Pneumatic System Final Test And Adjustment - Piper PA-44-180 SEMINOLE Maintenance Manual

5. Apply one brush coat of A-56-B cement to deicer and allow to dry at least one hour. Then apply second
coat and allow to dry at least four hours before operating deicers. Plane may be flown as soon as cement is
dry.
If A -56-B cement has aged 3 months or over, it may be necessary to dilute the cement
with Isopropyl Acetate to obtain proper brushing consistency. Mix thoroughly,
approximately 5 parts cement to one part Isopropyl Acetate.
FINAL TEST AND ADJUSTMENT OF PNEUMATIC SYSTEM.
1. Gain access to the pressure switch by removing the passenger seats and floorboards.
2. Install a combination vacuum/pressure gauge (minimum range 10 inches mercury [in. Hg.] vacuum to 25
psi pressure) in the crossover line within 12 inches of the pressure switch.
3. Start the left engine and adjust the vacuum regulator on the firewall so that the vacuum gauge reads 5 ± .2
in. Hg. with the engine operating at 1800 to 2000 RPM.
4. Bring the engine up to 2300 RPM and cycle the deicer boot system.
The vacuum gauge may momentarily drop as much as 1.5 in. Hg. during cycling.
5. During the deice boot inflation cycle, ensure that the green wing/tail indicator light on the deice panel
illuminates. The indicator light should come on between 8 to 13 psi and remain on above that pressure.
With boots fully inflated, pressure shall read 18 ± 1 psi and should occur within 7.0 seconds
(approximately). Upon full inflation, deflation and boot hold down shall occur within 20 seconds.
If more than one deice cycle is required, allow 30 seconds between cycle activations
to assure complete cycling.
6. Depress pneumatic deice switch for 20 seconds. Full inflation pressure shall not exceed 23 psi.
7. Shut down the left engine and repeat steps 2 through 5 with the right engine.
8. Repeat the above with both engines running at 2300 RPM.
9. Upon completion of the above steps, shut down engines, remove vacuum/pressure gauge reinstall
floorboards and seats.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
— Note —
— Note —
— Note —
— Note —
Cycle times may decrease.
2D24
PPS60054-3
3 0 - 1 4 - 0 0
Page 30-20
Revised: May 15, 1989