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Boeing 757 Engine Control Computer

Technical Information

Catalogue No: C0272
Category: Engine Control
Object Type: Signal/Data Processor
Object Name: Boeing 757 Engine Control Computer
Part No: None
Serial No: None
Manufacturer: Lucas Aerospace/Marconi Avionics
Division: Unknown
Year of Manufacture: Unknown
Width (mm):
Height (mm):
Depth (mm):
Weight (g):
Location: Rack RAA01 [Main Store]

Engine Supervisory Control


The Engine Electronic Controller (EEC) was produced as a 50:50 partnership with Lucas Aerospace and is fitted to the Boeing 757. The EEC was developed between 1979 and 1984 and first flew in 1981 entering airline service in 1983.

The EEC comprises two computers; the Limiter and the Supervisory, which communicate but are physically partitioned. The Limiter provides the engine with over-speed and over-temperature protection. The Supervisory trims the engine thrust so as to achieve optimal performance v. efficiency.

The RB211-535 EEC marked a major advance in avionic equipment. As well as employing for the first time the 16-Bit Texas Instruments 9900 microprocessor (one in each of the Limiter and Supervisory computers), the EEC was the first time that a digital computer was put in control. In fact digital computing was so new that the EEC was only allowed to trim the engine down from its natural over-rated condition. The EEC could never demand more thrust than allowed by the hydro-mechanical governor.

The benefits of digital engine management very quickly became apparent however and the reliability of the EEC was such that the Boeing 767, which followed quickly behind the 757 has Full Authority Digital Engine Control (FADEC); the engines are totally in the hands of the computer.

This unit's top cover is missing.

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