to between 0° and 3*0 (37F.) When chilled mter carniot be obtained, unchilled water will produce acceptable results. The main factor affected by the warmer water tenperature is the ice buildup rate.

I1-2.2 Pretest standard ambient checkout. Ail test items require a pretest standard ambient checkout to provide baseline data. Conduct the checkout as follows:

Step 1. Insert the test item into the chamber and stabilize the test item at standard anbient conditions per General Requirements, 5.1.

Step 2. Conduct a conplete visual examination of the test item

Step 3. Prepare the test it-em. in accordance with General Reфaiгemвnts, 5.2.2, and required test item configuration (1-3.2a).

Step 4. Conduct an operational checkout in accordance with the approved test

plan.

Step 5. Operate any integral deicing equipment, such as defroster, wipers, etc.. to assure satisfactory operation.

Step 6. Record the results for conpliance with the requirements documents(s).