AMC E 50  Engine Control System

ED Decision 2007/015/R

(1)     Applicability

CS-E 50 is applicable to all types of Engine Control Systems. For instance, these systems might be hydromechanical or hydromechanical with a limited authority electronic supervisor or single channel full authority Engine control with hydromechanical back-up or dual channel full authority Electronic Engine Control System with no back-up or any other combination. The electronic technology may be analogue or digital.

The Engine Control System includes any system or device that controls, limits or monitors Engine operation and is necessary for continued airworthiness of the Engine. This includes all equipment that is necessary for controlling the Engine and ensuring safe operation of the Engine within its limits as specified in CS-E 50(a). This implies consideration of all Engine Control System components including the electronic control unit(s), fuel metering unit(s), variable-geometry actuators, cables, wires, sensors, etc. The main Engine fuel pump is often Engine-mounted and physically integrated with the fuel metering unit. However, it is not usually considered part of the Engine Control System.

These specifications cover the main Engine Control System as well as protection systems against, for example, over-speed, over-torque or over-temperature.

When blade shedding or Engine design related means is used for over-speed protection, this would not be considered under CS-E 50 as being part of the Engine Control System, as this protection is purely mechanical and is designed to work without influence from the Engine Control System.

Engine monitoring systems are covered by this specification when they are physically or functionally integrated with the Engine Control System or they perform functions that affect Engine safety or are used to effect continued-operation or return-to-service decisions. For instance, low cycle fatigue (LCF) cycle-counters for Engine Critical Parts would be included but most trend monitors and devices providing information for maintenance would not. Where a device is not functionally or physically integrated into the Engine Control System and does not perform a function that affects Engine safety, it should still be considered under CS-E 170.

(2)     Objective

The purpose of CS-E 50 is to set objectives for the general design and functioning of the Engine Control System and these specifications are not intended to replace or supersede other specifications, such as CS-E 560 for the fuel system. Therefore, individual components of the Engine Control System, such as alternators, sensors, actuators, should be covered, in addition, under other CS-E paragraphs such as CS-E 80 or CS-E 170, as appropriate.

For EECS, AMC 20-1 and AMC 20-3 provides additional and detailed interpretation of CS-E 50 with special consideration to interfaces with the aircraft, and the Propeller when applicable.

(3)     Rotocraft Engines

For rotorcraft Engine Control Systems that have a power turbine speed governing mode, the specification of CS-E 50(a)(3) for modulation of Engine power should be interpreted as the ability to manage power as required to maintain power turbine speed within specified limits.

(4)     Integrity

The intent of CS-E 50(c) is to establish Engine Control System integrity specifications consistent with operational specifications of the various applications. In particular, the introduction of Electronic Engine Control Systems should provide at least an equivalent level of safety and reliability for the Engine as achieved by Engines equipped with hydromechanical control and protection systems, and magneto systems.

(5)     Aircraft Supplied Power

Engine Control Systems implemented in hydromechanical technology or technology other than electrical and electronic technology should inherently be compliant with CS-E 50(h). However, if the system has functions implemented electrically or electronically that depend on aircraft-supplied electrical power, the system should be evaluated for compliance with this rule (see AMC 20-1 and AMC 20-3 for relevant interpretation).

(6)     Air Signal Lines

CS-E 50(i) covers cases of ingress of foreign matter (e.g. sand, dust, water, or insects) which could result in blockage of the lines and result in an adverse effect on Engine operation. For example, the experience has shown that lines used for measuring the static pressure in the compressor of turbine Engines could be blocked by frozen water, leading to a loss of power. Precautions should therefore be taken, such as use of protected openings, filters, drains for water, heating of the lines to prevent freezing of condensed water. Corrosion effects should also be addressed.

[Amdt. No.: E/1]