KLM MD-11 - Engine Failure Detector System; Thrust Reversing System

MD-11 Flight Crew Operations Manual
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Engines -
Description and Operation
Eng.10.10
Engine Failure Detector System
An N1 difference detector alerts the flight crew of engine N1 loss on any of the
three engines during takeoff ground roll by illuminating the ENGINE FAIL lights
on the glareshield.
During takeoff between 80 knots and V1 the ENGINE FAIL lights will illuminate
when any engine N1 rpm differs by 11 percent or more with any other engine N1
rpm.
Thrust Reversing System
The reverse thrust system is designed for ground use only.
Reverse thrust is accomplished by aft movement of a section of the engine cowl
to expose fixed cascades and operate blocker doors that rotate across the fan
exhaust stream. Normal fan exhaust flow is then blocked and forced through
cascades at a forward angle.
Reversers are most effective at high speeds, however, some slowing force remains
at low speeds.
If a failure occurs, aerodynamic forces and mechanical loads on the reverser tend
to hold the reverser in the last selected position.
When airborne, engine power will be reduced to idle by the FADEC system
whenever throttle position disagrees with its reverser position.
The engine thrust reversers are powered by regulated pneumatic pressure from the
respective engine.
The thrust reversers are armed when the FCC software receives input that either
the Radio Altitude (RA) is seven feet or wheel spinup is greater than 80 knots. A
compressed nose gear strut will also arm the thrust reversers in case of an FCC
fault.
Each system is operated by movement of the associated reverser lever. Reverser
levers cannot be operated unless the throttle is at the idle stop. To deploy the
reverser, the reverser levers must be moved to the reverser interlock position.
The reverser interlock on engines 1 and 3 is a physical stop that prohibits further
lever movement until the reverser is safely deployed. When the reverser is 60
percent deployed, the ECU removes the interlock, allowing uninhibited
movement of the thrust levers.
Reverser lever 2 does not have a physical interlock. The ECU, however, prohibits
thrust increase beyond idle power on engine 2 until the nose wheel ground sensing
switch has closed and the reverser is more than 90 percent deployed.
October 02, 2006