Mooney M20TN, Service And Maintenance Manual

Page: 342 / 1169

MOONEY AVIATION COMPANY, INC.
M20TN SERVICE & MAINTENANCE MANUAL
Date
2006
Rev Date
Page 8
Barometric scale and reference
markers are out of synchronization
with pointers.
Shift in mechanism. Reset pointers.
Barometric scale and reference
markers are out of synchronization.
Slippage of mating parts. Replace instrument.
34--20--00 -- HORIZONTAL SITUATION INDICATOR
(HSI)
The Horizontal Situation Indicator (HSI) displays a ro-
tating compass card with letters at the cardinal points
and numeric labels every 30
°
. Major tick marks are at
10
°
intervals and minor tick marks for every 5
°
. The HSI
is displayed in a heading up orientation.
The HSI compass can be displayed as a 360
°
rose or
140
°
arc. The HSI displays the following information:
•
Heading indication
•
Turn Rate indicator
•
Course Deviation Indicator
•
Bearing pointers
•
Bearing information windows
•
Navigation source
Refer to Garmin G1000 System Maintenance Manual
for Horizontal Situation Indicator (HIS) service and
troubleshooting information.
34--21--00 -- SLIP/SKID INDICATOR
The Slip/Skid indicator (a component of the Attitude In-
dicator screen display) resides beneath the roll pointer.
The indicator moves with the roll pointer and moves lat-
erally away from the pointer to indicate lateral accelera-
tion. A slip/skid is indicated by the location of the Slip/
Skid indicator relative to the roll pointer. One Slip/Skid
indicator displacement is equal to one ball displace-
ment when compared to a traditional Slip/Skid indica-
tor.
Refer to Garmin G1000 System Maintenance Manual
for service and troubleshooting information.
34--22--00 -- MAGNETIC COMPASS (TRADITION-
AL)
The traditional magnetic compass dial, graduated in 5º
increments, is encased in a liquid filled glass and metal
case. The unit mounts on top of glareshield or on wind-
shield center post. The compass should be swung and
compensated at each annual inspection and whenever
new electrical equipment is installed.
To compensate for N--S deviation, adjust left screw; to
compensate for E--W deviation, adjust right screw.
Degaussing of tubular structure may be required if
compass cannot be compensated within limits. Care-
fully go over entire steel structure with degausser, from
center to outboard of structure (Left & Right), to remove
residual magnetism. It is recommended that an Arma-
ture Growler be used to degauss steel structure (Ref.
33--22--01). An Associated Growler/Armature Tester
No. AOE--6054, or similar device, may be used.
NOTE:
Check for outside magnetic influences if exces-
sive compensation is required.
A Horizontal Situation Indicator (HSI) is integral to the
Garmin G1000 system. This display indicates magnet-
ic heading, among other data. The traditional magnetic
compass, mounted on the windshield center post,
should be referenced as a backup instrument.
Refer to Garmin G1000 System Maintenance Manual
for adjustments and troubleshooting information for the
Horizontal Situation Indicator.
34--22--01 -- DEMAGNETIZING AND COMPASS
SWINGING PROCEDURES (TRADITIONAL COM-
PASS)
Check aircraft for magnetized structure as follows:
1. Center or remove compensating magnets from
compass.
2. Position aircraft on compass rose, run engine at
1200 to 1500 RPM, and check the four cardinal head-
ings starting at north heading. If an error greater than
±
30
°
is found at any cardinal heading, proceed to
demagnetize cockpit as outlined in Step 3. If error is
less than
±
30
°
at any cardinal heading, proceed to
swing compass (Step 4).
3. Demagnetize Cockpit:
-- CAUTION --
Improper use of a growler can induce more mag-
netism in cabin structure, making extensive de-
magnetizing necessary.
A. Remove compass from cockpit.
B. Position aircraft at a heading of either 90
°
or
270
°
.
C. Make sure growler is turned OFF. Place growler
in cockpit, position seats aft and support power cord so
that it does not touch or pass within six inches of any
structural member.
D. While sitting, straddling pilot and co--pilot seats,
hold growler inside cockpit center in a low position.
Turn growler ON and slowly move it forward, close to
instrument panel centerline, up toward and along wind-
shield center post and along overhead structure over
and to behind your head. Move growler down in a circu-
lar motion from behind shoulders to waist or mid--chest
height before turning it OFF.
NOTE:
Windshield center post is fabricated of non--mag-
netic stainless steel. This post requires no de--
magnetizing.
34--20--00