![img](MIL-PRF-550300009im.jpg)
MIL-PRF-5503G
cycles of operation. Leakage from any other area shall be less than a drop.
4.6.7 Proof pressure (first article only). The actuator shall be restrained and pressurized in one
or more of its critical positions, as specified in the associated specification, as a column with the
piston not bottomed. In each of these positions, 5 psi shall be applied for 5 minutes with the
opposite port open to atmosphere and oriented with the open port pointed down. Then a pressure
equal to 1.5 times the actual differential pressure to be encountered (that corresponding to the
maximum external piston load, including externally induced loads which may be in excess of
those resulting from application of actuating pressure) shall be applied for 5 minutes with the
opposite ports opened to atmosphere and oriented with the open port pointed down. Leakage
shall be less than a drop. There shall be no loosening, permanent deformation, or rupture of any
parts of the actuator.
4.6.8 Proof pressure (conformance only). The actuator shall be subjected to a pressure of 5 psi
and a proof pressure of 150 ± 5% of the operating pressure defined in SAE AS5440 or the
associated specification for a period of 3 minutes for each pressure application. These pressures
shall be applied to each port with the opposite ports open to atmosphere and the piston bottomed
at the opposite end. Leakage shall be less than a drop. There shall be no loosening, permanent
deformation, or rupture of parts of the assembly.
4.6.9 Endurance.
4.6.9.1 Cyclic endurance. The actuator shall be subjected to cyclic operation according to table
II. The test shall simulate the loads and duplicate the swiveling and bending loads occurring
during the operation of the actuator when installed in the aircraft. The pressures within the
actuator shall be those encountered during operation. The actuators shall be cycled against full
design external loading including the load-stroke curve specified in the associated specification,
and with pressure buildup at the end of each stroke to system design operating pressure. At the
completion of this test, leakage at each external packing gland shall not exceed the rate of one
drop per 25 cycles of actuation. Interport leakage in the proof pressure test shall not exceed one
drop per minute unless otherwise specified by the associated specification.
4.6.9.2 Pressure impulse. Each actuator shall withstand 50,000 cycles of rated impulse pressure
conforming to figure 2 with the piston bottomed in both the extended and retracted positions.
Unless otherwise specified, there shall be no leakage. There shall be no loosening, permanent
deformation, or rupture of the actuator. The maximum cycling rates shall be 300 cycles per
minute and the cycle rate shall be constant. The pressure rise shall be between 200,000 and
300,000 psi per second.
TABLE II. Endurance test conditions
Normal service actuators
Emergency actuators
Temperature
See note
See note
Number of full stroke cycles 20,000
2,000
NOTE: The temperature shall be 160°F or 275°F (see 1.2).
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