Functional Proof Pressure And Leak; Testing Of Emergency Blowdown System; Testing Of Explosive Valve - Piper Cheyenne IIIA Airplane Maintenance Manual

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Extension and Retraction (continued)
4. Functional Proof Pressure and Leak Test For EES (continued)
(k) Using the test cart, cycle the gear six times with the first cycle in the DOWN position initiating
the shuttle valve into the hydraulic position. This ensures the system and shuttle valve is in the
full hydraulic mode.
(I) Retighten cap on the tee test port.
(m) Perform same test on other gear.
(n) Reconnect and rig gear doors.
(o) Functionally test hydraulic system.
CAUTION: THOUGH THE GEAR IS ALREADY DOWN AND LOCKED AFTER PNEUMATIC
EXTENSION, THE GEAR HANDLE MUST BE MOVED TO THE DOWN
POSITION AND THE SYSTEM HYDRAULIC PRESSURE ALLOWED TO BUILD
UP. OTHERWISE, THE PNEUMATIC LINE AND THE UP LOCK HOOK
RELEASE ACTUATOR WILL BE FILLED WITH HYDRAULIC FLUID.
5. Testing of Emergency Blowdown System
The blowdown system, which consists of three individual blowdown systems, must have each unit
individually tested.
(a) With the airplane firmly jacked up, disconnect appropriate actuator from the gear system
linkage to be tested.
(b) Disconnect wires from squib unit to be tested. Ensure the two squib wires are interconnected
with either a U-clip or aluminum foil.
(c) Connect a multimeter to leads coming from the aircraft system.
(d) Turn on master switch. Ensure all other gears are locked in the DOWN position.
(e) While observing the meter, activate the blowdown switch and check for proper
voltage/amperage.
6. Testing of Explosive Valve
CAUTION: THE MINIMUM CIRCUIT RESISTANCE FOR THE SQUIB IS 0.6 TO 1.2 OHMS,
BUT MAXIMUM CONTINUITY TEST CURRENT ALLOWED IS 0.01 AMPS. DO
NOT EXCEED 10 MILLI AMPS.
(a) Using an ohmmeter with a 4 1/2 digit reader, which doesnt exceed 10 milli amps, test squib
circuit for 0.6 to 1.2 ohms.
EFFECTIVITY:
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Jan 10/90
32-30-00