Service difficulty report · Yoke · Bell 407

Difficulty date
August 9, 2010
Submitted
January 4, 2011
Operation
General aviation
Make and model
Bell 407
Aircraft time
414 hours
Engine
Allsn 250C47B
Part
Yoke
Part number
406012102109
Condition
Damaged
Location
Tail Rotor
Part time
624 hours
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

DURING HIS WALK AROUND, THE PILOT DISCOVERED A HAIRLINE CRACK IN THE PAINT OF THE FWD EDGE OF THE TAIL ROTOR HUB (IN LINE WITH THE AXIS OF OUTPUT SHAFT OF THE TAIL ROTOR GEARBOX) AND ON THE ORANGE BLADE SIDE. AME 1 WASN`T HAPPY WITH THE WAY IT LOOKED ON PRELIMINARY VISUAL INSP SO HE REMOVED A SMALL BIT OF THE PAINT FINISH AND LOOKED FURTHER WITH A MAGNIFYING GLASS. THERE WAS AN INDICATION OF A FAULT WHEN EXAMINED IN THIS MANNER. AME 1 ASKED AME 2 TO LOOK AT IT WITH HIS YOUNGER EYES AND SEE WHAT HE THOUGHT. HE TOO WAS CONVINCED THAT "SOMETHING" WAS AMISS WITH THE YOKE AND IT APPEARED CRACKED TO HIM ALSO. AT THAT TIME AME 1 ADVISED THE FLIGHT CREW THAT THE HELICOPTER WAS NOT GOING TO BE AVAILABLE UNTIL FURTHER INSP IN THE FORM OF A NDT TEST WAS CARRIED OUT. BEFORE REMOVING THE FINISH IN THE AREA, A PICTURE (PIC 1) WAS TAKEN TO SHOW THE FINE CRACK IN THE PAINT, IE. IT WAS NOT SCRATCHED THROUGH THE PAINT. THEN, THE PAINT WAS REMOVED AND MORE PICTURES WERE TAKEN. WITH THE PAINT REMOVED, ALL WHO LOOKED AT THE AREA WERE STILL CONVINCED IT WAS CRACKED. SEE PICS 2 AND 3. A MAGNETIC PARTICAL INSP WAS COMPLETED ON AUG. 12, 2010 AND THE FAULT WAS DEEMED NOT TO BE A CRACK, BUT LIKELY WAS CAUSED MECHANICALLY BEFORE THE COMPONENT WAS PAINTED. MFG HAS SUPPLIED NEW YOKE FOR INSTALLATION.

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