(b) ControlledDepressurization:
(1.) At altitudesabove 10,000 feet, if an unpressurizedconditionis required for an emergency (such as smokein cabin), depressurizeas follows: (a.) Apply oxygenmasks(allpersonson board). (b.) Place cabin pressure mode switch in DUMP position. (c.) Position ECSselectorswitchto EMERGENCY position.
NOTE: If smoke persistsor if cabin becomestoo warm, position ECS selector switch to OFF position andmove manual cabin air lever to OUTSIDE AIR.
(d.) Immediately reduce aircraft altitudeto less than10,000 feet. (e.) When emergencyconditioniscorrected,placecabin pressure modeswitchin PRESSURIZE manualcabinair
position,ECSselectorswitch in HI or LO position, leverto PRESS position,andreturn to aircraft cruise altitude. Thecabinpressurewill automaticallyreturn to preselected onrate-of-change
setting control.
EFFECTIVITY: 040-999
PAGE20 21-30-00
21-30-00
Jan 10/90
PIPERAIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCE MANUAL
A. PressurizationControl (continued)
7. PressurizationSystem Flight Check The following instructions explain how to perform a pressurization system flight check:
(a) Pre-Flight Procedure (1.) Ensure cabin door and pilot window are closed and locked. (2.) Set cabin altitude selector knob so cabin altitude indicates approximately 500 feet above
field altitude. (3.) Turn cabin rate control knob to NORM position. (4.) Move cabin air manual control handle to PRESSURIZE position.
CAUTION: CHECK FOR BROKEN OR DISCONNECTED CONTROL CABLE IF LITTLE EFFORT IS REQUIRED TO MOVE CONTROL HANDLE. DO NOT CONTINUE FLIGHT CHECK UNTIL INSPECTION OR REPAIRS ARE COMPLETED.
(5.) Set cabin pressure mode switch to CABIN PRESS position. (6.) Start engines, set both right and left engine bleed air switches to ON position, ECS selector switch to HI or LO, as desired, and establish steady cabin air flow. (7.) Ensure cabin door seal is inflated.
(b) AscentProcedure
(1.) After lift-off, when selected cabin altitude is attained and cockpit work load permits, select aircraft cruise altitude plug, 1,000 feet on aircraft altitude dial. Note when safety valve closes on lift-off, no appreciable increase in cabin pressure exists. The cabin rate of descent must not exceed 500 FPM from safety valve to outflow valve during transition of cabin altitude control.
(2.) Cabin altitude automatically climbs to altitude indicated on controller at rate set with cabin rate control selector knob. (3.) Monitor differential pressure gauge, cabin altitude gauge, and other pressurization controls during climb.
(c) CruiseProcedure (1.) Annunciator/Warning LightEmergency Pressurization System Check: (a.) With airplane cruising at 10,000 feet, position cabin pressure switch to DUMP position and allow cabin pressure to stabilize.
(b.) Initiate climb to 11,700 + 200 feet and ensure cabin pressurization warning light and annunciator have activated. Continue climb to 12,500 feet and ensure emergency pressurizationcomes on.
(c.) Repressurize cabin by positioning cabin pressure switch to CABIN PRESSURE position.
(d) Maximum Positive Differential Relief Test Procedure (1.) Monitor cabin differential pressure gauge continuously during test so maximum outflow
valve setting is not exceeded. (2.) Stabilize cabin altitude at 10,500 feet and initiate climb to 16,000 feet at climb power.
NOTE: Leave pressurization controls at 10,000 feet and rate full clockwise.
(3.) When 16,000 feet is reached, establish cruise power. The cabin altitude must stay at 10,000 feet with zero rate of change. (4.) Perform the following steps while maintaining cruise power at 16,000 feet:
(a)
Turn rate knob counterclockwise (decrease).
(b)
Select7,500 feet cabin altitude (outer knob).
(c)
Turn rate knob slowly clockwise until comfortable rate of descent is obtained. When cabin altitude nears 7,500, turn rate knob counterclockwiseuntil 300 FPM descent is obtained.
(d)
Waituntil cabin stabilizes.
EFFECTIVITY:
040-999
21-30-00 PAGE 21
21-30-00 Jan 10/90
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
A. PressurizationControl (continued)
(d) Maximum Positive Differential Relief Test Procedure (continued)
(4.) Perform the following steps while maintaining cruise power at 16,000 feet: (continued) (e.) Turn rate knob fully counterclockwise (decrease). (f.) Select 800 feet cabin altitude. (g.) Continue to monitor differential pressure gauge and test altimeter to ensure cabin
altitude does not drop below 800 feet or cabin differential pressuredoes not exceed
6.4 psi.
(h.) After cabin stabilizes at 800 + 500 feet, monitor pressurization instruments. Apply climb power and ensure cabin does not descent below 800 feet or exceed 6.4 psi differential pressure on gauge. Climb to 18,000 feet. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：夏延飞机维护手册 Cheyenne IIIA PA-42-720 AMM 1(63)
