1、AECMA PREN262i Edition approved for publication Comments should be sent within six months after the date of publicafion decision 88, Bd. Malesherbes 20th January 1990 A.E.C.M.A. 75008 PARIS - FRANCE 90 C4 Chairman Mr. STAIB - 724 2 A .E .C, M .A. STAN DARD NORME A. E.C. M.A. A.E.C.M.A. NORM prEN 262
2、4 Issue P 1 January 1990 DIT PAR LASSOCIATION EUROPENNE DES CONSTRUCTEURS DE MATRIEL AROSPATIAL 88, boulevard Malesherbes, 75008 PARIS -TL. 45-63-82-85 UDC : Key words : ENGLISH VERSION Aerospace series Pressure impulse testing of hydraulic system components Srie arospatiale Luft- und Raumfahrt Essa
3、i dimpulsion de pression Druckimpulsprfung des composants de systmes hydrauliques von Komponenten in Hydraulik-Anlagen This Aerospace Series pre-standard has been drawn up under the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green pape
4、r for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Commission following comment by the Member countries. Subsequent to the publication of this pre-standard, the technical content shallnot be changed to an extent that interchangeability is affected, phy
5、sically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreemenf of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Stand
6、ardization) for final vote. aecma 1990 AECMA PREN2b24 90 m LO123LL 0003725 4 D”FN 7674 ?ne 2 Contents 1 Scope and field of application 2 References 3 Definitions 3.1 Components 3.2 Shape of impulse trace 3.3 Rate of rise 4 Requirements 4.1 Rate of rise ,4.2 Cycling rate 4.3 Temperature 4.4 Number of
7、 cycles 4.5 Preparation of specimens 4.6 Test specimens 4b7 Test fluid 4.8 Perfomance after test 5 Test procedure 5.1 Accuracy 5,2 Component set up 5.3 Impulse test 5.4 Component verification Figure 1 - Pressure impulse trace AECMA PREN262Li 90 1012311 000372b b 1 prEN 2624 Page 3 1 This test method
8、 shall be used to vepify the structural integrity of certain Scope and field of application O - hydraulic components under pressure impulse-type loading. For the purpose of pressure impulse testing the hydraulic system components shall be divided into passive and active components. This standard est
9、ablishes the requirements and the procedures for impulse testing of passive hydraulic components only, Unless otherwise specified in the detail specification or in existing component related standards, the following procedures shall be used. Active hydraulic components shall be tested according to t
10、ailored test require- ments as specified in detail specifications. 2 References IS0 6772 , Aerospace-fluid systems- Impulse testing of hydraulic hose, tubing and fitting assemblies O 3 Definitions 3.1 Components 3.1.1 Passive components Passive components are units under pressure whose impulse loadi
11、ng in service primarily results from pressure fluctuations in the hydraulic system. The number of cycles, the amplitudes and the wave shape of these impulses in general cannot be predicted or calculated with sufficient accuracy. Passive components are, for example : - “manifalds“ and fluid distribut
12、ion components except lines, fittings and hoses - filter housings 3.1.2 Active components Active components are units under pressure which have to sustain (active) pressure pulses resulting from their own function in addition to the normal (passive) system pressure fluctuations. The active portion o
13、f the impulse loading in general can be predicted or calculated or derived from the duty cycle of the component. Active components are, for example : - flight control actuators and control components - landing gear and other utility hydraulics - braking and nose wheel steering hydraulics O prEN 2624
14、 Page 4 3.2 Shape of impulse trace When observed on an oscilloscope the impulse traces show as approximate pressure-time cycles. The dynamic cycle produced by the test machine shall be in conformance with the trace illustrated in figure 1. It is mandatory that the pressure time curve be confined to
15、the shaded area on figure 1. 3.3 Rate of rise The rate of rise is defined as the slope of the pressure-time curve in the straight portion of the pressure increase portion. For purposes of definition, the rate of rise shall be determined between 10% of the total rise above back pressure and 10% of th
16、e total rise below peak pressure. Sweep rate of the oscilloscope shall be adjusted so that the slope of the pressure rise shall take advantage of the full size of the screen. The trace and photos of the impulse cycle should be an accurate record of the impulse cycle and show a grid or other means to
17、 permit accurate checking. 4 Requirements When this EN is referenced in a design specification as part of the requirements the i-ollowing requirements shall be specified : a) Nominal system pressure b) Operating fluid and ambient temperature c) Fluid 4.1 Rate of rise The rate of pressure rise shall
18、be less than 1400000 kPa/a (14000 bars/) unless otherwise specified in the detail specification. 4.2 Cycling rate The cycling rate shall be between 1 cyclejs (large components) and 5 cyclesrs (small components), with the actual cyclic rate to be defined in the component detail specification. At rate
19、s higher than 1 cycle/s the component shall be instrumented to verify that intended stresses are applied. 4.3 Temperature The fluid and ambient temperature during testing shall be maintained at the nominal component operating temperature as specified in %he detail specification. 4.4 Number of cycles
20、 O Unless otherwise specified in thr: detail specification, the following number of pressure impulse cycles shall be applied as a minimum separately to both the pressure and returns (when applicable), cavities of the component. Avoid backflowing electro-hydraulic servo valves if present in the assem
21、bly under test. High pressure 300.000 cycles Low pressure 150.000 cycles See figure 1 4.5 Preparatioo of specimens The preparation of test specimens shall be defined in the component detail specification. 4.6 Test equipment The test equipment and circuit shall produce repeatable pressure pulses with
22、in the limits defined in clause 3.2. 4.7 Test fluid The fluid used for the test shall be the service fluid of the component undergoing the test, unless otherwise specified in the component detail specification. 4.8 Performance after test The comDonent shall conform to the performance requirements sp
23、ecified in the detail specification after completion of the impuise testing. 5 Test procedure This method of testing is intended to determine the ability of hydraulic system components to withstand hydraulic impulse for qualification testing. 5.1 Accuracy Set up and maintain .,quiPrnent accuracy so
24、that all data are accurate within 2% of actual. 5.2 Component Set-up Bleed entrapped air from the component and test circuit being pressurised. Allow all drains and low pressure ports that are not part of tne pressure containing envelopes to drain freely and keep them at atmospheric pressure. Metal
25、shot or loosely fitting metal pieces may be placed in the unit under test is desired tc minimize fluid volume, * I I AECMA PREN2b24 90 W IOI23II O003729 I prEN 2624 Page 6 e 5.3 Impulse test Conduct the impulse test as required in clause 4 and the detail specification. 5.4 Component verification Aft
26、er completion of the pr !sure impulse testing, the unit shall be tested to the performance limits specified in clause 4.8. The unit shall then be disassembled and inspected for cracks or structural failure. k 3 o) o) a, k a U Q) ci (I OI IH O ci C a, u k a, Q 135 120 1 IS 110 100 75 50 .25 O AECMA PREN2624 90 W LOL2311i 0003730 B ! prEN 2624 Page 7 Percent of Cycle Note : Rated Pressure for High Pressure Components: 100% nominal System Pressure Rated Pressure for Low Pressure Components: 50% nominal System Pressure Figure 1 - Pressure impulse trace
