TM 55-6610-247-40
ac. If calibration arm is adjusted with vernier
ag. If position error is adjusted with vernier calibration
calibration tool so drum moves distance two graduations,
tool so drum moves the distance between two
change in indications at 5,000 feet will be approximately
graduations, change in indication at different altitudes
20 feet, and at 35,000 feet change will be Seven times as
will be as follows:
great or approximately 140 feet.
(1) Approximate change of 20 feet at 5.000 foot
Ad. If diaphragm is shifted so hand indicates a
indication.
(2) Approximate change of 100 feet at 20.000 foot
change of 350 feet, change in indication at 35,000 feet
indication.
will be 350 feet, and at 5.000 feet change will be 35 times
(3) Approximate change of 150 feet at 35.000 foot
less or approximately 10 feet.
ae. Using ratios in preceding paragraph ab and table
indication.
ah. A change of 325 feet at 35,000 foot indication,
created by shifting diaphragm causes an:
calculated when working with both calibration arm and
(1} Approximate change of 125 feet at the 20,000
diaphragm corrections at same time.
foot indication.
Table 2-4. Adjustment Ratios
(2) Approximate change of 15 feet at the 5,000foot
indication.
METHOD
RATIO
ALTITUDE
NOTE
Calibration arm
1 to 1
5,000 feet
The following are not inflexible rules, but
Calibration arm
7 to 1
35,000 feet
are to be used as a guide in judging
Diaphragm
1 to 35
5,000 feet
irregular pointer movement. From 0 to
Diaphragm
1 to 1
35,000 feet
25,000 feet, without vibration, hand must
not jump more than an indication of 100
af. Move arm + 20 feet and diaphragm 350 feet.
feet, and from 25,000 to 35,000 feet
Refer to table 2-5.
hand must move smoothly, although not
necessarily regular when vibration is
applied.
Table 2-5. Correction Effect
CHANGE AT
CHANGE AT
CORRECTION APPLIED
5,000 FEET
35,000 FEET
Arm + 20 feet
+20 feet
+140 feet
Diaphragm --350 feet
--10 feet
--350 feet
Total Correction
+10 feet
--210 feet
sector. The point of mesh should be approximately 1/8
NOTE
inch from end of sector arc at sea level pressure. It is
The following observations are hints as
important to have this starting position in order to have
to where friction will be found. If
altimeter reach its maximum range of operation. To
noticeable sticking or jumping occurs
adjust position of sector, hold rocking shaft with special
every revolution of the hand, examine
pliers and with the sector wrench turn sector as required.
hand-staff pinion. In this event. Hand-
See figure 2-10.
staff pinion may be too large.
To
overcome this, make up several staffs
2-9. Position Error Adjustment !'sing Vacuum
and use smallest one found. If sticking
Chamber.
or jumping occurs once in each 12,000
Adjust as follows:
feet of indication, examine wheel of
a. Mount mechanism in stand assembly, part no.
wheel and hairspring assembly for
TE1357-5003. so diaphragm is on same side as 0 and
corrosion, a burr between teeth, or a
place it in vacuum chamber, part no. 16-11-2. so 0 is at
damaged tooth. If a noticeable sticking
top. By means of knob on stand assembly. set hand of
or jumping occurs once throughout
test mechanism so that it will read 0 when master
entire range examine sector for
altimeter or barometer reads 0.
corrosion, a burr between teeth, or a
damaged tooth.
ai. Observe point where pinion meshes with
2-14
