CSAS Motherboard Assembly

Technical Information

Catalogue No: C1170
Category: Flight Control
Object Type: Module/Sub-Assembly/Component
Object Name: CSAS Motherboard Assembly
Part No: 0 844.32-01-20
Serial No: 181
Manufacturer: Unknown
Division: Unknown
Platform(s): Tornado 
Year of Manufacture: Unknown
Width (mm):
Height (mm):
Depth (mm):
Weight (g):
Location: Archive Object Store

P/N 0 844.32-01-20
S/N 181
Mod.-Rec. C
P/N 7906-00281002
S/N 224
Mod.-Rec. A


This is the Motherboard for the CSAS pitch Computer which holds the main unit connectors, sub-assembly connectors and the connectors for the Circuit Boards. A company database identifies the Relay Sub-Assembly as part of the MRCA/CSAS.

The command stability augmentation system: (CSAS) is by its very nature one of the most complex systems on Tornado. Hardly detectable in the cockpit, the CSAS keeps the ride comfortable at all speeds and altitudes, and makes the aircraft controllable throughout the flight envelope.It is a “fly-by-wire” system with autostabilisation, the pilot’s control demands being signalled and augmented electrically to maintain good handling qualities over the wide flight envelope. In the pitch axis, the fly-by-wire system has mechanical reversion. The system is triplicated and includes triplex computing, triplex rate gyros, triplex position sensors and a triplex accelerometer, with quadruplex outputs driving quadruplex electrohydraulic actuators. These “fly-by-wire” actuators were originally designed by Marconi-Elliott Avionic Systems Limited and have now been integrated by Fairey Hydraulic into the aircraft’s main hydraulic power control units.

The CSAS electronics is packaged in two units, the pitch computing circuitry being housed in a single computer and the roll, yaw and spoiler circuitry in a similar computer.

The system uses very high-precision analogue circuitry to provide accurately- matched control lanes, and a unique voter monitor design which reduces transient effects, due to system failures, to a low level and is so designed also that nuisance warnings are rare.

Marconi-Elliott Avionic Systems Limited has design leadership on the CSAS programme, but shared the production with Bodenseewerk Geratetechnik.

The system was designed to Specification SP-P-41600.



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