CESSNA®
MODEL 525B
MAINTENANCE MANUAL
WARNING: The Air Data Test Set is the only instrument calibrated to do a
check for leaks in the pilot pitot-static system. The pilot PFD
is not acceptable for determining a leak in the pilot pitot-static
system.
(1)
Put the BATTERY switch to the ON position.
(2)
Do the pitot/static self test on the air data test set.
(a)
Set the test set to the Leak Check mode.
(3)
Connect the air data test set to one of the pilot static ports (lower left or upper right).
CAUTION:
Do not use transparent tape or paper masking tape. Paper masking
tape or transparent tape are not equivalent substitutes for red vinyl
pressure tape.
(4)
Use red vinyl tape to cover the lower left or upper right static port that is open. Refer to Navigation
- General, Tools and Equipment.
(5)
Connect the air data test set to the left pitot tube.
(6)
Push and adjust the BARO knob on the pilot GCU 275 PFD Controller and set to 29.92 inHg
(101.3 kPa).
(7)
Apply the pitot pressure until there is an airspeed indication of 150 knots, +2 or -2 knots, on the
air data test set.
(8)
On the air data test set select Leak Check mode.
(a)
If the system does not stabilize, repair leaks.
(9)
Put Leak Check mode to OFF.
(10) Apply the pitot pressure to get an airspeed indication of 250 knots, +0.5 or -0.5 knot, on the air
data test set.
(11) Adjust the static vacuum to get an altitude indication of 5000 feet, +22 or -22 feet, (1524 m, +7
or -7 m) on the air data test set.
(12) On the air data test set select Leak Check mode.
(a)
If the system does not stabilize, repair leaks.
(13) On the air data test set put Leak Check mode to OFF.
(14) Adjust the static vacuum to get an altitude indication of 31,420 feet, +40 or -40 feet (9579 m,
+12 or -12 m) on the air data test set.
(15) As the altitude on the air data test set increases, monitor the airplane altimeter for a parallel
indication with the air data test set altimeter.
(16) If the airplane altimeter does not align with the air data test set altimeter do the steps that follow:
(a)
Bleed the pitot system to 0 knots and the static system to current altitude.
(b)
Examine the static heater port and/or tubing for obstructions or restrictions.
(c)
If necessary, clean the pitot-static system to remove obstructions. Refer to Pitot-Static
Systems - Maintenance Practices.
(17) With the static system at 31,420 feet (9579 m) and the pitot system at 250 knots put the test set
in Leak Check mode.
NOTE:
With the static system at 31,420 feet (9579 m), a pitot system leak will cause the
airspeed to decrease.
(18) Make sure that within one minute:
(a)
The closed system altimeter indication on the air data test set does not decrease below
31,170 feet (9500 m) within one minute.
(b)
The closed system airspeed indication on the air data test set does not decrease below
245 knots within one minute.
(19) Bleed the pitot and static systems to the ambient pressure at a rate not to exceed 200 knots-
per-minute (370 km/min) or 6000 feet-per-minute (1829 m/min) respectively.
(20) If testing is complete, remove the vinyl tape from the ports.
(21) If testing is complete configure the airplane and air data test set to the pretest condition. Refer
34-11-00
Page 608
© TEXTRON AVIATION INC.
Feb 23/2022
ICA-525B-34-00004
Form 2261 Rev 1
