TM 1-1510-262-10
The lightning sensor system is to be used for hazardous weather avoidance, not weather penetra-
tion.
3-25. LIGHTNING SENSOR SYSTEM (LSZ-850).
The lightning sensor system (LSS) is used to detect and locate areas of lightning activity within a 100 nautical mile
radius around the aircraft. The system provides the operator with a visual display of the position and rate of occur-
rence of the lightning activity on the MFD. The lightning sensor system detects both visible and high energy invisible
electromagnetic and electrostatic discharges (lightning) indicating areas of turbulent activity. After evaluating the
LSS display and its relation to precipitation as indicated by the weather radar display, the operator could effectively
plan the proper course to avoid hazardous weather. The lightning sensor system consists of a receiver/processor,
an antenna, and the MFD. The system is powered by a 2-ampere circuit-breaker placarded LSS, located on the
overhead circuit breaker panel (Fig. 2-12). Because the system is a passive device (it does not transmit), it can be
operated safely on the ground. Weather in all directions around the aircraft may be monitored, even before starting
engines. Utilize the Universal EFI-890R operator s manual for full description and operation.
Figure 3-14. Lightning Sensor System control panel
Table 3-5.
Lightning Sensor System Controls and Indicators
Index No.
Description
1
Provides operator with power ON/OFF indication where if the annunciator is illuminated the
power is ON.
2
Provides operator with the option to discontinue display updates when the selector is illuminated.
3
Provides operator with Lightning Sensor Mode selection options where if the selector is
illuminated the system is in normal mode and detected energy is displayed.
4
Provides operator with ability to clear the display with a momentary press of the annunciator.
Holding the switch down for 3 seconds initiates the test function. The annunciator remains
illuminated during self-test.
a. Lightning Sensor System Display. The LSS shows areas of lightning activity on the MFD with symbols.
Each lightning symbol represents the center of a circular area with a radius of nine nautical miles. Three different
lightning symbols are used to represent three different rates of occurrence of the lightning within each 18 nauti-
cal-mile diameter circle. The lightning rate symbols represent the lightning rates-of-occurrence during the last two
minutes. The symbol s location on the display represents the average position of the lightning that has occurred
during the last two minutes inside each 18 nautical-mile diameter area. Lightning may not be occurring at the center
of the symbol. Because it is easier for the LSS to detect lightning at close distances than at far distances, the number
of lightning strokes required for each rate symbol is adjusted for distance to the storm.
3-38
