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 E E Thrust reverser command is provided through thrust reverser control lever and is given from separate sources to EIU and to ECU. The ECU monitors the reversing system and is able to reduce the engine thrust to idle in case of reversing system malfunction. Furthermore an additional Shut Off Valve (SOV) upstream of the HCU isolates the thrust reverser system from the hydraulic power supply. This SOV is commanded by the Spoiler Elevator Computer (SEC) based on the throttle lever and radioaltimeters information.

 G. Engine Parameters Transmission for Cockpit Display
 The FADEC provides the necessary engine parameters for cockpit display
 through the ARINC 429 buses output (Ref. 73-25-00).

 H. Engine Condition Parameters Transmission Engine condition monitoring is possible, by the ability of the FADEC to broadcoast the engine parameters through the ARINC 429 bus output. The basic engine parameters available are:
 - P0, PS12, PS3, T12, T25, T3, TC, TOIL, T495, N1, N2, WF

 - VSV, VBV, FRV, HPTCC, WF, RACSB, and LPTACC valve or actuator position

 - status and maintenance words, engine serial number and position. In order to perform a better analysis of engine condition some additional parameters are optionally available. These are P13, P25 and T5.

 J. FADEC System Fault Diagnostics
 (1) Fault Detection The FADEC maintenance is eased by internal extensive Built In Test Equipment allowing an efficient fault detection. The efficiency of this fault detection is at least 95 percent of probable failures of INPUT/OUTPUT and ECU. Failure isolation of no more than 3 specific electrical LRU's accomplished with a 85 percent efficiency. The results of this fault detection is contained in status and maintenance words according to ARINC 429 specification and is available on the output data bus.

 (2) Non Volatile Memory In flight fault data stored into an engine-provided non volatile memory and when requested available in an aircraft centralized maintenance display unit.

 (3) Communication with CFDS Ground test of electrical and electronic parts is possible from cockpit with engines not running through the CFDS. The FADEC provides engine control system self-testing to detect problem at LRU level.

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 The FADEC is such that no engine ground run for trim purposes is necessary after component replacement.

 K. Engine Sensors
 (1) T12 Sensor
 (a) General The T12 sensor is made to measure the engine intake air temperature. It is installed on the engine fan inlet case at the

 1:00 o'clock position.

 (b) Description and operation

R  (Ref. Fig. 021) The T12 temperature sensor has 2 components: the sensing element and the housing.
 1 The sensing element has a reference grade platinum wire
_ bifilar wound on the cylindrical metal mandrel. The mandrel is insulated with a ceramic material prior to the winding of the element. Through the center, 2 large wires run the entire length. These wires are insulated from each other and the mandrel with a ceramic insulator. At one end, the element wires are joined to the wires from the mandrel. The entire element length and lead termination area is then covered with ceramic insulation resulting in a solid construction of alternating insulation and metal to form a uniform cylinder. The element is sealed to protect it from severe environmental conditions by potting the element in a metal cylinder using ceramic as the insulator. Only one end is open to the atmosphere, the connector attachment end. The free ends of the lead-wires are joined to the connector during the final assembly of the element in the airfoil housing. The sensor assembly is inserted into the housing and brazed in place near its open end. To increase its flexibility while minimizing effects on performance, the element is protected by a coaxial perforated shield and is supported at 4 points by annular leaf spring spacers.
 2 The housing for the temperature sensing element is made to
_ protect the element and keep vibration to a minimum. The sensing element is located in a slot in the housing and forms a bypass for air flow. Air flowing past the housing changes direction to enter the slot. This prevents foreign objects from entering the slot and damaging the element. It also uses boundary layer control to ensure that the sensed temperature is the free stream temperature rather than that of the
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