Service difficulty report · Tube · Cessna 750

Difficulty date
November 7, 2014
Submitted
November 21, 2014
Operation
Air carrier
Aircraft
N706XJ
Make and model
Cessna 750
Aircraft serial
7500006
Aircraft time
7,540 hours, 4,756 cycles
Part
Tube
Part number
671440239
Part serial
NSN
Condition
Bent
Location
Lt Wing
Part time
7,540 hours, 4,756 cycles
Stage of operation
CR
How discovered
O
Nature of condition
J
Precautionary procedure
A

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

WITH THE WING ANTI-ICE SYS ACTIVATED IN FLIGHT, THE INBD TEMPERATURE SENSORS WOULD TRIGGER THE LT & RT WING ANTI-ICE HOT CAS MSG. RAN THE ANTI-ICE SYS MONITORED THE TEMP SENSORS THROUGH THE IMT WITH NO ABNORMALITIES NOTED. BLEED LEAK MSGS WILL MOST LIKELY NOT SHOW UP DUE TO REDUCED POWER & RUN TIME LIMITATIONS. THE INBOARD LEADING EDGES FROM THE WING STRUCTURE TO INSPECT FOR BLEED LEAKS. WITH THE LE REMOVED & ON THE WORK BENCH, TECHNICIANS USED SHOP AIR TO PRESSURIZE THE LE & FOUND LARGE LEAKS AT THE LANDING LIGHT PICCOLO BELL MOUTH TUBE. UPON DISASSEMBLY OF THE LE IT WAS DISCOVERED THE ANTI-ICE WELDED TUBE ASSEMBLY PART NR HAD BECOME BENT RESULTING IN A REDUCED RADIUS, THUS MAKING THE TUBE ASSEMBLY SHORTER & ALLOWING THE SEALING D RING TO DETERIORATE & SUBSEQUENTLY LEAK HEATED AIR ONTO THE TEMPERATURE SENSORS. IT IS UNKNOWN HOW THE TUBE BECOMES BENT, IT IS SUSPECTED THE DAMAGE OCCURS DURING THE LAST INSTALLATION OF THE LES. THIS CONDITION HAS BEEN FOUND ON TWO DIFFERENT ACFT.

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