getting to grips with COLD WEATHER OPERATIONS 寒冷天气运行(28)

system.
43
. When icing conditions are no longer detected, the system reminds the crew that the anti-ice systems are still selected ON.

MCDIU
Figure A5 - Dual Advisory Ice Detection System Architecture
The principle procedures relating to the DAIDS are summarized in the table shown below.
Event  FWC  Panel Indication  Crew Action 
ECAM Engine /Warning display (WARNING/MEMO)  CAUTION  NAI/WAI 
Normal  Ice detected  ICE DETECTED  MASTER +  Switch on NAI according to FCOM procedure 
Severe ice detected  SEVERE ICE DETECTED  MASTER +  Switch on WAI / NAI according to FCOM procedure 
No ice detected and NAI/WAI .ON.  ENG A.ICE / WING A.ICE (pulsing)  Nil  ON  Switch on WAI / NAI according to FCOM procedure 
Failure  Probe Failure  ICE DET FAULT  MASTER +  FCOM procedure 
NAI / WAI valve / control failure  NAI / WAI FAULT message depending on the failure case  MASTER +  FAULT  FCOM procedure 

 means Single Chime aural warning 
Figure A6 - DAIDS procedures 
44 

Ice detectors
Currently all A330/A340 aircraft - for the A320 family it is optional - are equipped with an ice detector pair, manufactured by Rosemount Aerospace (now BFGoodrich). These detectors form the essential part of the Dual Advisory Ice Detection System. The detectors are designed to measure ice accretion on the sensor probes.
The two ice probe type detectors are symmetrically installed in the front fuselage section, about 30 cm in front of the nose landing gear bay. Each sensor is mounted into a hole of approximately 80 mm in diameter, with 6 flush fasteners. The detector itself has an airfoil-shaped part standing out into the airflow for about 40 mm, with an additional cylindrical probe of 25,4 mm length and 6,35 mm in diameter. The airfoil makes it possible for the probe to perpendicularly stick out into the airflow beyond the boundary. The probes are also provided with a heating device to de-ice the probe. This is used to determine the severity of icing. The sensor can detect the presence of icing conditions and also approximate their ending.

Figure A7 - Ice Detector Location

COIL
FEEDBACK ULTRA SONIC VIBRATING COIL PROBE 40K Hz
FEEDBACK COIL
PROBE DRIVE HEATER COIL TERMINATION

THIN WALLED TUBE
Ice accretion changes the vibration frequency
Magnetostriction: The ferro-magnetic material changes dimension under the influence of a magnetic field

Figure A8 - Ice Detection Principle
Ice Detection Principle
The cylindrical probe, a tube of a nickel alloy, is oscillating axially driven by magnetostrictive (*) forces with a frequency of approximately 40 kHz. This is the resonant frequency of the probe, which is measured as the system feedback. If there is ice accreted to the tube, the mass of the probe is changed and therefore its resonant frequency decreases. After heating the probe, a new ice accretion is possible.
　
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：getting to grips with COLD WEATHER OPERATIONS 寒冷天气运行(28)