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BENDIX/KING KLN 90B
Page 1-20 10521I05.TDC Rev 5, April/2003
NOTE
The KPI 552/553/553A’s interfaced to the KNR 665
digital Gold Crown are not compatible with the KLN
90B.
xOBS Interface
For approach approval, the OBS resolver must be interfaced so that selected course
through the HSI/CDI indicator will be sent to the KLN 90B for D-Bar resolution. In me-
chanical indicators, it will be accomplished by switching the OBS resolver lines; and in
EFIS installations, it will be usually through the serial busses. Some EFIS applications
may require an adapter. (Refer to section 2.3.6.2.P for OBS resolver interface charac-
teristics).
xSwitch/Annunciators:
NAV/GPS (Switch/Annunciator)
If the navigation information is displayed on a shared primary indicator a
switch/annunciator will be required to select and annunciate the source unless the
indicator is part of an EFIS system that provides that function.
WPT/MSG (Annunciator)
The required annunciators are "WPT" and "MSG" only. Even though the information is
available on the KLN 90B display, a remote annunciator is also required in the pilots
panel unless it is accomplished in an HSI/CDI or EFIS display.
GPS CRS, OBS/LEG (Switch/Annunciator)
The KLN 90B may operate in either of two modes, LEG or OBS. In LEG mode, the
flightplan legs will automatically sequence as determined by present position. In OBS
mode, the active waypoint and inbound or outbound course will be manually selected.
The Remote OBS/LEG Switch/Annunciator is recommended for non-precision
approaches to reduce pilot workload.
GPS APR, ARM/ACTV (Switch/Annunciator)
The KLN 90B requires a switch/annunciator for arming, disarming, or deactivating the
approach mode. It will provide remote annunciation of ARM and ACTV and provide a
momentary switch function to arm, disarm, or deactivate the Approach Mode and
change the D-Bar scale factors. (Refer to section 1.6.C for typical switch/annuncia-
tors).
xAltitude Source
An altitude source is required for IFR certification. The altitude may be derived from a
compatible encoding altimeter, some RS 232 air data systems, and most ARINC 429
air data systems. (Refer to figure 2-17 for typical altitude sources).
xIsolation Diodes
KLN 90’s below S/N 1542 did not have isolation diodes on the encoding altimeter in-
puts.