Engines/APU Flashcards
Recall the rated thrust of the BR715 engine :
Two Rolls Royce BR715 high-bypass turbo fan engines power the 717.
Each engine is capable of delivering 21,000 pounds of thrust and
equipped with a clamshell type thrust reverser.
Recall how thrust reverser status is displayed:
When the reverser levers are moved to the reverse idle detent, the EECs
will unlock and deploy the reversers, provided the EECs are not detecting
any failure in the reverser systems.
When the reversers are out of the stowed position, the reverser unlock
indication (U/L) are displayed inside the EPR arcs on the EAD. When the
reversers are approximately 90% deployed, the reverse thrust indication
(REV) is displayed in green inside the EPR arcs.
A red REV will be displayed in the EPR arc if there is an uncommanded
thrust reverser deployment in flight.
The reversers will only deploy when the respective engine is
running. However, when landing with an engine shut down, the
reverser on the inoperative engine is permitted for 30 seconds to
deploy after nose wheel compression.
Built-in safety features prevent uncommanded reverser deployment
inflight, However, should this occur, the EEC will automatically
reduce thrust on the affected engine to idle.
Emergency reverse thrust is available by pulling the reverse thrust
levers through a mechanical gate. When selected, reverse thrust
above maximum is controlled by the EEC, engine damage can
occur, and a maintenance inspection will be required.
An amber REV emergency thrust exceedance reminder will be
displayed until cleared by the ENG EXCEEDANCE RESET button
on the overhead panel.
Recall that engine synchronization is accomplished automatically by the
EEC:
The engine synchronizer system automatically matches EPR or fan speeds
to reduce crew workload and reduce noise. The EEC automatically controls
the system. During takeoff the system synchronizes left EPR to the right
EPR. During climb, cruise and descent, the system synchronizes fan
speeds
Recall the required engine warm up and cool down times:
No minimum warm up time is required following an engine shutdown of two
hours or less.
It is recommended that after a shutdown period of greater than two
hours engines are warmed up at thrust settings normally used for
taxi operation for at least 3 minutes.
It is not, however, necessary to delay the takeoff unless the vibration levels
are higher than normal or the oil temperature is below the lower limit for
accelerating to takeoff power.
Engines require 3 minute cool down prior to shutdown. Verify ENGINE
COOL alert message illuminated on EAD
Recall how current EPR, throttle position, and computed EPR are
depicted on the EAD (Primary Engine Display):
EPR is the primary thrust setting parameter and is a ratio of the
turbine exhaust stream pressure to the engine inlet pressure. The
current EPR is displayed as a pointer line moving inside the scale,
and by a rolling digital readout.
A White “T” indicates the throttle position and moves along the
outside of the EPR scale.
A Magenta “V”indicates the computed EPR. When the T fits within
the V, the throttles are set to the computed thrust rating.
Recall the indications of an automatically aborted engine start:
Should an auto abort occur, the EAD message “ENG L/R START
ABORT will be displayed. This message may be cancelled by selecting
the FUEL switch OFF.
Recall the indications of excessive engine vibration:
Digits are shown in white but will turn amber and will be boxed in amber
if vibration level exceeds limit.
Recall the conditions where an engine start should not be attempted
(auto or manual):
If oil temperature is not above the minimum limit, do not start engine.
If the available starter air pressure is below 32 PSIG a start attempt
may lead to a maximum TGT exceedance and/or a hung start.
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Do not attempt to start the engine with a starter air pressure greater
than 43 PSIG or less than 32 PSIG.
Recall how normal and abnormal APU operating parameters are
displayed on the secondary engine (SD):
% RPM Display - white, red
% RPM - APU RPM is displayed as a percentage of rated speed. The white
digits become red and boxed when limits are exceeded.
% EGT Display - white, red
% EGT - APU EGT is displayed as a percentage of maximum continuous
exhaust gas temperature. The white digits become red and boxed when
limits are exceeded and return to white when those limits return to normal.
Recall the general precautions, concerning an APU restart, which should
be followed if the APU fails to start or shuts down automatically:
NOTES: If the APU fails to start or shuts down automatically, the
shutdown fault must be cleared before the APU can be restarted.
Wait until the APU rolls down to under 7% RPM, then clear the
shutdown fault by moving the MASTER switch to OFF, then use normal
procedures to restart the APU.
If the APU fails to start, do not attempt another start until after the APU
parameters on the Secondary Engine synoptic are no longer displayed.
This will provide time for any unburned fuel in the APU combustion
chamber to drain out. The APU may emit smoke or flame from the
exhaust pipe if it is started with residual unburned fuel remaining in the
combustion chamber.
Recall when the ECU will automatically shut down the APU when a fault
has been detected:
The amber boxed APU FAULT alert (Level 2) is displayed during conditions
which could result in APU damage inflight.
On the ground when these conditions are present the APU automatically
shuts down, the fuel shutoff valve closes, and the amber APU AUTO
SHUTDOWN alert is displayed.
Inflight, the ECU automatically shuts down the APU only for an APU
overspeed or an APU compartment fire. If an APU FAULT condition occurs
inflight, the APU automatically shuts down 10 minutes after landing, unless
shut down sooner by the pilot.
Recall the functions of the APU Master switch:
OFF - Shuts down APU and closes inlet door.
RUN - Allows APU to run and opens inlet door.
START - (Momentary) Starts APU.
Recall when the igniters operate:
AUTO - Selects an automatic start sequence.
ON - Selects a manual ground start sequence and provides continuous
power to the igniters.
In flight, AUTO or ON positions both provide power to both igniters during
starting.
During engine operation, a cyan lightning bolt is displayed over the TGT
digits to indicate ignition is commanded on.
The FCC will also command continuous ignition for 60 seconds after either
ENG anti-ice switch has been selected ON.
Recall how thrust limits and associated operating modes are displayed.
FMS limits and modes are magenta.
Manually set modes are white.
Recall the number of igniters and how they are controlled:
Each engine’s ignition system consists of two ignition units, two igniter
leads and two surface discharge semiconductor igniters.
The ignition system is controlled by the EEC. Each channel of the EEC
has the capability of energizing either or both ignition units.
The EEC energizes a single ignition unit during auto start and both
ignition units for all other modes.
