Category Archives: F900 Troubleshooting

Holds Falcon 900 specific troubleshooting information

F900ex Weighing

There was a little controversy on weighing, here is how it played out:




here is the math


716BH WB calculation



We have positively identified the correct nose arm for the F900/F900ex series.
The previous numbers are incorrect, as it refers to gear retracted.arm.
The confirmation came in the Loading Manual drawing , attached to this email.
Could you please change the nose arm to -287.57 on both reports and recalculate.
Also could you add these notes to your reports:

Basic Empty Weight includes these items on board:
Crew Headsets
Crew Smoke Goggles
3 Portable Extinguishers
Flight Manuals
Portable O2
Single First Aide kit
Light Fly Away Kit
Maintenance Laptop, plus cables
Basic Operating Weight includes these items on board:
BEW items plus:
2 Crew @ 200Lbs each
Avionics Operating Manuals
Light Galley service items
Ices plus Cokes
2 extra First Aid kits
1 tub of Pillows
1 tub of spare stock
Lav serviced
Potable serviced
Full DVD, CDs
Full Lav service items

F900ex 022



One half of 1 meter on climate control panel illuminates. You can press on the left half of the face, and it will come and go.




Scratches at flap handle


Lower left overhead panel inop


Pressirization computer lower left side light spill


#1 RTU upper rh corner light spill.


Both audio panels minor light spill all edges

Light spill at #3 IRU

No illumination on any keys at any of the 3 FMS controll heads

Placard brocken at horn silence













F900EX Generator traumas

Current troubleshooting: engines running:

  1.  Check for Bleed leak blowing on GCU.  BE very carefull if you elect to run the AI on the ground.  !!!!!!APU BLEED OFF!!!!!!, slats extended.    20 seconds ground test max. leave the slats out to cool.
  2.  Test “E” ground quality.  Fluke on volts.  Black lead to airframe ground, red lead to GCU Black test point.  Very small voltage~ .1v.  less is better
  3. Volt drop on line contractor.  Fluke meter on volts.  Red lead on upper contactor, bottom big bolt, black lead on same contactor, upper big bolt. Very small voltage~ .1v.  less is better.
  4. Ripple test.  use fluke MIN/MAX.

Run each test with only 1 gen online, 50 to 100 amps load, try to hold conditions quite similar for each test.

some other thoughts:
look at big E terminal, small 20awg terminal.

double check each  GCU voltage. Is it stable at 28.5? is it stable with load? is it stable with RPM change?

select cockpit red switch to off.  Is the voltage of a running generator, cockpit switch selected off,  .7v to 1.0v at idle? this checks the quality of the permanent magnets inside the Generator.

ASSURE that NO ENGINE GENERATOR  has a cooling fan installed. (possibly a borescope through the black sooty outlet.) or it mat be necessary to unbolt the cooling exhaust.

Initial problem definition:

#3 Gen Light occasionally, Much troubleshooting. Gen 3 amps tend toward zero. #1 seems to “take the load”



#3 gen troubleshooting, #1, #3 gen shunts…..?Removed?

Detailed summary of troubleshooting:


Old Auxilec presentation: