PDA

View Full Version : 737 classic, pitch limit indicators


buffet
3rd Oct 2003, 07:59
what source do the pitch limit indicators use? The MEL allows for the forward LE flaps transit light to be u/s. If the light remains amber whenever flaps selected (ie an indication problem) but the aft o/head panel confirms all flaps/slats correctly set, would the PLI's be showing a false indication?

LEM
3rd Oct 2003, 20:36
You needlessly complicated a good question.

The source for the PLI is the stall warning computer.

The stall warning computer determines the warning upon, amongst others, wing configuration .

So the question is: when it comes to wing configuration, does the system take into account only the Trailing edge flaps position, or also the Leading edge one?

Our only hope is avioniker :ok:

mono
3rd Oct 2003, 22:12
For stall computation only the trailling edge devices are used. However the leading edge devices are monitored for an assymetry condition which may alter the stall warning parameters.

Here are extracts from the MM

The angle of airflow sensor senses the airplane angle of attack and the
flap position transmitter senses the position of the trailing edge flaps.
The stall management computer receives these signals and signals from
other flight systems. At predetermined combinations of flap position and
airplane angle of attack, the computer outputs a stall warning signal to
activate the control column shaker. The point at which the stall warning
signal occurs is also influenced by engine speed, airspeed, and flap
asymmetry.

SMC 1 activates the captain's control column shaker. SMC 1 is powered by
28 volts dc through a circuit breaker on the P18-2 panel from the standby
bus. SMC 1 receives inputs from the following sources:
(1) Left AOA Sensor
(2) Right Flap Position Transmitter
(3) Engine Indicating System (EIS) Primary Display (AMM 31-42-00/001)
(4) Landing Gear Logic Shelf
(5) Left Main Gear Downlock Switch
(6) Leading Edge Flaps and Slats Position Indication Module
(7) Left Air Data Computer
(8) Left Inertial Reference Unit
(9) Flight Management Computer
(10) Takeoff/Go-Around Switches at Thrust Levers
(11) STALL WARNING TEST NO. 1 Switch on P5-18 module
C. SMC 2 activates the first officer's control column shaker. SMC 2 is
powered by 28 volts dc through a circuit breaker on the P6-1 panel from
the electronics power bus No. 2.SMC 2 receives inputs from the
following sources:
(1) Right AOA Sensor
(2) Left Flap Position Transmitter
(3) Engine Indicating System (EIS) Primary Display (AMM 31-42-00/001)
(4) Landing Gear Logic Shelf
(5) Right Main Gear Downlock Switch
(6) Leading Edge Flaps and Slats Position Indication Module
(7) Right Air Data Computer
(8) Right Inertial Reference Unit
(9) Flight Management Computer
(10) Takeoff/Go-Around Switches at Thrust Levers
(11) STALL WARNING TEST NO. 2 Switch on P5-18 module

avioniker
3rd Oct 2003, 23:04
Beat me to it...
:O
:ok:

LEM
3rd Oct 2003, 23:57
... next time I'll say "our only hope are mono and avioniker"!

:ok: :ok: :ok:

buffet
11th Oct 2003, 02:04
thanks for the replies.