Category Archives: F900 Troubleshooting

Holds Falcon 900 specific troubleshooting information

VQ-BYT squawks at PBI



1. Number 1 hyd qty reads zero all the time.

2. Occasional AUTO SLAT light, clicking noise from behind panel.

3. APU uncommadded shutdown after start.

4. #2 fuel bypass menelco occurred 1 time, no reoccur since. CND.

On site:

1. Failed number 1 gage verified. Gage due in at midnight. Friday night. Ops test 29-20-00-720-801. New gage S/N 1034 has knarly  pinged prints inside the front glass.

2. Suspect WOW Prox  going to ground while ac is in flight.  Could the clicking noise be the gear handle safety pin?  Evaluate Prox detectors. Checked voltage and sensitivity of all 6 Prox detectors.

3. Interestingly, the APU OVERSPEED Menelco was dark when I got to the airplane.  Every subsequent shutdown pops it yellow , which is normal.  All starts were normal for me.

4. EMERG LIGHTS one bulb out. APU MASTER 2 bulbs out. Replaced bulbs.

5. Crew temp amp motor is making a grinding noise. Goes quieter after 10 min. Info only.

6. Cabin pressure triple gage altitude needle hangs at 3000ft. Tapping panel resets it. Triple gage mount screws loose.1483199000798-708599262

Info only

6. Ron said Mr. Burnes keeps asking about the AFIS Printer paper jamb.  Fixed it.  It is old and grouchy, like me. Manual print select does not work.  Use NAV>AFIS INDEX>NEXT>AFIS CONFIG>NEXT>NEXT>OR>AUTO>ON then choose the services you want.

It will print any of the incoming stuff you want.

7.Minor fuel residue forward of RH ADF antenna inside belly faring.
Outboard of the inboard fuel sump, right wing root.

It is a screw or two. the number 10 to 20 screw outboard.

The guys left the tanks pressurized, so I am sure that made it worse.

It dribbles into the belly faring and made a puddle on the ground.  Looked dramatic, no problem.

If it is OK with you, I will brief Ron to vent the tanks each stop until we get to look at it.
8. Tire pressure gage needs cal.

Byt squawks at Portsmouth.

1. Hyd. pressure gage 2 inop. – Number 2 hyd gage dead below the zero peg until it warms up. PN 5502-360-80-10 SN 764, then it started working half way through our troubleshooting. rang wires.

 Number 1 gage will not go to 2100 lbs with the AUX pump,  hangs at 1600 lbs until you tap it. video.  PN5502-360-80-10  SN 765

2. Number 1 engine ignition –  L3KK left ignition switch.  820UN01S1BAOA.  IPC 31-11-30-21 .  SO number 403787. 1 gage only. ref.

3. Printer cockpit jammed – fixed paper jam

4. Look in radome  – visual inspection good

5. Landing LED taxi – provide quote

6. ANTISKID Menelco. – Suspect moisture in nose axle.

7 . Overhead panels loose – resecured

8. Face on entry away light – Reinstalled face.

9. Light check , logo lights – LOGO lights not installed on this AC.

10. reevaluate possibility of repair for overhead panel. –  paper overlay, month long repair removal.

11. change router password 




Why does the door pop on a f900 during climb?

There is a HUGE  amount of pressure that pushes the door outward when the airplane is pressurized.  It causes the feet to lock in place then jump a little as the fuselage grows with pressure.  The feet must be perfectly polished and clean to prevent this.  There must be a SMALL film of grease on each foot.


This is the dome shaped foot on the door.





This is  the flat foot on the air-frame. interestingly it has a slight pattern of vertical lines that are worn away on the contact patch.


the tiny polished spot is the contact patch1474911029365-546824352



The contact patch for each foot is only about a quarter inch around or less in some places



looking at the pressures applied to these feet:

Door is about 34 inches by 80 inches.

2720 square inches, 9.1 psi of pressure,

24752 pounds pushing out on the door.

10 door stops, so about 2400 lbs pushing on each stop.

.25 X. 25 inch contact patch means

2400lbs / .0625 sqin = 38000 psi pushing on each contact patch …….








What is the new MPD life limit on the door spring all about?

Basically, Dassault has taken a non-life limited part, and turned it into a life limited part. The part is no longer produced, so that forces the installation of an electric door lift.

The springs are out of production , at some time, every B model, C model and EX (1 to 81) will be required to install electric door lift.

This FSA describes the situation and encourages operators to install the electric door lift early:


Also, there is a commercial program that reduces the cost of purchase until 2016.

$95,000 to $130,000 total

Here is the existing (fall 2015) text from the MPD that will be corrected

Description: cid:image001.jpg@01D1389F.6D834510



If counterbalancing actuator spring blade (500MA) is without red “E” mark next to S/N marking and in or out of tolerance, please return part to approved repair agent (note 1) as per AMM.
If counterbalancing actuator spring blade (500MA) is marked with a red “E” mark next to the S/N marking on part, scrap part without exceeding 3750FC.


The correction will say that if you pass the tests, no need to return the spring for evalution.


Bob clarified that text in a email.

I confirm what I suspected yesterday. One should read the AMM as follow (in this order):

  • If the wishbone is marked with a E after its S/N and has more than 3750 flight cycles, scrap the part
  • If the wishbone does not have any damage, the wishbone can be returned to service.
  • If you If the wishbone has damages on it then act as described in the AMM 52-10-00-220-801. Id Est basically return the part to the repair agent. The repair agent is going to repair it and if necessary to add a E mark on the part (in order to reduce its expected service life to 3750FC).

Thank You



Sr. Command Center   Rep

Robert Menier


After further clarification by Bob Mernier, the “E” extension is to allow the spring to go to 3750 cycles  TOTAL time in service.

The work card allows minor repair of the spring in the field, but be aware that a spring returned to vendor will get a “E” stamped on the serial number.

Also if you have a spring with more than 3750 cycles since installation, it will be scrapped if it is returned to the vendor?  no matter the condition?  That is brave, even for Falcon.


As of December 2015, Dassault has 2 serviceable springs, and certain repairs are allowable.  However, once the supply od repairable springs pays out, it is straight to  Electric motor fo’ you!

here are the structural drawings for the bushings on the airframe side of the door spring

F900MED SpringMount2_20151222_135814 F900MED SpringMount1_FGFB222030030A4-F00-7


F900MED SpringMount1_FGFB222030030A4-F00-7


Looks like P/N 47101C2J060050P is correct for the hat section bushings on the airframe side, if you have the 6 MM pin, rather than the 8MM pin. (wrong ID )




This requies a custome bushing and a Drilland Ream on the casting in the airplane:

MED Hat Bushings F2MA222030033A1

reamer from:


Order # Manufacturer Description Price
7950081 MEDA – SUPERIOR IMPORT 8/A Range: 1/4 – 9/32″ $13.90