Hydraulic Pump Operational Check; Procedure After Hydraulic Pump Failure - Piper Cheyenne IIIA Airplane Maintenance Manual

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Main (continued)
1.Body,
Filter
10. O-Ring Seal
2. -Ring Seal
9. Screw Pressure
Screw Pressure
3. O-Ring Seal
8. Spring
17.
Valve, By-Pass
4. Filter
5. Spring
6. Bowl
Hydraulic Filter
Figure 409
62. Hydraulic Pump Operational Check.
To determine operational condition of each hydraulic pump, conduct following check:
(a) Start one engine and allow to stabilize at idle.
(b) With engine operating at 52% gas generator speed, move gear selector handle to gear down
position. One pump must build up pressure in hydraulic system and return selector handle to
neutral position within 3 to 9 seconds. Again select down position and check handle return
time.
(c) Shut engine down and repeat preceding steps for other engine.
(d) If selector handle does not return to neutral during operation check for one pump, but does
return within required time during check of other, remove pump and determine cause of
malfunction.
63. Procedure after Hydraulic Pump Failure.
If pump breakage occurs, metal particles could exist in hydraulic system. To rectify condition, flush
hydraulic system as follows:
(a) Replace defective engine-driven hydraulic pump and prime it. Do not connect pump to
hydraulic system until system is flushed.
(b) Flush system.
(c) Remove filter elements and check for metal particles. If metal particles are found in filter, clean
filter bowl with dry cleaning solvent. Dry with compressed air and install new filter elements.
EFFECTIVITY:
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040-999
Jan 10/90
29-10-00