Downloaded from https://www.everyspec.com MIL-STD-810C In this case, factors Al, A2, and (N/3T) shall be set equal to one. The value of q shall be the maximum value attainable during free flight. The duration of this functional test, per axis, shal1 equal the maximum free flight time expected at maximum vibration level, but not less than 30 seconds. In the event that all free flight functional checks are made during the captive functional test and the captive functional test levels are larger than or equal to those derived here (4.6.3.2.7), no free flight functional test is required. . 4.6.3.2.8 References a. Dreher, J. F.; Lakin, E. D.; Tone, E.
A.; “Vibracoustic Environment and Test Criteria for Aircraft Stores During Captive Flight,“ Shock and Vibration 8ulletin No. 39, Supplement (pp15-40), NRL, Wash., DC, April 1969. b. Dreher, J. F., llEffe~t~of Vibration and Acoustical Noise On Aircraft/ Stores Compatibility,r!Proc. Aircraft Store Compatibility Symp., Vol. 6, pp 245-272, Eglin AF8, Florida, November 1969. c. Piersol, A. G., I!Vibration and AcOustic Test Criteria for Captive Flight of Externally Carried Aircraft Stores, !!AFFDL.TR-71.158 Wright-PattersonAF8, Ohio, December 1971. 4.6.3.3 Procedure IIC, assembled externally . carried stores for helicopters d 4.6.3.3.1 Purpose.
To determine that externally carried stores attached A tothe wings and pylons of helicopters (with a main rotor speed of 324 rpm, two blades, such as UH-IB, UH-lC, AH-lG, etc) are capable of withstanding expected dynamic vibrational stresses normal1y induced by the helicopter during flight conditions and to qualify the equipment for service life. If the equipment normally operates while being carried by the helicopter, then the equipment is expected to operate satisfactorilyduring the vibra- tion test. For helicopters other than the above, use values of frequencies and g levels applicable to the helicopter on which that item is to be mounted. NOTE:
This procedure is only applicable to the operating phase of the equipment and does not include the common carrier transportationphase. 4.6.3.3.2 Test fixture. A rigid test fixture shall be designed for attaching the test item to the vibration exciter in all three axes with the mounting lugs in the up, position. The test item shall be attached to the fixture by its normal mounting means (e.g., suspension lugs for, 2.75-inch FFAR launchers). The vibration levels shall be controlled from an accelerometermounted at or near the attachment point on the test item. METHOD 514.2’ 514.2-14