1811D INSTRUCTION MANUAL
56-101-00164 Rev. F
SECTION 3
Apr / 19 / 13
Page 17 of 38
A. Leak Test
Caution: Do not exceed aircraft vertical speed indicator (VSI) range while performing the
following test.
(1) Open the VACUUM valve (#5) to produce an altimeter reading of 1,000 ft above the
reading noted in test 7.
STATIC SYSTEM TEST, paragraph A.(6). Close the
valve fully.
(2) Allow the instrument indications to stabilize. Observe the altimeter (#E) for one
minute. Ensure that the altimeter decreases no more than 100 ft plus the leak rate
determined from the Static Pretest in test 5, paragraph B.)
(3) After the test finishes, gradually open the CROSSBLEED valve (#3) to return the
system to ambient.
(4) When the system returns to ambient pressure, open the CROSSBLEED (#3) and
VACUUM VENT (#4) valves fully. Disconnect aircraft line from VACUUM port (#F).
(5) Gradually open the VACUUM valve (#5) to bleed off the vacuum supply. When the
VACUUM TANK gauge (#G) returns to zero, close the VACUUM valve (#5) fully.
B. Static Leak Test (Pressurized Aircraft or for an altitude indication of more than 1,000 ft
above field level ambient)
(1) Preliminary
Note:
Perform all steps described in tests 5. PRETESTS, 6. PITOT SYSTEM
TEST, and 7. STATIC SYSTEM TEST first. There must be no significant
leakage seen. Verify that all Pitot System tests are satisfactory.
(a)
If using an external vacuum source, connect it to the EXTERNAL VACUUM
port (#K). If not, ensure that this port is vented.
(b)
Open the VACUUM VENT (#4) and CROSSBLEED (#3) valves fully. Close
all other valves fully.
(c)
Operate the VACUUM PUMP (#H) or the external pump to develop 20 inHg
on the VACUUM TANK gauge (#G). If vacuum needs refilling, close the
valve (#5) before operating the hand pump.
(d)
Close the VACUUM VENT (#4) fully.
Caution: If any step fails, close the VACUUM VALVE (#5) fully clockwise. Open the
PRESSURE VENT valve (#2) to return the system to ambient before
disconnecting the T/S.
Note: If the T/S is used outside the aircraft, connect an auxiliary vertical speed indicator
(VSI) to the VACUUM PORT (#F) to ensure not exceeding the aircraft VSI range.
Verify the aircraft altimeter accuracy by comparing readings with the T/S altimeter
with the calibration card corrections applied.