Flight Safety: Aircraft Icing on the Fuselage

Author(s):
Oscar Serrano Vargas - INTA. Laboratorio de telemetria e Instrumentación

Industry:
Aerospace/Avionics

Products:
LabVIEW, PXI Real-Time Controllers

The Challenge:
Perform either certification or research on aircraft icing flight test

The Solution:
Using National Instruments LabVIEW, PXI and FPGA to control scientific instrumentation used during aircraft icing flight test either certification or research applications

Article

Aircraft  icing is  a situation  (ice  build  up  on  the  front  surfaces)  that  happen  to  the  aircraft  when  are  flying  in  clouds  atlow  temperatures.  Turbo  propeller  aircraft  and helicopters  are  most  exposed  to  icing  encounters  because  of  its  altitude  operation  and  low  speed.

This  is  an  area  of  great  interest  to  aerospace  industry  because  it  is  mainly  concerned  with  the  aircraft  flight  safety,   manufacturers  and  authorities  have  to  demonstrate  that  aircraft  can  cope  with  icing  for  its  entire  

operation  life. 

In  order  to  fulfil  aircraft  icing  requirements ,  aircraft  have  to  be  certified  under  JAR/FAR  25  Appendix  C ,  where  the  icing  envelope  is  characterized  by  certain  parameters  as :  water  droplet  diameter  ,  temperature  and  liquid  water  content  ,  etc. Despite  of  this  ,  it  exist  some  icing  conditions,  called  Super cooled  Large  Droplets  which  are  droplet  bigger  than  50  micrometers  ,  not  defined  by  the  standard  yet,  but that  they  will  have  to  be  included  in  the  near  future. The  icing  certification  procedure  includes  flying  in  natural  icing  conditions  for  some  flights  under  standards.Actually  aerospace  industry  and  agencies  are  interested  in  improving  aircraft  safety  under  SLD  conditions  so  this  implies  icing  research  flights  programmes  between  industry  and  research  agencies.

Solution:

So in  other  to  perform  aircraft  icing  flight  test  (Certification or Research),  an  instrumented  aircraft  and  some  specific  cloud  microphysical  instrumentation  is  necessary  (  FSSP,  OAP,  King,  Temperature,  etc).  So  the  challenge  was  to  prepare  a  data  acquisition  system  that  could  monitor  and  record  the  parameters  needed  in  aircraft  icing  flight  test.

In  the past  we  had  problems  using  other  applications,   it  was  like  having  a  black  box,  we  have  a  lot  of  possibilities  but  we  only  need  a  little ,  and  the  system  were  not  able  of  providing  us  some  of  them  because  it  was  an  inflexible solution.  Furthermore  the  interfaces  cards  were  running  on  MS-DOS  and  using  the  ISA bus , so for us  this  system  was  obsolete  and  there  were  some  flight  tests  with  several  specifications  that  we  were  not  able  to  fulfil  due  to  this  inflexible  solution.Actually  according  to  the  aircraft  icing  standard  (JAR/FAR  25  Appendix C),  the  mean  effective  droplet  diameter  has  to  be  measured,  this  is  normally  done  with  a  FSSP-100 (droplet  diameter  sensor)  that  we  controlled  via  a  NI  digital  card.  The  temperature  has  to  be  measured  also;  this  was  done  with  a  Rosemount  temperature  sensor  and  was  monitored  via  a  NI  RTD  card.  The  Liquid  water  content  has  to  be  measured  also  and  this  is  done  by  a  NI  analogic  card.Furthermore  for  SLD  conditions  measurement,  this  was  done  with  an  OAP- 2D (Image  droplet  scanner)  controlled  via  a  NI  FPGA  card  with  a  intelligent custom  communication protocol.  Additional data  as  GPS  was  monitored  via  NI  serial card,  and  some  video  recording  on  a  model  for  ice  accretion  rate  was  done  via  a  NI  video  card. SLD    post-flight data  analysis  can  be  done  with  the  NI  Image  and  vision  module.Now  with  the  use  of  NI  products  we  have  a  modern  and  flexible  platform  for  performing  flight  test  and  now  we  are  able  to  offer  an  aerial  instrumented  platform  to  the  scientific  community  for  performing  aircraft  icing  test  with  independence  of  customer  requirements..

For  this  application  we  installed  two  computers on the aircraft,  the  first  the  target,  was  a  19”  PXI  with  a  NI  PXI-8187  controller  with  real  time  software  plus  several  PXI  cards,  and  the  second  the  host,  was  a  desktop  computer  with  windows  XP  for  real  time  display  connected  to  the  PXI  via  Ethernet.  We  have  used  the  PXI-6534,  PXI 7831R,  PXI-6289M and  for  software  we  work  with  LabVIEW  8.20,  FPGA  module,  and  LabVIEW  Real  Time  module, NI  Image  and  vision software .The  role  of  National  Instruments  products  to  us  has  been  to  have  an  operative  scientific  aerial  platform  so  we  can  offer  it  to  the  international  scientific  community,  this  is  based  on  a  real  time  data  acquisition  system  for  monitoring  all  the  cloud  microphysical  instrumentation  installed,  getting  real  time  display  and  recording  parameters  for  post-flight  analysis  in  aircraft  icing  flight  test.

Author Information:
For more information on this Case Study, contact:
Oscar Serrano Vargas
INTA. Laboratorio de telemetria e Instrumentación

Browse All Case Studies »